Introduction: Sonicare Elite 7300 - Battery Replacement

Picture of Sonicare Elite 7300 - Battery Replacement

This will show you how to replace the internal battery on your Sonicare Elite 7300. After having my 2nd one die on me within 3 yrs I figured out how to rip it apart and fix it.

Step 1: Disassembly

Picture of Disassembly

The first part of disassembling the elite 7300 is removing the small trapezoidal rubber bumper at the top back of the unit. This piece has two small clips which holds the internal components inside of the casing. Next, slide the main screw ring (upper left) off of a brush head. Twist the screw ring down onto the handle all the way and pull the internal components straight out.

Step 2: Remove Battery

Picture of Remove Battery

On the PCB there are two solder points which hold the battery in place (red arrows). Use some de-soldering braid and a soldering iron to free the legs holding in the battery and which also provide the electrical contact between the battery and PCB.

Step 3: Battery Removed

Picture of Battery Removed

This is what the battery looks like removed.

Step 4: Prepare for New Battery

Picture of Prepare for New Battery

Solder a wire to each of the pads shown in step 2 and route them through the plastic to the back of the PCB so we can use them to form the connection to the battery.

Step 5: Battery In

Picture of Battery In

Get your 4/5A cell the OEM was NiCd but I used NiMH which should have longer life.
Scratch up the positive and negative terminals of the battery with a hobby knife so that way solder will stick to it. Use a low watt soldering iron (you do not want to apply too much heat to the battery) to solder the correct wires to the positive and negative terminals. Stuff the battery back in the compartment and tuck the wires in so we can reassemble.

Step 6: Put It Back Together

Picture of Put It Back Together

Slide the internal part back into the handle casing. You might need to apply a little force to get it to click in all the way. Replace the small trapezoidal rubber stopper and you are done! Enjoy your Sonicare which will now hold a charge and function like it did when it was new. Charge it up and away you go.

Recycle the old NiCd cell.


Nate Ocean (author)2009-12-30

This is a good Instructable.  Here are a few more tips.

1)  The bottom of the charger stand has a three-part illustration of how to disassemble the unit.  It was difficult to remove the side key.  It broke, but it's not an essential part.  Discard it.  I used an OLD brush head collar, in case I cracked it (I didn't).  I found that by tightening it down, and then rocking it slightly from side to side, using some leverage action would extract the core about a half millimeter.  Then tighten again and repeat the rocking action until you've pulled the core.

2) For safety reasons, locate the solder bridge labeled "JP1" near the charging coil at the battery "-" end and remove it.  Use solder wick or a solder sucker.  This now isolates the battery from the circuit in case you short something out.  (On reassembly remember to re-solder this jumper as your LAST connection.)

3) I chose to remove the entire printed circuit board.  I show the pictures here for those interested.  When desoldering the Battery "+" it was helpful to remove the plastic LED lens so I didn't melt it.  There is a three part plastic chassis inside.  One for the drive coil, one for the charge coil, and one for the circuit board and battery.  However, it appears that Philips has glued these together during assembly.

4) I located a replacement battery online for only $1.50, however, like everything on the Internet, the Shipping and Handling was too expensive ($8).  Online, Batteries Plus had the battery for $4 (and an extra 25-cents for solder tabs).  However, in the actual store they wanted $7.50 and $1 extra for EACH solder tab.  Sorry, that's a rip-off.

5) In the end I realized that the cavity for the 4/5 A-cell would easily accommodate a single AAA-cell NiMH rechargeable.  I choose a 900 mAH battery.  (Others are in the range of 800 ~ 1000 mAH.)  Scrap or sand the terminal ends, and solder a spare lead to each end.  Use a hot iron and do it quickly to avoid damaging the cell or forcing it to internally vent.  Be careful inserting the leads to the circuit board as the battery could damage the circuit if you touch the wrong contacts.  It helps to have extra long leads to guide them in, then trim them off after you've soldered them.

6) So far the AAA-cell is working well.  If I later see problems I will replace it with a AA-cell (AAA -> AA), as the AA-cell is closer in capacity to the original 4/5 A-Cell.  However to accommodate the longer AA-cell I'd need to remove some of the plastic chassis.  For the time being I'm sticking with the AAA-cell.  The charging characteristics of the NiMH are nearly identical to NiCd.

7) I had also considered using a battery holder inside, however, I suspect the contacts would be more trouble than they are worth.  There is nice AA-cell holder available from Radio Shack for $1.  That would be useful for those that don't have access to a soldering iron a year or two from now, in case the battery needs replacement again.

8) To reassemble, I used a small amount of KY-gel to lubricate the rubber O-ring and seat.  I had some Teflon gel available, but decided the KY-gel being water based would be more compatible with the rubber O-ring since Philips obviously expected this to be a water environment.  The KY-gel makes it a lot easier to pull the core again should the need arise.

9) I was surprised how clean the inside was.  The tube and o-ring design is much better than the split shell design used in other Sonicare brushes.  I only wish that Philips had used a AA-cell.

m.wakileh (author)2009-12-29

Hi... I just started repair of my sonicare and wanted to let everyone know you may not have to desolder the battery from the pcb... 

I used the wire clipper in the image below to extract the battery (leaving the battery tabs soldered in for possible use with the new battery)...
Vibrations may cause brief disconnection from these tabs if the new battery isn't soldered to these tabs...

ToddB30 (author)2015-11-03

MY SONICARE wouldn't come out of the case! Finally I succeeded by applying butter to the threads of the screw ring, AND by gripping and twisting the top of the case, very tightly and firmly to create HEAT, a lot of heat, almost painful, on the surface of the case.. Thus it expanded, and released its grip on the internals.

ToddB30 (author)ToddB302015-11-03

Also the 4/5 AA batteries are around $5 now on eBay, with free postage, don't pay $10, $20, etc.

maretsar (author)2015-09-18

Could someone please help me out. I need to know the label of the "D1" element on the lower part od the back side of the circuit board. I have accidentally destroyed it when desoldering.

rocketrancher (author)2012-09-02

(sharing this here and also with the "repairing sonicare" thread)

I, too, suffered the brush's short-cycle personality after replacing the battery. After charging, I lost a tick on the gauge on the third day and on the fourth it went to zero and sounded the three-beep low battery alert. If ignored after another day, there was still plenty of power but the brush would shut itself off mid-cycle and emit the single, long tone for deep discharge.

The battery reset procedure that appears on many sites, allegedly confided by Philips, is hogwash. The put-it-in-the-charger-and-press-the-power-button trick is described in the use instructions and only enables/disables the easy start power ramp for the comfort of a new user. Any correlation with battery charging or endurance is a fabrication or coincidence, at best. Also, the doomsday theory about Philips programming the death of the product is unfounded, as I am enjoying a nicely renovated Elite.

This may be the answer many are waiting for: Yes, there is a battery quality monitor/charge controller "gas gauge" and it can be reset. Exact design is not obvious, but it seems similar to Unitrode's bq2014. Some have reset it by accident but here is a deliberate method:

First, disassemble the brush if it's not already apart. We'll assume the battery has just been replaced, so drop the inner assembly into the charger and give it a full charge by the level gauge. Then, take it out and look at the board, just below the clear diffuser for the LED's. There will be two square pads near the word "reset". These are of interest. Also nearby is an oval pad labelled "vcc". Leave that one alone.

Next, secure the assembly in a padded vise or have someone hold it securely on the bench top while you press the "on" button and then jumper the two "reset" pads. This can very easily be done with probes from your voltmeter, allowing you to verify ~3.3 volts across the pads when the brush is "on", and then cross the probe tips and let them touch. So far, you will know two things: The gauge indicated a full battery when you switched the brush "on", and then the brush switched itself "off" when you shunted the reset pads.

Now, drop the thing into the charger again and you should see the gauge indicate an empty battery. Allow it to complete another charging cycle, which will take overnight, and then reassemble the brush. The recalibrated battery monitor should now offer a full reading for two or three days, gradually ticking-down over two weeks to the recharge signal, and then another three or four days before the deep discharge warning.

Advice here: Use silicon grease on the o-ring, not sealant or aqueous gels that turn to glue, like K-Y. The electrics are sustainable, as long as you can get to them, and there is no need or excuse for butchering the case. If it is fouled with pasty drool residue, run warm water over the joint and scrub with a toothbrush between attempts to jack the unit open. Once it starts moving, use no more water. The o-ring will do its job; just make sure the board and case interior are dry before reassembly.

Thank you for the suggestion.

When I've done replacement of NiCd cell, I found new one wouldn't start re-charging. Then I tried factory reset procedures, it worked pretty well.

mickkell (author)2014-11-19

I just replaced my battery and found that Batteries Plus will transfer the terminals for you for about 7 bux including the Battery.I bought 2.

Getting it unsoldered is a trick even with a sucker.I clamped the battery with needle nose visegrips and pulled as I melted the Solder and used a small drill bit to open up the holes.Just a FYI.

aomega79 (author)2014-05-11

This is an awesome article! I had a question, do you, or does anyone know how to turn off the 2-min cycle for the toothbrush? Basically when the toothbrush is on, I want it to stay activated until I hit the button again.

jplee3 (author)2013-09-08

I've got an older Sonicare Elite model that I've been trying to remove the battery compartment from but just cannot for the life of me. I'm not sure how it's stuck in so much but it is. I removed the tab and have even tried using channel lock pliers to twist the base off. No go - the most I've done is scratched the plastic at this point. I've even tried chiseling around the base where it separates to remove any gunk but I don't think that's the problem. It must be so corroded or something inside. I don't think I'll be able to remove this thing.

TurboPT (author)jplee32013-09-14

Mine is an HX7300 [as listed on the bottom], and it WILL pull apart [NO twisting!], but it is NOT very easy -- it is getting past that o-ring seal.

My son and I both had to pull in opposite directions, each of us using one of those small rubber jar-opener-pads to get a better grip. I was holding the [screwed-on] head end, and he pull the case end.

JazzAzz (author)2012-05-03

My unit is a HX7500, it says on the bottom, and appears to be all one piece, apparently seeing no place to open it, take it apart. On the other hand my Wife's who is having a problem now after many many years, must be at least 5 yrs old, her model does have that little rubber pop out thing, and I am certain could be taken apart. But I am not sure that I want to tackle that, her's being of service to her that many years, no less than five. And her and I ALWAYS keep it on the charger after each use, regardless of it being a NiCad. Hasn't been a problem. She bought me mine for Christmas, probably 4 years ago, and I stupidly broke the on/off button trying to re-seat the rubber button cover that was sticking out on one side. But seeing the three contacts that were left after that button broke off/out, I just short out a couple of the contacts with one of the devices from my Swiss Army Knife, works fine. Hers after so many years service, and mine once it gives out, will just be replaced with new one. But as I say my model HX7500, looks to be, Its' case, a one piece THROW AWAY, anyway, no rubber pop out thing to remove, to apparent seal area to pull apart.

fma_battery (author)2012-04-12

The size of Sub C is: diameter 23mm, height: 43mm. While 4/5A is: 17*43mm.
So be notice larger size battery can't fix in the holder. The size of AA is: 14*50mm, AAA is 10*45mm. More larger space, more capacity it has.For 4/5A size battery, we have solder tab on it already, it is easy to solder to PCM.

grayshirt (author)2011-01-29

Minor adjustments to the process:

I just did two of these Elite 7300 (HX7300) battery replacements.  The first one took about 2 hours; the 2nd took about 20 minutes.  Things I did differently the 2nd time around:

(1) To remove the rubberized bumper, try slipping a thin knife blade under it from the long edge of the trapezoid.  This little plastic piece isn't critical, but it's nice to keep it intact, to keep the brush from rolling around on the counter.

(2) Don't bother desoldering the battery pins.  I wasted a ton of time trying to get that done, and it just isn't necessary.  Instead, ...

(3) You'll see a couple of plastic tabs that hook over the top (+) end of the battery.  Use a diag cutter and/or utility knife to remove those.  Also use a utility knife to remove much of the soft plastic blades that hold the sides of the battery.  Try to leave the wide black rubber band around the battery intact.

(4) Melt the solder on the top (+) battery pin, and lift the battery until the pin is all the way out of the circuit board.  (If the black band is still intact, you can slide a paperclip or tiny jeweler's screwdriver under it and use it as a handle to lift the battery.)

(5) Repeat for the bottom (-) battery pin, and lift the battery clear.  If you feel the need, now you can easily desolder the holes.  :-)

For one tootbrush, I replaced the battery with a regular old AAA Energizer NiMH rechargeable (850 mAh).  It constantly complains that it wants to be charged, but it goes a good sixteen 2-minute brush cycles between charges.

For the other toothbrush, I bought a real "4/5A" from (NiMH 2200 mAh, $6.50 w/ free shipping).  I haven't managed to run that one all the way down yet, but I suspect it'll do just fine.  :-)

Quick thoughts on my experience.
Just did two too. 15 minutes for the second one, as the experience from the first was useful. :-)

As an experiment, i purchased both NiCad (1300ma) and NiMH (2000ma)batteries.
I have a few more of these to do in the house, so I am hoping to conclude which is better based on evaluation over then next several weeks. Specifically hoping to shed more light on the questions on charge and display behavior, as they pertain to the different battery types. Stay tuned, or write if there is no followup post by October.

A quick hint on battery insertion that worked for me:
buy batteries with tabs.
Trim these to ensure a small enough stint that will fit through the reasonably cleaned hole in the circuit board after desoldering. (metal or even kitchen sheers should work fine to do the trimming)
If the tab is long enough, bend the last millimeter back onto itself. Next, loop some thread over these tab ends and feed this back through the original circuit board holes. Now you should be able to pull the new tabs directly through the original circuit board (presuming a reasonably clean hole) For me, the battery alignment and insertion and soldering took about 2 minutes with this approach.

Quick follow on after a bit of new battery usage experience...

The short answer on the battery comparison is that it was inconclusive from my perspective. The problem is that despite the fact that I have two units, I was only able to get one to work with the replacement. My experience with the one is  "good".
By this I mean that I have a unit with a NiMH battery that is charging reasonably, and working for about 10 days (20 uses) between charges. This might be "excellent" had I gotten up to two weeks usage, but I am not quite there...
The other unit "failed" with both battery types. I am another example of the "something funky in the software, can charge but only use it for a few seconds" crew that is cited a few times on this thread. My limited effort to get past this have failed consistently. I may try the "remove battery and power and let sit for a longer time" approach again some time, but have not had the will to do so given the one brush that is working.

As an aside, I shared my extra NiCad (I had bought several batteries for this experiment) with somebody, and their experience has been also "good"

The fellow's recap follows:
"Well, I have fantastic news. After battery replacement and a full 24 hours on the charger, I first used it on January 23. Sixteen uses later, I got the low battery light and triple beep at the end on February 5, this past Sunday. It took four days to lose one bar on the battery indicator, which I think is outstanding. So, it looks like I'm back in business again with a full two weeks of battery life. One thing to note: Since I got this device back in 2008, I NEVER kept it on the charger. Rather, I only charged it when it needed it. I think that kept the battery functioning much longer than others have experienced. I was still getting nearly four days out of the old battery, and that is after nearly four years of having the device." Hope this is useful...

I would really welcome any further advice on approaches to "reset" the charge/usage/incapacitating software from anybody (else) who has lived and gotten past this issue.

srekveld (author)grayshirt2011-10-04

Just swapped the original NiCd battery in my HX7500 for a 4/5A size Ternergy 2000 mAh NiMH battery from Batteries in a Flash for less than four USD and working like a charm.

jehan60188 (author)2008-09-18

what about replacing the battery with a small capacitor? it would offer much more reusability, right?

jimluschen (author)jehan601882011-12-12

You need a battery -- a capacitor probably wouldn't hold enough energy to brush even one tooth.

2000se (author)2011-10-19

Well - i know this was started a while back (2008) but I have had my sonicare elite since then and have replaced the batteries 3 times since then. Not that they needed replacing (now that i think about it why am I ?) Anyway - I'll share my thoughts a little seeing I read through all of these post.

Yes, you have to remove the little rubber clip at the top that keeps it from rolling around on the table before attempting to 'pull' the innards out.

Secondly, just pull the innards straight out. You don't need to twist it or anything, but you do have to really pull hard.

Thirdly - Get a solder sucker or something to really remove the solder from the joints....makes it sooo much easier. If not, you just get globs of solder everywhere and it really makes a mess and could damage the board with stray solder

Note - Do not remove the pcb board from the unit unless you really have to. If you do, try to clean out all of the solder holes and "post" very good before putting it back together. The board is sitting low on the post so it gives room for the power button to clear the sides. When you put it back together, make sure the on/off switch doesn't get press all the time. If you don't get that board low enough on the post it will. So if you do remove it, make sure you re-solder it way down on the post so it fits back in cleanly.

Fourthly - I have always replaced the battery with the same kind..NiCad…never any problems with charging and such.

Fifthly - I always have the battery tabs spot welded when I get the battery.

Note - The tabs that I get attached are almost needle like. This makes the insertion into the battery holes on the pcb very easy. You can see this in the picture.

Also, you can see that in one of my pics, you do not have to have that jp1 jumper 'jumped' with the negative terminal to make it work.

Also, i have had the battery out of mine for about a week now. No ill effects with having the battery out that long

Now that is done - I have thought of something. The pictures at the start of this show to the board as having 2 buttons. I only have one BUT do have a spot on the board to solder another button to. It is named 'SW2'. I might try that to see if I can regulate the timer and such as you can with the one that is posted here.

2000se (author)2000se2011-10-19

"""Now that is done - I have thought of something. The pictures at the start of this show to the board as having 2 buttons. I only have one BUT do have a spot on the board to solder another button to. It is named 'SW2'. I might try that to see if I can regulate the timer and such as you can with the one that is posted here."""

I meant to say SW1 -- not SW2. My fault

HunterHTS (author)2011-09-27

Has anyone sourced a lithium rechargeable battery that is used in the HX6950 models?


dooger (author)2009-03-10

Great Instructable! Here are my experiences: Disassembly of the housing proved the most difficult step for me, and required prying and expanding the housing with several small jeweler's screwdrivers. The prying left several nicks on the housing, but at this point, I didn't really care. The battery de-soldering is tricky, especially if you've not done it before. Use a fine solder tip, flux, and solder wick (copper braid). Flux is mandatory, the solder will not wick without it. chuckk has some good de-soldering tips, too. I was tempted to try a NiMH replacement, but there seemed to be a few people having trouble with them, so decided to stick with the oem NiCd, since the original did last for several years. I ordered the exact Sanyo oem replacement battery from digikey (SY110T-ND) - only $6.67 shipped, and that part number included pre-attached solder tabs. The new battery looked nearly identical to the oem. Everything went great finishing this project, except my new battery behaves exactly like the old one. It takes a couple days to charge full, and then only lasts for a couple brushings before the bottom LED is amber, indicating dead. Either I got a dud replacement battery, or there's something wrong with the battery circuit in the handle. Considering the high cost of the these toothbrushes, it was still worth the time and money to attempt the battery replacement, but unfortunately, I'm going to be shopping for a new Sonicare.

Kelvin273 (author)dooger2009-10-20

I had the exact same experience (still won't hold a charge for mor than about 2 brushings).  I got my battery from Batteries+.  Maybe there is an internal timer or counter or some such that needs to be reset?  Or maybe this battery is a dud too.  The Batteries+ guy attached the leads to the battery, so maybe he overheated it or some such.  Does anyone know if there is a "Reset" function?"

Mine says HX7500 on the bottom but from the picture it looks the same as the 7300.  Except mine has only 1 button, and the one in the picture looks like it may have 2..

ob2s (author)Kelvin2732011-01-07

A year later, I doubt you still care, but I replaced the batteries on 2 sonicares with a NiMH battery, did both the exact same way. Brush #1 charges and stays charged for over a week +, better than the NiCad. brush #2 only goes 2 brushes before it needs to be recharged. I swapped batteries (pain !), still the same, brush #2 sucks. There is some electronic trickery going on.....what did you do in the end ?

Kelvin273 (author)ob2s2011-01-08

I still care....stuff like this bothers me. I work with electronics tech things way more complex than this every day, so it is especially frustrating when something which should be so simple doesn't go right, and for no aparrent reason.

Anyway, a year later and things are still the same- 2 uses then recharge. After overnight charge, bar graph indicates successful full charge. Interestingly, after first use, charge indicator still says fully charged. But at the end of second use, I get the "recharge now" vibration signal, and the charge indicatior is has only the bottom led lit and it is flashing amber, just as it normally would do, but after a week or 2 of uses not the second use. If the battery were marginal I think it would have failed by now.

Not this part is pure speculation... but It is as if the electronics which manage the battery looses it's settings, possibly due to being without any battery "keep alive" voltage at all for too long (even after the battery won't power the device anymore, it still may be keeping some memory alive or something like that). You may have noticed this with other electronic devices, if you swap out the batteries fairly quickly, you don't have to reprogram all the settings, but if you take a few minutes to complete the swap, you end up having to reprogram it. So if you do as I did and remove the old battery and then wait a day or 2 before finding and installing the new one, the electronics has lost it's settings, and the default it powers up with doesn't work so well. Something like this could enplane why one of your toothbrushes responded well to the battery replacement and the other did not (one spent more time with no battery voltage at all, and lost it's memory, while the other had it's battery replaced in time. Then when you swapped the batteries (probably fairly quickly, all in one sitting), the problem remained with the brush which lost it's settings, instead of the problem following the battery to the other brush.

Also, I just want to mention that substituting between a NiCad with a NIMH is not 100% proper, the different chemistry have different optimal charging profiles / charge termination processes. You may get away with it most times / sometimes / in a pinch, but you won't get top performance from the battery.

I will continue to use my sonicare until it drops dead or gets to the point where it won't get through even one complete brushing cycle after charging. Then I will be forced to evaluate sonicare versus their competition. All in all, I have to admit that it has been a good toothbrush and has lasted a long time. It just rubs me the wrong way that after all the work to get the case open and the search for the replacement battery, and delicate surgery to replace the battery that I did not get my just reward of a few more years of proper function out of it.

Please let me know if you think my speculation about loosing the memory fits with the timing of how you did your replacing and swapping.


ob2s (author)Kelvin2732011-01-14

Well I did both back to back. Each had the batttery out for about 5 mins. I think I might have unknowingly shorted something on one, I mean you can't really turn it 'off' while removing the battery. I didn't have a solder sucker so my battery removal was not delicate, so maybe I am to blame.

Kelvin273 (author)Kelvin2732009-10-20

Oh, and yes, I did the hold down the button while in the charger thing but it didn't help.

mandango (author)2011-01-01

Thanks for the valuable hints especially Nate's add-on to Jumper J1.
I had some trouble getting the inside part out of the tube but then I used a 1mm sheet metal, made a suitable hole in it and seized it tight at the body with the brush head screw.
Then I drilled another slightly larger hole in a wooden board pulled the toothbrush assembly through the hole and rapped the metal against the board.
This way the inner part came out without any fuss.
For a replacement battery I got a NiMH battery with solder taps for 3,5 € (
I used a side cutter to bring the solder taps into shape and soldered the battery into place.
The new battery is smaller than the old one so putting it in place without breaking anything was not too difficult. Yet the capacity of the NiMH cell is larger than that of the original NiCd cell.
I used some hot glue to fill the gap and to keep vibrations forces off the solder joints.
Finally I applied some silicon grease from my underwater equipment to the O-ring and reassembled the device.
It now works again like a charm.

mermaldad (author)2010-11-14

I used a brute force approach to open the thing up. I grabbed an old head that was worn out and screwed it onto the unit. Then I clamped it in a vice and pulled. That pulled the brush part off the head. Glad I used an unwanted head! Then I clamped the metal part that stuck out in the vice and pulled again. Then everything came out neatly!

Folding Chair (author)2010-11-10

My attempt at this battery replacement pretty much ended at "getting the battery out". I was confused by "rubber bumper at the top back of the unit" (or "side key" as is written in Nate Ocean's comment). A visual indication of what that was and how the author removed it would have been appreciated.

It may not have mattered, because I think the one on my model worked differently than the one on this example model. At any rate, it did not come off or even budge under any circumstances. But I'm not one to let the Man win, so I had to do whatever it took to get into the thing anyway, just to see what was going on. As you can see from photo, "whatever it took" involved pulling and tearing and scraping all of the plastic off around the top, until finally the "instructions" on "how to" "remove the battery" that are printed on the charger base could be "followed". For those who have never interpreted ancient Egyptian before, let me put it into simple language for you: screw the cap thing back on sans toothbrush head, and then simply rock the cap back and forth in there until the innards slide out. Mine didn't begin to slide out until it was torn up, but I was never sure if I was doing it right as I was doing it anyway, making it all the more difficult. Turns out I was doing it right, it was just very hard.

(I recently replaced the battery and hard drive in my iPod following instructions from a video, so while I'm not a regular handyman I'm also not entirely clueless : )

In the end, it would have likely been an academic exercise for me anyway, as I don't have a soldering iron and may not have been willing to get one for this project. Now though, I think that even if I did replace the battery the toothbrush would be useless because there is no longer any seal preventing water and toothpaste from getting into the works. I did muck about a little with removing the battery anyway, but then it hissed at me and spit out some smoke, so I figured I was in over my head. Word of warning.

I post this here so that, if anyone else has the same troubles as I did, you don't have to feel (too) stupid and alone. Just calmly admit that Philips corporation has won this round, and make peace with yourself and the universe.

Incidentally, the death of my Sonicare came 2-3 years after I bought it. It worked perfectly for all that time, with no indication that it was dying. When I got back from a 2 1/2 week vacation in which workmen had been in my apartment mucking about with things, the toothbrush was in its charger with the bars green all the way to the top, but pushing the power button had no effect. It wouldn't turn on, and has been thus ever since. I don't know if the problem was that it sat in the charger all that time, that it didn't sit in the charger all that time, that someone dropped it, or what. Could be anything. At any rate, I find it ecologically reprehensible and a personal affront that this battery is essentially irreplaceable for all but the handiest of people. The more things get better...

matt68000 (author)2010-11-05

Has anyone tried reconditioning the included battery yet? My Elite is finally losing its ability to hold a charge more than a few brushes after 3 years. I was about to take it apart and try to fit a AA NiMH but then I realized my fancy pants recharger had a "recondition" mode where it deep cycles the battery a few times to restore it a bit. I have friends that have had luck reconditioning old rechargeable AAs. I'm running the cycle now but it should take a few days to fully charge and recharge/trickle half a dozen cycles. I'll let you know how it goes, just curious if I'm wasting my time and should bust out the soldering iron. BTW, my charger is the latest model of La Crosse Technology BC-9009.

toomanyprojects (author)2010-10-05

Bottom line: go ahead and replace your Sonicare Elite battery! NiMH is fine.

If you have read all this, you are probably demoralized - you do the work, and the new battery won't charge any better than the old one.

NOT TRUE! Everyone, except Eurojojo, has missed a critical point. Just because the battery indicator says it is dead (one blinking amber light), is the battery is really dead? The answer is no. For NiCD and NiMH batteries, unlike alkaline batteries, the voltage remains essentially constant from fully charged to almost completely empty, so you can't use voltage to determine how full the battery is. That means the software has to keep track of how much charge is currently stored vs. the software's notion of the capacity of the battery, and report out the ratio (the fractional charge) as the level on the LED indicators. I switched my battery to a new 2200 mAh NiMH, charged it for 24 hours, and started using it. After 3 days, the indicator said the battery was dead (same behavior as with the old battery). However, with the old battery, at that point it would have really died and stopped working in the middle of a brushing cycle. With the new battery, two weeks later the indicator is still blinking yellow, and the toothbrush is still working just fine and feeling peppy.

The software must manage a dying battery by reporting lower and lower capacities (mAh) as "full" or 5 green bars (just like it does on a Prius!). It remains to be seen whether the software can revise its estimation of battery capacity upwards as well as downwards. If so, my charge indicator will become more accurate over time. We'll see. Most chargers will "trickle charge" full batteries, so if I leave it charging long enough, it should fully charge even this larger capacity battery.

Oh, and a few more tidbits: the plastic clip that holds the plastic casing over the electronics is shaped like a staple (l_l), with teeth on the inside surface of the vertical legs that hold it in place. To remove it, squeeze it from the sides with a plier, slip a thin screwdriver underneath it, release the plier, and pry it off while pushing outward against the legs to free the teeth so they don't break off. Also, getting the new battery terminals through the holes in the board is a pain and takes longer than anything else. Solder wick is your friend here. Have fun!

jondabomb (author)2010-08-11

Hi Musick7, i love this website and I love that there are people like you out there who wanna help!

jondabomb (author)2009-12-14

Thank you for this simple post. I cant believe that Sonicare is so lame.
I just replaced my battery per your instructions.
I just want to start doing this for everyone to keep the waste down!

patti111 (author)jondabomb2010-01-11

Dear Jon, I am a little old lady, in fact today is my birthday!  I actually own two Sonicare toothbrushes. An elite and an older model.  They died at virtually the same time.  I would love it if you would help me get my toothbrush working again.   What would you charge?  Thank you.   patti111

musick7 (author)patti1112010-08-11

Hi Patti111 Did The Writer of this Instructables "AaronX2621" ever reply to you? If not Please let me know and I would be happy to help. Please email me and I will send you a price list for the Battery and shipping charges to me and back to you. If you would like my qualifications and experiences You can check out my Latest Project on I might be posting a DIY Hearing Aid on Instructables, But chances are, Not many will attempt such due to size of components and equipment needed to complete a project of this size. If anyone is wondering, My Dad needed a hearing aid and the cost of something worth having is upwards in the $3K price range. He needed two Hearing Aids and if your math is good you come up with about $6000. +- $2k. Let's just say, I have about $150 − $200 per ear. for a Completely In Ear (CIC) dual mics, dual Receiver. Telecoil and a kitchen sink in this little guy! Well if I can be of any help please email me in Instructables. Have a great day! PS Not really a kitchen sink in the CIC Hearing Aid. But you'd think with all thats in there.

thue (author)2009-02-09

I went through the process and the unit shows it is now charging but it's not showing that a charge is building, it's dead when I take it out of the base. I put in a new nimh battery which may have been on the shelf for who knows how long, got it from Interstate. I am contemplating ordering one over the Internet and trying again. Any ideas out there?

waynesl (author)thue2010-05-03

I don't pretend to know a lot about the various Sonicare models, but my HX7800 has a NiCd cell, not NiMH.  If your 7300 is designed for a different cell chemistry, that could be the problem.

eurojojo (author)2010-02-18

These instructions helped me a lot to replace the battery in the first place. But, there are some difficulties, and here is how I overcame them.

I got a Sonicare Elite HX7551 in September 2004, and it worked until October 2009. 5 Great years for our teeth! We use the same base with two persons, each with their own brush heads. We needed to charge the toothbrush every week, and left it off the charger until it was blinking orange. In October 2009 it stopped charging.

So I turned to these pages. First I got a NiMH replacement. In Europe probably cheapest at RS-Online. I got a Sanyo Tagged 4/5A NiMH cell,2150mAh, RS-stocknumber 400-7178 for 8,45 Euros, incl. VAT, incl. postage. Quite reasonable, I think, and they even delivered by courier.

But, it did not charge fully, discharged in a couple of days, and, most important, it charged less and less. Sometimes it would suddenly start charging, but when you used the toothbrush and put it back in the charger, it would not continue to charge.

So, I got at the end of January 2010 the same NiCd that was in the toothbrush when I started the project. A Sanyo Tagged 4/5A NiCd cell,1.2V 1250mAh, RS-stocknumber 377-7753 for 6,71 Euros incl. VAT, incl. postage (courier again).

This cell displayed the same problem! So, I started analysing. People here at the blog suggested there might be timers in the electronics. Philips writes in the manual that the battery does not suffer from the  memory problem , which is quite an overstatement if you use NiCd cells, but we had 5 years of good operation with the thing, which hints at extra electronic measures.

So I thought: I will get the battery from the brush, charge it, and put it back in. Indeed we could brush for a week, but funny enough the light blinked orange all the time! With a guaranteed fully charged battery! Proof of electronics. And it did not charge properly. Same erratic behaviour: sometimes it would suddenly charge, and stop after being used.

Conclusions: 1. Apparently the green/orange blink light has no real relation to the power in the cell. 2. Charging is not provoked by the real charge level left in the battery. 3. The level of success of the people responding to this instruction is dependent on the level in the timers built-in the electronics when they started soldering the replacement battery.

But then I experimented, to try to align/reset the timers. I noticed that after soldering the brush would always start charging. I took the charger from the light socket for 15 minutes. Then put it back in: charging started! Time after time I could provoke the charging this way (yes, it would not overcharge, and display normal behaviour when full: stable green lights which go off once and a while). So, I put a timer between the charger and the light socket. Twice a day it disrupts power for 15 minutes. And what do you know: it now charges my brush every time to the maximum, and when taking the charger off power it will last for a week without charging. Finally it is as good as new. And I do not have more noise than before. It is nothing more or less than  as good as new .

I guess this trick would not have needed me to buy the NiCd, and should have worked with the NiMH as well. For now I keep the NiCd in, since it works perfectly (as new). I hope in a couple of months the timers are all aligned again, and I can remove the timer.

One trick I learned in this instruction: use a bit of grease (apply with a match stick) to easily open and close the brush when experimenting.

Thank you all for your contributions, it helped me a lot.

rakudrama (author)2010-01-21

 Batteries are available with circuit board pins - check out the Terminal Style drop-down at

Does anyone here find it outrageous how close this design is to one that lets you easily change the battery?

The only reason I am looking at this is that I just bought a 4-pack of heads.  My dentist says the newer (FlexCare?) brush does a noticably better job.  (I trust my dentist - all the latest gadgets to support but one filling in 10 years.)
There is a review here:
The review says it is 77% more efficient. Has anyone does an analysis (e.g. Kill-a-watt) to see what it costs to run a toothbrush?

rychang109 (author)2009-12-27

I replaced my Sonicare battery using an NiMH battery (with tabs already attached) from Batteries in a Flash.  It's been a couple of months now and it is still working like new.  After going through this once, here are some tips/thoughts:

1) I did not do the trick for soldering wires onto the new battery proposed in this instructable b/c I did not read the instructions carefully.  After reading some of the bad luck people were having in the posts below, I wonder if the extra wire may be picking up some current from the charging field.  So, how much wire you use and which way you wrap it around to the battery may interfere with the charging of the battery.  I'm an EE, but one with no "practical" skills.  So it's possible that a few turns of wire would not pick up anything that could interfere with the circuit.  Maybe someone else can do a back of the envelope calc?

2) Desoldering trick: solder sucker and de-soldering braid were not working for me.  A friend told me to "flick" the solder off, and it worked like a charm.  Mix some new solder in with the old solder to get a nice glob, turn the board over while still applying heat, and flick the board at the table, hitting the edge of the toothbrush against the table.  Voila, the solder comes flying out!  After 2 or 3 flicks, it's gone.  Put some newspaper down, or you'll burn your table.

3) I replaced the old battery and tabs with a new battery and tabs.  It is IMPOSSIBLE to get the new tabs into the holes on the board b/c of the tight fit of the battery.  I had to cut away all the plastic that holds the battery down, so I could just drop the new one in.  Then, I taped the battery snuggly into it's spot.  Not ideal, but it seams to have worked.

4) Disassembly: it was not clear to me, but screwing down the brush head only lifts the body away from the internals about 1mm.  After that, you need to pull straight out.  I used a small screwdriver to work the internals away from the body a bit more.  At first, I kept trying to twist the body off, but there is a guide that keeps the internals from rotating with respect to the body.

5) The next time I do this, I will try what one other poster did - pry the tabs off the old battery, and solder the old tabs onto the new battery.  I think this would be easier than what I did.

tgone (author)2009-11-04

My board was a little different from the one in the pictures.
I picked up a 4/5A from batteries plus and it was too long to fit into the orig slot. had to modify the plastic and relocate the crystal. its a good thing I've got a talented EE to help me out when i get into trouble, this wasn't something I would have been capable of on my own.
Also, he warned about soldering on the battery terminals and seemed convinced that the battery with pre"welded" posts would be available online. from his info, welding is much hotter, but also much quicker and soldering changes the battery so the outcome is not gauranteed. So, make sure you take a look around to find the right one dimensionally (it'll save you A LOT of time and effort).

chaosdivine (author)2009-10-23

Well I removed my comment because it turned out I was wrong about getting the toothbrush to work without issue. It only lasts 4 days off the charger. I also wanted to clean up my comments because they were getting messy and didn't make sense.

Here is the whole ball of wax in one go:

I followed these instructions to get my Sonicare HX7800 Elite Pro when it died recently. Be prepared - It is very difficult to get the brush apart and I destroyed the toothbrush head doing so but I have three replacement brushes so I didn't care too much. I should have just pushed the toothbrush part itself up through the rubber hood. For some reason it wouldn't work though so I resorted to tin snips...brute force sometimes works well, but it's not pretty.

I did succeed in removing the battery itself only after breaking the solder bond attached to the contacts on the battery while it was still attached to the toothbrush board (I did this by sliding a thin flat screw driver behind the contacts and prying them off). I saved the metal tabs soldered on to the battery and reused them later on the replacement battery.

This is the information written on the outside of the battery:


When I looked this information up using Google I found it was a 1200 mAH battery in a PS-4/5A size (style). If you see one written as PS-4/5A-T  it just means it has SOLDER TABS already attached to the battery. If you look at the screenshot I have attached it will give you more specifications on the battery if you are curious.

I found a video on YouTube that helps the disassembly of the unit (the video is just still camera shots - NOT actual motion video!)

That video is for a 9000 series but it is the same as the 7800 as I have. That guy is selling batteries for $18.95 which is a rip off though. Buyer beware...they are available in a price range of between $2.50 - 8.50 US each depending on who you buy it from. I found mine for $7.35 CAD here locally.

For those interested here is were I bought my battery from in Calgary, AB, Canada (They constantly stock thistype of battery):

Battery World
#103, 6036 - 3rd Street SW
Calgary, AB
T2H 0H9

(403) 252-0074

The cost was $5.00 for the battery & $2.00 to have my old tabs soldered on to the battery. They did not have PS-4/5A-T style batteries. The total price, including sales tax was $7.35 CAD.

I noticed that in order to get the battery to work at all I had to make sure the 2 soldered points labeled JP1 needed to be bridged together ALONG with the  - (negative) battery tab. ALL 3 needed to be connected together in one large horizontal solder.  If these were not connected (all the solder sucked off) nothing worked at all. Once I completed all three solder points the battery worked once more.

Putting things back together was pretty hard. It required a lot of force to be able to get the retainer clip in once more. I decided to use a piece of plumbers tape (teflon tape) around the top of the components when putting things back together to help keep out moisture. You could even use silicon sealant but that's more permanent.

I charged the battery for 24 hours and then reset the battery by holding down the green button while the toothbrush is on the charger. I then let it sit on the charger for another 24 hours. This didn't really help me out in the end.

One thing I noticed about the toothbrush once I replaced the battery is that the unit is much louder than before and I attribute this to breaking the initial sealed connection of the unit when taking it apart. Though great care was taken to put things back together, I still feel there is a bit of a gap in the seals. They most likely use some type of sonic welding to snug things up. As such, I have used a piece of surgical tape (its see through plastic type) used on large bandages and such to provide the seal around where the parts come together. It keeps out the moisture. When I am holding the unit in my mouth the sound is reduced (the vibration is probably being transferred through my hand & arm).

In the end, I too have only managed to get four days use off the charger once the new battery was installed. No where close to the original two weeks off the charger. I thought I had this solved but it turns out I was wrong. There must indeed be some type of logic on the board (or maybe in the battery) that prevents these OEM batteries from being seen as new. For now at least I will be able to put up with this for I don't take this toothbrush with me when travelling. Unless someone else can figure this out I think I will have to just bite the bullet and buy a new toothbrush.

jace_mi (author)2009-09-27

Good instructions, mixed results on my end. Like some other people, I ordered the Sanyo OEM replacement battery from Digikey - it came to around $6 and arrived in about a week. I successfully removed the old battery, dropped the new one in and dropped it in the charger. Unfortunately, after two days, it never seemed hold much of a charge - I barely got one brushing out of it. I tried resetting the battery (put the brush in the charger and holding the green button down for 3 seconds) with no success, either. Since, with the old battery, I was able to get at least a couple of full brushes in before it died, I decided to put the old battery back in ... unfortunately, now that doesn't seem to be holding a charge like it used to. Strange. It's looking like I'll be shopping for a replacement soon. My disassembley experience was similar to other people that have commented. Before I was able to separate the outer housing with the inner assembly, I needed to run a thin screw driver around them to loosen them up as dried toothpaste had mostly bonded the two together. Removal of the old battery was a bit touchy and, in the end, involved a bit of brute force to get it free. Of all the steps, this is the one that, if not done carefully, will likely toast your Sonicare. Soldering the leads on to the PCB was straight forward. Considering replacing the brush is at least $100, I figured $6 and an hour or so of my time was worth it.

onmythirdsoniccare (author)2009-06-30

I called Sonicare after my second brush stopped working after I left it off the charger and went on a 3 week vacation. Sonicare's rep named Roxan told me that the brush has to be plugged in at all times. I even asked her if she was sure because I used to let mine run down before charging it and she once again said it must be plugged in at ALL times

hacknmod (author)2009-03-23

I replaced the battery in a sonicare elite with a usb battery from

This is a 1300mah NiMH. .The battery has solder tabs once you remove the usb head. It is physically a bit shorter than the original, so lead extensions must be soldered on. A little electrical tape or shrink wrap for insulation and a few dabs of hot melt glue to keep it in place and eliminate vibration. Still testing charge life.

Tried Digikey for a true Sanyo replacement SY110T-ND but they said 8 weeks. Too long! In fact, this battery is cheaper once the shipping and taxes for Canada are thrown in.

chuckk (author)2009-02-22

My wife's Sonicare finally reached the point where it had to be charged every day and she allowed me to crack it open for the battery replacement described above. Finding the correct battery was a little tricky. The description of 4/5A cell was enough to find a cell online. However I wanted to do the project in a single day and went to a local "Batteries+" store in the Chicago area. I expected the worst with a name like Batteries+, but was surprised to find them knowledgeable and able to find a match. I bought a 1200mAh NiCad as it was all they had in a matching size in 1.2V. The store tech also spot-soldered a couple of prongs onto the battery. The de-soldering is difficult if you're new to it. Just be patient. The connection on the outside end, the negative, is easier to de-solder. If you use some pressure on the soldering tip to push the pin through the board it is easier than trying to pull all the solder out. The positive connection,up by the LEDs is more difficult. I puled the battery halfway out and intentionally broke the leads off the battery in oder to get the battery removed before trying to de-solder this point. Once the battery was out I just used pressure on the tip to push the pin through the board. Once the battery leads are out of the board it is much easier to clean up the remaining solder on the board with copper braid.

Gilberge (author)2009-02-13

We had 2 Sonicare Elites, so when one died, I tried the other charger stand. It turned out the charger stand was what died. I used to know a band called Fungus Amungus, so this is the one I responded to when I saw it.

fewolf (author)2008-12-27

How do I find he replacement battery.. I looked at Tenergy and couldn't find a match is it "sub C" ? thanks

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