Sonicare Elite 7300 - Battery Replacement

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Intro: 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

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

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

This is what the battery looks like removed.

Step 4: 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

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

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.

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    63 Discussions

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    Nate Ocean

    8 years ago on Introduction

    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.

    Sonicare 018.JPGSonicare 011.JPGSonicare 012.JPGSonicare 013.JPGSonicare 016.JPG
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    m.wakileh

    8 years ago on Introduction

    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...

    IMG_0223.jpgIMG_0224.jpgIMG_0225.jpgIMG_0226.jpg
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    ToddB30

    2 years ago

    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.

    1 reply
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    ToddB30ToddB30

    Reply 2 years ago

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

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    maretsar

    3 years ago on Step 6

    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.

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    (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.

    1 reply

    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.

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    mickkell

    3 years ago on Introduction

    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.

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    aomega79

    4 years ago on Introduction

    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.

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    jplee3

    5 years ago on Introduction

    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.

    1 reply
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    TurboPTjplee3

    Reply 5 years ago on Introduction

    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.

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    JazzAzz

    6 years ago on Introduction

    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.

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    fma_battery

    6 years ago on Introduction

    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.

    FH2200-17430PL copy.jpg
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    grayshirt

    7 years ago on Introduction

    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 BatterySpecialists.com (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.  :-)

    3 replies

    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 claudio@patriot.net 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.

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    srekveldgrayshirt

    Reply 6 years ago on Introduction

    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 http://www.batteriesinaflash.com/assembly-cells/nimh/4-5a/tenergy-4-5a-size-rechargeable-battery-2000mah-nimh-flat-w-tabs and working like a charm.

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    jehan60188

    10 years ago on Introduction

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

    1 reply
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    jimluschenjehan60188

    Reply 6 years ago on Introduction

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

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    2000se

    6 years ago on Introduction

    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.

    IMG_0521.jpgIMG_0522.jpgIMG_0523.jpgIMG_0524.jpgIMG_0527.jpgIMG_0528.jpgIMG_0533.jpg