This is my Braun 5510 shaver with rechargeable batteries. The batteries no longer hold a charge. It is possible to use the shaver with the AC cord normally used for charging. I wanted to replace the NiCad AA batteries with new cells.

Step 1: Opening the Case

The first problem is how to open the case of the shaver. This graphic from the shaver's manual gives some description. But, these instructions assume you will no longer use the shaver after opening to remove the old batteries for recycling. The seal is green as shown. Use a larger coin to push and break the seal. Then rotate the round fitting where the cord attaches counterclockwise about 45 degrees. Rotating this cord jack fitting required considerable force. I had to grasp a US quarter dollar with a pair of pliers to apply enough force.
What NiMh AA flat top batteries did you use with your shaver? &nbsp;There are a number of models available with different mAh ratings.&nbsp; I'm just curious if that makes a difference to the shaver firmware, as the higher the mAh rating the longer the charge.&nbsp; Braun probably did not use the highest mAh rated batteries as OEM, to save on cost.&nbsp; I'm wondering if 2200mAh cells (2.4v combined) would be a good replacement.&nbsp; What do you think?<br />
&nbsp;I had a couple of new NiCad AA cells in my possession and used them. &nbsp;I think the 2200 mAh cells you mentioned would work. &nbsp;I did not see any chipsets inside my shaver (1990 vintage), which would be necessary for any firmware. &nbsp;<br /> <br /> It was immediately after doing this project that I went to replace the NiCad cells and learned they were no longer in stores available to me (Radio Shack, Batteries Plus). &nbsp;The folks at Batteries Plus suggested simply using NiMH cells as substitutes for NiCad cells. &nbsp;That surprised me, based on what I had read up to the present. &nbsp;I have not tried it yet, though. &nbsp;<br /> <br /> Thanks for your comment.&nbsp;<br />
<p>The easier was of dismantling the 5510 is to un-clip the two little covers either side of the cord socket and unscrew the screws under them, this involves no problems with the poison pills. These covers can be accessed using a knife either side of the bottom cover, just press the knife in and pop them off. Now all I need are the new batteries and the value of that blown resister on the circuit board.</p><p>PS: you can use NiCad's to replace NiMH cells but it's not a good idea the other way as the pique voltage on the NiMH cell is different and the charge circuit may not cut off.</p>
Interesting.&nbsp; Yeah sorry, when I said &quot;firmware&quot;, I&nbsp;had a later model in mind.&nbsp; The 6000 series on up has firmware to regulate various things, and to run the LCD when present.<br /> <br /> I just learned that someone used a set of 1650 mAh NiMH 1.2v batteries in their shaver and they worked out fine.&nbsp; I'm going to go with the 2200 mAh ones; it'll be interesting if the shaving time is extended between charges over OEM performance.&nbsp; Maybe I'll do a writeup of replacing the cells in the 7000 series.&nbsp; :-)<br />
&nbsp;I wish you well with your project. &nbsp;I would be interested if the process for opening the case and removing any poison pills that might prevent battery replacement by the owner has changed. &nbsp;I hope something in my Instructable will be useful to you. &nbsp;
Thanks.&nbsp; I hadn't heard of any &quot;poison pills&quot; before seeing your posting. Braun must have done away with those on later models, as I opened up my 7526 and 8595 shavers, disassembled, cleaned whisker debris out of the casing, then reassembled with success--both shavers still work.&nbsp; I've got a spare shaver (model 7526) that has well worn batteries, which will be the tester for this battery replacement.&nbsp; If it works well, I'm going to replace the cells in my other Braun shavers.&nbsp; Higher mAh rating means longer life.&nbsp; The new cells I'll be putting in are rated at 2300mAh (still 1.2V) and can take up to 1000 cycles (versus the usual 500 on the generic NiMH AA cells).
I neglected to follow up with results here... just thought I should make a note, for posterity.<br><br>My attempt to use 2200mAh and higher batteries failed miserably. The additional storage capability of the batteries seems to confuse the shaver firmware. As I had suspected might be the case, it is tuned to deal with a specific battery capacity. So, it's important to use batteries that are as close to the originals as possible. I believe the originals were more like 1400mAh or 1500mAh. 1650mAh is probably on the edge of tolerance for the shaver, and it probably doesn't give much more shaving time than a 1500mAh battery. I'd say it's best to stick as close to the original specs as possible.
I am sorry it did not work for you. Will you try again with different batteries?
That's my intent. I located a set of 1500mAh and 1800mAh cells that weren't very expensive, but seem to be of similar construction to the original batteries (plain mono colored vinyl sheath around the cells, generic printing on the sides indicating model/mAh). I've had other projects that have taken priority, and I picked up another used shaver on the cheap with batteries still working well. So, it'll be easier to do the battery swap, as any failure won't leave me without a working shaver. :-)
Just a follow-up... My old 7500 series shaver just wouldn't work properly with the replacement batteries. I think the introduction of the 2200mAh batteries must have caused some kind of damage. Not sure what that would have been, perhaps a dependent capacitor external to the processor. In any case, I eventually decided to junk it. I'm using an 8995 and a 760 now and... not looking back. ;-)
xevious, Are you still around? I found this thread and see that you saw you successfully opened your 7526... how? <br>It doesn't match the description/picture above. The charger plug isn't round so doesn't turn/unscrew.<br>
Pmiller10 - just thought I'd share - I just replaced the batteries on my 7526 (almost bought a new one before deciding to try the battery replacement) - am I glad I did - I bought new 1650mAh from www.batteriesamerica.com for about $13 including shipping, soldered them in and voila, a like new shaver - LOVE IT! Before the batteries did not hold a charge anymore and I had ot use it plugged in, but now it is like a speed racer. I read elsewhere the original batteries were 1100 mAh on the 7526, but the max. people have had success with was 1650mAh, so that is what I went with. Be sure to get the batteries with Soldertabs attached - much easier. Good Luck!
Hello pmiller,<br>Yes, the 7526 is a different model; this instructable is based on a 6000 series shaver. The bottom socket surround is rectangular, with a protrusion in the center where you insert the cord. To remove the surround, or &quot;plug&quot;, you insert a small screwdriver just within the lip of it (so you are getting leverage on the plastic). You then apply pressure to pry the surround off. There are 4 little hooks that hold the surround on, pointing to the front and back panels of the shaver. So you want to pry in that direction for easier removal. Good luck!
Well, my attempt failed.&nbsp; I detached the old cells from their tabs, installed the new ones, soldered the tabs to the cells, did a circuit check to be sure the contact is good, reassembled the shaver, then tested it out.&nbsp; The shaver actually worked, but the battery level was low--clearly they needed to be charged.<br /> <br /> So, I plugged in the shaver and let it go through a charging cycle (60 minutes).&nbsp; When the flashing light went off, I&nbsp;disengaged the shaver from the cord, then tried to operate it.&nbsp; DEAD.&nbsp; I&nbsp;plugged it back in and tried to run the shaver, and it did work.&nbsp; It just won't run off the cells.&nbsp; I&nbsp;double checked the circuit again and it showed OK--the batteries are fully charged.&nbsp; I&nbsp;suspect that something must have gone wrong on the circuit board. &nbsp;The only thing I can think of is that it isn't designed to handle a 1.2v battery that has a 2300mAh rating.&nbsp; I quite sure I didn't introduce any issues directly (e.g. short or broken circuit).<br />
Good news!&nbsp; I determined that my soldered connections were faulty. &nbsp;I didn't have proper solder for the job (too small a wire and too quickly curing flux) and my extreme caution against heating up the batteries caused poor soldered connections.&nbsp; So, I&nbsp;used adhesive backed aluminum tape to secure the leads this time.&nbsp; It works!&nbsp; The higher mAh rating seems to be confusing the firmware, as the low battery light is flashing on the shaver, but it's running very strong.&nbsp; It'll be interesting to see how much run time I get on a full charge.<br />
&nbsp;I am glad to hear you found the problem. &nbsp;I have heard of poor solder joints acting like a diode. &nbsp;I would not have expected quite the problems you had. &nbsp;I did not worry too much about overheating the batteries. &nbsp;Roughing the battery ends up with sandpaper and tinning them before soldering the wires to the battery ends worked very well.&nbsp;
I've soldered wires on dozens of batteries, the trick IMO is to use a plenty big iron (40 or even 60 watt) so you get on and off fast, keep the battery upright and if you can have a small fan to cool it off as soon as possible.
Hi Phil, <br> <br>My Braun 5311 has the same twist notches like your 7765 but with 2 screws on either sides, which I've removed. <br> <br>The 5311 is the same as the 5312 and 5466 [see pictures]. <br> <br>I'm afraid to pop and break off the wrong panel. I did that one too many times with my cars and stereos. <br> <br>I have removed the 2 screws holding the swivel blade holder but nothing. <br> <br>Regards, <br>Arohl
Hi, <br> <br>I have a Braun 5311. I've removed 4 screws [2 bottom and 2 by the flex head]. <br> <br>I still can't figure out how to open it. <br> <br>Do you have a service manual or instructions for it? <br> <br>Arohl
I do not have any instructions for your shaver. Could there be catches like I described in step 3? It has been a long time since I took my shaver apart and I do not remember as much as I would like about it.
Thanks for creating this instructable, Phil. I had found how to remove the case over a year ago, but got side-tracked and eventually on to bigger and (better?) thing. Today I tried to back-step myself to see where I had gotten to back then (I'm 63, give me a break!), and came up with the locking pins that you have shown us here. I'm just glad I found your post instead of going to my reserve method of &quot;using a bigger hammer&quot;. ;) <br>I understand that this (feature?) is more a safety precaution, but I can't help but think Braun placed those pins in there so we would have to buy a NEW razor. (The little pins and springs are precision made!) <br>Although Braun is a well respected company, I'm sure that this product, like most others on the market are designed to be replaced. (Planned Obsolescence)
Ron-Ray,<br><br>I love your self-description on you profile. I am glad this Instructable helps at least somewhat with your shaver. I am sure there are differences with an NiMH shaver than with a NiCad shaver. Our church's electronic organ has a memory circuit powered by two AA NiCad batteries. We know the day is coming when we may not be able to get NiCad batteries. Some have advised simply substituting NiMH batteries. I guess that works if the charging is slow and gentle enough. I am sure Braun would eventually discover the joys of planned obsolescence. <br><br>Where in Alabama are you? I lived in Chattanooga for a dozen years. The north end of Alabama was quite close. We did also go to Gulf Shores once, too..
This is an old thread but I hope Phil B is still watching - <br> <br>I have just replaced the batteries in my Braun 6550. I used Sanyo Eneloop which are Nimh low self discharge of about 2000mAh. They ran the shaver but did not charge properly the first time. I removed them and recharged, replaced again and similar. When fitting them I did notice some lazer cuts on the pcb and wondered if this was some trimming for the batteries but rather hoped that the firmware would calibrate itself to the batteries after the first full charge/discharge/charge cycle. The shaver info says the originals are Nimh but not the capacity. <br> <br>I bought my batteries already tagged and there is a limited choice. I got these as I used some for a torch at the same time where the low self discharge is useful. <br> <br>Looks Iike I have fallen foul of the firmware. It has been such a good shaver I thought it was worth having a go at replacing the batteries. The dilemma now is whether to try some others when I have no idea of what capacity to use and I don't have a selection to experiment with. I have not been able to find the capacity of the batteries, they are not labelled and I've not found the info on the web; it is not in the service manual which I have. <br> <br>Any advice would be welcome!
@ wphil <br>The best I can find out is that &quot;1650 mAh NiMH 1.2v&quot; batteries will work best in any of these razors. (Pre-soldered tab ends help) <br>I also wanted to use Sanyo Eneloop batteries, as they are the best thing on the planet to date, but the charging system is a lot different from NiCad &amp; NiMH.
Thank you for the comment. Your shaver is much newer than mine. Have you tried contacting Braun to see if they would be so nice as to give you the information you need? I know it is a long shot, but stranger things have happened.
I really don't think Braun are likely to tell me and I couldn't find a circuit diagram online which might have had the value. Anyway, nothing ventured nothing gained. I raised a question against Braun UK service and was not prepared for the answer. They decided it had some synergy with a question asking about replacement brush heads for a toothbrush! Well it does; they are both made by Braun! Then there was this reply &quot;All you need to do is contact our service centre. they should be able to fit a battery for you. However, if the toothbrush is over 2 years old, they will charge you for this.&quot; along with details to contact. I guess the only word they latched onto in my post was &quot;batteries&quot; and didn't read the rest. Oh well. <br> <br>I've noticed xevious seems to know quite a lot. If you are monitoring and could let me know where you located information on the capacity of the original batteries I'd be grateful. It might help me track down the capacity for mine.
I successfully replaced my battery with a 1200 mAh NI-MH battery with tags, that I ordered online. &nbsp;I left the old tags protruding from the circuit board, and cut the new tags to length. &nbsp;The razor now holds charge as new.<br /> <br /> Elsewhere I found instructions for a better way of opening the razor: undo the screws at the top, then pull it apart until you can use a long screwdriver to move the plastic lug (held by a spring) visible at the bottom sideways. &nbsp;The lug has a catch on it that holds it in position for reassembly.<br />
I wonder if our shavers may have been constructed differently.&nbsp; <br />
Sorry: you are right. &nbsp;<br /> <br /> The picture looks the same, but mine is a 2450. &nbsp;I am guessing that the technique I used will not work for the 5510?<br />
Nice. Defeating those &quot;poison pill&quot; mechanisms designed to prevent equipment from being user-serviceable is <em>so</em> rewarding, isn't it?<br/>
Thank you for the comment. I think this is the first poison pill device I have encountered after a lot of years of working on all kinds of stuff.

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Bio: I miss the days when magazines like Popular Mechanics had all sorts of DIY projects for making and repairing just about everything. I am enjoying ... More »
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