Just to update my previous answer.
The new battery lasted 12 days on its first charge (using it for about 2 and a half minutes per day) - a bit less than expected, especially given the higher capacity of the new battery. This may be something to do with the different type of battery. Perhaps it's not being charged fully - or it's being overcharged (NiMh types have a lower voltage falloff upon full charge which may not be detected properly by the charging circuit until it's lost quite a lot of its charge.) I might try just charging it for 12 hours say, rather than waiting until the light stops flashing. This should extend the battery life because most chargers overcharge in order to detect the consequent voltage falloff which is how they detect that charging is completed.
Even so, it's a very cost effective repair and it's no problem for me to use a once-a-week charging regime which should give many more years of service.
Hope this helps someone.
 Ian
 April 2010
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The battery types seem to vary between the different Braun models - my answer relates to the Braun Sonic Complete. Usual problem - after years of good service the ni-cd battery isn't holding its charge.
To get in to the unit - place a suitable object in to the recharging hole in the base and turn a quarter turn. There's a stub on the back of the charging stand for precisely this purpose. Very gently remove the innards by pushing down on the metal brush shaft - this pushes everything out through the base. Be very careful of the thin wires from the main circuit board to the base of the unit.
Having extracted the innards you'll need to desolder the battery. The negative terminal is closest to the base of the unit, the positive is closest to the middle - this is quite difficult soldering. First desolder the positive terminal from the circuit board using desoldering tape or a desoldering pump. Then bend the metal tag up to allow it to pass back through the board. Pull it out by pulling out the battery (still attached at the negative end).
The negative battery tag is soldered to the board under some other connections, making it very hard to get to. So, bend the battery upwards and cut through the nagative tag as close to the battery as possible (use wire cutters) - this leaves you something to solder the new battery to, and means you don't have to unsolder the hard-to-get-to solder point on the board.
The battery is actually two 2/3A (pronounced two-thirds A) size cells soldered together. If you cut off the outer plastic coating from the old battery you'll see that it's actually 2 cells. You'll need to buy 2 of these (the tagged type) - they're 1.2v - I bought NiMh ones. It's not always possible to replace NiCd with NiMh but they seem to work fine here. My replacements were 1500mAh which is a greater capacity than the stock parts - so should last longer between charges. Don't worry too much about the capacity - it's not critical - 750mAh or above will be fine. You can pick these up on ebay - they're typically used in things like remote control models. You need to buy the individual cells (two of them) not the ready made battery packs.
The positive end of the cells usually have a groove round the body.
Solder the two new cells together (positive of one to the negative of the other) by butting the cells together and soldering their tags. Fold soldered tags flush to cells. Now solder this new battery in to place. It's really hard to shape the +ve tag to the required shape and solder it in place - so I used a piece of wire on the positive end as follows: Solder a suitable piece of wire through the +ve hole in the circuit board. Fit the battery in place with the +ve tag sticking out towards you, and solder the battery tag to the other end of the wire. Trim and fold down neatly.
Then solder the negative battery tag to the remains of the tag you cut through when you removed the old battery.
You'll probably notice some moisture in the unit when you open it up - the seals start to fail after a while. Make sure everything is dried out before reassembly. You can spray the entire innards with WD-40 or similar if you like, but try to keep it away from the rubber o-rings. If you want to grease the o-rings you should use proper silicone grease - ordinary oil based lubricants are likely to attack the rubber.
Reassemble the unit and attempt to charge. If it appears totally dead you may need to jump start the battery. Temporarily wire the old battery (with a little charge in it) in parallel with the new one and charge for a few minutes to get some juice in to the new battery. I'm not sure if the charging circuit needs a little battery charge to be present in order to work, but I had to follow this procedure.
My unit took 21 hours for its first charge - longer than before because of the higher capacity battery - and the unit detects full charge OK despite being a NiMh battery.
You really need to be fairly good at soldering and especially unsoldering to attempt this. But if you're patient and careful, it should work OK.
Ian
April 2010
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Ours has been on constant charge & its still working after 10 years. It is never used away from our own bathroom and now wouldn't hold a charge for long enough.On holiday we resort to manual brushing. Judging by peoples experience we will buy a new unit.
Gus
March 2010
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Question for Paul (or others for that matter): the battery on my Oral B Triumph Professional Care 9000 is starting to lose it's charge after about 5 - 7 days instead of the usual two weeks. I had a look at your photos and instructions which are great. Nice of you to take the time to do that! However, after getting the bottom off my toothbrush I soon realised that replacing the battery was beyond my technical capabilities. I contacted Braun and they say that you're not meant to replace the batteries. How ridiculous! More sales for them I guess.
Would anyone be willing to discuss an arrangement whereby they would replace the battery for me? I would obviously give payment for time/parts etc if the cost was agreeable. Thanks in advance.
Glynn
May 2009
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Ref Wiz.Au's comments regarding fitting more powerful batteries, I'm not convinced that you can interchange NiCd and NiMh batteries. As I understand it they need two quite different charging regimes (I think one gets a constant voltage whilst the other is pulsed?) Hopefully someone who knows what they are doing will pass through here and be able to resolve that one for us.
Ref Chris R (March 09) Don't worry about breaking the fine wires to the inductive charging coil, they are easily fixed. See my Answer of Oct 08 for details.
Ed Vine
April 2009
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I recommend "Replacing the NiMH battery in a Braun electric toothbrush" (http://www.blinkenbyte.org/braun-battery-replacement/index.html ). Very good description of how to do it, with pictures.
I've just replaced the battery in a Braun Oral-B 3D and the internals looked just like those in the article above.
The battery types can vary but mine was a single NiMH cell, size 4/5A size. These are 'industrial' size cells, not consumer AA, AAA,C etc. In the UK, you can buy an exact replacement for these at RS (www.rswww.com) and Rapid (http://www.rapidonline.com). About 5UKP, plus delivery.
Be warned the spring in the bottom of the toothbrush is very strong; be careful when undoing the bottom and don't let the bottom cap spring away from the body or you may break the very thing wires that connect to the charging coil.
ChrisR
March 2009
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It seems like people might be talking about two or three different models here! I say this because I read people using only _1_ battery?? in some repairs.
For those people with a pack that looks like two small fat cells, they are size "2/3A", 1.2v NiCd cells, in series to produce 2.4V
http://www.jaycar.com.au/productView.asp?ID=SB1716
If you want better batteries, go see your local electric radio control car toy shop. They will sell NiMH in up to 1400mAh, compared to the miserly 600mAh NiCd which Braun use as standard.
Wiz.au
February 2009
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I have managed to get tagged battery the same size, AAH, from Budget Batteries, www.budgetbatteries.co.uk. Excellent service but costly postage.
Norman
January 2009
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REPAIR SWITCT THAT OPERATE INTERMITTENTLY
DANNY HIBBERT
January 2009
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I did this last night and took pictures of the entire process: http://www.blinkenbyte.org/braun-battery-replacement/index.html
Paul
January 2009
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Replaced my battery yesterday. The exchanged battery was a 4/5AF which is slightly shorter, wider and more expensive than the AA battery. So I drilled the bottom of the charge "hole" out which gave enough room for a 2500 mAh AA battery. Once soldered I had to connect it to the charger to get it to work. This is my second succesfully converted toothbrush.
Ontop
December 2008
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Have finally made the time to fit a new battery as promised and I'm pleased to report that the brush is now working fine.
I couldn't find a supply of decent quality batteries, so the one I've had to fit is a bit pants, but it still brushed my teeth morning and evening for a week before needing a recharge.
It was a 1.2v Ni-Cad for anyone in the same boat.
I managed to break both the wires to the inductive charging coil while re-assembling it, but this is easily rectified as a fresh bit of wire can be peeled off the coil quite easily. You will need to scrape or burn the insulating lacquer off the end of the wire before you will be able to solder it though. Holding the tip of the wire in the yellow bit of the flame of a normal gas lighter for a few seconds does this fine. Try not to remove the lacquer any further back than that, as you may cause a short circuit when it all goes back together. If in doubt, test it with a simple meter set to resistance.
I notice that the newer versions of this machine use NiMh batteries, so I can't be sure whether you will need 1.2v or larger cells.
I hope this is of use to someone.
Ed Vine.
October 2008
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Have finally made the time to fit a new battery as promised and I'm pleased to report that the brush is now working fine.
I couldn't find a supply of decent quality batteries, so the one I've had to fit is a bit pants, but it still brushed my teeth morning and evening for a week before needing a recharge.
It was a 1.2v Ni-Cad for anyone in the same boat.
I managed to break both the wires to the inductive charging coil while re-assembling it, but this is easily rectified as a fresh bit of wire can be peeled off the coil quite easily. You will need to scrape or burn the insulating lacquer off the end of the wire before you will be able to solder it though. Holding the tip of the wire in the yellow bit of the flame of a normal gas lighter for a few seconds does this fine. Try not to remove the lacquer any further back than that, as you may cause a short circuit when it all goes back together. If in doubt, test it with a simple meter set to resistance.
I notice that the newer versions of this machine use NiMh batteries, so I can't be sure whether you will need 1.2v or larger cells.
I hope this is of use to someone.
Ed Vine.
October 2008
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Victor, I'm in the same boat, but as I just found a new one going cheap this has become an amusing puzzle, so I can afford to get it wrong now. I've bought a 1.2v tagged ni-cad and will be fitting it when I get a chance, probably at the weekend, watch this space...
Ed Vine
October 2008
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Hi, in trying to find replacement batteries for my shaver, the only battery supply is http://abtecparts.com/Philishave_Norelco_Shaver.htm
Click the batteries pic. I am sure that if you look at the battery types you will find one that matches the Braun one. Regards Jonathan
Jonathan Garstin
October 2008
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Actually, no of this answers the question I have. I have took apart the "behind" and got the battery out. It does not have any marking on there that tells me any info on the battery's identity. I have no idea what size and still have no confirmed answers about the voltage of the battery. I was thinking CA123A batteries. However, I just do not know for certain. Size doesnt look right.Could someone please assist with this? Thank you.
Victor
September 2008
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I have just dismantled my old Braun AdvancePower brush. It's the basic single speed one with a simple mechanical switch and contains a single tagged AA. Problem is that there is no voltage marked on it, (it is showing about 0.8v fresh from the charger which is why it's now in bits!) I was all set to order a 1.2v replacement until i saw that CPC only supply 3.6v tagged AAs, no 1.2v ones at all... Apart from trying to measure the charger's output voltage, which will be difficult what with the airgap transformer and all, how can I tell what voltage the battery is? Apart from one diode protecting the charging loop there is no circuitry in the the thing at all, and the motor has no markings on it either... Any ideas anyone?
Ed Vine
September 2008
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What's the voltage of the original battery? Is it a single cell 1.2V or a double cell 2.4V??
Edd
September 2008
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I cut the base away a bit with a dremmel, drilled a hole where the +ve terminal fits, and threw away the spring, and now it fits a normal 2300mAh AA battery. Soldered wires to the terminals, so it isn't so fiddly to change over if I ever decide to do it again. Only the seal needed to be repaired - nothing else is damaged during replacement if you're careful. Thanks to Rob Kirke for the tip to jump-start it!
David
August 2008
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Thanks to all who have replied to this I've just fitted a new battery (4/5ths AF size) to mine by following your instructions ...tho' the tags on the new one were a bit wider than the original so had to be filed to fit thru' the slots on the unit...and I applied PTFE (plumbers tape) around where the seal was ..it's early days but will see how the seal holds out!!
Peegypops
August 2008
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Yes you can but with a lot of difficulty and the process will damage the water sealant rubber gasket at the top of the unit making it prone to water leakage and damage. I used the method described by Richard G above and got as far as removal of the battery pack. Then I realised that there would be other damages during the battery replacement and considered it not worth while. Mine was an old one with not much battery life. Mine had lasted 2-3 years with continuous use. This must be my third Braun tooth brush and they are really great compared to philips and others in the market. If you are looking for a good electric tooth brush with replaceable rechargable battery (as if in a flash light) buy Krups.
Raj
June 2008
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I just sucessfully replaced the battery in a Braun electric toothbrush - It's worked well for over a year serving two people, but had recently become a bit sluggish. All things considered this is a fairly decent lifetime for a NiCd battery - nearly 1500 shallow discharge-recharge cycles. It was replaced with a newer 2500mAh NiMH battery with tabs, which should work just as well in its place, and provide plenty of extra capacity for camping trips etc.
One strange thing I found was that after replacing the cell, there was no sign of life at all, until I 'jump started' the unit by briefly jumpering positive from the battery to the gate of the mosfet IC (the only lead not paralelled together on the largest IC near the motor end). After this the unit and timer worked properly. I wonder if this is a new attempt to make a "limited lifetime" appliance? I know the contollers in some laptop batteries will not fire up again once cell voltage has reached zero (i.e by replacing the cells).
Rob Kirke
June 2008
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you can replace the batterey as follows:
1) if you have the charger unit, at the rear is a 'stub' which fits int the base of the toothbush-insert brush and turn a 1/4 to release the base
2) turn bush upside down and push on a firm service (this moves the battery out of the stem)
3) pull battery of out stem and unclip the battery holder
4) remove circuit board and remove/replace the battery
5) refitting is reversal
Richard G
April 2008
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you can change the battery,but it will have to be soldered,
to open the unit you need to turn the base anticlockwise to unlock it, there are two cut-outs across it, use thin nosed pliers, then push it out from the top. take great care of the loose leads on the pick up coil in the base they should'nt break but make sure you don't trap them when you put it back together.
you must bear in mind the heat produced when soldering could damage circuit board!
steve
March 2008
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With a big coinshape like tool you will be able to open de bottom off the machine. Turn it about 1/4 and pull to open. You will have to replace the batery with same one witch has tabs attached to it. The machanics of a Braun are such that it is worth to replace the battry only once. After that the toothbrush is mostly worn out mechanicly, water leaks in to it at the axle where you put up the brush itself. Sorry about my English but i'am Dutch.
Techman
October 2007
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I can't answer the question but I've just bought my THIRD one. The first one packed up so I took it apart and there was no way I could get it back together (design?)
Ther are some very tricky wires- very fine. Now I've got another so I'm gonna have another look at no. 2
Even the new one has ni-cad (circa 1980 ! )batts. I'm sure Braun know exactly what they're doing.Let's see and maybe Braun will start putting batteries in that last more than a year.
Brauned Off
October 2007
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