New Batteries for a Braun Shaver

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Introduction: New Batteries for a Braun Shaver

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.

Step 2: More on Opening the Case

In MS Paint I added some colored lines to illustrate the steps in opening the case. As described in the previous step, rotate the fitting around the charging cord jack counterclockwise (red arrow). There is an end cap on the case as shown by the yellow lines. When the fitting around the cord jack has been rotated, the end cap slides off (yellow arrows). Then the major portion of the case slides away from the innner workings of the shaver (green arrows).

The inner carcase of the shaver is not shown here, but it is a clamshell. Pry it open only as far as needed at the end of the shaver shown in the photo. Slide the inner case for the circuit board and motor out of the shaver.

Step 3: Inner Case Catches

The inner case around the circuit board is an upper piece of translucent plastic. The lower piece is black plastic. Four snaps hold the two pieces together. Gently pry each off of its hook. The graphic illustrates the hook catches.

Step 4: The Cells

The photo shows one of the original cells. Metal tabs spot welded to the ends of the cells protrude through slots in the circuit board and are soldered in place. I marked the circuit board with "+" and "-" so I would not forget the polarity. It is easy to become confused.

My new cells did not have metal tabs spot welded to them. I decided to use some bare stranded wire. I pushed it through the slots in the circuit board and soldered an end to the circuit board. Then I cut it to length to reach the point of contact on the cell ends. I roughed up the ends of the cells with sandpaper and tinned them with solder. I soldered the cells to the wire pieces.

Put the circuit board back into its case and slide its case into the shaver.

Step 5: Assembly

Braun builds a poison pill into its shavers so you cannot assemble the shaver after replacing the batteries. Working around that poison pill is the second important thing in this Instructable, after how to get the case open.

Not recommended is what I did. You can see that I tried chewing up the cord jack fitting with a Dremel tool and cutter bit. It is not necessary and does not work, anyway.

Step 6: The Poison Pill

Braun uses two metal pins like the one shown below to fall into place and lock the cord jack fitting so it cannot be rotated clockwise back to its original position after the seal has been broken and the shaver has been opened. This pin is shown vastly enlarged. The actual pins are only about one quarter inch in length in all. As long as the cord jack fitting cannot be rotated back to its orginal position, the charging cord cannot be used with the shaver. These pins need to be removed, but they are hidden from view.

Step 7: Removing the Locking Pins

In the graphic you will recognize the cord jack fitting (black face with grey contrasting color to highlight the three dimensional aspect of the graphic). The two pins are inside the cord jack fitting where you see the red dots.

When the shaver case is open you will see a plastic piece shown here as tan. It is actually grey, but I wanted its color to contrast with the rest of the graphic. The pointed ends are inside pockets made of translucent plastic. With a drill bit or a jeweler's screwdriver push the pointed ends toward each other to release the piece. Then slide it away from the assembly (arrows with feathered back ends). The cord jack fitting can now be lifted out very easily. The locking pins will likely fall out while you are removing the cord jack fitting. Discard them.

Reinstall the cord jack fitting and its retainer. You can now rotate the cord jack fitting in either direction as needed.

Step 8: Assemble the Shaver and Charge

I could not get the cord jack fitting to engage so that it also locked the parts of the case to keep the case from sliding and opening when I applied pressure to the shaver's sliding switch. It should work, but it did not for me. So, I drilled a hole in the side of the shaver and inserted a short screw to keep the parts from sliding away from each other. My screwhole came to be larger than I wanted it to be, so I filled the hole with hot glue and pushed the screw into the hot glue. It looks ugly, but it works.

Step 9: Attaching the End Cap Again

The end cap also did not want to stay in place, since I could not get the cord jack fitting to lock the parts of the case. So, I ran a small bead of hot glue on the front and back of the shaver and pushed the end cap into place. You can see a little of the hot glue bead in the seam above the word "Braun."

Other than looking a little worse for the wear, my old shaver now works very well with its new batteries.

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31 Comments

What NiMh AA flat top batteries did you use with your shaver?  There are a number of models available with different mAh ratings.  I'm just curious if that makes a difference to the shaver firmware, as the higher the mAh rating the longer the charge.  Braun probably did not use the highest mAh rated batteries as OEM, to save on cost.  I'm wondering if 2200mAh cells (2.4v combined) would be a good replacement.  What do you think?

 I had a couple of new NiCad AA cells in my possession and used them.  I think the 2200 mAh cells you mentioned would work.  I did not see any chipsets inside my shaver (1990 vintage), which would be necessary for any firmware.  

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).  The folks at Batteries Plus suggested simply using NiMH cells as substitutes for NiCad cells.  That surprised me, based on what I had read up to the present.  I have not tried it yet, though.  

Thanks for your comment. 

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.

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.

Interesting.  Yeah sorry, when I said "firmware", I had a later model in mind.  The 6000 series on up has firmware to regulate various things, and to run the LCD when present.

I just learned that someone used a set of 1650 mAh NiMH 1.2v batteries in their shaver and they worked out fine.  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.  Maybe I'll do a writeup of replacing the cells in the 7000 series.  :-)

 I wish you well with your project.  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.  I hope something in my Instructable will be useful to you.  

Thanks.  I hadn't heard of any "poison pills" 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.  I've got a spare shaver (model 7526) that has well worn batteries, which will be the tester for this battery replacement.  If it works well, I'm going to replace the cells in my other Braun shavers.  Higher mAh rating means longer life.  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.

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. ;-)