Only now is this page coming up in my search results!
If changing the battery is your only goal then Step 6 desoldering the dual motors' leads is unnecessary.
The board can be flipped out from the other end leaving them connected by careful levering (finger nails or small jewellers' flat head screwdriver) each of the side of the board alternately whilst at the same time applying slight sideways pressure on the small black retaining clips on either side of the black plastic car chassis just after it tapers inwards on each side.
Worked for me anyway and I now have clear access to the battery connectors to desolder and replace.
Sticky black spongy material easily comes off old battery to apply to new one.
They come with a micro sized battery of 75mAh (as posted above). I cannot find an increased capacity of equal size.
I can find one of increased capacity of greater size / weight (roughly double weight) that may fit but is unlikely to and also has a completely different connector without wires, which I suppose could be overcome if it would fit.
Of course a greater charge time would be needed that sort of defeats the object of about 20 minutes play with a roughly 10 / 11 minute recharge time.
Today I determined they are 75mAh.
I asked myself the same question about increased capacity.
You can find the mini/micro equivalents on many sites (not necessarily Fullriver) but I cannot find a mini/micro of larger capacity.
In the first instance though I merely want to repair the cars that will no longer hold charge because they have not been used in a while.
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