Dual Cell via Button Batteries?

[syncronized]

Hey guys,

I was thinking about the layman's dual cell and was wondering whether or not one could just purchase some 1.2V NIMH button cells(watch type batteries-rechargeable) and hook them up in series and voila. You could easily fit in 3 or 4 of them!

These are the specs I found on www.gpbattery.com

-Diameter 9.4mm
-Height 2.5mm
-Current mA 1.5 (not mAh)
-Nominal Capacity at 5-hr rate(mAh)15

The last spec is what kinda sucks!

[Spanky]

i would say go for the 80mah button cells.. they may be a bit bigger but this way you will still get the same run time..

[actofgod]

If you read farther down in the Layman's dual cell thread, you'll see a tri-cell mod using those same button cells. You can fit three in the original battery compartment without any wiring/soldering needed. That sounds like what you're wanting to do, only with different batteries. Keep in mind the dimensions of the battery compartment when picking cells. Stacked end to end they should be about the same size as an original battery, unless you're planning on dremeling and soldering. You can use any button cell you want, but I don't think you'll find a better price than the 6-pack at allelectronics, unless you live in an area where they will not ship to. Check the Layman's thread for the link.

True, you could fit possibly 4 of the 15mAh cells in there instead of three 40mAh cells, but the current provided by those 15mAh cells would be so low it would hardly be worth the effort; plus, the capacity is really tiny. Even the 40mAh cells have noticeably lower current compared to the massive 1/3aaa NIMH cylindrical cells. There is a tradeoff between adding extra cells to increase voltage and losing current because you're using smaller and smaller cells. Imagine an extreme case of using 20 wafer-thin cells; in theory, you'd have 24 volts, but the current would be so tiny it probably wouldn't even move the car. 40mAh cells are about as small as you can get without trading too much current.

80mAh cells do offer increased runtimes and current, but they won't fit in your bit without modification. For an example of a mod using 80mAh button cells, see the BFM-9000 link in my sig.

Good luck.