The Layman's Dual Cell Mod (tm)

[actofgod]

If you can swap a battery, you can dual-cell mod your bit!

This mod is for all the people who don't like the idea of using a dremel on their bit to do a dual cell mod. This is the easiest dual cell mod you can do since it fits in the original battery space without modification or soldering required.

Other advantages include the fact that it does not adversely affect your weight distribution. Your car will not flip over, spin out, or wheelie because of extra battery weight; in fact it weighs less than the stock battery which is great for those interested in trimming off extra weight to increase speed and acceleration.

The one disadvantage is that the capacity is only 40mAh, less than the stock NiCd's 50mAh and much less than the 150mAh NIMH replacements. *BUT* if you've been following the Peak Charg'd thread over in the Bit Science discussion area, you know that even the stock NiCd is not charged fully with the rapid charge method. A fully charged STOCK battery will run for 45 minutes if fully charged! So this one would run for "only" 36 minutes fully charged. You probably won't fill up the capacity anyway with rapid charging from the controller or a custom built charger, so it should run just as well as any other battery. I charge my Layman's Dual Cell with a 3v 500mah adapter for a few minutes and it runs longer than my stock controller-charged bit. You should probably charge at a lower current (250mah for a few minutes longer maybe) since the batteries are so small, but even if you manage to burn one out, you have four more batteries left from that original pack, and each pack of 6 cells is only $1.50 anyway. Pics are attached below.

Installation:

First, I have to thank Ovgron for finding the batteries I used. Check out allelectronics.com for the listing of the multipack we'll be using, CAT# NMH-11. If you do order this item and are already paying shipping, you should also check out my Infinite Speed Potentiometer Mod (tm) for a potentiometer that this store also sells, CAT# SVP-20.

First, remove the heat shrink from the batteries, and you're left with a string of six (not seven like the catalog says) tiny button cells, all connected by strips of metal. Snip off the two closest to the end with wire cutters (setting aside the other four for extras). Break them apart in the center (superglued) and fold them in half. You've just finished most of this mod!

Grab a bit battery (preferably stock since the NIMH replacement batteries are actually a little shorter) to use as a measure; bend the center metal piece still connecting the two batteries until the total length is the same as the bit battery. Now test-fit the battery inside your bit (the narrow end goes where the positive "button" end of the stock battery went). The idea is for the metal piece connecting the two tiny cells to serve as a spring to tension-fit the cell in place. You may have to trim any little bits of metal left from the original attachment and use a razor to scrape off excess superglue, but leave the center piece of metal alone. It takes a little fiddling to get it to fit correctly, but I've found that the easiest way to fit it is to put it in place while it is stretched a little wider than necessary, angling the lowest part of the metal connector down and pushing down on it with a small flat screwdriver. Once it is in place, you can take two small screwdrivers and pry the batteries apart, pushing against the terminals as snugly as possible. Test it before you put the PCB back on to make sure it is charging. Shake it around a little and make sure it is still connected. If not, you may have to put a dot of solder on the terminals to hold it in place (but since I promised you wouldn't have to solder, you can wedge a thin piece of metal in there instead). If you can't get it after several tries, take it out and stretch it back to the original dimensions, then try again.

This is the dual cell mod of choice if you want to have room for other mods and stay inside the stock case, like the Infinite Speed Potentiometer Mod (tm) mentioned earlier.

Let me know if you find this post useful or have any questions. Happy modding!