Battery Charging Clamp: My Variation

DonShock

Flashlight Enthusiast
Joined
Dec 28, 2005
Messages
1,641
Location
Belton Texas
As many here will recognize, I got the idea for this clamp from Cy's Battery Charging Clamp.




I actually went to the store to get a clamp to make a holder identical to Cy's. However, one of the things I wanted to do was charge cells directly in their 3AA-1D holders. Since the SmartCharger I have is 7.2 - 12 volts, it needs a minimum of 6 cells, so I have to stack 2 or 3 holders together. Obviously, this would be a rather wobbly setup in Cy's clamp so I had intended to use PVC tube cut to length to put around them to steady the stacks of 2 or 3 holders.

However, when I was at the store I saw a caulk gun and the half-circle shape with a fixed full circle end and a movable end gave me an idea. Sure enough, it was long enough for 3 cells, so I figured I might be able to make it work. I spent almost 2 hours in the store trying various parts until I thought I had a way to insulate the positive connection from the metal body of the caulk gun. But just in case I couldn't make it work, I bought the clamp too in case I had to fall back to Cy's proven design.

A little work at home and it was done. Most of the time was spent making the PVC spacer and the foot for the positive end. A caulk tube is a lot larger diameter than the battery holders so the nipples on the battery holder were below the centerline of the caulk tube and the contact was iffy. Also, there was some risk of shorts with the post ends on my Modamag 8aa-2d holder. I had previously built a battery drainer light out of a 1d battery holder and a damaged NiteIze PR based LED. I used pieces of PVC pipe on that to make shims so that I could drain all the power from Ds, Cs and AAs. I decided to do the same thing here. Cut the PVC to length, cut it in half, and heat it with a heat gun so I could get the right diameter. Two thicknesses of PVC were just about perfect. Battery holders line up dead center now.

I am going to try it for a while, but I'm not too happy with the positive end. I think I may change that. I may try filling the end with JB Weld and then tap for the positive lead bolt once it hardens.
 
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Aircraft800

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Apr 24, 2007
Messages
1,487
Location
DFW Texas.
Don,

Are you still using this charging setup? I accidentally found this old thread looking for some ideas on how to make a charging adapter for AW's "C" cells. I'd like to be able to charge both in series without magnets.

Nice work! I'll have to make one, and when I'm done charging, I'll caulk my tub:).
 

DonShock

Flashlight Enthusiast
Joined
Dec 28, 2005
Messages
1,641
Location
Belton Texas
Yep, still working fine with few problems. The only issue I've had is with thw white plastic 3aa-1d adapters. The positive contacts on them are kind of pointy and sometimes when I apply pressure with the clamp to get good contact on 3 of them in series, the center one pops out.

BTW, make sure you understand the risks of charging li-ion cells in series. There are several threads in the Battery area discussing this. Personally, I only series charge about half the time just to minimize the risks.
 
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