Discharge cutout circut for Lipo packs

[thermalking]

Does anyone have a design for a simple circut to discharge Lipo packs to a user specified specific voltage? I suppose a circut that would work for 3s Lipo packs would handle most of my packs, but I do have a couple of 2s and 4s packs in my inventory.

What I want the discharger to do is to discharge at 8-10A and cutoff at a user defined 50% usage level.

Any ideas are appreciated.

[Dan Baldwin]

This thread has a couple of approaches to discharge controllers. http://www.rcgroups.com/forums/showthread.php?t=725572
I posted one that should work for you in post #6. You could use light bulbs in parallel to get the 8-10 amps you are looking for, but you'll probably want to use a lower RDS(on) fet than the IRF520 for that much current.

Dan

[thermalking]

Dan, thanks for the reply. I dont know a great deal about building circuts, but I am interested to try this out. Will I have to order these parts from mouser, or will my local radio shack have equivalent parts? Do you have a picture of the circut you built so I could get an idea of what I am looking at?

Thanks,

-Jay

This thread has a couple of approaches to discharge controllers. http://www.rcgroups.com/forums/showthread.php?t=725572
I posted one that should work for you in post #6. You could use light bulbs in parallel to get the 8-10 amps you are looking for, but you'll probably want to use a lower RDS(on) fet than the IRF520 for that much current.

Dan

[Dan Baldwin]

Radio shack won't have some of the parts. If you have a real electronic store nearby they probably will, or you can order them from Mouser.

I don't have a picture of the circuit because I only built it on the breadboard. The discharger I use is the first one I posted in that thread.

Dan

[coriolan]

Have built several from that circuit:http://www.uoguelph.ca/~antoon/gadgets/cycler.htm
Which can be adapted to any voltage cut-off and amp load by varying Rload
and adjusting P1. My latest is for 2 or 3 cells Lipo with cut-off at 6V and 9V
and a load of 3 4 ohms resistors in parallel (about 1.3 ohm). They are 50watts and get quite warm in use despite their built-in heat sink and being
mounted on a heavy heat sink with fins. For relay I use an automotive 12V/30amps relay.