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Old 02-14-2009, 11:47 PM   #23 (permalink)
rmay635703
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Join Date: Jun 2008
Location: Somewhere in WI
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I believe the most important thing to make a diy on is the CHARGE CONTROLLER

It is easy to make a dumb charger out of most anything, I even made a higher tech version of this thing to desulphate/controlled overcharge bad batteries

3 Dollar Battery Charger

As stated earlier, The trouble with any of the DIYs is we need a

1. SIMPLE
2. Cheap
3. Reliable
4. Safe will be a function of the charge controller

Device that can turn a contactor or mosfet on and off at preset voltage levels, example my pack voltage should be around 76.5v the max overcharge is usually around 81v if I had a simple, cheap and reliable device that could turn the juice on when voltage was below 76.5 and turn it off once it reached a preset max like 80/81v or whatever pleases me at the time (adjustable would be best) we would be a long way toward making existing cheap chargers safer and ones we build more effective and safe.

The next step would be to make a charge controller, I hear there are AC pwm dimmer switches around for lights and other household items (never knew that) if a controller could be setup to trim the pwm dimmer switch or equiv you could easily control charge current and follow a taper pattern. The beauty of any PWM system is that you end up with a pulsing pattern which helps desulphate batteries as well as charge them.

I think this is a more logical 1st step as suitable transformers are in almost every device I can think of, I just trashed out an audio system for someone to get their CD's out and got a boatanchor multi rail power supply with either of the above devices and a simple diode or bridge rectifier I would have a cheap reliable 8 amp multi volt charger.

Another type of charger I have been contemplating is a cap dump charger you need an input cap of high capacity and an output cap of very low capacity, 50/50 pwm oscillation speed determines charge rate (strap ac to large cap 1; unstrap ac and strap large cap to small cap2, cap 2 discharges into battery while cap 1 charges off ac line current through a bridge or diode)

Anyway I think a workable DIY charger is MORE important than a diy motor controller because it is simpler & cheaper to impliment on your own without lots of knowlege, it also seems to be an item that burns out more often as well. Not to mention a decent charge controller DIY could also spill into other things such as renewable solar and wind systems.

Cheers
Ryan
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