Battery charger help

As some of you may already know, I'm planning on building an electric car this summer. Its all planned out, but instead of using regular transformer based chargers I was wondering if someone could help me design a transistor based charger to reduce weight. Requirements 48 or 72 volts Needs to charge marine deep cycle batteries over night Needs to not have a transformer. Needs to be relatively small (under 1 cubic foot) Needs to be simple enough for me to build myself (I can do it if you can design it) Can anyone give me some links or some good schematics for this? Thanks

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110100101109 years ago
I'd charge the batteries in parallel off a computer PSU Or hack the PSU to add higher volt output Or just charge the batteries with pulsed 240 V DC thru resistor (wont be nice if something fails but the most lightweight solution ever)
LinuxH4x0r (author)  110100101109 years ago
Yeah, thats what I was thinking, except off of 120. I was also considering a PSU for each individual battery
You dont need PSU for each battery. They output some 10 A on the 12 V wire and maybe more if you improve cooling in the PSU I am looking now at the circuit board of a PSU like this It looks like if you connect a 4 diode bridge from the 2 12 V outputs on the large transformer you can get 24 V DC (with some relation to earth - not floating) Max current on 24 V with good diodes is 1/2 what you could get on 12 V
LinuxH4x0r (author)  110100101109 years ago
Yes I would, I need huge amounts of current if I want to drive it and fully recharge it every night.
edgarcia579 years ago
I got a capacity charger for my EV. It has 3 large capacitors, a timer, and a multimiter. Paid $165.00 w/shipping. Got it from Nile Cole at It charges my 90 volts system.
LinuxH4x0r (author)  edgarcia579 years ago
sounds like a good deal!
CameronSS9 years ago
Battery chargers aren't really all that big or heavy, particularly if you're only charging a small 72V pack. I would recommend just buying a used 72V battery charger, as building your own charger will take up a lot of time that you could be spending modifying the car. Is that a Honda CRX?
LinuxH4x0r (author)  CameronSS9 years ago
I was thinking of individually charging the batteries, but your suggestion might also work. Yes, its a 86 crx (the most efficient model, forgot the name)
And why are you bothering hybridizing an '86 CRX? They already get better gas mileage than a Prius.
LinuxH4x0r (author)  CameronSS9 years ago
Prius is the biggest fake ever. I'm doing more of a plug in hybrid. The batteries aren't charged by the engine. I just want to have an electric and still be able to go to Albuquerque or Los Alamos or some other place farther than 20 miles. Actually, I might make it charged by the engine once I finish it.... If I was buying a new car I'd buy a VW golf TDI. 48 mpg!
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