I stopped in my local recycling center to drop off a few things and scrounge for computer power supplies to reuse their casings, unfortunately with no luck.
However, I did find these very long, heavy UPS units that look like they were a part of some industrial rack mount server set up. I grabbed two and stuck them in my trunk, as I figured the cases might be useful in the future.
But when I got home and cracked them open, I found perfectly good batteries at or above 12v and already wired in series, giving 100+ volts per setup. I took off a couple of batteries and wired the two packs together to give 177v, exactly what I had been advised by Mike D to set as the top end for the basic grid chargers.
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I stuck them in my trunk open just to see them in place. The current cases could be used, but with some modification. I figure that these wouldn't work as a replacement for a parallel pack, because the batteries state a max draw of 2.8A. However, if you're in a spot where you can't plug in (like at work, if you've got a job, or at the mall, etc). They're also 7AH, which should be more than enough capacity. But how would these batteries respond to significant cycling?
Charging Off The Grid? by
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The 2.8A is more than enough, and something would have to be put in line with something to limit the current. Cobb mentioned using PWM, but I'd have to do some learning in that area. Suggestions?
What do you guys think... would it be worthwhile? It seems in certain situations, where you might drive 25-50 miles one way and not have an opportunity to charge for the trip back, it might work well. But this would be offset by around 70lbs of weight (assumed as they say 40lbs per pack, minus two of the batteries).
Alternatively, they could be wired up in Parallel and an AC-DC converter could be used (stripped from a standard UPS) to power a grid charger. The low power 350ma wouldn't be enough to give you a good charge over the course of a few hours, but running it in parallel with my 1.05A lunchbox charger could give a significant boost while spending a couple of hours in the mall, etc. But that's an extra step and more power would be lost, giving off more unwanted heat in the cabin, no?
"Delta" - 1A Lunchbox Charger by
Artric, on Flickr
Note that this unit is not limited in any way, so there are no protections against forgetting and leaving both running, pushing 1.4A into the pack for a number of hours. A lamp timer or other shutdown circuit would be needed. I'm working on learning Arduino with a new friend and may integrate that into my system to cut it off at a certain voltage, temperature, or under other conditions. It's a really neat platform.
Any ideas on putting these puppies to use, or advice as to why even tinkering like this is a bad idea, please feel free to let me know!
Using Lead Acid UPS Batteries to Charge off the Grid? Junkyard SCORE!
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