Getting 36v from a 12v battery

On Sun, 01 Apr 2007 20:39:52 GMT, snipped-for-privacy@msn.net wrote:
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Danged if I know! If you have 3 panels, I'd just connect 'em to the batteries and call it done. Series or parallel, pick yer pony and take yer ride, either should work. I'd panel each battery individually if the batteries aren't the same model and age -- but we've been over that a couple of times already.
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Correct.
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I can only work on taxes for a little while, then I *need* coffee and a break. It's just typing, TurboTax asks questions and I type in the answers. No, I didn't have any distributions from diamond mines in Zanzibar. Yes, I did have some o' this and a little o' that, lessee, enter amount in box 3, roger. And so on.
I'll probably build the little inverter anyway just for fun. I have the few necessary parts at hand and I'm curious to see it work. Meanwhile, you could have your gate swingin' by sundown.

Hey Don, isn't amazing how much electronic engineering comes out of people who mostly seem to have learned all they know from E-Bay ads ? :-) ...lew...

On Mon, 02 Apr 2007 21:33:45 GMT, Lew Hartswick
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Hey, I didn't learn it all from e-bay ads - I just didn't have my reference books handy, and wanted to show what could be grabbed off ebay (scrounge mode). without getting into anything complicated.
I used to do some product development - stuff like conversion boxes to run 12 volt trailers on 24 volt landcruisers - both the lights and electric trailer brakes. Sold several dozen of those conversions years ago. Also built and drove my own electric conversion of a Fiat 128L coupe. Used to do board level repairs on computer motherboards too - back when it made financial sense to do it.

clare at snyder.on.ca wrote:
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Hey Not refering to you specifically just in general the kind of things that pop up here and there. There are a few electronic engineers around here, some have been retired for a few years and are a little behind all the latest developements :-) ...lew... vacuum tubes through CMOS :-)

On Tue, 03 Apr 2007 02:01:08 GMT, Lew Hartswick
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Ain't that the dyin' truth! I don't even understand most of the acronyms used in the trade rags anymore -- but I still have my tube manuals! I won't mess with any surfacemount part having more than 20 pins if I can avoid it, and I need a dang microscope even to do that. I think Jenny picked the right pony in using a stack of solar panels, but I've continued to mess with that little dirt-simple inverter anyway just for fun. It works quite well.

On Sun, 01 Apr 2007 20:39:52 GMT, snipped-for-privacy@msn.net wrote:
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This circuit is not a charge controller, it is a 12 to (whatever voltage the battery stack requires to charge) converter. It's essentially a current supply with indeterminate output voltage. The series battery stack (and perhaps a zener clamp) will determine the stack voltage under charge.
Read back thru the thread. I did too, and saw that I didn't make it clear that this would run off your 5W panel and up-convert.
Jenny: "But a 10-buck 12-36 charger sounds good and I do already have the 5W panel."
Roger that, here ya go. I undershot the 10 bux by a bit but you could always buy spares. <G>
Not to say that this would be better than or even as good as buying more panels and stack them in series, not at all. That'll work too, and it's simpler. Simple is best when it works, and it should here. Pick yer pony. If you use small batteries then I agree with Clare that you probably should zener-clamp whatever charger you use.
You should definitely zener-clamp this little converter circuit because it could easily produce 60 volts if a battery came unstuck. It draws energy from the solar panel at whatever voltage the panel supplies for a little while (some microseconds or milliseconds) and then delivers that lot of energy to the load at whatever voltage it needs to accept it. Then it does it again, and so on. Bit like an impact wrench, flywheel effect sort of thing.
BTW, I got my taxes nearly done YAY! I've told myself I won't go pick up a pistol that's waiting for me until I have my taxes done, and I *want* to try it out ASAP, oh my yes!
You have several choices before you now. Pick one and go do it!

Thanks again Don and Clare,
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I am going for the most simple for me which will be 3 of the HF 1.5W panels individually hooked to 3 batteries. I have some gell cells stripped from old UPS' I was given. I hadn't thought of using anything that small but will give it a shot. I already have one of the HF 1.5W panels so will order another two.
Thanks to everyone who jumped in to help. Much appreciated.
I am making new geometry mounts today and the gate should swing later this week. Got other stuff to do as well, including MY taxes before May. Haaaa! Fat chance. <grin>
Phew I am glad THAT thread is over. LOL

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This has gotten waaaaay to complicated.
Solution l. Use three 12 v. batteries in series. Harbor Freight has solar chargers on sale for $14.99. Buy three, one for each battery. No fancy connections required...
Solution 2. If you already have a big 12 v. solar panel you want to use, again, use the three 12 v. batteries. Build a simple charge pump to generate something over 40 volts (a four stage charge pump should do it) and charge the whole series string together. You should be able to build a 4 stage charge pump for around ten or fifteen bucks...

On Thu, 29 Mar 2007 17:19:21 GMT, "Jerry Foster"
Hi Jerry,
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Thanks for the splash of cold water to the face. That's where I started with this except using 5W panels, but after some Math and as you point out, the 1.5W ones will do fine. Besides I already have one of those somewhere, just need two more.
I am still thinking about that pneumatic version. Got a nice ring to it. <g>

What's that Lassie? You say that snipped-for-privacy@msn.net fell down the old rec.crafts.metalworking mine and will die if we don't mount a rescue by Wed, 28 Mar 2007 17:11:05 GMT:
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Could use a DC-DC converter to boost the 12V from the solar cells to 36V to charge three batteries?
Dan H.

On Fri, 30 Mar 2007 03:39:24 GMT, snipped-for-privacy@privacy.net (dan) wrote:
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Thanks Dan, I looked at them a few days back and a bare converter from Mouser was around $72. Makes the $125 surplus unit look pretty affordable. I am currently going with the 3 x $15 panels from HF and see how that works.