SLA in parallel, charging

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SLA in parallel, charging

Postby ShreddinPB » Wed Aug 08, 2012 12:17 pm

Hey guys.. this is my first burn!
I am in the process of making a bucket swamp cooler that I saw on here and have a question about running it, and possibly some other items (lights most likely).

I have 3 x 12v SLA 12Ah batteries. I also have this solar panel and charge controller already.

charge controller ... ry+charger

panel ... sim_auto_2

I guess my question is simple.. can I just wire all three batteries in parallel, and hook the panel to the charger, charger to the batteries, while running the pump and fan at the same time?

There shouldnt be a problem having them all connected at the same time correct?
Is that panel and charger combination going to even make a dent in charging essentially a 12v 36Ah battery?


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Re: SLA in parallel, charging

Postby some seeing eye » Wed Aug 08, 2012 1:04 pm

Welcome to Burning Man and eplaya.

That is a pretty small panel. Maybe 40 hours from that panel to charge 1 of those batteries.

Here is one approach. Carry your batteries over to Snow Koan camp which is bringing a 30?KW array (big), and also setting one up by the Man, to charge people's batteries, for free, of course. Snow Koan and the Alternative Energy Zone give on playa advice and training in solar. For free!

Bring the batteries, try to buy any other stuff later.

Also good to buy 12v LED lights, make your 12v swamp cooler and all for this year. A plastic tub for the batteries and connections, and a fuse holder with a bunch of fuses is a good idea. Also a volt meter to check the charge on the batteries.
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Re: SLA in parallel, charging

Postby ShreddinPB » Wed Aug 08, 2012 2:59 pm

Thanks for the advice!
Already planned the rest of that.. led lights, tub for batteries (it came off my electric skateboard that I crashed and killed the front of) and a multi meter :)


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Re: SLA in parallel, charging

Postby Trishntek » Wed Aug 08, 2012 5:38 pm

In parallel, your three batteries have a full potential of 384 watt-hours. You really do not want to go much beyond 45% discharge in order to:

1. Recharge them in a reasonable amount of time.
2. Prevent more than 50% discharge which decreases the life-span of your batteries by nearly half.

The answer to your question about simultaneous charging and service, the controller should handle both load and charging at the same time. Think of it as the gate keeper to keep juice going where it should and prevent it from going where it should not.

Your panel is very small. Assuming you might use 200 watt-hours per day. it would require your panel to optimally produce for 40 hours per day. The sun doesn't shine for more than 10 useable hours and maybe only SIX of those would be near optimal.

So consider a larger panel capable of producing 40 watts. That would provide you with more than 200 watt-hours per day. That would be pushing your batteries hard to use that much juice every day. But that is a good worst case scenario given the equipment you have.

ETA: That would mean a larger capacity controller. You would need one in the 5-10 amp range. The one you are looking at is 7watts. You need one that could easily handle the 40 watt solar panel. Go with a 60watt (5 amps) controller, and you'll be golden.
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Re: SLA in parallel, charging

Postby BBadger » Wed Aug 08, 2012 6:33 pm

I swear, this is a troll post.
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Re: SLA in parallel, charging

Postby ShreddinPB » Mon Aug 13, 2012 11:08 am

well since I already have the things listed I Am going to stick with them for this burn..
I did drop my waterpump down to a 500ma one so that is going to save me a lot of power!

And BBadger, which post? Mine is real, I am trying to figure everything out.

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Re: SLA in parallel, charging

Postby nixiebunny » Wed Aug 15, 2012 6:59 pm

I concur that the 5W panel you bought is way too small to have any effect on those huge batteries.

If you want to charge the batteries with your own solar power, try this company for panels that cost a lot less per watt:

I don't get kickbacks, I just use their stuff because it works and doesn't cost too much.

Scroll down past all the weird stuff to get to the raw panels that are priced about half what you paid through Amazon.

As the previous poster said, 40 watts is about what you'll want.
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