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sparky30_06
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# Posted: 9 Jan 2019 07:51am
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ok it's not a fancy solar set up like many of you are running but need to build a solar charger to keep some sealed lead batteries charged up. I have several small sealed lead batteries like you find in exit lights that I want to keep topped off. Currently have 3 spares that i want to do this with. I was thinking about using a small solar panel, paralleling the batteries with a diode at each battery. am i thinking correct?
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FishHog
Member
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# Posted: 9 Jan 2019 07:55am
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you will need a small charge controller, don't go direct from solar panels to battery. I made that mistake once, cost me a battery.
No need for the diodes, check out method 3 in this link.
http://www.smartgauge.co.uk/batt_con.html
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sparky30_06
Member
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# Posted: 9 Jan 2019 08:09am
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reason i was thinking Diodes was in case on battery failed it wouldn't drain the others down.
these are small 12v 12 Ah batteries
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ICC
Member
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# Posted: 9 Jan 2019 02:41pm - Edited by: ICC
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A diode could possobly prevent some problems with one battery affecting other batteries. However, diodes cause a forward voltage drop. The diode controlled battery isolator that is used in some RV's, for example, cause about a 0.55 to 0.7 volt drop to the battery that is downstream of the diode isolator. That is simply what a diode does.
So a diode protected battery will never truly reach full charge. In lead-acid, that is a slow death sentence.
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toyota_mdt_tech
Member
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# Posted: 9 Jan 2019 08:45pm
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Battery Tender actually makes small solar panels just for that, controller built right into panel, comes in 5, 10 and 15W, I have the 5 watt unit.
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ICC
Member
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# Posted: 9 Jan 2019 09:02pm
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I have a similar small panel with small controller on each piece of farm and ranch machinery to keep the =ir batteries up. Easier than removing the batteries and trying to care for them in the shop the way we used to. But one panel and controller per battery. Of course those are $150+ batteries, not little $20 things like the OP was about.
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sparky30_06
Member
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# Posted: 10 Jan 2019 07:21am
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ICC oh I remember the days growing up and having to haul batteries out of the shop to the shed to start the tractors in the spring. I forgot about the voltage drop across the diode, been a long time since I had used what i learned in electronics class 25+ years ago. lol
Toyota I'll check into battery tender. The batteries are cheap but i like to keep one or two extra ones charged in my shack. I have 6 feeders with solar panels that usually keep charged but once in awhile the squirrel will chew the wire from the solar panel and then the battery goes dead so I keep spares
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