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Battery Solar Panel Charging


Guest Brian Thomas

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Guest Brian Thomas
Hi, Until 18 months ago I used to be a caravanner and used 2 small solar panels connected in parallel to keep my 110 amp liquid battery charged up. These panels were sufficient to keep the battery topped up for a weekends rallying with about 3-4 hours TV usage (wintertime) per nite. This last weekend I thought I'd take the panels with us on our weekend away with the Motorhome. These were connected through the fitted solar panel connection point and then direct to the battery but despite some good sunshine and daylight, didnt make any difference to the battery. The battery in the MH is a Gel type, so my question is should this make any difference, and if so why? Would be grateful for any reasons for this.
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The battery being "Gel" type should make no difference. I am suspicuous of the wiring and other aspects of the instalation. If it worked before it should work now. I guess the special connection for a solar panel has never been used or checked previously?
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Guest Brian Thomas
Yes, I didnt think it should make any difference either. Wired it thru the 'special' solar panel connection (2004 Adria so shud be ok) but made no difference, hence the wiring direct to battery, still no joy. Wired exactly same as I used to use it on the caravan.
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Frankly, I'm surprised that what you describe as two small solar panels ever made a difference! It may be that your motorhome has a background use of power greater than a caravan - things like water pumps, lights, spark ingition, etc., all use power. And a small solar panel will not provide much output. If you have a couple of 15 watt panels, then each is going to supply less than 1 amp under full, direct sunlight (15watts / 16.5 volts (the output voltage) = 0.9 amps. And this is ideal conditions; under cloud you'll get maybe 0.1 amps. Even if you keep them at right angles to the sun's rays, you'll be lucky to get 10 amps per panel on a clear sunny day. Enough for the TV, yes, but that output falls drmatically if a cloud blocks out the sun or if your panels are not propped up but laid flat. You can check the output by measuring the amps between the positive lead and the battery positive terminal (with the negative lead connected to the battery negative terminal. If you haven't got a multi-meter with amps, but one at Maplins - under a tenner and an essential motorhome accessory!
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Guest Terry P
Hi Brian With reference to your Solar Panel problems I am surprised that you ever got as much out of your panels on your caravan I have a 75 watt panel on my Motorhome and yes I can do must of what you are saying but if I have the tele on and run the water pump you soon see a dip in the power and thats with no lights on, I have in side my van a sunray gauge this tells me what amps is going in and if I press a button on the gauge it tells me the volts going I wired all of this in to my zig panel the best I have ever seen going in to the battery is 3.6 amps but again this depends on the state of your battery if you have just had a decent run the battery may be well charged. I have proved by taking the leads of the lesuire battery and tested with ameter across the leads and the volts /amps are almost the same as the Sunray meter I would suggest as Brian advises that you test across the leads as they go to your lesure battery you can get as I have a clip on ampmeter from any good car excesery shop althought these are now spot on the do give you a good guid if anything is going into your battery Terry P
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