Solar panel question

[chrisga]

Please excuse me, I have absolutely zero understanding of electrickery. Anything mechanical fine, but electricity confuses the hell out of me.

We have a 100W panel mounted on the roof of our caravan. We were away without hook up for the last few days. As Thursday was unbearable heatwise we had a 12v fan plugged in pretty much throughout the night which I think may have drained most of the battery. As the following days were overcast/torrential rain we seemed to be struggling a bit for power.

We've never had a problem before and the leisure battery was new in August last year and is kept topped up at all times.

I have a briefcase type 80W fold up solar panel in the garage from our old caravan. We are soon away for 10 days, also with no hook up so was wondering whether I can just connect the smaller panel to the battery as well as the larger one. Both have their own charge controllers. Would they see if the battery needed topping up and work together, or would they somehow get confused, cancel each other out and not charge, or worse still blow the battery up if both charging full bore?

[Zoon]

chrisga said:

Please excuse me, I have absolutely zero understanding of electrickery. Anything mechanical fine, but electricity confuses the hell out of me.

We have a 100W panel mounted on the roof of our caravan. We were away without hook up for the last few days. As Thursday was unbearable heatwise we had a 12v fan plugged in pretty much throughout the night which I think may have drained most of the battery. As the following days were overcast/torrential rain we seemed to be struggling a bit for power.

We've never had a problem before and the leisure battery was new in August last year and is kept topped up at all times.

I have a briefcase type 80W fold up solar panel in the garage from our old caravan. We are soon away for 10 days, also with no hook up so was wondering whether I can just connect the smaller panel to the battery as well as the larger one. Both have their own charge controllers. Would they see if the battery needed topping up and work together, or would they somehow get confused, cancel each other out and not charge, or worse still blow the battery up if both charging full bore?

Does it not have a charge gauge?

[chrisga]

It has a digital voltage read out, not so much of a gauge. Battery got down to 10.9 ish at points before everything went off in the caravan.

[Condi]

What is the capacity of the battery and what is the draw from the fan? Seems unlikely that it would have used most of the battery in 1 night, but you can calculate how much of the battery capacity the fan uses per hour, and the see if anything else was drawing more. Fridge, etc.

[Zoon]

chrisga said:

It has a digital voltage read out, not so much of a gauge. Battery got down to 10.9 ish at points before everything went off in the caravan.

I'd say the battery is defective or at least one cell is.

[chrisga]

Zoon said:

I'd say the battery is defective or at least one cell is.

Hmm that's annoying if it is as it was new toward the end of last year. Think it was a 100mah one.

Edited by chrisga on Monday 29th July 16:14

[chrisga]

Condi said:

What is the capacity of the battery and what is the draw from the fan? Seems unlikely that it would have used most of the battery in 1 night, but you can calculate how much of the battery capacity the fan uses per hour, and the see if anything else was drawing more. Fridge, etc.

100mah I think from memory, and yes I admit we didn't turn everything else off as quickly as we perhaps should, as have not had a problem before but the sun never reappeared and the solar panel was under about 3 inches of water it was raining that hard.....

[Condi]

Was it a large or small fan? Quick google suggests anything from 0.5-1amp for a 12v fan, so if that was the only thing on it would take 100 hours to empty the battery from full. More than likely a combination of load, plus the battery not being full, plus the sun not shining very much. Even with your 100w panel in direct sunlight it would at best only keep the battery topped up if you had other electrical things on, eg fridge, tv, phone chargers, stereo etc. Doing 'a few days' away from mains power with just a 100ah battery is probably pushing your luck depending what other load you had on, and if your engine charges the battery etc.

[FlipFlopGriff]

Just put a 100w panel on the top of our motorhome. Was away from Thursday to Monday at Silverstone and although wasn't increasing the voltage much on Friday-Sunday it didn't drop below 12.5v. Fridge runs on LPG but needs 12v to stablise (apparently), so lights, a LP gas detector, water pump, charging phones, radio on 2-4 hours a day but thats it. We have 3 batteries with a combined 260Ah. I did start the engine to boost a couple of times as I was worried it would drop below 12.0v. Thursday was cracking the flags and the rest of the weekend was either extremely cloudy or pi55ing down. Mondays sunshine boosted it back over 13v.
I'd made provision for another 100w panel so going to add another now for non sunny days. We could get 8 up there but that would be overkill.
FFG

[oblio]

chrisga said:

Please excuse me, I have absolutely zero understanding of electrickery. Anything mechanical fine, but electricity confuses the hell out of me.

We have a 100W panel mounted on the roof of our caravan. We were away without hook up for the last few days. As Thursday was unbearable heatwise we had a 12v fan plugged in pretty much throughout the night which I think may have drained most of the battery. As the following days were overcast/torrential rain we seemed to be struggling a bit for power.

We've never had a problem before and the leisure battery was new in August last year and is kept topped up at all times.

I have a briefcase type 80W fold up solar panel in the garage from our old caravan. We are soon away for 10 days, also with no hook up so was wondering whether I can just connect the smaller panel to the battery as well as the larger one. Both have their own charge controllers. Would they see if the battery needed topping up and work together, or would they somehow get confused, cancel each other out and not charge, or worse still blow the battery up if both charging full bore?

Personally I'd be surprised if the battery was knackered already however I am no sparkie!

If it were me I'd do some research on some of the more dedicated MoHo/Caravan forums where you get more folks who would be able to advise you. Places like MotorhomeFacts, Motorhomer, MotorhomeFun etc where you can usually join for free or else get a certain number of free posts before you are asked to part with any readies...

It wouldn't matter that you are a tugger although I guess the forums for the big clubs (C&MC and C&CC) would also probably be able to help too...if you are a member that is.