Thread: 12V caravan battery charging

I don't think that is bad at all. What is the max output into the batteries? If they are fell cells they don't need to be running at 14.5 volts like car lead acid batteries. Anyway 0.6v drop on 4hrs is pretty good.

After re reading. I'm pretty sure you're not meant to mix different types of batteries on the output of the inverter. I don't mean brand i mean gell cell vs lead plate batteries. The solar panels are not necessarily running 100% efficient just because its sunny. If you're panels are charging the batteries and running your tv it could explain poor performance if you do indeed believe it should be better. If those 3 batteries are wired in parallel it doesn't matter if one has more wires to it. It is more likely a battery is on its way out or because the batteries are mis matched and have different charge and discharge characteristics.

The way I read it....


if the batteries are good and you reached a static voltage of 12.9v, your 300ah of battery storage has gone from 100% to 70% in 4 hours.....so average 22.5amp load.


or, with a 3.5amp load...you have 46ah of usable battery storage...

Thats the sort of figure i worked out Rick,, but there just isnt that sort of load--

Try fully charging batteries seperately, then put a moderate load on them for 15min or so. Guessing you have one dead one, and it will drop its voltage very quickly. May also be stopping the other two from fully charging.

If I disconnect all the batts, can I assume the one with the low charge is the bad one?
charging all three at 48 hours each to check Volts is a worry,,,

I'm a bit confused What's the purpose of the S240-12 device? From the specs ...you input (say) 240V AC and you get (say) 12V DC out of it. ... Is this device running the TV? So is the TV a 12V DC device? Or is the S240-12 powered from the batteries via a "12V"- sinewave inverter to get clean 240V AC which feed the Meanwell which feeds the 12V TV?... ..if it's the latter then you might only be getting about 70% efficiency out of the inverter plus more losses through the S240-12 ...
How did you calculate the 3.5Amp current draw?

EDIT: do you have protective diodes in the solar charging circuit to prevent the batteries charging the panel at night?

Originally Posted by Pedro_The_Swift

If I disconnect all the batts, can I assume the one with the low charge is the bad one?
charging all three at 48 hours each to check Volts is a worry,,,

Maybe...


Think a dud one may get a surface charge pretty quickly, this may fool the solar controller into float and result in none of the batteries actually getting a full charge.


Would be worth a go tho, I certainly would as a 1st step, and if one is considerably lower, drop it out and see how it goes with just the two others.