Posted by nicksanspam on October 5, 2008, 5:36 pm
That sounds more like a max than a min.
If a battery takes 3 weeks to self-discharge, we might keep it charged
with 80AH/(3x168H) = 160 mA, ie 1.9 watts, on a continuous basis.
Posted by Eeyore on October 5, 2008, 11:43 pm
Which is ~ 45Wh per day. With maybe 2 hours eqivalent peak sunlight in winter
that would require a 25W panel (allowing some margin).
@ a typical 15% efficiency a 1 metre square panel only provides 150W so you'd
need a 0.17 m^2 panel. Say 1 foot by 2 feet and it must be in direct sunlight !
No guarantee of that so maybe a 2 foot sq panel would do.
BUT, with heavy loads on it, I bet his battery won't last 3 weeks either.
Increase the numbers accordingly.
Posted by John on October 6, 2008, 6:49 pm
Apologies but I've not had time to read all the responses yet, but
just to quickly confirm my battery is only an 48amp 12v gel type
battery in my car. It is just for a small 1.6 litre engine petrol
Thanks for all the help and advice,
Posted by John on October 6, 2008, 6:54 pm
So 48 amp battery 4.8 amps to charge.
If it lost 32 amps I don't think it would start at all ;) it would
only have 16left.
okay, taken onboard.
Would 15w do for 48 amp battery? I am guessing the 25w was for 80amp?
Posted by Eeyore on October 7, 2008, 10:38 am
Not a hope in hell.