I Have A 1.8V Eliminator Solar Charger. How Long Would It Take To Charge An Almost Dead 12V Car Battery

There are 3 Answers

1. UCANTCME says:

   24 to 48 hours.

   Remember that if a battery was slowly discharged then you will need to slowly recharge it because charging it fast will cook it and it is just the opposite for a battery that was discharged fast.
2. pbleek says:

   These things are used to maintain a battery, I doubt you could fully charge a battery with a small solar charger. You may only have 6-8 hrs of effective sunlight per day, and depending where you are many cloudy days.
3. Don K says:

   I am guessing you meant 1.8 Watt not 1.8 Volt? If it is 1.8 volts you could only charge a small double A battery or the like.

   You will never charge a car battery with a 1.8 watt solar charger.

   I don’t know the math right off hand to convert Cold Cranking Amps over to Amp-Hours. Car batteries use Cold Cranking Amps where Solar batteries normally are rated in AH.

   It normally takes a minium of 5% rate of charge but should be 10%. So if you have a 100 AH battery at 12 volts.

   100 times 12 = 1200 watts. 10% would be 120 watts in solar power or about 10 amps.

   Now something else to think about is what do you call dead?

   If you took 50% of the power out of the 100 AH battery you would have draned it by 50 Amps. At 10 amps from the 120 watt panel would take a min of 5 hours of sun. And there will be some power loss in the system.