1.5w solar charger on a 50-60Ah starting battery

[AbyssUnderground]

Hi all,

I was just wondering...

I have put a 1.5w solar charger on my car battery (around 50-60Ah) and was wondering if it is safe to leave it connected indefinately with no charge controller or do I risk boiling it away (the electrolyte levels are perfect at the moment)?

Its only there to keep it topped up while Im not driving it as starting it up for 15 mins every few days doesnt seem worth the diesel or the time.

Max output 125mA, connected directly to the battery (which is disconnected from the car anyway).

Any thoughts? I do have a spare C/C I could use but its not very good (off at 14.2v on at 13.2v).

Thanks.

[margusten]

Hi,

You don't need any controller.

This tiny solar panel can't hurt 50AH battery.

Only problem:

If battery is empty, You have to wait 3 months before it's full.

You can always check the voltage of battery.

[AbyssUnderground]

The battery read 12.90v before I hooked it up so its not flat, its just about full.

[Ungrounded Lightning Rod]

Its only there to keep it topped up while Im not driving it as starting it up for 15 mins every few days doesnt seem worth the diesel or the time.

If it's anything like the Yanmar on my boat you'll want to start it and run it for 15 min at least once per month, to keep the surfaces in contact with fuel and exhaust clean and protected from corrosion, circulate the oil, and boil out any condensation.

[AbyssUnderground]

Yes Im aware of this one, and I will be doing. But I dont want to be starting it every few days/once a week, but leaving it a month without starting will drain it past the safe 5% by quite a lot.

[Ungrounded Lightning Rod]

Yep.  A month is too long to let the battery go without some sort of charging.  (Especially once it gets old and starts to self-discharge:  Not keeping it floated once that starts will produce a positive-feedback that end-of-lifes the battery in short order.)

I just wanted to make sure you weren't planning to leave the engine stopped for months at a time.

[tecker]

The battery maintainer will keep it up no problem the small amp connections need some grease to keep them clean . Over charging is a problem in some cases .A lm317 is a good add and you can adjust the voltage max with a fixed resistor . The only other problem is sulphation . The jury is still out on that one . I use a 15 amp Batteryminder an also several different pulse chargers . It seems like the Batteryminder preforms well there's two pots inside the case of the unit a little tweak and your always doing a maintenance charge .

[AbyssUnderground]

Would 14.45v from the alternator be safe for this battery? I was testing it earlier and this is what it was at.

[tecker]

Two volts is nominal an 3 over is good If the water is good .