any issues with trickle charging and maintaining AGM battery with solar panel

[nmanchin]

I have a small Deka AGM battery on a car i drive every 4-5 days. with the alarm and ecu back-up the battery discharges to about 10 volts in that time which may or may not start the car. i ordered a solar trickle charger from battery junction.

any issues with letting this maintain the battery for 4-5 days? any worries about overcharging? looks like it should provide a nice slow trickle when the sun is out. i doubt it will even top it up completely. just looking for a little more longevity.

Power: 2 Watts max.
Working voltage: 12V max.
Working current: 150mA max.

 

[drmaxx]

Are you sure that you don't have an other problem with your car? ECU and alarm should not drain a battery in 4-5 days. I would check for leakage current or then the state of the battery just might be lousy.
If this is the case then the optimistic 2 W will not help to fix the problem.

 

[nmanchin]

it's a 15 lb battery compared to the factory 37lb unit used to trim weight for auto-x. with a regular lead battery the car will stay charged for a month or longer w/out issue. i just need the solar to keep it topped up.

 

[SilverFox]

Hello Nmanchin,

I have a piece of equipment that is powered by a 12 volt gel cell. I picked up a solar panel to charge it while in the field. In direct sunlight, the open circuit voltage from the panel was 18 - 21 volts. It worked fine during the week when I was using the equipment every day, but over the weekend it "cooked" the battery.

I have used the same solar panel on an automobile sized battery without problems. The panel I have was designed to keep a boat battery topped up. To use it with my smaller gel cell battery, I purchased a voltage regulator for it. Now I don't have any "issues" at all.

My guess is that it should work.

By the way, the "industrial" method of dealing with your problem is to install a battery shut off switch. When you park the car, you flip the switch and it disconnects the battery. When you get back to the car, flip the switch again and you are good to go. This doesn't help with your radio presets or your computer information, but it does remove all parasitic loads from the battery.

Tom

 

[nmanchin]

Thanks Tom,

I'll keep an eye on the voltage. supposedly it's regulated, but it is made in china.

 

[Probedude]

If you're draining your batt that fast, I don't think this panel will overcook your battery at all. The 150mA is going to be in full sun and you won't get that for many hours when sitting on the dash of your car. Even outside of the car you won't get maybe a couple of hours at best of 150mA charge current. If it's truly regulated to only 12V out, there won't be hardly any charging going on either.

In other words, this panel may not be able to keep up with your parasitic losses.

Dave

 

[nmanchin]

thanks for the reply. even a little bit of charge should help me out a bit. if i can let it sit for a week and not worry about it starting it will be worth the $20. i don't plan on having the car sit for any longer. i hate to let them sit any longer. they need driven