Solar battery charger?

demarpaint · Sep 28, 2008

My son came back from a deployment to Afghanistan and had to replace the battery in his BMW. He will be headed back again this spring and we were wondering if a Solar Trickle battery changer will keep the battery charged? He has a place to park the car, but I had told him not to have his buddies wife start it, since he did a pretty good job prepping the car prior to storage. I figured the 30 minute idle once a month might do more harm than good.

If the solar charger is any good does he have to disconnect the battery and leave it connected to the solar charger? Or can he leave the battery connected to the terminals and connect the charger leaving everything as is?

As always thanks!
Frank D

XS650 · Sep 28, 2008

I would recommend taking the battery out of the car and leaving it hooked up to a smart charger like a Battery Tender Plus. The BT+ is a trickle charger that shuts off when the battery is fully charged, then comes back on when the battery voltage drops a bit.

They a good enough that they won't stress a small motorcycle battery but they will keep a full sized car battery charged.

JHZR2 · Sep 28, 2008

demarpaint · Sep 28, 2008

Thanks for the info. I should have mentioned this time around I think he will be parking it in a fenced in area on the base and will not have access to any electric. Any other suggestions? He has a new battery in the car now.

Frank D

chevrofreak · Sep 28, 2008

I've used 1.5W solar battery chargers and they do their job. I only get about 2/3 of the rated wattage of solar panels in Montana, so 1W at peak isn't actually that much.

You can find some solar battery chargers on Ebay that plug into the OBDII port to keep the battery charged, and they have suction cups to hold them to the windshield. They're usually ones that VW had on their cars to keep the batteries charged before the cars were sent to dealerships.

mstrjon32 · Sep 28, 2008

If you're in NY, I'd definitely take the battery out of the car and leave it inside the house where it won't be subjected to cold weather and temperature variation.

demarpaint · Sep 28, 2008

Originally Posted By: mstrjon32
If you're in NY, I'd definitely take the battery out of the car and leave it inside the house where it won't be subjected to cold weather and temperature variation.

I'm in NY, my son with the car in question is on Whidbey Island in WA, and can't take the battery out. The car will be parked on the base in a lot this time.

Frank D

Aldaris · Sep 29, 2008

FWIW I had bad luck with the solar chargers that get plugged into the cigarette lighter on my Toyotas. No word yet on if directly connecting one to the battery would work better or not.

chevrofreak · Sep 29, 2008

The ones that plug into cigarette lighter sockets won't work on all vehicles since they're a switched socket on many newer ones.

I wonder if that was your issue?

johnd · Sep 29, 2008

It isn't in a car but I have a solar setup at the house to charge deep recycle batteries for my ham radio setup. Harbor freight makes a solar charger regulator that works very well for this. Costs about $30. You are going to need a solar panel that is at least 6 watts-12 would be better, based on what I have seen at home to float charge a battery. My setup is two 45 watt, three panel sets but I'm charging two car batteries, not maintaining one. He cigarette lighter would be the easiest access point.

Aldaris · Sep 30, 2008

Originally Posted By: chevrofreak
The ones that plug into cigarette lighter sockets won't work on all vehicles since they're a switched socket on many newer ones.

I wonder if that was your issue?
Absolutely must have been.

JustinH · Sep 30, 2008

VW puts solar chargers on the cars when they come from europe on the boat.

They find their way onto ebay, search vw solar or similar.

Usually about 30 bucks and they work fine.

You might be better off taking the battery inside and keeping it warm instead of letting it stay ice cold.

moribundman · Sep 30, 2008

Originally Posted By: JustinH
VW puts solar chargers on the cars when they come from europe on the boat.

They light up the inside of the car carrier vessel sufficiently to keep the batteries topped off via a solar charger? And they do it via the OBDII Port instead? It's only a two week trip!

JustinH · Oct 1, 2008

http://shop.ebay.com/?_from=R40&_trksid=m38.l1313&_nkw=volkswagen+solar&_sacat=See-All-Categories

Yep, obd2 port..

moribundman · Oct 1, 2008

I know those chargers are on ebay. My first question remains unanswered.

daves66nova · Oct 1, 2008

why not sell the battery and buy a new one when he gets back?

Trav · Oct 1, 2008

IMHO the VW solar seems be a great way to go.A fully charged battery doesn't need much to keep it that way.Going through the OBD II port is nice,one of the big plus points i can think of is the ECM and radio settings will be kept with this unit.If you live in a state with OBD II inspection this means the ECM wont need to go through setting the monitors which can be a real PITA with some cars,in any case keeping the ECM settings means no re-learning so drivability will be the same as when he parked it.
A little STA-BIL in the gas would be helpful also.

eljefino · Oct 1, 2008

I bought one of the vw/audi solar panels on ebay and it had a cig plug. Guess they updated them.

Cold is not bad for batteries as long as they don't discharge and freeze.

One could pull ECM and radio fuses and cut most of the parasitic draw, while leaving the cig lighter active. Put the fuses in an envelope with instructions in case heaven forbid someone else needs to start and move the car.

Solar battery charger?

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