View Full Version : Solar car battery charger

03-13-2015, 16:03
Last summer my car started after sitting 33 days at a trailhead, but recently I needed a jump after leaving the car for only 10 days. The mechanic suggested using a solar car battery charger to prevent this in the future. He said that merely disconnecting the battery won't necessarily help much. Has anyone used one of these? Was it stolen or vandalized, or left alone?

03-13-2015, 18:23
You should be able to route the wire so it's in the windshield of the car and expose very little of it on the outside so it is basically invisible.

Disconnecting the battery worked great for me for at least 2 months.

kayak karl
03-13-2015, 20:07
i thought they plug in cigarette lighter and sit on dash (http://www.harborfreight.com/15-watt-solar-battery-charger-68692.html). they work great.

03-14-2015, 06:40
i thought they plug in cigarette lighter and sit on dash (http://www.harborfreight.com/15-watt-solar-battery-charger-68692.html). they work great.

Mine shuts off the cigar lighter when the key is off.

03-14-2015, 08:39
If your battery isn't holding a charge for 10 days, either it is on its way out or you have a parasitic current drain. While there are things in modern autos that draw very small amounts of current when the vehicle is off, a healthy battery should still have enough stored energy to start the car over that time period. If you are going to leave it for longer periods of time than 2 to 3 weeks, one of those solar trickle chargers will definitely help as it will supply enough energy to replace what is lost keeping the memory alive in all the electronics. Typically auto batteries have a lifespan of 3 to 5 years. Some may last a bit longer, but if you have a problem with one that's at that age, it's only a matter of time before it dies - usually at the most inconvenient time.

03-14-2015, 16:22
Readily available:


03-14-2015, 17:30
I would try to figure out were your drain is coming from.

03-14-2015, 17:52
VW used to ship cars with a solar panel that mounts in side the window and plugs into the harness. They are usually for sale on Ebay. Some cars electronics will pull down a battery over long periods.

kayak karl
03-14-2015, 19:49
Mine shuts off the cigar lighter when the key is off. so do mine, so i rewired it :)

03-14-2015, 21:16
Some solar chargers are NOT regulated and can do more damage than good. Be cautious when choosing a system.

Any battery that holds a charge properly will last 6 months easily before it starts to sulfate WITHOUT any parasitic loads. Your battery is junk, replace it and unhook when leaving for your hikes. If this is a regular occurrence install a master disconnect for ease of use.

It is better to fain ignorance than to open one's mouth and remove all doubt.