Keeping Battery from Dying When Vehicle Parked for Several Weeks

There was a question in the column that was in my paper today, June 22, about how to keep the battery of a 2016 RAM from dying when the truck was parked in an airport lot for 3-5 weeks. Ray suggested only an AC-powered trickle charger or disconnecting the negative battery cable as potential solutions.

I think a much better solution: a solar trickle charger. It could be just laid on the dashboard and plugged into an always-on 12-volt outlet, if there was one. If there wasn’t one, it would be easy to install one under the dash and wire it directly to the battery. These chargers are inexpensive and readily available. See

Also, if were planning to disconnect the negative battery cable more than a couple of times, I would install a high-amperage switch like the ones used to shut off DC power on boats in the negative cable.

Yeah that might work. We have been warned here about problems with cutting the power on newer cars and the problems that could cause. A portable battery booster but its not good to run the battery down continuously. Something wrong though it loses charge that fast though.

You have a parasitic drain somewhere and a good mechanic can quickly determine where it is. I agree that constantly boosting a battery is not a good idea.

My Corolla started right up after 6 month of inactivity and I have a kill switch that is blinking all the time.I bought a portable battery booster just in case I get stranded somewhere with a discharged battery. No need to call AAA with those.Capturebooster

how much is parking $$$ for 5 weeks? take a taxi to the airport.


If you’re parking at the airport that long, you’re probably taking an international flight. Some people have to drive 100+ miles to get to an international airport. Cabs aren’t always an option.

I’d want to use a “Battery Tender” brand solar charger, to make sure I didn’t over-charge the battery.

Here’s the most common thing I find . . . leaving stuff plugged in the power port or cigarette lighter, many of which are hot at ALL times

Even if you leave your phone charger plugged in, but take the phone with you, that charger’s led will draw power, and it’s surprisingly high when measured with the dmm

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I’m using two 5W solar chargers that sit on the dashboard, wired into a constant 12V line with a connector under the dash.

I started with one a year ago and added another a couple months ago for more boost.
In bright sunlight it holds the battery at 13.1V.
I drive mostly on the weekends only and mostly short trips, so I want to keep the battery full.
On my previous car I’d take the battery out every 3 months and fully charge it.
Last replaced battery was going strong after 9 years.

A friend’s MR2 spent the winter in the garage and the battery was too weak to get it cranked in the spring so the next year I disconnected the battery and all was well the next spring and several more until it was sold. My usual check for a parasitic discharge didn’t indicate a problem and sitting a week or two at a time never resulted in a problem.

A ~1amp solar charger does sound like a good solution. will it work laying on the dash plugged into a cigarette lighter type outlet and the car facing south?

Depending on latitude and season it may or may not matter which direction the vehicle faces.
About 4 hours of direct sun is plenty.
The cig lighter has to stay connected when the car is off.
Otherwise (like with my Tucson) you have to find a constant 12V wire to tap into.
Best to pick a branch circuit with a low current fuse, 5 or 10A.
I also used Anderson PowerPole connectors.