Tender a safe, cool option to keep a battery alive
Dear Car Talk: We will be gone for a couple of months, and I want to keep the battery charged on our 2018 Honda Accord while we’re away. My plan is to buy a fully automatic battery maintainer for the car.
I will attach the thin wires to the battery, and the main unit will sit outside of the engine compartment and be plugged into a wall socket. Do I need to keep the hood up while the battery maintainer is connected? My concern is the rod that props open the hood will bend or warp over those months.
Option 2 is closing the hood on the wires. Option 3 would be to prop the hood open an inch or two with blocks on each side, allowing for ventilation while supporting the hood.
Thank you in advance for your advice. — Tim
A: Sounds like you’re worried about burning the house down, Tim. In which case, ask a neighbor if you can park the car in his garage. Actually, there’s no reason why you have to keep the hood open at all.
The automatic battery maintainer you bought — sometimes called a battery tender — plugs into your wall socket and monitors the charge level of your battery.
When the battery drops below a certain voltage, the maintainer turns itself on and charges the battery until it’s full again.
That’s a job normally handled by your car’s alternator while the engine’s running. But if your car is going to be parked for a long time, a battery maintainer ensures you won’t come home to a dead battery.
And I’m guessing you’re worried about the device producing too much heat. But charging your battery in small doses hardly produces any heat.
Put it this way, if you were freezing to death and your only source of heat was a charging battery, I hope you’ll consider leaving the 2018 Accord to me in your will, Tim.
Plus, there’s already plenty of ventilation in your engine compartment. You have an open grill, and if that’s not enough, the entire bottom of the engine bay is open to the outside.
So, Option 1, hood all the way up, is unnecessary. Option 2, hood all the way closed, risks pinching or fraying the charging wires and rendering the battery maintainer useless.
So, I’d lean toward Option 3. If the unlatched hood doesn’t leave enough room to slip in the wires, then prop both sides of the hood by an inch or two with a couple of wooden blocks.
Or just run the wires up from under the car. You can route them around the engine, attach them to the battery, close the hood completely and forget about it.
But make sure you put a “Just Married” sign on the battery maintainer. That way, if you forget about it when you return in a few months and drive off, dragging it behind you, at least you’ll get a few honks and congratulatory thumbs up.
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