Car Battery Charge Maintenance

Looking for a good way to maintain the charge on the battery of a car that is driven infrequently-about once a week or two weeks.

My first thought was a solar charger but the car is parked on the north side of a building and doesn’t get much direct sunlight. Should we put a plugin trickle charger in the car and leave it plugged in all the time while it’s parked? Does the charger still use power when the battery is charged? Harmful to the car or charger? Better solution?

A good charger will turn off but most cheaper ones do not.

If the battery is not holding for 2 weeks, it is probably time to buy a new battery which won’t cost much more than a good charger.

Thanks. It’s my daughter’s car and I’ll see how old the battery is when she gets it boosted and gets here. Still, I wonder about modern cars that use all kinds of power when they’re “turned off”. Today is the first time it hasn’t started and it’s about -33C outside.

Just came in from plugging our car in for errands later today. It’s chilly.

There’ve been long threads here about how it’s the heat that kills batteries, but in my experience, they always die on days like today. If I get three years from a battery, that’s good; four is great. Can you check to see how old it is? When CAA installs one, it usually puts a label with the date on it.

Wait, never mind my advice. If you’re hitting temps like that the battery might be fine. I’m wasn’t adjusting for temps below -17°C (0°F)

Definitely, around here, if I can make a battery last until spring, it’s usually lasts until fall. I’ll be able to look at it in an hour or 2.

You’d think I’d mention something like that! Yeah, it’s cold. The block heater was plugged in but I still expect the issue is the batter was not fully charged.

…And just got word that the car is started. Coming from Weyburn for any locals in the thread. About an hour and a half away.

Wasn’t there a thread not too long ago where one or more posters were arguing that it’s heat, not cold, that reduces the life of a car battery? (Cold makes the car harder to start but doesn’t actually harm the battery.)

I have a years-older version of this guy. Works great.

I take it you’ve never have a battery freeze and crack? That seems to me to be cold harming the battery.

That matches what I know. I use to know a lot about battery maintenance but that was a long time ago.

In New Jersey, a battery should easily hold 2 weeks without driving anytime of year and still start the car. But in very cold places, it just gets a lot tougher to start the car.

I never had one do that but NJ. What Thudlow is referring to is sulfation. The lead plates build up a crystallization that prevent the battery from getting a full charge.

OK, so while the cold prevents the battery from getting and maintaining a full charge it generally doesn’t cause the battery to degrade. Though if the case cracks from the cold, that is a whole other thing.

Over-heating and very hot weather will cause battery fluid to evaporate which is bad. It can cause overcharging that leads to sulfation. It can cause corrosion to the lead plates which shortens battery life and reduces max charge.

That looks perfect if it comes to that. Designed for maintenance rather that occasional charging. Thank you and thanks all.

Should be fully charged after that trip. If it doesn’t start well tomorrow, may be time to get a new battery.

Unless the alternator is not 100%. Connections etc. The stuff you don’t think to check until it’s subzero by a lot.
My work car sits a week or two sometimes but until now we haven’t been subzero F. My truck is just much nicer to drive in these conditions.

My dad’s favorite trick was to use steel wool to clean the corrosion off the battery connections. He got a car or two to start by doing that.

I’ve used steel wool between the clamp and post at times. Smear them with Vaseline first. I’ve also had clamps that wouldn’t tighten and ran wood screws into the gap to get through the winter.

How long is it driven when it is driven? That would be a factor. It may be prime conditions for gradually depleting the battery then one day it doesn’t start. Also it would stress the alternator as it tried to charge a losing battle. So yes if you want to do a battery tender, no harm no foul. Solar charger would require mounting to an always live circuit of the car, so may or may not be as simple as plug in to the car cig. outlet.

A ‘smart charger’ is the way to go. Plenty on amazon etc, but be sure it is the right one for your battery.

If your car is hard to start, consider what oil you are using - is it the correct viscosity?

There is a different product generically called a “battery tender” sold exactly for this purpose. They tend to be smaller than chargers but otherwise look the same. Their design intent is to stay connected to the battery all the time, or, if it’s a vehicle, connected all the time the vehicle isn’t driving. They apply more or less current depending on the battery voltage and the temperature, to keep the battery ready. However, they don’t have much current capability, and would take a long time to charge a dead battery.

I kept one on my old tractor for many years, and now on the new one. I keep one on my battery-start 10 kW backup generator. I also got another one to put on my car but haven’t yet gotten around to figuring out how to do it conveniently, as you need someplace to run the wire out of the vehicle where you can reach it, and of course some way to do the same on the house and box side.

As far as I know, she doesn’t drive in town. The car is only used for highway driving so, when it’s started, it gets charged right up.

She has come and gone now and hasn’t had problems. I expected to see a date on battery but could not see any stickers so I don’t know how old it is. The connections were shiny clean.

Bought her a CAA membership and spelled out her options so it’s mostly out of my hands for now. Thanks for all replies.