I was taught growing up that in order to charge a car battery one had to actually go out and drive around. So recently I passed this information to friends whose plan was to just leave their cars running in the driveway for a few minutes to charge them. But lately I’m seeing a lot of facebook hints and such that are making me doubt myself.
I do know that starting the car is the most battery draining thing you can do to it, so once you do, it’s important to run/drive it long enough to recharge. I also find that I have no idea of how far one might need to go to be certain it’s fully recharged.
So what say you Dopers? Am I wrong? Does running the car standing still in the driveway charge the battery sufficiently? Or do you actually need to drive a few miles?
And whichever it is, for how long? Or how many miles?
I have a work van that goes to farmers’ markets in season, but sits for months in the winter.
I was advised to run it for about fifteen minutes about every three weeks. Works fine.
I don’t go anywhere with it when I run it – a large part of the idea is not to get salt on it so it won’t rust; but I do move it forward and back, just in case anything’s considering freezing up.
Yes, just the idle will charge the battery.
It might charge faster driving it (higher RPM), but as long as all the accessories are off, 10-15 minutes once/week should be fine.
But, it’s a good idea to drive the car once a week anyway, just so the tires don’t get flat spots.
Get something labeled as a battery maintainer, I have a couple and have been using them on my second car and bike for years. Both always start right up after sitting for months. Be aware of anything labeled trickle charger. Not all of them will “float” and can end up killing the battery if you don’t disconnect it.
It’s a little late now to be suggesting getting anything, since most non-essential places are closed, but a while ago I got one of the new types of Li-ion portable boosters. As opposed to the old ones, which used lead-acid batteries and were huge and weighed a ton, this thing is about the length and width of a cell phone and about three times the thickness, and barely weighs a pound, if that. It has USB charging ports which I found extremely useful when we had a multi-day power outage due to a major windstorm, where I used it to keep my cell phone charged, as well as my Kindle which was running low at the time.
Another time when my car battery was getting pretty weak, I left it in the garage for nearly a week because friends were visiting and we always took their car when we went out. After they left, I had some doubts as to whether my car would start. Hah! The battery was so shot that I didn’t even get the classic clicking sounds – just absolutely nothing. Plugged in the special alligator clips into the “car starting” port of this amazing tiny Li-ion device, and the car started immediately!
Caveat emptor: there are good brands and shitty brands of these Li-ion devices, and to make matters worse, there are cheap knock-offs of the known good brands. So read the reviews and be careful what you buy.
All of that said, if your car has a decent newish battery and no unusual electrical drain it should be fine for many weeks. If you’re really concerned, start it up every week or so, drive it around for about ten or fifteen minutes if that’s permitted, let it idle for ten more if you want, then forget about it for another week or two.
If you do that, though, you’ll have to redo settings – clock, radio, etcetera. You may need a code number to get the sound system working again.
When I’m charging the van battery, I rev it up a bit for some of the time – not really high, but it’s not running the whole time on low idle. Not sure how necessary that is.
You don’t need to drive the car to charge the battery–the alternator will top it off automatically–but it is a good idea to at least drive around the block once a week or two so that lubricating oils get circulated. How long a battery will last depends on how old it is, what kind of temperature changes is sees in service, and how well sized it is for the engine. I had the stock Tacoma battery die within two years because for someone reason Toyota picked a battery with the minimum peak amp rating, and replaced it with a larger, higher cranking amp battery without issue.
Also, just in case anyone is wondering, lead acid batteries don’t suffer from from so-called “battery memory”, which is really a NiCad phenomena and has been partially mitigated with better chemistry though it is still good to occasionally deep cycle NiCads. However, a lead acid battery that is too deeply discharged or is allowed to fall below the necessary charge can degrade irrecoverably, so it is important to exercise them to a certain degree, especially in winter.
Those things are great and keep one in my breakdown kit all on top of the jumper cables because I’d rather use that than perform a vehicle-to-vehicle jump if possible, but they won’t fix an irrecoverably discharged battery or trickle charge a battery. If you’re going to leave a vehicle not running for months on end, trickle charging or removing the battery is really the smart move.
Also available on Amazon and delivered right to your door. I believe Walmart on line or Lowes etc. are also delivering to the door these days.
I keep a maintainer on my tractor and mower when they are not in use. The ones I have came with a lead that connects to the bolts holding the battery cables on. the lead then can be fed out through the grill and plugged into the maintainer. No need to open the hood to connect/disconnect.
Right, that should be good enough in those conditions. I’m not able to use tricke chargers since where I am now I get to use a common surface lot, but fortunately the lot is quite largishso I can just wander around for a little bit so that the tires are not always in the same spot. And I can just sit there and listen to the radio/Sirius for a while and just enjoy not being in the same room.
If maintaining charge is your only concern, then 10 minutes once a week will work fine. I do it all the time for my Expedition, which isn’t a daily driver. It’s still good to go out once a month or so and run every system through its paces, though.
This is the same Expedition that I stored in my garage from 2011 to 2016, taking it out once every year or so whenever I made it home. It runs fine. I do need to change the tires, though. They’ve only got about 6000 miles, but are close to 10 years old.
We have a 2006 CR/V which I drive on our very rare outings. Our other car is a 1998 Civic which is my son’s car; it’s been in the garage since he returned from college 2 weeks ago. I’ll have him take it out of the garage and run it for a few; maybe around the block once for the tires etc. as others mention.
I second the solar battery maintainer. As mentioned above, if you just unhook the battery, you’ll eventually lose all presets and OBDII (on board diagnostic 2) information. Losing all OBDII info means that, if you have to get an emissions test to register it, there won’t be enough information in the computer to pass. Also, lead acid batteries will slowly self-discharge over time and it can eventually do so to the point of no recovery.
Since you said you can’t use a plug in maintainer, that leaves a solar set up. Inexpensive doesn’t automatically mean cheap. Check reviews.
A battery tender jr is about $25, and other similar ones are even cheaper. That is much less expensive than replacing a car battery that was deep cycled and died prematurely. My rule of thumb is that I put the motorcycle on the battery tender after two weeks of no use, and the truck on it after four. According to the battery tender, both batteries are below 80% charge at that point. It will take lots of idling to burn $25 of gas, but it is worth my time to just plug in the tender and leave it rather than mess around with running the car when I don’t otherwise need to.
My general policy is it’s good to drive a vehicle at least 20 minutes every couple weeks or so, or whatever gets it up to normal operating temperature. That will keep the battery charged and mechanical parts moving/lubricated. Even now with shelter in place I believe most places allow travel for supplies, I wouldn’t stop anywhere if you don’t need to, but if questioned you can say you were going to get supplies.
Idle will charge it, but you have to leave it running a pretty significant amount of time. You can charge it by driving it on the highway for about 10 minutes, but you have to idle it for like 1/2 and hour if it’s been drained. If you are just making sure it’s topped off, I’d leave it for 10 minutes in warm weather, 15 in cold. Starting it is in fact, the most draining thing you can do. Starting it, and letting it run one or two minutes is VERY BAD.
Something else people don’t think of, is that if you are driving it ONLY to the store and back once a week, and those trips are about 5 minutes, or less, each way, you are draining the battery. A trip through town that is 3-4 minutes after starting it, followed by another through town after restarting it, and NO OTHER driving is going to drain the battery. Either leave it running for about 20 minutes when you get home, or take a 10-minute detour on the highway every other time you go to the store.
