jerryc41 Loc: Catskill Mts of NY

A couple of friends had their car batteries go dead because of lack of use. There is always a drain on batteries while they are in the car.

Longshadow Loc: Audubon, PA, United States

Most I've ever let a car go without running it to charge the battery was maybe three weeks.
Usually only two.
Then it should be run to get up to temp for a bit to prevent condensation from collecting in the exhaust system, which will accelerate the degradation of the system (rust).

Country Boy Loc: Beckley, WV

This should not happen to a good battery for just a month or two. I would suspect they have a weak battery to start with or have a low water level if it is not a sealed battery. As batteries get older they weaken and work normal if regularly used but as they age, their ability to hold a charge goes down.

Longshadow Loc: Audubon, PA, United States

A while at least.
Batteries do get weaker with age and lack of maintenance.

47greyfox Loc: on the edge of the Colorado front range

In the 70s and 80s, I’d often be gone for over a 100 days at a time while in the navy. While gone, I stored my car with a reputable garage. They disconnected the battery and put it on something like a battery saver. I never had a problem. I also knew plenty of friends who left theirs in secure outdoor lots. Most were fine except for an occasional jump. One of the worse things you can do to a battery is deep discharge for any reason.

TriX Loc: Raleigh, NC

You’re correct Jerry. Modern cars often have a small load on the battery which, in addition to self discharge can slowly drain the battery. Unless it’s designed as a deep discharge battery (which automotive batteries aren’t), they are not designed for complete discharge, and a long term discharge can permanently damage the battery, especially if it’s done repeatedly. One of my cars has a low voltage cut-off that disconnects all load from the battery to prevent deep discharge below a certain level (and so the car will still start if you inadvertently leave an interior light on), but I make a point of starting both cars every week or so and let it run long enough to bring the engine up to temp and top off the battery.

Longshadow Loc: Audubon, PA, United States

Once a car battery goes down well below being able to start the car, it will never be the same and go sooner than normal.
(Better chances of it surviving if it is new though.)

dpfoto Loc: Cape Coral, FL

When I needed a new battery for my Toyota Sienna, I went to the local Toyota dealer. I know I could have paid quite a bit less elsewhere, but this one has a lifetime warranty. That way I should never have to pay for another battery as long as I have this vehicle.

jerryc41 Loc: Catskill Mts of NY

When you see liquid dripping out of a tailpipe, that's water produced by the combustion process. When the exhaust system gets hot, that water evaporates before it gets to the tail pipe. That dripping is a sign that the car hasn't warmed up.

When Zeppelins were flying between the US and Germany, the engineers developed a way to capture that water and save it. That helped to compensate for the loss of weight resulting from burning fuel.

burkphoto Loc: High Point, NC

Yep. For Prius owners here:

Prius models need to be driven weekly for about 20 minutes to keep the high voltage traction battery and the 12-Volt accessory battery charged.

If a Prius has a “smart key system”, it can be disabled with a button under the dashboard. That makes it easier on the 12V.

Getting into a locked Prius requires a manual key. Getting to the 12V requires crawling over the back seat, removing a mat, lifting a flap, pulling an emergency hatch release, and then removing everything from the trunk to get to the right wheel well.

Changing the 12V is easy. Videos are on YouTube. (I’ve done it several times.) The battery is $200 to $240 because it’s an AGM type. But new OEMs have seven year warranties. Most last 5-10 years if treated properly. (i.e.; don’t drain them deeply!)

jerryc41 Loc: Catskill Mts of NY

When JC Penny sold batteries, I had one with a Lifetime Guarantee. The battery failed, and they gave me a new one. Good deal.

dennis2146 Loc: Eastern Idaho

I can't tell you how happy I am that you brought up this subject. I have a friend who owns two vehicles. He has put a vehicle battery charger on each of them since new. I believe both are 2013 models but am not positive. One is a Ford and the other a Jeep Grand Cherokee. The battery on the Ford recently died while he was shopping. He called AAA and they came to jump start the vehicle. He purchased a new battery for that vehicle and then purchased a new battery for the Jeep as well. As I said he keeps one or the other vehicle on a charger when not in use. He now has a battery charger on the brand new batteries when not in use.

I have owned a number of vehicles and have never put one on a battery charger. All have started up right away even if I have not driven the vehicle for maybe three weeks to a month on one occasion.

My friend and I have had discussions where I have told him I did not think the battery charger was necessary. He insists that it promotes longer life and keeps the batteries in better condition. My experience points to a different conclusion. Can someone give me the right answer or is it one of those things where, it depends? Presently we ar in So. CA but my vehicles are generally in much colder Western states, CO, ID and WY.

Dennis

Longshadow Loc: Audubon, PA, United States

Interesting tidbit about the Zeppelins.

Longshadow Loc: Audubon, PA, United States

Both excessive heat and cold kills batteries if they are not used regularly.
My five year batteries in Central Florida would last maybe three+ years, and that was with kinda with regular use.

TriX Loc: Raleigh, NC

I will just note that my MB still has the original battery after 14 years. I attribute that to several things: the battery is in the trunk where it stays cool (why don’t all manufacturers do that?), it has a low voltage cut-off that prevents deep discharge if you leave an accessory on (they should do that too), and it uses the same large AGM battery that is in the diesel engined cars. A replacement is almost $300 (remember when batteries cost $30?), but based on past experience, I’ll buy an OEM MB battery when this one fails.