How to store a car with AGM battery for a few months?
Posted by Express_Blueberry445@reddit | askcarguys | View on Reddit | 16 comments
About 3 months ago, I came back from a road trip and parked my car in a big parking garage. The battery should have been fully charged at that time.
Two weeks ago, I started the car, let it idle for about 20 minutes, and drove it around the storage garage at 10-20 mph for 5 minutes. I believe the car read the battery as 13.4 v or something like that.
I don’t plan on driving it again for another 3–6 months.
So I’m wondering:
- Is it better to disconnect the negative terminal and just let it sit? (I can’t use a battery tender since the hood needs to stay closed.)
- I have a battery jump pack—should I connect it to “charge” the battery before disconnecting it?
- Or would it make sense to leave both terminals connected, and connect the jump pack every week or two to “charge” the battery?
roosterb4@reddit
Don’t do anything just leave the car. More than likely, it will be OK. If it doesn’t start when you come back, use the jump pack.
Express_Blueberry445@reddit (OP)
the car is around 3 years old so I assume the battery is original (2nd owner)
I used to have an older car (05) where I left it sitting for a year with a 2 year old battery and had to get it replaced but I think AGM batteries are supposed to be better at maintaining charge?
livingoutloud373@reddit
For a modern car definitely put it on a battery charger. There are so much electronics in them, and most are pretty finicky about voltage. That why old car can be left untouched for long, no complicated electronics.
Battery will absolutely be dead in 3-6 months, all the electric stuff draw some voltage.
Battery tender, fuel stabilizer (in a full tank of gas), and change oil when you get back
RJsRX7@reddit
Disconnecting the battery is a good way to be reasonably sure it'll survive for however long you're going to let it sit.
For general care, it makes more sense to drive a car at least a bit something like weekly, but if it's gonna sit regardless there's absolutely no reason to keep the battery connected unless you want to replace said battery.
JustAnotherDude1990@reddit
Disconnect the battery and leave it. Keep the jump pack in case it doesnt start on its own. You will be fine.
Odd_Chemical114@reddit
This 100%. I’ve had a car sitting for a year with AGM disconnected using a $10 battery isolator - I recommend. Once reconnected it started right up, just to keep fluids moving etc.
I used to use a good quality trickle charger, but eventually that seemed to kill the battery. Note I live in a mild climate.
EngFarm@reddit
Is it an option to drive the car a few laps around the storage garage every 2 weeks?
You are focused on preventing a battery issue. Getting everything up to temperature and circulating and turning will prevent all sorts of non-battery issues, and will also prevent battery issues.
Express_Blueberry445@reddit (OP)
yea I can definitely drive a few laps for 30+ min. Can even floor it to 20-30 every now and then. Is this enough?
PiggypPiggyyYaya@reddit
The safest course of action is just disconnect the positive terminal and put some sort of rubber cover over the battery so there's no change the positive terminal coming in contact with anything. Use actual key to unlock and lock car.
Express_Blueberry445@reddit (OP)
u mean disconnect both positive and negative, right?
interlnk@reddit
AGM's hold their charge well, disconnect the negative and you'll be totally fine. I do this every winter with my RV, bought AGM specifically because I couldn't use a battery maintainer at the storage lot, and the battery is 7yrs old and still going strong.
Gunk_Olgidar@reddit
Disconnect the negative terminal. Yes is usually better to store a fully charged battery. If you can store it with an AGM rated battery tender connected, then feel free to do so. A jump pack won't suffice.
Also 13.4v is surface charge typically observed shortly after a car is shut off after driving (or after a charger is removed). 12.6v is normal at rest full charge that one would typically see the next morning under normal conditions after the car slept overnight with its normally low <25mA sleep state while powering the antitheft and small part of the remote start module that's listening for your fob signal.
9BALL22@reddit
I use a maintainer on mine from around Thanksgiving to Easter. My last 72 month AGM battery lasted 11years.
supern8ural@reddit
you can absolutely use a battery tender as you can either snake the wires out from the gap around the hood or else down through the bottom. I would do that, as some more modern cars don't like having the battery go dead and you might end up with a dead immobilizer or door lock module or something when you charge it up again (this actually happened to me on my old GTI after it got wrecked, I had to pay again to have the immobilizer bypassed)
Joe_B_Likes_Tacos@reddit
The op can also remove the battery and put it on a trickle charger at a different location.
yukonnut@reddit
Not a car guy, so I might be wrong. I would pull the negative terminal to keep low draw items from depleting the battery over a long period of time. Then it kind of depends on how old and how good your battery is. When you finally go to pick it up, take jumper cables or battery pack in case your battery has discharged. Also kind of depends on how cold it gets where you live. There will be people who are more experienced and will probably give better advice than me.