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Leaving Your Car for a While? Here’s One Mistake You Should Never Make

If you’re planning a vacation or looking to get away and perhaps escape a frigid winter, there’s one thing you should never forget to do to your car before you leave. If you do happen to forget, it could result in a costly repair.

Disconnecting your battery from your car before you leave could potentially save you from having to replace it with a brand new one when you return. Even if you aren’t driving the vehicle, the electrical systems such as the on-board computer and clock can still slowly drain the battery, meaning your car might not start if left sitting for too long. This is especially the case in newer, more advanced cars, said Fred Rashidi, a Ford service manager.

“Some of these new cars have so many electronics and modules, the battery could get drained in a matter of weeks if left alone,” he said. Rashidi doubts it would make a difference on older cars, however.

ALSO SEE: How Far Can You Drive on Empty?

Should your battery drain completely, the average battery can cost between $40 to $100, plus installation, and some of the higher-end ones can even cost upwards of $200. You could jump-start it, but this will still leave your battery with a reduced life. Jump-starting also makes the alternator work harder because it is then powering the battery, which will reduce the life of the alternator as well.

Alternatively, you could also buy a trickle charger and leave it connected to the battery to slowly charge, but these can cost anywhere from around $40 to $150. Getting a trickle charger is actually much better than disconnecting your battery, though it isn’t the cheapest option.

Top 7 Best Trickle Chargers for Your Car’s Battery

“If someone is going away for a few months over the winter, they should definitely disconnect the battery. It’s the only way to prevent battery drain,” Rashidi said. “But the complication is, whenever you disconnect the cable from the battery, you have to make sure it’s secured somewhere so it’s not contacting the ground or any of the positives. I would recommend taking the negative battery post out, and wrapping something around the end so it doesn’t touch anything while you’re not there.”

If the cable end is touching the negative terminal or is even in proximity to it, it could create a spark and cause a fire. Rashidi said a quick and easy method would be to get some Ziploc bags and wrap them around the cable end so that it stays contained and doesn’t touch anything.

Rashidi also notes that disconnecting the car’s battery will reset all electronic systems and settings in your vehicle, so be prepared to reset the clock and any other systems. Familiarizing yourself with the settings is a good idea before disconnecting the battery. In some instances, more serious issues can arise when disconnecting or reconnecting the battery. Always discuss this with your dealer prior to disconnecting your battery.

ALSO SEE: Top 10 Best Portable Car Jump Starters

In order to disconnect the battery, all you have to do is remove the cable from the negative port. Do not let the negative and positive cable ends touch under any circumstances. If the cables do make contact or even get close, it could do a number of harmful things to your car, including frying your alternator, damage the cables, or worse, cause serious injury to yourself or others.

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29 Comments

Chris Smith says:

Before I went outta town this May 2018 for 21 days I charged my battery to the max and let the car sit all fully connected. No problem when I fired it up again after 3 weeks. About disconnecting a modern car battery per the Ford manager: puzzling. I learned the hard way disconnecting a modern car (2010) battery even when I thought the battery was dead enough to prove zero juice left .. Well the result was a series of dashboard lights that took alot of research to fix.

Chris Smith says:

Ok since we are at this topic: CAN YOU HELP ME? Before I went outta town I was agonizing over whether I should connect a booster pack in the footwell underneath the steering wheel to the obd2 for 21 days and cross my fingers the power won’t run out of the booster pack

when the green small LED light on the booster pack PLUS the large red LED on the obd2 cable (for saying “yes, connected well” do their majic action. I was worried that the two lights would drain the booster pack and then the battery in those 3 weeks i was outta town.

What’s your take? [[I did not pull through on that option due to drainage concerns by these 2 lights]]

Dave says:

Should I put additive in the gas tank when not using for a long period of time ( 4 months )

Rodger Archer says:

bought a car
the prev. owner said when he discon. battery for winter and reconec. in the spring the alarm horn sounded and had to go to the internet to reset it
now I am storing the car and will have same problem in the spring…what will i need to do to make this simple
Rodg

Daniel l szydlowski says:

disconnecting the positive cable always worked for me

john Kozak says:

I have a Buick Envision. If I go away for three winter months can I hook up a trickle charger to the battery after disconnecting the NEGATIVE terminal? Or, do I have to disconnect both the negative and positive terminals and then place the trickle charger on the terminals?
Thank you.

David Traver Adolphus says:

Hi John,

You don’t need to disconnect anything if you’re using a trickle charger; just clip it onto the terminals as is (make sure they’re clean enough to make a good connection, though. Disconnecting a terminal is to help prevent battery drain, but you won’t have that problem.

Be sure there’s some ventilation in case your battery decides to offgas a little while you’re gone—leave a window cracked open, if you can, or at least open the doors and let air circulate when you get back.