I will be leaving my Focus alone for around a month in (scottish) winter weather. Ordinarily I would make sure to take the vehicle out at least once a week to prevent the battery going flat in the cold, but obviously if I'm away I can't do that. What should I do to prevent it going flat while it's unattended?

3 Answers 3


A decent battery should last 4 weeks, at least it does in dutch weather, with temperatures above -5 degrees celsius.

If it doesn't, on older cars, you can simply unplug the + connector from the battery. To be safe, make sure the loose cable doesn't make an electrical connection with other parts of the car.

On newer cars (say after 2005), disconnecting the battery might mess with the electronics, although it shouldn't do real harm.

  • Why specifically the + connector? I would assume either would work (and assuming the - connector is ground and is connected to the body that would avoid the risk of making contact between the connector and other car parts? (Not saying that it is wrong, just trying to understand why).
    – Hennes
    Commented May 7, 2013 at 22:06
  • Having the + grounded wouldn't hurt. But it shouldn't matter which of the two you disconnect, as long as at least one is fully disconnected, no current can flow.
    – Mr. White
    Commented Jun 16, 2013 at 11:43

Put it on a trickle charger. This will keep the battery topped up and replace the charge used to keep the alarm etc going.

Mains-powered chargers can be found very cheaply from any motor factors, or from chains such as Maplins and Halfords. If your parking space is too far from a power source for that, you can also get solar powered ones, although with typical Scottish winter weather you might need a fairly decent sized one!


Keep negative terminal of your battery detached from battery's terminal. You may get the desired result.

  • Isn't there any risk in leaving a battery lead removed for extended time?
    – Suhas
    Commented Jun 4, 2016 at 13:10

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