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Battery Draining?

Q. Hi, We own a 1988 VW Jetta. The battery is going dead in about 2 weeks time. I measured the current drain from the battery with everything off and there is 360 milliampere of drain. With the door open it jumps up to 1.3 amps. I figured a third of an amp isn't a bad drain with the clock and computer running. I checked for voltage change with the engine on and off and the alternator is working. With the engine running the voltage is 14.5 volts. With it off the voltage is 12.5. The battery has died twice and it can't stand any more deep drains. There's something here I'm not seeing or have got wrong. Please give me a nudge in the right direction. Any help will be greatly appreciated.

Many thanks,

A. 300 milliampere is the spec for key off current drain, so you are just a tad on the high side Mark. The charging voltage is okay as is the battery voltage with the key off.

Do you have a problem with the battery draining in two weeks? Probably not. A battery will lose it's charge over time under normal circumstances. How long it takes before it will not have enough to start a car depends on how old the battery is. How cold it is outside and engine condition.

The first thing I would do is have the battery load tested and find out what kind of shape it's in. If it's a couple of years old, then I don't think you have a problem. You may want to hook up a small 6 amp trickle charger to it to keep the battery up or just drive it about ten miles once a week. With batteries if you don't use it, you lose it.

The Charging System - Part 1: The Battery

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