What drains 1988 - 928S4 battery while parked in winter?


Asked by Feb 24, 2013 at 06:42 PM about the 1988 Porsche 928 S4 Hatchback

Question type: Maintenance & Repair

My 1988 928S4 stays parked for two weeks at a time with no one to start it. This is OK in summer but in
winter the battery goes dead after three or four days. Battery is relatively new and nothing is left "on" in
the car except the clock. Is there a block, fuel or radiator heater controlled by T-stat that is coming on in
the cold weather that would be running the battery down?

14 Answers

James Ramond

security consumes some,a battery is downed by cold bigtime,you may need big cca, cold crank amp battery for this one, no, no heaters unless seats have them and left on?

There is a phenomenon called leakage current, which for a car battery is a known characteristic. You may notice that all your batteries will not stay even in the fridge for six months. They discharge themselves....this is totally normal. Fully charge this ole boy before putting it in storage...when you pull it out with any luck will have a plenty good charge left....if it doesn't might take a charge but may be time to replace this one.


Cold weather causes batteries to lose their charge faster. My guess is the car has a computer that is constantly draining the battery. In warmer weather it isn't enough to kill the battery because the battery can hold it's charge longer. My suggestion is disconnect the negative (-) battery cable while not using the car. Or bring the battery inside where it's warmer. HTH. -Jim

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Your trunk light is probably on.

I would argue that cold weather DOES NOT cause the battery to discharge, however the output is significantly reduced in cold weather...the battery IS THE SAME hot or cold. The amount of leakage current is probably actually higher at higher temps. Can check with my Dad who's been doing this since the 1950s, but a little bird told me.

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Pop says it's "self dishcharge" loses capacity sitting around, The loss is a discharge slope that starts on high and inceases with time- 20% per month---

they are made calcium alloy intead of antimony--

since 1967...still working at it 45 years--

James Ramond

bob neuske? you a sasage mongol from out west?the name rings a bell,if so how the hell does that tie with such efficacious replys for motorcars and their workings

He's just a guy. I'm just a guy. we might be the same guy?

Actually this is a carmel colored half-pakistani guy, who moved to Milwaukee at the tender age of 3 months, have known nothing but divorced parents, and perhaps a dozen carrers ranging from copyboy at 15 to Mechanical Design Engineer at 40- after diagnosed with MS can no longer work....they don't allow it.

If I rub a can of beer, 7jim7 appears!

spent three years with a prybar and wrench taking showers in coolant and having Ford Rancheros trying to run me over. Had a stack of about fifty timing belts was going to make 'fashion belting' out of them, like the way maddona used to wear an oil filter seal as a bracelet, but the wife threw all of them away...still have one I use as my tool tray handle. 93-96 qualifies me for somethin' no?


Consider a "Battery Tender" from local auto parts store & use it in winter. Works for 911s, so assume it would work for 928.

1 out of 1 people think this is helpful.

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