Newbie Problem: Battery drained on '86 Carrera, what am I missing

[CiscoSF]

I got an '86 Carrera a few weeks ago. I drove it from Maine to Virginia without any problems with the battery. It was parked there for a few days without any problems and then shipped to California.

It got to California on Friday and the shippers informed me that the battery wouldn't stay charged. When I got it, it seemed to hold a charge and I was able to start it a few times without any problems.

I had it parked from Friday evening until Sunday morning and the battery was drained. I feel like I am perhaps missing something obvious like leaving a dome light on.

Could someone do me a favor and list some obvious possibilities to check? Many thanks.

[twistoffat]

Take a voltage meter and measure the battery at the terminal. You should have around 12V. It might just be an old battery, has it ever been changed?

[DRACO A5OG]

it must read 12.6+ to crank, our 911's when sitting will lose 6% per day, cumulatively

buy a good charger like cTek or battery minder, the cheaper ones will not help maintain it properly and will eventually cease charging.

after fully charged anddriven daily, you do not need to trickle charge it but if you get either I mentioned above it will help lengthen the life of the battery

[boyt911sc]

Originally Posted by DRACO A5OG

it must read 12.6+ to crank, our 911's when sitting will lose 6% per day, cumulatively

buy a good charger like cTek or battery minder, the cheaper ones will not help maintain it properly and will eventually cease charging.

after fully charged anddriven daily, you do not need to trickle charge it but if you get either I mentioned above it will help lengthen the life of the battery

Jim,

That's a lot of power drain because after 10 days that would amount to 60%. Are you sure of the number? Maybe 0.6%? Please advise.

Tony

[pete3799]

Mine sits for 3 weeks to a month with no charger on. Never had to jump it yet.
Have your battery load tested.......may be time for a new one.

[Venetian]

I have left mine as well for many weeks without any starting problems. Got to be 0.6%. Other than the clock, what else would be draining battery...maybe factory alarm?

[porschenut]

I've left mine for 3 months over a winter many times without any kind of charger, and it starts right up. These cars pull almost nothing from the battery when they sit. If you're losing 6% per day, your battery needs replacement.

[ClickClickBoom]

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Internal discharge
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[Barrpete]

Check that the door switch is working correctly. I seem to recall that after the ignition is turned off, the power window relay stays energized until the door is opened & closed. If the dome light circuit doesn't activate then the relay stays energized and can drain the battery fairly quickly.

[CiscoSF]

Take a voltage meter and measure the battery at the terminal. You should have around 12V. It might just be an old battery, has it ever been changed?

It has a nice looking Interstate Battery that was replaced within the last few years. I have a multimeter (not that I know what I'm doing with it) and I'll check. I'll also try unhooking the battery for a day to help narrow things down.

I have left mine as well for many weeks without any starting problems. Got to be 0.6%. Other than the clock, what else would be draining battery...maybe factory alarm?

Anything else like that I should check?

[techman1]

Get in the car, close the doors, turn on ignition and put windows down. Turn off the ignition, open the door and see if the windows still work. From my past time with an '88 the windows have a relay to allow the windows to operate till the door is open.
Something I did not have a chance to check. My issue was the main ground cable needed replacing, alt. was not charging good.

[jdbunda]

With unknown history, I would have the battery checked before wasting too much time troubleshooting. If you do have a drain, the easiest thing to try is hooking up an ammeter and start pulling fuses.

[schumicat]

the most obvious possibility is that the battery died. not holidng charge is a common failure mode. no way any battery loses 6% per day. you wouldn't be able to start car after 4-5 days. any reputable auto parts store will charge & test battery for free. 12.6 volts is fully charged. 12.0 volts is almost completely drained.

[Ramathorn]

if i let mine sit for 3 day my voltmeter reads 11.9. im running a pc680 and have just come to grips that i need to either start the car every few days or disconnect the negative terminal.

[FastCarFan]

Originally Posted by Barrpete

Check that the door switch is working correctly. I seem to recall that after the ignition is turned off, the power window relay stays energized until the door is opened & closed. If the dome light circuit doesn't activate then the relay stays energized and can drain the battery fairly quickly.

When I bought my car in 2001 the battery would go dead in a few days. Turns out the door "plunger switch" (not sure what the correct name for it is) was sticking, so the car never "knew" the driver's door had been opened - all accessories stayed hot. A little WD40 & a new cover for the plunger fixed the problem.