Car won't hold a charge - sound like the battery? - 986 Forum - The Community for Porsche Boxster & Cayman Owners

JoeFromPA · 11-15-2010, 10:41 AM

Hi all,

About 2 weeks ago my boxster, after sitting in the garage undriven for 3-5 days and having no problems beforehand, wouldn't crank and showed the signs of a very low battery:

1. Windows didn't go up down upon opening a door or, if they did, very slowly.
2. Lots of rapid clicking happened upon turning the key
3. Dash lights dimmed substantially when trying to start

The car has about a 2-3 year old interstate battery in it, but the battery has seen alot of full drains during it's lifetime. I trickle charged it back to life and it started up and drove fine. Drove it 32 miles to work, started up fine at the end of the day (no unusual effort), then 32 miles back home.

Garaged it for 3 days....wouldn't crank again. Trickle charge'd it. Started up fine. Drove it around onSaturday for about 20 miles with 3-4 stops in there. Each time, it started back up fine. No unusual effort.

Sunday morning (about 16 hours since last start) - wouldn't turn over.

Trickle charge'd it till this morning, added distilled water into the battery (it drank probably 8-12 ounces of distilled water without ever over-flowing). Drove it to work, where it's now sitting outside.

Now to me, this sounds like a clear case of a battery going dead. However, I'm just wondering if there is anything unusual that could be simply draining the battery when its sitting still for more than 10 hours in a row?

Thanks all,

Joe

eightsandaces · 11-15-2010, 10:48 AM

8-12 oz is a boatload of water to add to a battery, when the battery is charged with the lead plate sandwiches out of solution it can ruin the plate, even when the solution is eventually restored to the proper level. I'm betting the battery is bad but if you're still not convinced see if it holds a full charge with it's posts disconnected from any draw.

extanker · 11-15-2010, 11:00 AM

use a good DVOM check before charge,after charge,before starting,running at idle......get back with readings

mikefocke · 11-15-2010, 11:22 AM

load test them for you. If your battery took that much "water" I'm betting the plates were exposed and that can lead to them warping and a battery that won't charge up.

Plus a battery that has been drained of charge multiple times is more liable to be unable to accept a charge than one kept fully charged.

3 days to drain the battery is a very short time. Done anything to the car recently? Any aftermarket electronics?

There are lots of batteries that fit our cars listed here.

J'sboxie · 11-15-2010, 11:34 AM

also check that all of your lights in the front and back boots are turning off...I think I have read that sometimes a bad switch can keep on a light even after the compartment had been closed...Good Luck!!

JoeFromPA · 11-15-2010, 11:52 AM

Quote:

Originally Posted by J'sboxie

also check that all of your lights in the front and back boots are turning off...I think I have read that sometimes a bad switch can keep on a light even after the compartment had been closed...Good Luck!!

Any tips on checking to see if a trunk (boot) light remains on with the door shut? How does one check that, since opening the cover turns the light on?

JoeFromPA · 11-15-2010, 11:33 AM

Thanks all. My main question was: is there something that can consistently drain batteries that is not obvious - maybe a bad part allowing continuous draw after shutdown or something that tends to happen in these cars. Sounds like nothing that frequently occurs.

When I took the covers off the battery, I could see liquid clearly near the top. Nevertheless, I poured a good amount of water in all 6 holes. More than I would've expected without it coming up into the pour tubes.

I'm going to pick up a Wal-Mart everlast battery.

JoeFromPA · 11-15-2010, 11:37 AM

P.s. No recent major changes to the car. I took ownership of it from my father. In the past 2 years, the horn has been going off in the evenings due to poor bushings seperating the airbag from the horn sensor.

I've temporarily fixed that using folded up business cards (amazing how well that worked!), but the battery did FULLY drain several times. It gave me absolutely no problems for over 2000 miles of driving it, which included about 60 fully cold starts in both boiling summer weather and 40 degree days. Until 2 weeks ago, when it suddenly just completely would not turn the car over.