LlBr

Nice. Good. Makes me wonder about the 997 source. But no problem for now. I'm just glad the OP is definitely on his way to figuring out his problem with good info.

dshepp806

What prompted the original battery changeout?

rusnak

In this thread:
https://rennlist.com/forums/911-foru...l-problem.html

Loren noted that a 60ma draw would drain a typical battery about 50% in about 3 weeks or so.

Typical battery - 60 Amp-Hr
For 1/2 capacity to start - 30 Amp-hr

Days = 30 /.06 /24 ~ = 20 days

If you accept the basic equation, then does that mean a 100ma draw would drain a battery in about a week and a half? That seems way too fast of a drain to live with, even starting with a 100% healthy battery.

RSWiser

In answer to the question, what prompted the battery change in the first place. When I bought the car it had one of those 18" Interstate batteries with the terminals on the wrong side of the battery and it was weak from sitting for several years with only and occasional start. I also replaced the negative battery cable as it was shot.

I am pretty sure based on all of the responses that my rear window defrost relay is the culprit. As soon as I can get to it that is the place I am looking.

I don't think my battery is going to hold a charge. I charged it using the two battery parallel method, then just the charger and now the Battery Tender. Will test it tomorrow morning when I leave for work then again when I return home. May need new battery.

Rob

OptimaJim

Hello, I saw our batteries being mentioned and wanted to help out any way I could. The link HarryD provided for the pelican board does provide some useful information on recharging deeply-discharged batteries. We also have a video which explains this procedure- http://www.youtube.com/watch?v=dIoaL3DWWEg

RSWiser, if your battery is only reading .21 volts, it is probably not recoverable and should be exchanged under warranty. However, as others have mentioned, checking for a high “key-off” load and using a battery tender/maintainer will help extend the life of your battery, regardless of brand. If you have any other battery questions, I’ll do my best to answer them.

Jim McIlvaine
eCare Manager, OPTIMA Batteries, Inc.
www.facebook.com/optimabatteries

LlBr

That's what I've been "taught" (the hard way) with my 997. It's only supposed to draw 25mA when properly parked and then that's good for 5 weeks maximum with its brand new 75A(h) battery in mild temps. 100mA seems a lot. Besides, what's in those older cars that needs to be going all the time?

RSWiser

Well I did the parallel battery charge thing described earlier and my Red Optima seems to be holding a charge.

Today I put the battery back in the car and went for drive. Came home and did some testing to find the battery drain.

It was not the rear defrost relay because according the the Bentley manual diagrams, I don't have one. Not there. Pulled the fuse and tested it. No drain.

I go in the car in the dark garage and found the drain. My glove box was slightly ajar and the light was on. I guess leaving that on for a week would do the trick.

So I put my Battery Tender on and feel pretty good about my battery power.

Thanks to all for the advise.

Rob

srf506

A stuck relay or problem with the voltage regulator and rectifier on the alternator can drain a battery and won't even cause the alternator light to come on. Its not a lot of fun chasing an electrical gremlin, good luck.