Flat battery

Submitted: Thursday, Jul 18, 2002 at 00:00
ThreadID: 1512 Views:2001 Replies:5 FollowUps:5
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Trying to help a friend with an electrical problem in a Commodore. Battery dead flat one morning, started with jumper leads and replaced battery. New battery fine until following day - dead flat again. No obvious signs of anything left on and it's a wagon so no concealed nboot light - not that that would flatten it in 12 hours. Any way of testing for drain on the battery? Or maybe the new battery is a dud? thanks in anticipation ...
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Reply By: ExplorOz Team - David - Thursday, Jul 18, 2002 at 00:00

Thursday, Jul 18, 2002 at 00:00
Fred,Have you checked that the alternator is working and charging the battery. Put a meter on the battery, start the car and make sure you get a reading of over 13 volts when you rev the car. This is the first thing to look at anyway.
David
AnswerID: 4941

Follow Up By: Wayne - Thursday, Jul 18, 2002 at 00:00

Thursday, Jul 18, 2002 at 00:00
David,
Even if the alternator was not charging, the battery should not go flat o'night. sounds to me like a short is draining all the power out of the battery. This can cause what ever it is shorting out on to glow red hot and start a fire. i'd have it checked out by a auto elec asap.
Wayne
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Reply By: paul - Thursday, Jul 18, 2002 at 00:00

Thursday, Jul 18, 2002 at 00:00
I still think you should check the alternator. David is an electrical engineer and wouldn't something that wasn't worth checking. What he didn't say but probably thought is that a new battery is not necessarily, more like rarely if ever, fully charged. I helped replace a battery in a mate's Hyundai the other day - the brand new battery he bought was putting out 12.30 volts, almost only half alive. I bought a brand new yellow top optima a few months ago, unwrapped the plastic and it was dead - charged it up slowly and no problems. The point being that if your mate started it a couple times and say has a decent arlarm system then that can put a not insignificant drain on a not very charged up battery and who knows, maybe it could flatten it in 12 hours.

Its just a starting point that all.
AnswerID: 4944

Follow Up By: Fred - Thursday, Jul 18, 2002 at 00:00

Thursday, Jul 18, 2002 at 00:00
Thanks Paul - I think your reply must have come in when I was thanking David and Paul. Understand your point about the new battery .. but it started OK when installed at 7pm then again at 8am but was dead flat at 4pm. I wouldn't expect it to discharge completely after 2 good starts and some driving. I had trouble starting it with jump leads tonight so it was very flat. After starting it I drove it with lights on and it was fine. The original battery was fine after being unused for 5 days. I started it, moved the car for the owner and when she went to use it the following morning it was dead - I assumed the battery had simply failed and replaced it. very surprised to find the same thing happen to the new one!!
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FollowupID: 2122

Follow Up By: Member - Nigel - Saturday, Aug 03, 2002 at 00:00

Saturday, Aug 03, 2002 at 00:00
How much do they charge for yellow top optima's in your part of the world? I'm in a small town and want to make sure I don't get ripped off.
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FollowupID: 2325

Reply By: Fred - Thursday, Jul 18, 2002 at 00:00

Thursday, Jul 18, 2002 at 00:00
Thanks David and Wayne, Alternator not a problem as both the old then new batteries went flat in 12 hours without use. Also started the car with leads and everything went fine - drove some distance with lights on. I'm really looking for a way of measuring and isolating current flow from the battery eg can I measure the flow of current through each fuse in the fuse box and therefore pinpoint the offending area? No signs or smells of burning. Will get it to an autoelectrician ASAP but time and distance is a problem for all concerned at the moment. Thanks again!
AnswerID: 4945

Follow Up By: Ray - Thursday, Jul 18, 2002 at 00:00

Thursday, Jul 18, 2002 at 00:00
Fred if you have a ameter disconect one battery lead and put one lead from the ameter to the battery terminal and the other lead from the ameter join to the battery lead you should have a reading of zero with everything turned off.If you have any current flow remove and refit the fuses one by one to find the short.The alternator could also be discharging the battery through a faulty diode (one way switch) even though it is still charging the battery.Check this also with the ameter conected just remove wires from the alternator to check.Hope this helps
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FollowupID: 2125

Follow Up By: Fred - Friday, Jul 19, 2002 at 00:00

Friday, Jul 19, 2002 at 00:00
Ray that sounds like the help I needed!! Thank you very much - I'll try it asap!!!
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FollowupID: 2127

Reply By: Fred - Sunday, Jul 21, 2002 at 00:00

Sunday, Jul 21, 2002 at 00:00
Problem solved. The alternator was the problem. It was charging OK but the bearings were shot (at first I thought the unusual noise was the belt). The worn bearings were sometimes allowing it to short the battery when stationary. Hence both a new and an old battery were randomly flattened. Thanks again those who helped. Anyone want to buy a new battery - used for only a very brief time!! LOL
AnswerID: 5016

Reply By: Wayne - Wednesday, Jul 24, 2002 at 00:00

Wednesday, Jul 24, 2002 at 00:00
Sorry I doubted you David,
Wayne.
AnswerID: 5112

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