View Full Version : How long should a good battery take to discharge hooked up...
ryan roopnarine
10-18-2009, 02:07 PM
to a parked car? I have a autozone 49d that i have had in my e34 for about 6 weeks now, undriven. The battery is about 6 years old, so this is mostly for my curiousity. I tried to start it this morning for a little 1-2 mile drive, and found that the starter wouldn't even click--the fasten seatbelt display just dropped somewhat dimmer than it was. I want to drive the car to canada in december, more likely than not, so I'm probably going to change the battery before then. Thanks.
Interceptor
10-18-2009, 04:27 PM
6 year old battery uncharged for 6 weeks? I'd say that's pretty normal. I would definitely buy a new one.
Tiger
10-18-2009, 05:58 PM
6 years old is old... but you can try that battery conditioning trick that is well document on this forum to bring it back alive...
Autozone has 7 years prorate warranty so you might save several bucks. Colder temp really does kill weak battery.
ryan roopnarine
10-18-2009, 06:45 PM
If you are talking about the one with the carbon pile, I'm pretty sure that I wrote it :D
this battery has been ryan-conditioned once about 2 years ago. it has kept on trucking up til this point. the longest i've left this battery before has been 3 weeks, and it started right up then.
6 years old is old... but you can try that battery conditioning trick that is well document on this forum to bring it back alive...
Autozone has 7 years prorate warranty so you might save several bucks. Colder temp really does kill weak battery.
Tiger
10-18-2009, 11:03 PM
LOL... it is probably you. Try charging it up and see what voltage it holds and when cranking... If it drops to below 9.6V during starting, you know it is bad.
632 Regal
10-18-2009, 11:12 PM
If you are talking about the one with the carbon pile, I'm pretty sure that I wrote it :D
this battery has been ryan-conditioned once about 2 years ago. it has kept on trucking up til this point. the longest i've left this battery before has been 3 weeks, and it started right up then.
Praises the method and have a 1 year batt that just wont respond to anything. Direct short nothing, batt tender zero, maybe dump the acid and add acid from other known dead battery?
ryan roopnarine
10-18-2009, 11:23 PM
Praises the method and have a 1 year batt that just wont respond to anything. Direct short nothing, batt tender zero, maybe dump the acid and add acid from other known dead battery?
what was it on? a boat, a pump of some kind? is this one connected in series or parallel in some way to other batteries. I've never done the dump and wash myself. I take it that your warranty is toasted before I suggest something?
I've had better luck using Ryan's method than dumping and refilling with fresh electrolyte.
Yours sounds like it's shorted internally. I've heard that if enough of the "stuff" on the plates precipitates off it can build up enough to short circuit the cells so may be a dump and wash out could help but at one year I'd be trying hard for a warranty claim instead.
BigKriss
10-20-2009, 06:54 PM
Where is the old post by Ryan for reconditioning old batteries?
When reading the battery in volts, what amount is too low to restore a dead battery?
ryan roopnarine
10-22-2009, 11:56 AM
Where is the old post by Ryan for reconditioning old batteries?
When reading the battery in volts, what amount is too low to restore a dead battery?
I'd try it even if it is too low, you've only lost your time if it doesn't work.
http://www.bimmernut.com/forum/showthread.php?t=39870&highlight=battery+ross
Jeff, If you don't mind d*cking around with the acid, I have something to suggest and a table of acid concentrations. all you'd need is new acid and the gravity tester.
oh yeah, and about the original thought in the thread. i tried starting it at 5 in the morning, when I was leaving at 6. I didn't have time to try to charge it or jump it. I'll look at it when i'm back in town.
BigKriss
10-22-2009, 05:30 PM
okay thanks for that Ryan.
I'd try it even if it is too low, you've only lost your time if it doesn't work.
http://www.bimmernut.com/forum/showthread.php?t=39870&highlight=battery+ross
Jeff, If you don't mind d*cking around with the acid, I have something to suggest and a table of acid concentrations. all you'd need is new acid and the gravity tester.
oh yeah, and about the original thought in the thread. i tried starting it at 5 in the morning, when I was leaving at 6. I didn't have time to try to charge it or jump it. I'll look at it when i'm back in town.
Qsilver7
10-25-2009, 12:45 PM
...I have a autozone 49d that i have had in my e34 for about 6 weeks now, undriven. The battery is about 6 years old...I tried to start it this morning ...and found that the starter wouldn't even click....
BMW recommends that if a car is being stored or not driven for periods of time (like 4-6 weeks)....that the battery should be kept on a charging schedule. If not, repeated long periods of discharge cna damage the battery.
http://www.bimmerboard.com/members/q/original/BMW%20Battery%20Charging%20Calendar.jpg
When the battery is at 11.89 volts...it is a 0% state of charge (basically running on reserve capacity). You may get some interior lights, radio, horn, etc...but may not have enough juice to start the car...especially when you start to get lower than 11.2 volts:
http://www.bimmerboard.com/members/q/original/BMW%20Battery%20State%20of%20Charge.jpg
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