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#3316247 - 03/18/14 08:55 PM Battery completely dead ... but at 9V?
Miller88 Offline


Registered: 04/09/08
Posts: 7174
Loc: Onondaga County
Went out to my Cherokee today to try to continue playing around with the broken ujoint strap bolt.

I noticed my drivers side rear door was open. Battery was dead. The headlight switch was in the parking light position and interior lights were set to on.

So, obviously nothing happened.

I pulled the battery out and it still have 9V?

It's also having some issues taking a charge.

Shouldn't something at least happen with 9V? I'm wondering if the local lowlives also screwed up my electronics.
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#3316251 - 03/18/14 08:58 PM Re: Battery completely dead ... but at 9V? [Re: Miller88]
redbone3 Offline


Registered: 06/09/12
Posts: 218
Loc: Reno, NV
You are measuring 9V with no load. Measure the voltage under load and it is probably a whole lot lower. With the battery in the car, you can turn on the headlights and see a big drop in voltage.
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#3316254 - 03/18/14 09:01 PM Re: Battery completely dead ... but at 9V? [Re: Miller88]
Miller88 Offline


Registered: 04/09/08
Posts: 7174
Loc: Onondaga County
Nothing happened with headlights turned on or cell phone charger plugged in.

No dome light either.
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#3316261 - 03/18/14 09:08 PM Re: Battery completely dead ... but at 9V? [Re: Miller88]
Donald Offline


Registered: 03/21/04
Posts: 13760
Loc: Upstate NY
Some of these items may be controlled by relays that won't kick in at 9V.

Charge it with a plug-in charger than have it load tested. Check the cells for low battery acid level.

How old is the battery?

Some fancy chargers will not charge a very low voltage battery.
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#3316281 - 03/18/14 09:25 PM Re: Battery completely dead ... but at 9V? [Re: Miller88]
123Saab Offline


Registered: 10/27/10
Posts: 1347
Loc: PA
Dead cells can reduce the amps so it wont do much but still show some volts.

It's dead most likely.
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#3316282 - 03/18/14 09:25 PM Re: Battery completely dead ... but at 9V? [Re: Miller88]
jeepman3071 Offline


Registered: 04/15/10
Posts: 1837
Loc: Storrs, Connecticut
Did you leave the door open or did someone force their way in?

Once the battery gets discharged enough, it can refuse to take a charge. Anything that low will result in weird things happening with the electronics. I had a dead cell in my battery, and all the gauges went crazy in my Jeep and it would run for 2 seconds and shut off. Chrysler electronic systems seem to be sensitive, and I think you might need a new battery. frown

How old is the battery?
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#3316285 - 03/18/14 09:29 PM Re: Battery completely dead ... but at 9V? [Re: Miller88]
morris Offline


Registered: 08/24/08
Posts: 3681
Loc: ks, wichita
i am not an electronics engineer. BUT i have learned that electronics chips if the needed voltage is not sent to them they CAN act very strangely. so if one just stops be glad.

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#3316290 - 03/18/14 09:33 PM Re: Battery completely dead ... but at 9V? [Re: Miller88]
Chris142 Offline


Registered: 06/05/03
Posts: 11742
Loc: apple valley, ca
A 12v car battery is considered discharged at around 12.2volts. 9v is way dead.
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#3316299 - 03/18/14 09:39 PM Re: Battery completely dead ... but at 9V? [Re: Miller88]
Miller88 Offline


Registered: 04/09/08
Posts: 7174
Loc: Onondaga County
Battery is less than two years old.

I left it unlocked. That way the locals will just open it up and not break into it.
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#3316307 - 03/18/14 09:43 PM Re: Battery completely dead ... but at 9V? [Re: Miller88]
901Memphis Offline


Registered: 08/14/10
Posts: 6352
Loc: Northern Kentucky
9v is extremely dead. Anything under 10.50v is basically flat. A fully charged battery with no charge or discharge for 6+ hours would be at least 12.60v or higher.

Get that battery charged before the damage gets worse, they don't like to go that low but it should recover fine. You may need a special charger to get it charged since it went so low. You can take it by an auto parts store for a quick charge or take this as an opportunity to buy a new charger.
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#3316314 - 03/18/14 09:49 PM Re: Battery completely dead ... but at 9V? [Re: Miller88]
Miller88 Offline


Registered: 04/09/08
Posts: 7174
Loc: Onondaga County
Electrolyte levels are good and it didn't freeze.

Up to about 10.6 volts. I have it on the 2 amp charge. I try to avoid 6 amp charge.


Edited by Miller88 (03/18/14 09:49 PM)
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#3316335 - 03/18/14 10:02 PM Re: Battery completely dead ... but at 9V? [Re: Miller88]
JHZR2 Offline



Registered: 12/14/02
Posts: 34213
Loc: New Jersey
Classic shorted cell. No practical energy as the battery discharges into it, but yet open circuit reflects the chemistry on the other cells.

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#3316347 - 03/18/14 10:13 PM Re: Battery completely dead ... but at 9V? [Re: Miller88]
Miller88 Offline


Registered: 04/09/08
Posts: 7174
Loc: Onondaga County
Likely put another battery into it frown

Nothing like a $500 month on vehicle repairs.
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#3316369 - 03/18/14 10:30 PM Re: Battery completely dead ... but at 9V? [Re: Miller88]
Rolla07 Offline


Registered: 11/05/11
Posts: 1926
Loc: MTL, CANADA
Where do you live?!! My city its hit and runs!! Always something...
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#3316414 - 03/18/14 11:36 PM Re: Battery completely dead ... but at 9V? [Re: Miller88]
Barkleymut Offline


Registered: 01/27/04
Posts: 2497
Loc: Richmond, VA
Google tells me that he is very close to Syracuse NY
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