New battery drained, will not jump start

Hey guys,
I did a few searches, but did not see anything exactly like my issue. If anyone knows of an FAQ or previous thread that applies to my issue, please direct me there.

I have a 96 Cherokee XJ 4.0 AT with a battery that is just a few months old.
Some genius left the lights on over the weekend. (that genius would be me )
The Jeep was of course dead this morning.

I borrowed a car, (A 2003 VW Pasaat/12v battery) and followed the instructions on both the jumper cable package and the Chilton manual for jump starting the Jeep. The other car idled for a bit, maybe 5 minutes. I tried to start the Jeep, it, it tried to turn for a second, then clicking then nothing at all.. After that first failed attempt, the Jeep did not respond at all when I turned the key. Put it in neutral, no change.

I took the jumpers off, waited a minute, then started the whole process over, this time the VW was revved above idle (as recommended in the Chilton manual) Still, no sign of life whatsoever.

The battery, after the jump attempt, read about 2v on the volt meter.

Is it possible I did some harm to the electrical system?
Is there anything else I can try before having this towed to the shop? Should I let it charge for a while longer before trying to jump start? If so, how long? Would a battery charger be worth trying? Could it be a fuse? The batter is new and under warranty, I could have it replaced I guess.

I am a computer tech who is new to cars, but I am game for doing things myself to a limit..

Thanks in advance for any suggestions,

you aren't going to get a jump start on a comletely dead battery like that.

Try a battery charger, for at least 12 hours. If it still doesn't hold a charge you've damaged the battery and need a new one.

You should not have done any damage to the electrical system, unless you hooked up the jumper cables wrong.

Edit: I just read that the battery is under warranty. I'd just go replace it and your jeep should start right up. automotive battereis don't take to well to being completely discharged like that.

2v??
you gotta be kidding - at that voltage it should be a puddle of slag!!
87manche is right - you fried that puppy good (I think the plates probably look like crinkle cut potato chips).
get a new battery

Thanks for the replies and advice guys.
Heh... yeah 2v, I messed it up good leaving the lights on... But should it really be this dead? Admittedly it would've been well over 24 hours that it was left like this. Yes. I am a genius!

I'll try to get it swapped out. Is there anything I should say or not say when getting the new one under warranty? All warranties have their exclusions, but leaving the lights on does not seem like a good reason to deny a replacement.

Just want to have my facts straight and answers ready before I go in asking for a new battery.

Thanks again guys,

Actually you need to measure the voltage across the battery terminals with the battery disconnected - that 2v can't be right.
I am pretty sure you will find it's actually 8 or 10v worst case.
It needs a long slow charge, don't try and charge at high rate as this will cause damage to the plates. On a 4 amp charger you will need 24 hours on slow charge to achieve the best result.

Thanks Roadhog, it sounds like I should just replace it under warranty if I can. That would be the easiest route, rather than doing a long slow charge. But that is good info to know.

I'll check it again when I get home with the terminals disconnected and see what it reads.

If you are going to get a warranty replacement, tell them it is not holding charge and discharges very quickly (24 hours or so) - say you borrowed a friend's battery for comparison and it doesn't have the same issue. They should be forced to assume it is a manufacturing defect - breaking down under load.

Most parts stores will test the battery and charge it for free. I did the same thing to my battery and left it on a float charger for 18 hours and still got nothing. So I took it down to kragen/o'rielly thinking it was just a core for the new battery, but had them test it anyways. The battery was good and their high-amp charger topped it off in 30 minutes.

Actually just leaving the lights on shouldn't have damaged the battery, the relays would have dropped out of circuit around 11v or so.
I often kill my battery running the sound system whilst monkeying around in the garage (those 2 amps suck juice!) - and after an overnight recharge everything is 100%

OK, so maybe I can just take it back to the store and let them test/charge it. Should I trust them to determine if it needs to be replaced or not? Or just press for a new battery?

Thanks for all the advice.

If you don't feel comfortable accepting the vendor's advice, take it elsewhere for a second opinion.

jwolford said:

OK, so maybe I can just take it back to the store and let them test/charge it. Should I trust them to determine if it needs to be replaced or not? Or just press for a new battery?

Thanks for all the advice.

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How about you take the battery back to vendor, man-up by telling them exactly what happened, and see what they can do to help you.

Try bringing it to a shop and having them charge it, honestly I thought the battery I got with my MJ was completely kaput, it turned out that if you leave the blower on low, you can't hear it but it's still running with the key off... or maybe I took the key out in accessory because the thing is so worn, I'm not sure. Regardless, after 24 hours on autismzone's charger it worked fine and I discovered the blower issue while leaned over the engine compartment holding the keys going "why is it still making noise?" The battery has not failed me since, it's started up in 2-3 cranks through all of February and it's a few years old and starting a motor with 210k on it.

The lowest 12V lead acid I've ever seen was at 6 volts float, and that was a completely sulfated gelcell I picked up for free approximately three years ago and had fully discharged, then left in storage, sitting on a cement floor, until I pulled it out last month. Yeah, that one went to the recycler...

I talked to the shop, told them the situation, and I'll be taking it in tomorrow and they'll try to charge it and test it. If it doesn't take, they can replace it under warranty.

The point of posting here was to figure out if there was anything I missed or might have done to make things worse. Which doesn't seem to be the case. It appears to be just a totally drained battery. I'll report back the good news or bad news in a few days.

Thanks for the helpful replies.

I pulled the battery this morning and tested it while disconnected, it read 1.8v on my meter. Ouch. Took into the shop I got it from, they checked and got 1.7v. There ya go. D_E_A_D...... :skull2: They did not even bother trying to charge it and just swapped it out.

The new battery is in and the Jeep is up and running again. Thanks again for the good advice.

definitely a defective unit - there's no way a simple battery drain will destroy it like that

X2... I've drained my battery a number of times (the one in the MJ was drained two or three times a week for upwards of a month by its previous owner before we figured out that issue I mentioned with the blower) and it probably isn't as good anymore, but it still works. Glad you got it replaced.