New Battery Help!!!!!!

[wardogs]

I just bought a new battery 3 weeks ago for my 04 jeep liberty 4x4 and I had left my aftermarket fog lamps on all night and had to jump it off. Well now the battery will not hold a charge I have left the jeep running for about an hour and disconnected the fog lamps and tested the alternator by disconnecting the battery post while it was running. Please I need to figure this out I'm station in Cuba right now and don't really have a good auto shop here.

[Airjer_]

If the battery is only 3 weeks old why not see if they will warranty it.

I would probably not recommend disconnecting the battery while the vehicle is running. If you want to see if the alt is charging than a volt meter and an amp probe will be needed. You should see at least 13.5 volts and preferably more. 14-14.5 volts would be great.

Depending on the quality of the battery it may have gone bad after being fully discharged. Or you may be better of driving it for an hour to see if it can put out a little more charge. My bet is the battery has gone bad!

[MagicRat]

Why did you replace the old battery?

Test the system voltage when the engine is running. (As noted above, it should show 13.7 to 14.5 volts, no more).
It is possible that your alternator is overcharging, it cooked the old battery and is now cooking the new one.

However, it is more likely the new battery is bad and should be replaced free of charge. A lead-acid battery that is fully discharged, like yours was loses about 10% of its effectiveness, even when fully charged again; so its worth it to get a new one under warranty.

[jdmccright]

I would find a good battery charger and attempt to charge it...overnight...up to 24 hours. Some will allow you to choose how fast to charge. I would start with a fast rate to at least see if it will take a charge at all. Test the voltage first, then connect it and start charging and leave it overnight. Then test the voltage again in the morning...if it is nearly recovered, then switch to a trickle charge to complete charging.

Or you can just haul it back to the store for a replacement....

A car's alternator isn't really designed to replenish a dead battery...you'd have to run the car for a lot longer than an hour to replenish all the amps discharged overnight. Hope this helps!

[jb_85]

Try to provide as much information as you can when asking for diagnostic help. It would help isolate the problem more effectively.

Have the battery tested at where you got the battery or some auto shop. Since the car was running for an hour, I would ASSUME the alternator is OK. I would think the most likely cause is a dead battery that's not holding a charge. If you had a multimeter or some sort, you can do a couple of tests yourself to help determine the problem.

[bobss396]

You generally charge a battery the same was it was discharged. Yours is in the slow category, so a slow charge would be fine. Check the battery connections make sure they are clean and dry.

While I don't recommend taking the negative terminal off on newer cars to see if it is charging, it was always the acid test on pre-computer cars. So if you have already done it, did it stall or keep running?

You should really get a full check done on your charging and starting system. Most auto centers do them free or cheaply enough.

Bob

[534BC]

What are general guidelines for testing battery?

I'm interested in current and time for a certain ccw or sizes.