Battery in Jeep Grand Cherokee dead this am and less than 1 year old. I have a Everstart 100 battery charger plugged in and on the car. How long does it take to charge the battery. The charger is plugged into an extension cord. I have never used this charger and do not have the users manual.

moved you out of computer repair (wow) TO jeep.
parked how long 1 month , 3 years, what? TIME MATTERS.
for sure bad fuel, and now useless sulfated battery
always store cars with battery float charger attached,
the car has no 120vac power, unless fitted with an inverter.
the Car is dead
the Engine is dead. (ill run the list that you forgot)
the engine will not crank
the cluster is dead.
the headlights on USA car can turn on with NO KEY AT ALL
a safetly LAW here.
so the head lamps are dead. this A KEY FACT here.
if HL are dead the fuses main are blown or pulled by the smart guy that parked it long term.
FUSES ! or battery is NO GOOD.
no charger sold can tell you if a battery is good ever.
on a full load tester can you do that, puts a 100amp load on the battery and then if over 10v , the battery may be good
call AAA and they will do all this, easy as pie. call tow.

If the battery is old(2 to 2/12 years) the battery is sulfated and worn out inside. Going dead is just the nail in the coffin. Plus, a discharged battery will freeze in cold weather, allowing the ice inside to bend and break the lead plates inside, causing shorts to occur and will drain the battery after charging. If it were me, I would bring the battery somewhere warm for 8 hours, slow charge it, then have it tested. If it's more than 2 1/2 years old, I would just replace it.

Could be, might have it programmed first. If still won't start, check for fuel delivery and spark.

try putting your key in the passenger side door , lock and unlock the door manually , then try starting it usually if the battery dies it will cause the jeep to go into security mode . when you try this have the jeep hooked up to a battery charger in case the battery is dead . good luck

check the voltage on the battery with a volt meter, it should be around 12.6 to 13 volts, if not charge battery with a charger, after charge try to start vehicle, if the vehicle starts use your volt meter at the battery again, the voltage should be around 14 to 14.5 any lower and the battery isn't being charged and the alternator should be checked and or replaced to solve the problem..

Replace the battery if it is at least 4 years old. The computers will not power up if it does not have suficent voltage. put a new battery in it and check the charging system.

If you installed a stero system make sure the amp is not on all the time. Other than that try testing the starter and components.

Well go to the battery and make sure the connections are tight also would be a good idea to put a battery charger on it . Im from minnesota and it was -51 this am so i feel ya pain

the alternater may need exciting try reving it pretty hard to excite it