my cherokee wont start. WTF?

[AKASHAJEEP]

So I just finished putting the lift on and everything. I put her down on the ground and double check everything. get in and turn the key. and the battery is completly dead. ok I can live with that cause I am the dumb a$$ that left the stereo on for the first 5-6 hours, and didnt start her back up.2nd day i had to leave the door open so that stupid alarm wouldnt go off everytime i bumped something under the jeep and not to mention the tilt switch.
so I can say that yes the battery is dead, but I put it on a charger for over 4 hours @ 12v6amp and it sounded like it really wanted to fire but didnt. ill just give her more juice then!! pull the other truck up to her and checked the voltage(13.75V going through the cables) should be more than enough to fire up. well same thing, sounds like she wants to fire but nothing.
what gives here? the motor sounds like it is wanting to turn over and is a very strong sound. maybe more than what it was before i started this whole adventure. and now nothing.

I did check the fuel rail and make sure there is at least fuel going to the injectors. I am not 100% that it is getting a spark though. but what could I have possibly done to disrupt anything on the motor? (I did put on the 1" trans drop but still nothing to do with the electrical system at all)

[XJNick]

Hi,

Congrats on completing your lift

It would have been best if you had disconnected the battery before taking the Jeep apart, as leaving it sit over time with stuff still connected can run down the battery due to what i'd call "phantom" loads (i.e. the clock, vehicle computer, etc..) which actually use some power even when the Jeep is off.

However, the "phantom" loads should NOT drain the battery. It is normal for them to run it down slightly though.

The most important question here is what was the voltage that the battery was run down to? If it was under 7-8 volts, it's almost certain the battery is ruined. The reason for this is that standard car batteries are NOT designed for (and cannot withstand) being drained past 60+ or so % charged. Deep cycles are more tolerant of being drained down, but can still be damaged if done frequently or drained to far down.

What happens is that you risk damaging or reversing a battery cell (of which there are 6 on a 12 volt battery). Even if you were able to charge the battery back up to 12+ volts after it had been drained, a cell could still be bad, thus deratting the current output of the battery. The starter motor requires alot of current so if your battery cannot supply it, you don't start the Jeep. Try putting a smaller load on the battery (like some tail light bulbs) and see if the voltage rapidly drops or not.

Also check that it is charging properly. Most 12 volt batteries are 100% charged at around 13.4 volts

-Nick

[LGR]

looks like time for a new battery. If that doesn't fix it you got a bigger problem on your hands.

[AKASHAJEEP]

well I got it fixed this morning and I have been driving all around!! LOL
it had something to do with the air intake? dont know why that caused any problems but it did. what I ended up doing was just taking the air filter cover and the throttle body hose off and plaied with the position a little. it finally started up so i let her run for a bit to make sure the batt was charged, shut it off and put the hose and air box cover back on. then tried it again and she just fired right up.

of course all this was done after I had determined that the enginge was getting fuel and spark to the plugs.

[jeepmaster]

its wierd how they work sometimes