investinwaffles

Ok guys, on the way to work this morning I had to floor it to merge with traffic, and as soon as I did my battery voltage gauge dropped to zero. I drove it 5 minutes to my office, popped the hood and threw a multimeter on it (thank god I have my tools in the back today).

Battery voltage was 13.4 at idle, and 13.8 at 2000rpm in neutral. I shut the thing off, and it started right back up but was throwing a P1682 check engine light. Battery voltage was the same, but the gauge was reading proper voltage (about 13.5v) instead of just flat zero. I turned all the lights on and cranked up my stereo and the voltage is staying pretty consistent.

1. So my first question is, can I still drive it with the battery voltage being that low (13.2 was the lowest I saw)?? Basically I dont want it to die on me when I am on the highway

2. I actually have time to go to the junkyard today and was going to remedy this situation tonight with a new alternator, probably just pulled from another XJ but I want to make it to the JY without the battery going flat on me, but at over 13v I should be OK right?


Im gonna pull a bracket off as well so I can slowly do a Durango/ZJ alt upgrade as well, but going from 117a to 136a isn't a huge jump (minus the part about my alt. not working correctly). Might need to hunt for a 160 amp or just buy one from the parts store.

Creature85

How old is your battery? I'd look at that first before getting a new alternator.

investinwaffles

****, forgot to mention that. Battery is literally 1 week old - its a Duralast Gold 800 CCA type 34 battery.

Slightly larger than the stock one, but it should really not be an issue (I have never really had an issue oversizing a little from a stock battery). I am 100% the battery is good because I was tuning my stereo over the weekend and it was on for about an hour. I recharged it using my battery charger on 10amps though, and I didnt drain it down that much.

I also have the big 3 done, with a 150 amp fuse between the battery and the alt, and the original wiring is all still in place as well (sort of doubling up, and in my mind - providing a failsafe backup route for the electrons).

After googling, it seems that 13.8v is normal when the battery is "topped off" and the car is running, but everyone says 14.4v is perfect to see at idle.
Sound Correct? Pretty sure its the alternator if thats the case

EDIT:
Also, alternator voltage is set within the PCM, correct? Hope thats not the culprit