JY95ZJ

Ok so I'm having issues getting my jeep started without having to jump it, so I was thinking maybe a problem with my battery or alternator. It has the 5.2 motor and the battery is only 6 months old. After I jump it and get it started it runs great no issues but as soon as I shut it off it won't start again. Haven't had a chance to take the battery/alternator to have them tested yet but I did the classic get it running and pull the battery cable and it kept running no issues. The battery shows 13-14 on the gauge when running. Could it be the voltage regulator?The only thing I have changed in my setup is add 8mm plug wires. Any ideas or other stuff I can check would be greatly appreciated

IStoleIt

theres a common problem with the ZJs and many other Jeeps, especially after wheeling, there are parrasitic draws in the system. For a few weeks I had to disconnect my battery during any long park. At night or at work all day.

Turns out leaving my phone charger plugged in was enough to kill the battery.

Do some searching and you should be able to find threads on the subject.

Basically, connect a multimeter on AMPS, between the Positive battery cable and the post, after you disconnect them. Then start pulling fuses and find which ones are draining. Careful with the high amp ones like the headlights and HVAC, they will likely blow the fuse in your meter. Theyre probably not the issue anyways after you shut the engine off.

I believe there will always be a small draw, but it should only be like 10-15mA

dave1123

Yes, and when you do the parasitic draw test, make sure the courtesy lights and underhood light are off. Give the electronics time to go to sleep also.

rangermonroe

I had a similar problem. It was a dead battery.

Get it checked. Sometimes we overthink the obvious.

wingless

This topic shows me testing my generator per the FSM.

Bustedback

Have you tried cleaning and tightening the battery terminal connections? That is where I would start.

JY95ZJ

Awesome suggestions everybody thanks. It's been sitting for a little over a month now due to what seems like a chain reaction of problems. I started it at least 3 times a week and would let it run for about 5 mins each time while it sat and would roll the windows down because it's been in the upper 90s all summer and I have no shade at my house. I know cold weather can kill a battery but was just wondering if the heat would do the same? Either way I'm gonna have the battery and alternator tested tomorrow, after that I'm going through the checklist of ideas from the forum members and hopefully come up with something. Thanks again everyone

dave1123

I don't think just 5 minutes of running is going to top off a battery that's just cranked an engine, plus operated the windows. Besides that, you need to let the engine at least reach operating temp each time to expel the moisture from condensation. I think in the long run, you'd be better off just leaving it sit with the battery disconnected.

JY95ZJ

Thanks Dave I always appreciate your input. So I took the battery to autozone and sure enough the battery was drained. Gotta go pick it up in about an hour and hopefully this will solve my problem.... so after leaving the battery to charge at autozone for 4 hrs it was only at 80%, left it there for another 2 hrs on trickle charge and sure enough it was toast. Thankfully it's only 6 months old and still under warranty so I swapped it out for a new one. If this doesn't help it's going up for sale

JY95ZJ

Thanks ranger

dave1123

Don't tell me you bought a Duralast? OR as some people say Don'talast?

I bought an Interstate battery 5 years ago and it's still putting out very near rated output. The one that was in it when I bought the jeep gave me no warning at all except one day it cranked very slowly so I drove it immediately to Battery World where they put the Interstate in. Mine still has cell caps on it where you can check electrolyte levels.

Bustedback

I have an Interstate boat cranking battery in my ZJ, works awesome.

dave1123

That's a deep cycle battery and better at rebounding after a discharge. Most automotive batteries are top-charge where only a light discharge is needed for starting before the alternator kicks in. The more they are discharged, the harder it is for them to recover. Some people tell me you don't need a deep cycle battery in a vehicle, but a winch or other devises like transmitters will draw a top-charge down quickly. They tend to heat up under a heavy load. Deep cycles are usually used in electric golf cars and fork lifts and such. Back in my younger years, my neighbor built an electric lawn mower with a starter motor and 2 small deep cycle batteries. It was a bit heavy, but cut his lawn before running out of juice.

rangermonroe

Glad to help. Mine was doing similar, and I was sure it was something just awful & expensive.

My dumbass 19yo son said 'hey, Dad... why don't you just toss this battery in it and see if it works?"

Still driving on that battery a year later. [embarrased]

JY95ZJ

Yeah when I first posted and saw some of the ideas everyone was giving I was like holy **** I'm selling this thing haha. Definitely gonna start with the simple stuff next time. Thanks again