Thunderknuckles

Howdy! Brand new to the forums here and just wanted to get some knowledgeable opinions. I'll try to be as brief as possible. Recently I traded in my 2010 Wrangler Unlimited Sport for a newer pre-owned 2015 Jeep Wrangler Sport 4 door (hard top). All seemed well for the first couple of weeks when I learned that I had a parasitic power draw. The dealership will hardly return calls and when I do get someone on the line they deflect me to someone else who also won't help. Took it to my mechanic (very solid older guy who's one of the rare honest ones). He did a voltmeter test on it and it turned out it was the stereo. M12 fuse and the only 2 things on it were the radio and amplifier. It would seem that the previous owner had pulled their very good stereo and very hastily shoved in/wired up a Walmart brand stereo.

So...I take it to a highly rated stereo installation place here locally. The owner assured me he could work around the power draw, despite the original wiring harness having been cut. He did the work and all seemed well. Two weeks later and my Jeep is now intermittently starting up very weakly or not cranking at all on the first try (along with clicking noises). When it won't start on the first try I crank again and it'll usually start up within the first 3 tries. Today I pulled that fuse again just to see if it starts with no trouble without that fuse in. Nope, still a weak crank after 8 hours. So it's doing this without the radio fuse in.

My question is: could the original power draw have weakened the battery so badly that I now need to replace it? Maybe the starter going bad? Big thanks in advance to any friendly replies! By the way, I also mistakenly (I think) posted this under the Electrical, Lighting, and Sound Systems forum, so re-posting in what I think is the right one.

jedg

I'd start with taking your battery to the auto parts store of your choice and have them run a load test on it. That will let you know how many cranking amps the battery is putting out.

Tech Tim

Use a multimeter, check your battery first thing in the morning, it should read between 12.4v and 12.7v. If it reads less, then it isn't fully charged. It could be the battery or could be the alternator.

Then fire it up, wait until the idle drops and check it running. It should read between 13.5v and 14.4v~ish. Higher or lower and the alternator is probably the culprit.

Thunderknuckles

Thank you, Jedg. I took it to a local battery store who will test your battery for you. It pulled 517 cold amps this morning, when it should be at around 650. Last month it tested strong. Back to the mechanic for another ammeter test.

Rednroll

Purchase one of the micro controller battery chargers. As well as recharging your battery, they often have a battery reconditioner feature which can breath new life into a failing battery.

My 1st Die-hard Platium Marine AGM battery lasted 2 1/2 years. The 2nd one I got, I additionally purchased a micro controller charger, where I use it twice a year to top off my battery and recharge it anytime it's been run down. I used the reconditioner on it twice. I'm going on 5 years with the 2nd battery.

Thunderknuckles

Thank ya Tim and Rednroll! I forgot to mention in my original post that when the M12 fuse was pulled during the original ammeter test the draw dropped down to .02 milliamps. That's why I wondered if that parasitic draw (.551ma) had actually weakened my battery so badly that it now intermittently cranks up slowly or won't crank up until the 3rd or 4th try. It went like that for a good month before I took it in to have the ammeter test done.

Tech Tim

How long does your Jeep sit between use?

Parasitic draws are not a problem unless the battery is weak already. A 25ms parasitic draw is common on newer cars, some have upwards of 50-75ma or more. A .551ma draw is nothing unless you let it go for months between start ups. The problems arises if you let the vehicle sit too long with a parasitic drain and the battery voltage drops below 12.4v. That's when the battery starts to sulfate and you could start seeing problems with it over a period of time.

Another possible problem is the starter itself. However the easiest first two tests are the ones I mention above.

Thunderknuckles

Before I had a new stereo put in it would go dead after a day and a half. So if I drove it Saturday afternoon and then parked it in the early evening and let it sit till Monday morning till around 11A (when I head to work) it would usually be dead. Now it's happening even after driving for 40 minutes straight. Sometimes it'll crank up powerfully and other times it won't start at all till the 3rd or 4th try. Other times it'll crank very weakly.

chipflyer

After I bought my 2010 it too would go dead (with a good battery) in about a day and a half. Found out on another forum that it's common for the fuel pump relay to stick on after shutting the engine off and it would kill the battery in a day and a half. That relay is on a circuit board inside the TIPM and can be purchased for under $10. I have an electronic/mechanical background and replaced the relay myself and now my Jeep can sit for 2 weeks without the battery even getting low, The video below can walk you through the replacement but it's not for everyone to try and do themselves. You can send the TIPM away and have it done also. I would bet you have the same issue, something else to look into anyway.

TIPM info

Thunderknuckles

Very much appreciated, Chip! I'm taking it back to my "pit crew" on Monday and will definitely suggest that! Edited to ask if that fuel pump relay sticking "on" would show up on an ammeter test?