Battery Charging

[Freems]

Andy29847, Thank You for the chart of understanding, it has given me some clarity to this Rube Goldberg system concocted in the name of a thimble full of fuel savings across the entire life of the Jeep. Mine has a service appointment in 8 days to hopefully correct these issues. The other point of mention, if you need to jump the rig…it won’t let you with the hood up! If your by yourself you can‘t be in two places at once to hold the two plunger buttons down and push the start button on the dash. So far my routine is put a charger on the battery consistently measuring at 10.56v (after it dies) for a few minutes (brings it to 14.50v)remove the charger cables, shut the hood, push the dash button and it starts. Insane.

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[Andy29847]

Andy29847, Thank You for the chart of understanding, it has given me some clarity to this Rube Goldberg system concocted in the name of a thimble full of fuel savings across the entire life of the Jeep. Mine has a service appointment in 8 days to hopefully correct these issues. The other point of mention, if you need to jump the rig…it won’t let you with the hood up! If your by yourself you can‘t be in two places at once to hold the two plunger buttons down and push the start button on the dash. So far my routine is put a charger on the battery consistently measuring at 10.56v (after it dies) for a few minutes (brings it to 14.50v)remove the charger cables, shut the hood, push the dash button and it starts. Insane.

I'm guessing you are doing this with both batteries hooked up as delivered. I'd also guess that you main battery is bad. I won't be embarrassed if I am wrong. The Jeep system seems like it was designed to confuse. That's one of the reasons that I recommend that the aux battery be abandoned at the first sign of battery trouble after your warranty has expired. I disconnected mine by removing the aux battery negative cable from the negative post of the main battery, insulating the end, and stowing the wire out of the way. I then pulled fuse F42 out in the fuse bock (which disables the power control module). My truck work great on one battery. Even the stop/start works until I remember to turn it off. One of my goals is to NOT have to rely on the dealer to diagnose battery problems.

 

[Freems]

I'm guessing you are doing this with both batteries hooked up as delivered. I'd also guess that you main battery is bad. I won't be embarrassed if I am wrong. The Jeep system seems like it was designed to confuse. That's one of the reasons that I recommend that the aux battery be abandoned at the first sign of battery trouble after your warranty has expired. I disconnected mine by removing the aux battery negative cable from the negative post of the main battery, insulating the end, and stowing the wire out of the way. I then pulled fuse F42 out in the fuse bock (which disables the power control module). My truck work great on one battery. Even the stop/start works until I remember to turn it off. One of my goals is to NOT have to rely on the dealer to diagnose battery problems.

Thanks for the response, as soon as the dealer corrects the issues (it still under warranty), I’ll follow your advice and disconnect and pull the fuse. I’m in the process of installing a winch 8k up front and was planning on a battery in the bed, in a box that I run for my ARB fridge, HF modified crane. I was planning on leaving this battery off the JT’s electrical system except for taping the 12v charge line coming from the alternator through the 6 pin plug in for towing for keeping it topped off. If you look at the picture i attached I mounted a Warn remote for the 2k crane winch and a charge port for the ARB. Also I‘m well underway building my own JT rear bumper with a swing out tire carrier and a vertical receiver on the corner for the “old guy, me” HF crane to lift crap in and out of the bed. I had this set up on my old f150, but traded it off for the JT. Haven’t research or measured how much current/amps are coming through that line yet, any thought on this approach? My battery in the box is a group 31 marine first interstate, that goes three full days with the ARB in the summer without charge.

 

[ShadowsPapa]

Thanks for the picture. I have a 2020 and I removed the cable that has the negative clamp on in your picture. Is there an additional step I need to do?

No, as pictured, that charges the aux battery and only the aux battery.

 

[Beemer533]

Andy29847, Thank You for the chart of understanding, it has given me some clarity to this Rube Goldberg system concocted in the name of a thimble full of fuel savings across the entire life of the Jeep. Mine has a service appointment in 8 days to hopefully correct these issues. The other point of mention, if you need to jump the rig…it won’t let you with the hood up! If your by yourself you can‘t be in two places at once to hold the two plunger buttons down and push the start button on the dash. So far my routine is put a charger on the battery consistently measuring at 10.56v (after it dies) for a few minutes (brings it to 14.50v)remove the charger cables, shut the hood, push the dash button and it starts. Insane.

I'm confused about this; you can definitely start the truck with the hood open, you just can't use remote start with the hood open.

I've had to jump my truck many times with my NOCO jump pack and the hood is always open when I start it.

 

[sharpsicle]

I'm confused about this; you can definitely start the truck with the hood open, you just can't use remote start with the hood open.

I've had to jump my truck many times with my NOCO jump pack and the hood is always open when I start it.

You can definitely start it from the cabin. You cannot, however, remote start it. I think this is confusing people a lot.

 

[Freems]

Now that makes sense, I was trying to use the remote start, outside the truck fusing with the battery charger, Thanks for that. These ESS issues are working my last nerve.

 

[ShadowsPapa]

I'm confused about this; you can definitely start the truck with the hood open, you just can't use remote start with the hood open.

I've had to jump my truck many times with my NOCO jump pack and the hood is always open when I start it.

The reason that you can't remote start with the hood open may be obvious to some - someone is working on the truck, hood open, hands in the belt area, and someone hits a remote start and that person loses fingers.
Techs/mechanics must be able to do a big round button start with the hood open, but it's just plain dangerous to allow someone to start it from 50 feet a way with a fob, or from 100 miles away, with a phone, with the hood open.

 

[Andy29847]

Thanks for the response, as soon as the dealer corrects the issues (it still under warranty), I’ll follow your advice and disconnect and pull the fuse. I’m in the process of installing a winch 8k up front and was planning on a battery in the bed, in a box that I run for my ARB fridge, HF modified crane. I was planning on leaving this battery off the JT’s electrical system except for taping the 12v charge line coming from the alternator through the 6 pin plug in for towing for keeping it topped off. I Haven’t research or measured how much current/amps are coming through that line yet, any thought on this approach?

I’m not the guy for these questions. I do not have much accessory wiring experience. That doesn’t mean I don’t have an opinion.

I’d charge the bed battery from the alternator using an isolater. I’d use bigger wire than what is in the factory harness. In fact, I’d be surprised if the trailer harness is wired with charging current. BTW, I think the plug is a 7 pin arrangement. Group 31 batteries are big and strong.

 

[Freems]

Thanks for the input…the isolater is safer, and up sizing of wiring prevents forest fires.

 

[Andy29847]

Thanks for the response, as soon as the dealer corrects the issues (it still under warranty), I’ll follow your advice and disconnect and pull the fuse.

HAHAHA! Almost as soon as I posted to this thread, I started having issues with the stop/start on my second Jeep. This one is a 2020 Gladiator. I reported earlier that the charging voltage never went below 14.4. This Jeep is generally driven once a week. I went out Monday morning and it was cold (29°). The Jeep started normally, and I drove it for 15 minutes before I noticed the stop start showed "not ready/charging." The voltmeter was still on 14.7. I didn't think this was abnormal. The cold and the week without driving probably had the battery down. I went on a sightseeing tour of the county, thinking that a 45 minute drive would restore the charge in the batteries, and the stop/start would start working. It didn't matter. The stop/start feature was still "not ready/charging." That left me with some choices. Should I charge both batteries and see if the stop/start will start working? Should I go for a longer drive? Should I take it to the dealer (still in warranty)? Should I try to isolate which battery is bad myself before making a decision? I chose the last one.

Both batteries tested 12.6 volts with a hand-held voltmeter. I wasn't surprised. I had just returned from and extended drive. The stop/start should work at 12.6. I don't know why it wouldn't.

I could have waited 24 hours for the surface charge to bleed off of the batteries and tested again. I didn't want to wait that long. Instead, I charged the main battery using my Everstart 15 Amp charger, disconnected the aux battery, and planned to run on just the main for several days.

I expect that the main will eventually drop down to 12.4 volts and the stop/start will quit working. I can't replicate the cold weather - spring is here now. I haven't been able to let the Jeep sit still since I disconnected the aux battery, but I need to do that to draw a fair conclusion. In the mean time, running on just the main, the charging voltage, as read from the dash, starts at 14.4 and reduces to 14.1 after 30-45 minutes of driving. All of these numbers are telling me that I have 2 batteries that are good, but are near the end of their useful life. "Useful life" is the catch word when talking about JL/JT vehicles and batteries. That useful life seems to end at 12.4 volts. One question that is sticking in my mind is why the Jeep can't charge both batteries to the point where the stop/start would work after a 45 minute drive. The answer to that would seem to be that the charging current is too low to recover both batteries.

PS: I've never had a vehicle where I spent so much time looking at the voltmeter. I'm sorely tempted to just spend my own money to change the main battery, leave the aux battery disconnected, and just move on to a carefree life. I was in Walmart this AM and saw this battery: 850 cold cranking amps, 140 minutes reserve, 4 year warranty, $170. That is a good deal!

 

[DenverGladiator]

I’ve been getting the message “Aux Switches Temporarily Unavailable Battery Charging” message for a few weeks. I bought an Aux battery yesterday and installed it, still getting the message. Had the main battery checked, showing 749 (out of 750) cold cranking amps. Is the main battery going bad but still tests as fine or is there something else in the system to check?

 

[Andy29847]

I’ve been getting the message “Aux Switches Temporarily Unavailable Battery Charging” message for a few weeks. I bought an Aux battery yesterday and installed it, still getting the message. Had the main battery checked, showing 749 (out of 750) cold cranking amps. Is the main battery going bad but still tests as fine or is there something else in the system to check?

Battery testing seems to be a voodoo art. To do it right takes time and special equipment. I expect your battery is OK for most uses, but will not pass some test run by the Jeep systems.

Besides that, I haven't seen anyone qualify battery performance by measuring cold cranking amps. Who did the test and did you see their equipment?

I had to look up testing for CCA. Here is one article I found.

How To Test Cold Cranking Amps With A Multimeter - All About Cars News Gadgets (cars-care.net)

 

[Mr._Bill]

I’ve been getting the message “Aux Switches Temporarily Unavailable Battery Charging” message for a few weeks. I bought an Aux battery yesterday and installed it, still getting the message. Had the main battery checked, showing 749 (out of 750) cold cranking amps. Is the main battery going bad but still tests as fine or is there something else in the system to check?

Did you charge the battery before installing it? The life expectancy of the AGM batteries used in the JT is about three years. I would also replace the Primary battery.

 

[Andy29847]

I tried the cold cranking amps test w/multimeter on my 4 month old battery. Note that this test seems to be a pass/fail test and doesn't actually give a CCA reading.

So How To Test Cold Cranking Amps With A Multimeter?

Keep your multimeter attached to the battery terminals while testing the cold-cranking amps, and then start your vehicle. This is a two-person task, with one person controlling the ignition and the other checking for variations while the engine is running.

If the measurement dips to 10 volts but then rises to approximately 12 volts, it is the optimum scenario. If the reading remains consistent after the initial value drop, your battery is in good working order. Throughout the process, the engine must be running.

If the first measurement is at 5V and not below, the battery is steadily fading and will not last long. Also, if the measurement is much below 5V, the cell should be replaced.

I added a couple of steps just to illustrate how load on a battery changes the measurements. My battery was reading 12.5 when I hooked it up with everything off. It went down into the 12.3 range when I turned on some stuff. It went to 11.14 when I cranked the vehicle. The 11.14 number was repeatable, at least for the 2 times I tried. My measurements are well above the guidelines provided in the article I shared. Note that I said in the movie that the battery is 2-1/2 years old. I was confused. This battery is just 4 months old. It is good to have a new battery.



On my other Jeep (2020 - original batteries), when I had stop/start issues a few days ago, I disconnected the aux battery, used my Everstart charger to recondition the battery (takes 24 hours and ends with a full charge), and then reinstalled the battery. The stop/start has been working as expected since then. Charging the batteries is always a good first step. It would probably buy you some time if nothing else. Since you have already bought a new aux battery, I would plan on springing for a main battery soon.

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