Truck Died Last Night on a Main Thoroughfare, replacing batteries in 2 hrs or so, what may be needed? (Details in thread)

[LouisvEarlleJT]

Ok, new test just now:


Main (engine on) 12.75v

N1 12.65v

N2 12.75v

N4 12.75v

N7 12.75v

Main (Engine Off, leads disconnected) 12.9v

reads to me like your alternator isn’t pumping out enough juice.

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[Thunderspud]

reads to me like your alternator isn’t pumping out enough juice.

Same. I actually thought that might be the case by the end of the first page when OP stated he made it two blocks down the road after installing new batteries and the truck was reporting 11.8v on the dash while (assumedly) charging, I just didn't want to chime in and derail the thread due to my ignorance on how these trucks work. Plenty of folks here that seem to know much more about this than I do....but I for sure would be testing that alternator the first chance I got.

 

[tjk]

reads to me like your alternator isn’t pumping out enough juice.

i did a quick search and found this:

https://www.jeepgladiatorforum.com/forum/threads/alternator-or-battery.58673/post-963902

not saying it’s not alternator, but is it possible IBS is still calibrating?

 

[tjk]

Same. I actually thought that might be the case by the end of the first page when OP stated he made it two blocks down the road after installing new batteries and the truck was reporting 11.8v on the dash while (assumedly) charging, I just didn't want to chime in and derail the thread due to my ignorance on how these trucks work. Plenty of folks here that seem to know much more about this than I do....but I for sure would be testing that alternator the first chance I got.

I thought the getting down the road was an issue because N3 was blown? Damn cars are too complicated haha.

 

[Thunderspud]

I thought the getting down the road was an issue because N3 was blown? Damn cars are too complicated haha.

Could be. I have zero experience with replacing the batteries on any of three Gladiators we have had. Lucky I guess. But my old man way of thinking wouldn't let me leave the parts store without at least testing the alternator. Assuming thats possible without some extra bits or equipment for these trucks.

 

[KQL]

If you fully charged your batteries using your trickle charger, those voltages might be fine: since the alternator output is variable depending on the needs of the system, why would it run at 14.7V when the battery is reporting fully charged? I.e., when I use my charger for a few days before driving (or just driving for hours on a long trip), my voltage will be in the high 12s on the dash while driving. Everything is fully charged = no need for alternator to keep pumping high voltage

 

[tjk]

If you fully charged your batteries using your trickle charger, those voltages might be fine: since the alternator output is variable depending on the needs of the system, why would it run at 14.7V when the battery is reporting fully charged? I.e., when I use my charger for a few days before driving (or just driving for hours on a long trip), my voltage will be in the high 12s on the dash while driving. Everything is fully charged = no need for alternator to keep pumping high voltage

i Was worried yesterday it didn’t fully charge the main battery because I didn’t isolate it. So I’m doing that now.

 

[KQL]

Maybe that was not clear in the thread: you don’t need to separate the batteries to trickle charge them (heck I’m doing mine through the trailer plug when not driving much), it charges both batteries at the same time. If you really wanted to charge each individually OR if you brought home a new main and were keeping your old AUX, then you’d want to change the main outside the truck fully and charge the aux fully, but that’s just so they’re BOTH fully charged when the reset IBS goes back into the truck. But if both batteries are already installed, using a trickle charger on the top of the main posts (on top of IBS) charges both batteries at the same time. You could remove the IBS, separate the neg cables and charge each individually, then reinstall IBS, but not for routine trickle charging.

 

[tjk]

Finished charging the isolated main (I read the above, but since I started this well before I kept going) and disconnected ibs for 15 minutes. Started up and saw 14s across all N posts (alternator too) and in the instrument cluster. Will see how it looks tomorrow morning I suppose.

 

[Jteakus]

I have aux batt delete on mine. Is the reason for attaching negative clip of tender above IBS to charge both batteries? I have been attaching mine to the batt posts.

 

[KQL]

I have aux batt delete on mine. Is the reason for attaching negative clip of tender above IBS to charge both batteries? I have been attaching mine to the batt posts.

The IBS monitors the flow of energy from and to the battery, so the idea is you don’t want to backdoor juice into the current/existing battery that the IBS is not aware of. My understanding is that this concern is preserved even if you delete the AUX. Trickle charge on top of the IBS. Just as the charge from the alternator would be seen by the IBS, you want the trickle charge to also be seen by it.

If you’re replacing any of the batteries (or both), then you want to remove the ibs, charge both batteries fully and reinstall the ibs into the fully charged system and it will start relearning the current in/out from there.

 

[Jteakus]

As soon as I read this I moved it to the top. My (incorrect) theory was to get the battery good and charged then let the alt take over when I start it.
Thanks

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