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Question on Voltage you see when ESS has the motor stopped

CreepyJeepy

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Hey there. Curious. I have a JTRD 3.0 21'.

I have been keeping it on a trickle charger because it has stated Battery Charging for quite a while. The system seems to work now, but when the Engine is stopped I watch the voltage fall to about 11.7v before I either take off from a light or it just starts back up.

I imagine the ESS battery is dying, but before I take it in and see if they will toss a new battery in it, I am curious what voltage you are seeing when the engine is not running.

Thanks!
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I think that's normal, same voltage with my diesel when the engine stopped, while engine are running. But, it should be above 12.6v after parked overnight. I'm in the process of replacing my Aux battery at the moment though. ESS stopped working and displaying battery is charging for the last few weeks.
 

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Hey there. Curious. I have a JTRD 3.0 21'.

I have been keeping it on a trickle charger because it has stated Battery Charging for quite a while. The system seems to work now, but when the Engine is stopped I watch the voltage fall to about 11.7v before I either take off from a light or it just starts back up.

I imagine the ESS battery is dying, but before I take it in and see if they will toss a new battery in it, I am curious what voltage you are seeing when the engine is not running.

Thanks!
Your batteries need checked, but it could be the main battery that is the problem. I'm still running on my original ESS battery. I had to replace the main at 39 months.
 

ShadowsPapa

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Hey there. Curious. I have a JTRD 3.0 21'.

I have been keeping it on a trickle charger because it has stated Battery Charging for quite a while. The system seems to work now, but when the Engine is stopped I watch the voltage fall to about 11.7v before I either take off from a light or it just starts back up.

I imagine the ESS battery is dying, but before I take it in and see if they will toss a new battery in it, I am curious what voltage you are seeing when the engine is not running.

Thanks!
It's not so much the lowest voltage you see - it's where the voltage starts and how FAST it drops to that level.
I understand this is diesel, but the battery and charging tech should be the exact same - even if the battery is on the other side.

12.8 is fully charged.
That will drop to 12.6 or 12.5 after a few hours of sitting due to the "parasitic draw" from the truck itself. Again, how fast that drops while it sits unused is an indicator of battery health. As they age, the drop is faster. As they are cycled more times, the voltage drops faster, if they don't get completely charged through use (like infrequent or short drives) they age faster and voltage drops faster.

Your batteries need checked, but it could be the main battery that is the problem. I'm still running on my original ESS battery. I had to replace the main at 39 months.
I agree with Mr._Bill that they need to be checked -
They need to be fully charged before being checked.
The aux battery is not always the real culprit no matter what the "internet experts" in forums believe or repeat. Too often it's blamed when in reality the main or crank battery was a problem. Too much bad info out there............
Could be EITHER battery - so do the proper testing - and the dealers have a multi-page process they must follow. DO NOT LET a parts store do the testing! No way I'd let those people test a battery in a sophisticated vehicle - maybe a lawn mower battery....... maybe, but not in a modern vehicle.
(Those clowns have tested charging system parts as ok that get sent to me for restoration and I find some crazy stuff they've passed as "ok". )

I have yet to prove this to myself, but I believe the voltage you see on the dash during an ESS stop is the AUX battery voltage - I can't see a new crank battery of the size I have dropping from 12.8 volts down to 12 volts just running the computer and electronics during a stop.
Could be wrong - but...............I plan on wiring my fluke into the system and watching in the near future.
 

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Gas engine here, gauge shows up to 14.6v while running. When the engine shuts down at a stop light, it drops pretty quickly down to 11.8 or so at a stoplight. I’ve tried to test how low it will go, but I get bored easily:-D Voltage seems to stabilize in the high 11s
 

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Gas engine here, gauge shows up to 14.6v while running. When the engine shuts down at a stop light, it drops pretty quickly down to 11.8 or so at a stoplight. I’ve tried to test how low it will go, but I get bored easily:-D Voltage seems to stabilize in the high 11s
Same here. Just for sh*ts and giggles, I tried this today. I always push the 'cancel ESS' button when I first start up and move out so, today I wanted to see this for myself so I let it do it's thang.

I saw the same results. 14.5 volts when running. Stopped at a traffic light, the ESS kicked in. The voltage dropped to 12.8 then quickly to around 11.0. Mind you, I had the radio going, the heated seat on high, the heated steering wheel on and, the halos on my headlights so there was pretty good draw on the system.

As soon as the light changed and I took my foot off the brake, she started right up and the voltage meter went right back to 14.5 volts.

2020 Overland, ordered May of '19, built in June '19 and delivered July 19th, 2019. I have around 24,000 miles on her. So, built before COVID so I'm guessing quality control was better then than when COVID hit in early 2020 and onward.
 

ShadowsPapa

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Same here. Just for sh*ts and giggles, I tried this today. I always push the 'cancel ESS' button when I first start up and move out so, today I wanted to see this for myself so I let it do it's thang.

I saw the same results. 14.5 volts when running. Stopped at a traffic light, the ESS kicked in. The voltage dropped to 12.8 then quickly to around 11.0. Mind you, I had the radio going, the heated seat on high, the heated steering wheel on and, the halos on my headlights so there was pretty good draw on the system.

As soon as the light changed and I took my foot off the brake, she started right up and the voltage meter went right back to 14.5 volts.

2020 Overland, ordered May of '19, built in June '19 and delivered July 19th, 2019. I have around 24,000 miles on her. So, built before COVID so I'm guessing quality control was better then than when COVID hit in early 2020 and onward.
Things like heated wheel and seats are a big draw. LEDs are efficient, heated seats, not so much.
I've seen a big difference in mine when it's stopped - whether or not I have the seat and steering wheel heat on, or certain other accessories are running.
Mine was running 14.9 for a while then settled to 14.7 and when ESS kicked in, it dropped to 12.2 after a bit over a minute - heated seat and wheel off and blower on low.
If I leave the seat and wheel heat on, it drops another tenth or two fairly easily.
Hook electric heating elements to a small 12v battery and you can watch the voltage drop.
It would be interesting to know the amperage each draws (I don't mean the fuse capacity as that's always more than the true draw)
 
 



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