Battery Voltage reading? What is normal?

WWRuby_Svi

WWRuby_Svi

New member
When the Jeep has been running but is shut off in ess, what does the battery voltage show for you guys?

After thawing out from our -30s temps last week my ess system has finally charged my battery up to work and I noticed that when the Jeep shuts off for ess, in less than a minute my battery gauge reads about 11.5v. It was 18f today and I had my seat heater on low with the alpine radio. I’m fairly certain this isn’t normal but I wanted to see what everyone else was seeing. I also haven’t had a chance to actually measure individual battery voltage since it’s been freezing rain the last few days.


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Wranglerman

Wranglerman

New member
WWRuby_Svi said:
When the Jeep has been running but is shut off in ess, what does the battery voltage show for you guys?

After thawing out from our -30s temps last week my ess system has finally charged my battery up to work and I noticed that when the Jeep shuts off for ess, in less than a minute my battery gauge reads about 11.5v. It was 18f today and I had my seat heater on low with the alpine radio. I’m fairly certain this isn’t normal but I wanted to see what everyone else was seeing. I also haven’t had a chance to actually measure individual battery voltage since it’s been freezing rain the last few days.


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When your JL shuts down on a normal ESS operation the relay opens and the main battery and ESS battery are separated and the accessories you have on like lights, radio etc ... are powered by the ESS battery, initially the EVIC displayed voltage you see once it shuts down should be in the 12.5-12.7 range but the more you have running the quicker the voltage will drop and I have seen mine as low as 11.8 while testing.

When you let you foot off the brake and ESS disengages the relay from my understanding closes back and the engine is cranked off the main battery and while running both batteries act as one and are charged together and the voltage is monitored by the IBS that is connected to the negative battery terminal.

From talking to a few FCA techs my understanding is the voltage displayed in the EVIC can vary from 12.8-14.3 and anything in between as the JL only charges when needed and the amount of charge is dependent on how depleted the batteries are so the days of the alternator constantly throwing 14+ all the time is gone but like I said it depends on how depleted the batteries are.

Hope this info helps
 

WWRuby_Svi

WWRuby_Svi

New member
Wranglerman said:
When your JL shuts down on a normal ESS operation the relay opens and the main battery and ESS battery are separated and the accessories you have on like lights, radio etc ... are powered by the ESS battery, initially the EVIC displayed voltage you see once it shuts down should be in the 12.5-12.7 range but the more you have running the quicker the voltage will drop and I have seen mine as low as 11.8 while testing.

When you let you foot off the brake and ESS disengages the relay from my understanding closes back and the engine is cranked off the main battery and while running both batteries act as one and are charged together and the voltage is monitored by the IBS that is connected to the negative battery terminal.

From talking to a few FCA techs my understanding is the voltage displayed in the EVIC can vary from 12.8-14.3 and anything in between as the JL only charges when needed and the amount of charge is dependent on how depleted the batteries are so the days of the alternator constantly throwing 14+ all the time is gone but like I said it depends on how depleted the batteries are.

Hope this info helps
Click to expand...

Thanks, that’s a bit different than what I heard before on the system. I’m use to batteries holding 12+ volts but I guess the electrical system is enough to pull it down... part of me just feels like something isn’t right if I drive my Jeep 30min each way to work with limited stop and go and since last week the ess said it wasn’t engaging because the battery was charging.


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Wranglerman

Wranglerman

New member
WWRuby_Svi said:
Thanks, that’s a bit different than what I heard before on the system. I’m use to batteries holding 12+ volts but I guess the electrical system is enough to pull it down... part of me just feels like something isn’t right if I drive my Jeep 30min each way to work with limited stop and go and since last week the ess said it wasn’t engaging because the battery was charging.


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Click to expand...

Usually when I leave for work and my JL has been parked a few days the starting voltage displayed is usually 13.2-13.7 and my assumption is that these newer vehicles have more parasitic draw than the days of manual windows and no computers driving them so the longer it sits the higher that starting display voltage is going to be but after say 30-60 mins of driving that displayed voltage is going to drop as the batteries get charged.

If you are really concerned on what the actual battery voltage is the only way to get that is to take voltage readings directly at the battery and you will have to pull the ESS negative cable from the main negative so to will get the true voltages of each battery.

Battery voltages of each should be in the 12.4-12.7 range and 12.7 is ideal but realize that temps effect this greatly somthe colder it is the lower the voltage, when my ESS said charger all the time it was due to my main battery being defective and it never reached a full charge but once replaced it all worked like it’s supposed to.

You can also pick up a trickle charger for a very reasonable price and put the JL on it for 12-16 hrs and then see what happens but in all honesty you need to get a voltmeter to see what’s going on directly at the battery
 

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