Weird Charging Issue

[WranglerMan]

So when my voltage regulator was malfunctioning, it would eventually drain the battery down to 12.6v after 3-4 days. It would stay at that voltage. During highway cruise, my dash gauge would show around 12.6-12,8v. That's not enough voltage to fully charge the battery. It'll keep it around 60% charge. When I would disconnect the negative, it reset the IBS and I'd get 14.x volts for a day or so, then it would keep going lower with each successive start-drive cycle. That's how I determined the alternator was capable of making adequate charging voltage, but something was commanding it to low voltage. So, I changed the IBS and drove it a week. It did the same thing, and the battery eventually went to 60%. I had a spare PCM (original) and installed it. Problem solved. (the voltage regulator is in the PCM)

My Jeep had been parked for several days and yesterday I had a few appts to make, the EVIC display showed 14.4 on startup and after approx 90 mins of drive time mostly on sides roads with speeds mostly in the 30-40 mph range and lots of stop lights at the end of my errands it showed 13.2.

its been parked about 12+ hrs so I’ll get my tester out to see what numbers I get.

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[roaniecowpony]

My Jeep had been parked for several days and yesterday I had a few appts to make, the EVIC display showed 14.4 on startup and after approx 90 mins of drive time mostly on sides roads with speeds mostly in the 30-40 mph range and lots of stop lights at the end of my errands it showed 13.2.

its been parked about 12+ hrs so I’ll get my tester out to see what numbers I get.

That doesn't sound bad at all. But if you are cruising on the highway and the voltage drops below 13v, I would be concerned.

 

[WranglerMan]

That doesn't sound bad at all. But if you are cruising on the highway and the voltage drops below 13v, I would be concerned.

It has dropped below 13 on a super long drive, have started off at mid 13 and after some highway driving dropped to 12.9-13 and stayed there.

Right after coming home I have manually disconnected the relay that connects the two FT-750 Full River batteries and wait 30 mins to check after surface charge has dropped off and battery tests have been good at 30 minis and 12 hrs later with voltages in the 12.8 range, CCA 675-700( rated 750) res less than 4 and SOH 80%

I drove the jeep yesterday for maybe 2 hrs and this morning for maybe an hour, here are some recent tests after it’s been parked for several hours, first pic is primary and second pic is aux and both are new and installed 11-24 ( 18 months)

 

[roaniecowpony]

It has dropped below 13 on a super long drive, have started off at mid 13 and after some highway driving dropped to 12.9-13 and stayed there.

Right after coming home I have manually disconnected the relay that connects the two FT-750 Full River batteries and wait 30 mins to check after surface charge has dropped off and battery tests have been good at 30 minis and 12 hrs later with voltages in the 12.8 range, CCA 675-700( rated 750) res less than 4 and SOH 80%

I drove the jeep yesterday for maybe 2 hrs and this morning for maybe an hour, here are some recent tests after it’s been parked for several hours, first pic is primary and second pic is aux and both are new and installed 11-24 ( 18 months)

I think you're charging properly. On the FullRiver website, there's a link to a pdf with the state of charge voltages. I think 12.9v was 100%

 

[roaniecowpony]

Here's the FullThrottle table for state of charge.

 

[ScotM]

I don’t think I ever had my battery at rest be over 12.7. I am under the impression that the IBS needs to be disconnected for 24 hours to reset. I am currently chasing a parasitic draw , and am just getting all the intricacies of the system

 

[roaniecowpony]

I don’t think I ever had my battery at rest be over 12.7. I am under the impression that the IBS needs to be disconnected for 24 hours to reset. I am currently chasing a parasitic draw , and am just getting all the intricacies of the system

Different battery types will have different state of charge voltages. Toss in battery age/condition, charging systems etc, and there could be some variability.

I'll look at my factory manual for what it says about resetting the IBS.

On the parasitic draw, have you done a test where you put your multimeter in series with the battery?

 

[ScotM]

Different battery types will have different state of charge voltages. Toss in battery age/condition, charging systems etc, and there could be some variability.

I'll look at my factory manual for what it says about resetting the IBS.

On the parasitic draw, have you done a test where you put your multimeter in series with the battery?

My multimeter didn’t support that, so I have a new one coming tomorrow that will. So I’ll start there, at the battery, meanwhile, I have charged the battery with my trickle charger, and found that my wolf box dash cam has been turning on for no reason. So I’m looking forward to diving into it

 

[THAW]

My multimeter didn’t support that, so I have a new one coming tomorrow that will. So I’ll start there, at the battery, meanwhile, I have charged the battery with my trickle charger, and found that my wolf box dash cam has been turning on for no reason. So I’m looking forward to diving into it

Another option is JScan. The IBS tracks all current in and out of the CR[an]K battery, so you can check it before and after an engine shutdown and parked period (use screenshots to log it). You'll be able to calculate an average rate - excluding any power provided by an AUX (ESS) battery - over the time period, versus a multimeter reading of a single point in time. Both measurements are useful, but the multimeter has a higher likelihood of registering a temporary current draw.

MODULES -> BODY CONTROLLER -> LIVE DATA -> Intelligent Battery Sensor Lifetime Charge Received (AmpHrs)
MODULES -> BODY CONTROLLER -> LIVE DATA -> Intelligent Battery Sensor Lifetime Charge Released (AmpHrs)

 

[WranglerMan]

I think you're charging properly. On the FullRiver website, there's a link to a pdf with the state of charge voltages. I think 12.9v was 100%

I don’t put my batteries on a charger very often like maybe once every 3-4 months and it does not get driven on a daily basis, I do use my tester and test monthly to compare the previous month to see if anything major changes.

Full River has advised that frequent charging is not necessary and can actually be detrimental to long healthy battery life so I follow their advice as these batteries are fairly pricy so I want to do all I can to get the most life from them.

 

[bmpcamry09]

All of the battery behavior described in this thread is completely normal. To the OP, this is normal. A bunch of you guys are making something out of nothing. There is nothing wrong with your Jeep.

Almost every modern day car on the road has a heavily monitored and regulated battery charging system. The days of seeing 14+ volts all the time while running are long gone. This is not your typical voltage regulator system either. The PCM will command different voltages based on electric load, battery temperature, on throttle, off throttle, and more.

This is all for efficiency and “supposed” battery cycle life increase. Now if this behavior actually improves battery life? Yeah doubt it. Haven’t seen evidence of it. But that’s a whole other discussion.

But you guys are worrying about nothing. You all would flip out if you saw how some other companies let their electric system run. I’ve worked on several Nissans that all regularly hang out around 12 volts while accelerating. Sometimes into the 11s. And then go back to a charging state during decel and light cruise. My 5th Gen 4Runner does the same.

All a vehicle Canbus system needs to run normal is usually 11.9-12.2 volts while anything over that is reserve. My brand new Jeep battery voltage when not running is anywhere from 12.0-12.7.

 

[Terrymo]

My understanding is with current AGM batteries and a microprocessor controlled multistage AGM charger from a reputable manufacturer, frequent and/or long term charging concerns are almost completely eliminated.

 

[THAW]

My understanding is with current AGM batteries and a microprocessor controlled multistage AGM charger from a reputable manufacturer, frequent and/or long term charging concerns are almost completely eliminated.

I think that's correct.

A temperature-compensated, continual/continuous float voltage prevents sulfation, and therefore actually improves battery life.

On the other hand, if float voltage is not well regulated, there is a risk of boiling off electrolyte.

 

[Mguy]

My understanding is with current AGM batteries and a microprocessor controlled multistage AGM charger from a reputable manufacturer, frequent and/or long term charging concerns are almost completely eliminated.

A temperature-compensated, continuous float voltage prevents sulfation, and therefore actually improves battery life.

On the other hand, if float voltage is not well regulated, there is a risk of boiling off electrolyte.

Lead acid batteries generally do not benefit from continuous float voltage. Float stage voltage regulation is intended and necessary for systems which also have simultaneous loads, particularly if those loads vary.

When charging is complete in a no-load system the voltage regulator should stop charging. A healthy battery will then self discharge at an appropriate, and acceptable, rate (about 3% a month for AGMs).

Note, system loads after engine shut down in stock JLs revert to virtual nil and are not an issue at least for a week or two, and even longer with a well maintained battery. Of course, with added electrical equipment that is "on" after shut down, anything goes.

 

[THAW]

Lead acid batteries generally do not benefit from continuous float voltage. Float stage voltage regulation is intended and necessary for systems which also have simultaneous loads, particularly if those loads vary.

When charging is complete in a no-load system the voltage regulator should stop charging. A healthy battery will then self discharge at an appropriate, and acceptable, rate (about 3% a month for AGMs).

Note, system loads after engine shut down in stock JLs revert to virtual nil and are not an issue at least for a week or two, and even longer with a well maintained battery. Of course, with added electrical equipment that is "on" after shut down, anything goes.

Mostly misleading; in fact, float voltage is very much intended to offset AGM self-discharge.

In any case, modern, brand-name, multi-mode AGM chargers can be left connected to a JL (or JL with a Genesis Offroad battery system). Doing so is very likely to prolong battery life - and, inversely, highly unlikely to shorten it.

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