Battery charging issues and a fix??

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

djkaosone

'11 LR4 HSE LUX 5.0L V8
Joined
Oct 26, 2015
Posts
1,012
Reaction score
682
Location
SoCal
Ok, I've been battling battery issues for quite some time. If you don't know, I'm on my 4th battery.

This time I got a Duracell Platinum AGM H8 850CCA 92Ah. I decided to change the battery type with my IIDTool in the CCF settings under Body Control and Battery type.

I seriously tried all of them and ran through the battery reset too. Each time, the truck would fire up and start at 13.8V and then drop to 12.0V-12.8V. I left the setting in the CCF at H8HD 900CCA and drove 25 miles and the whole time the it read 12.0V-12.5V.

I even emailed Pat at GAP Diagnostics and he pretty much said that I'm SOL and indirectly pointed to go back to a flood battery.

Long story short, if you have these issues or go to an AGM battery this is how I fixed my issue and now it reads a full 14.xV. While the truck is running, remove the plug connected to the BMS on the negative cable, wait 10 seconds, plug it back in, and check voltage. Worked for me and now I'm getting 14.5V. I'm assuming the BMS reset from the IIDTool helps it relearn the Amp draw and tries to recalibrate the alternator's output to charge the battery, but by removing/reseating the BMS sensor cable it interrupts the signal and ultimately resets change in signal. That's just my guess.

Hopefully this helps someone with battery issues. I just did this and I'll update this after a week or so.
 

avslash

Full Access Member
Joined
Nov 22, 2011
Posts
1,255
Reaction score
1,101
Location
The Lone Star State
Will be interested to see if it stays there. Mine seems to jump up to that range after any kind of "event" like vehicle reset, sensor removal, etc, but it always seems to find its way back down after a week or so.

Looking forward to update.
 

Robuk

Active Member
Joined
Apr 11, 2019
Posts
30
Reaction score
5
Location
UK
Just disconnect the sensor and leave it disconnected, you will then get around 14.2 volts dropping to around 13.8 lowest, by disconnecting the sensor smart charging is disabled, you now have a standard continuous regime. I have been running my Merc for over a year with this sensor disconnected, it has also been disconnected on my Porsche, should work on Land rovers. I did it to get rid of stop/start.

 

930dreamer

New Member
Joined
Aug 25, 2012
Posts
2
Reaction score
1
djkaosone - was this a permanent fix or did it eventually settle back to 12.x V?

also, do you have a picture of the BMS plug?
 

avslash

Full Access Member
Joined
Nov 22, 2011
Posts
1,255
Reaction score
1,101
Location
The Lone Star State
It will always settle back eventually.

best ideas I've heard so far are to rig a disconnect switch somewhere inside the cabin so you can flip it every now and then to get back to a full charge, or have someone figure out what the output of the sensor is that drives it to 14 ish volts and a modify the sensor electrically to only present that feedback to the ECM.
 

bigphil

New Member
Joined
Jan 19, 2022
Posts
1
Reaction score
1
Location
TN
I know this is an old post, BUT, this worked for me! Installed a new battery and after using my Gap tool for the battery reset, my LR4 started to show voltage of 12.2 volts. Turned it off and on and drove around the block, all the time reading 12.2v. Walked away for a bit adn came back, same result.

As soon as i unplugged the BMS sensor, it went back to 14.7v and seems to be normal now.
Thanks djkaosone

Is it normal for the battery voltage reading to change so much when connected to car? New battery read 12.8v. As soon as i connected it up to the LR4 it immediately goes to 12.3 - 12.4v
 

jlglr4

Full Access Member
Joined
Mar 19, 2019
Posts
932
Reaction score
477
Location
Northern California
New, fully charged battery at complete rest (nothing connected) should be about 12.8v. When you hook it up to the LR4, certain systems will immediately start up (even if the key is off). Let it set, hood up and key away from the car, for about 15 minutes, and all those systems should shut back down - there will still be some parasitic drain, but you should see about 12.6 volts or so. If your not seeing 12.6v after letting it set for 15 minutes with the hood up, then you probably have an unusually high parasitic drain. You can try to track it down by testing for voltage at the fuses.

With the engine on and reading the voltage in the system, things are a little different. The BMS regulates the voltage and can even start to shut systems down if the voltage is too low. When the alternator is charging, I believe you can see voltage anywhere from 14.7v down to about 12.2v depending on the voltage drain on the battery and state of battery charge (the amount of charge delivered from the alternator to the battery can actually be varied as I understand it).

I think the state of charge of the start/stop battery also can affect the voltage when running (i.e., some voltage shunted to the start/stop battery to charge it) but shouldn’t affect the voltage tested at the main battery with the system off unless the isolation circuit is somehow faulty. I’ve read that the system is designed so a low start/stop battery will not run down the main battery with the engine off.

Without the BMS (leaving it disconnected), I’m guessing you’ll get full voltage (14.7v) delivered to the battery regardless of the state of charge. I think this can damage the battery if the battery is full and the drain is less than 14.7v.
 

Nechaken

Full Access Member
Joined
Nov 19, 2017
Posts
634
Reaction score
258
Location
Colorado
Maybe a bit of a tangent, but how accurate do we think the IID tool voltage readout is? I’ve noticed that when getting in the car in the morning with the IID attached, I’ll see 11.5-11.7 volts (which would be a significantly discharged battery). But headlights are bright and it cranks quickly.
 

jlglr4

Full Access Member
Joined
Mar 19, 2019
Posts
932
Reaction score
477
Location
Northern California
When I plug the GAP tool in, the voltage shows up on the dash, but it never changes. So, I don’t think it’s reading correctly and I simply ignore it. I haven’t tried going into the menu to live views for the voltage.
 

Latest posts

Members online

Forum statistics

Threads
36,222
Posts
217,575
Members
30,473
Latest member
OnoA
Top