BMS Module (Possible failure)

[SpaceWhiteF150]

What happened- I have the factory H6 agm battery in my truck I was getting a low power fault on my cluster. I proceeded to charge the battery with a battery charger. It was not an agm specific charger so I only charged it for a short period of time. I then had the battery tested a AutoZone it tested at 94%. Then had a state inspection done where they then tested it again.

This is how it tested.

The only reason I think it’s the battery or the BMS module failing is that before this all happened I wired in “rock” lights and bed lights on a switch. It is a fused custom 16awg wiring harness made by yours truly. My lights now do not work, they previously worked perfectly fine. No other modifications where made. After I attempt a BMS reset shown on other threads the truck doesn’t flash the battery light 3 times but seems to reset the system. After this all the lights stay on for ~2 secs then flash multiple times and turn off. Leading me to think low voltage. I then tested the battery and wiring harness with a multi-meter where the battery showed ~11.4 volts (seemed low to me) and the wiring harness showed ~.4 volts. The truck was off when this was tested. I then traced the wiring harness with no imperfections found, the harness is wrapped in tesa tape and wire loom covering. So no rub through or tension. This leads me to believe low voltage from the battery or the BMS not allowing power through the module? I have checked all grounds and reattached with dielectric grease. I then tried to unplug the BMS from the battery with no difference. Any suggestions? Thanks

Sponsored

 

[Nighsight]

How was the charger attached to the battery (which side of the battery sensor)? Any DTCs? What does the BCM say the battery SOC is?

Where did you grab power for your lights?

 

[SpaceWhiteF150]

How was the charger attached to the battery (which side of the battery sensor)? Any DTCs? What does the BCM say the battery SOC is?

Where did you grab power for your lights?

The battery charger was attached to the two posts on the battery, both wire terminals where removed while charging.

I do not know how to read the SOC through the BCM? Sorry. But at AutoZone it tested 94% SOC and Caliber Auto it tested 100% SOC.

I grabbed power from the positive on the battery and grounded it to the frame.

Thanks

 

[Nighsight]

Do you have a scan tool, or Forscan? It would be good to know if you have any DTCs.

Here's a good video on the battery monitoring system, how it works, and how to charge the battery.

 

[SpaceWhiteF150]

Do you have a scan tool, or Forscan? It would be good to know if you have any DTCs.

Here's a good video on the battery monitoring system, how it works, and how to charge the battery.

Thanks, I don’t have access to a scan tool or forscan.

Thanks that video is great, much better than others I have watched. After watching the video I have a question, I purchased a Noco 1amp trickle charger/battery maintainer (the truck is about to be sitting for weeks on end). Is that charger smart enough to know it has to overcome a draw even when the truck is off? I’m pretty sure it is the description says up to 30 amps. Thanks

Sponsored