Car confused about battery level?

[HoosierDaddy]

The car has a mistaken idea that the battery is low. If I get in and don't start immediately, within a minute or two will display a warning that the car is turning off to save the battery. But the battery is fully charged.

When the battery was replaced about a year ago, I went thru the procedure to let the car know.

Since then, a runaway dashcam has decided to record continuously until the battery is run down on a few occasions. I recharged it with my Genius 3.5 amp trickle charger which is connected to a ground on the strut tower and positive connection by the fuse box. Supposedly, connecting there makes sure the battery management system knows what's going on. But the car acts like the battery is almost dead when it's fully charged.

Any idea why or how to fix?

Sponsored

 

[#1ford]

My 2021, is doing the same thing except that it starts fine but the battery saver mode keeps coming on every day.

 

[86pagt]

Mine has also been doing this. New battery about a year ago and no issues until about a little over a month ago. During that time I would drive it about 3 times a week. I put my battery tender on .. no change, still did it a few times. Now since I have been driving it everyday for the past week I haven’t noticed it.

 

[Evolvd]

Do the manual reset. Turn on accessory mode and within 10 seconds flash the high beams five times and then press the brake pedal 3 times. The battery indicator light should flash three times and then come on steady.

 

[ice445]

Do the manual reset. Turn on accessory mode and within 10 seconds flash the high beams five times and then press the brake pedal 3 times. The battery indicator light should flash three times and then come on steady.

This might work, but I don't recommend it because it also resets the battery "days in service" value which can negatively affect charging strategy.

I've been seeing this a lot lately on here. Use a scan tool to reset KAM/adaptations, then lock the car and let it sit for 8-10 hours so it can properly relearn the state of charge. There's some software bug that causes the pcm to stop learning the state. No idea what causes it (other than letting the car sit for long periods).

 

[Evolvd]

This might work, but I don't recommend it because it also resets the battery "days in service" value which can negatively affect charging strategy.

I've been seeing this a lot lately on here. Use a scan tool to reset KAM/adaptations, then lock the car and let it sit for 8-10 hours so it can properly relearn the state of charge. There's some software bug that causes the pcm to stop learning the state. No idea what causes it (other than letting the car sit for long periods).

You verified this claim? Can you show us where that information came from?

 

[ice445]

You verified this claim? Can you show us where that information came from?

Verified what? I know for a fact doing what you suggested resets the BMS, including age modifier. You can test it yourself if you have the proper scan tool to look at BCM values.

As far as my solution, that's what's worked for me. It's happened to me twice now and both times resetting PCM adaptations fixed it.

 

[Evolvd]

Verified what? I know for a fact doing what you suggested resets the BMS, including age modifier. You can test it yourself if you have the proper scan tool to look at BCM values.

As far as my solution, that's what's worked for me. It's happened to me twice now and both times resetting PCM adaptations fixed it.

Well that’s the whole point, resetting the BMS so it stops screwing up the charging strategy that you’re saying it will screw up in the future lol.

So I guess what I’m asking is, can you show us an example of where doing the BMS reset has negatively impacted anyone ever?

 

[ice445]

Well that’s the whole point, resetting the BMS so it stops screwing up the charging strategy that you’re saying it will screw up in the future lol.

So I guess what I’m asking is, can you show us an example of where doing the BMS reset has negatively impacted anyone ever?

I just meant that it's not optimal. BMS logic factors in battery age when determining how much voltage to use. If you tell it that it has a brand new battery when its actually 5 years old, that can potentially impact battery life. If you don't care than that's fine, but it's still worth putting that out there.

 

[WD Pro]

All this bickering about where to connect the charger so your BMS knows what’s going on - and one solution to fix the OP’s problem is to leave it for 8 hours locked up so the BMS can figure everything out ?

Hey wait a minute, wasn’t that the main reason for not connecting directly to the battery, which incidentally gives a neater installation and allows (in theory) the battery charger to do the best job possible … ?

I’m kidding, but you can probably tell I’m in the charge at the terminal gang.

WD

@HoosierDaddy - sorry for crashing your thread and I hope you get this issue sorted

 

[ice445]

All this bickering about where to connect the charger so your BMS knows what’s going on - and one solution to fix the OP’s problem is to leave it for 8 hours locked up so the BMS can figure everything out ?

Hey wait a minute, wasn’t that the main reason for not connecting directly to the battery, which incidentally gives a neater installation and allows (in theory) the battery charger to do the best job possible … ?

I’m kidding, but you can probably tell I’m in the charge at the terminal gang.

WD

@HoosierDaddy - sorry for crashing your thread and I hope you get this issue sorted

Haha, I actually completely agree with you. For the longest time I was in the camp of "charge the car properly always and leave BMS in the loop", but then I realized that only really applies if you're charging the battery from a low state so you can start and drive the car ASAP. When it comes to leaving these on a low amperage tender for long periods of time, just connecting to the battery seems better, since the car seems to stop tracking the state of charge after some amount of time regardless. Without fail, if I left my car on my CTEK charger for long enough, the BCM would start reporting oddly low states if I bothered to turn the ignition on and check. Voltage at the battery would be fine, but the car would think it was at 70% SoC. Almost like it just estimates a set loss over time when it enters deep sleep mode and doesn't actually check anymore. It also seems to lead to this bug, where it refuses to learn the new state unless it runs several drive cycles, or you reset all PCM adaptations. The only other way I fixed this was by driving the car for 4-5 days in a row. Eventually it goes back to normal and you get the "proper" variable charging voltage. Probably takes less time in warmer weather.

 

[86pagt]

Mine has started to do this again… so it was good for about two weeks. It sat over the weekend and drove it to work today, I unlocked it at lunch and when I opened the door the screen says turn off ignition or start car… car started with no issues..

I did the manual reset when the battery was replaced

Sponsored