Voltage fluctuation issue

[decidave8]

So my voltage bounces between 12.5 and 14.5 and the air conditioner fan speed follows it is this normal or do I have an electrical issue?

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[Alan Applegate]

The voltage changes because the alternator output is governed by the Battery Monitoring System (BMS). Occasionally, the BMS tests the battery's State of Charge (SoC) and Depth of Charge (DoC). It unloads the alternator (disables charging), measures the voltage and current, and over time the drop in voltage at the given load. This operation is referred to as coulomb counting. These parameters, along with temperature, age, starting current, and a few others measured units, the system can calculate remaining battery life. Sounds complicated, which it is, especially the software driving it all. By the way, any vehicle with an auto Stop/Start engine system will also have a BMS.

 

[decidave8]

Thank you it just seems like it is constantly doing it which changes the fan speed a significant amount it’s kind of annoying, but thank you very much for the insight that makes sense

 

[dusman59]

I would run a complete battery test which should include load test. There has been some battery problems causing issues.

 

[decidave8]

So a few weeks ago, my app informed me that the car was in low power mode and was disabling the remote features due to low power. I had it all checked and it all checked good and hasn’t happened since but my gut is just telling me there’s something off with the charging or something.

 

[Tschroll]

I am having same issue, mine does it just sitting in the garage

I bet the battery will test fine, im going to have it check

 

[Zig]

By chance have you tried a recharge and bms relearn?

 

[decidave8]

First I’m hearing of that procedure but I will try it thank you

 

[Skye]

So a few weeks ago, my app informed me that the car was in low power mode and was disabling the remote features due to low power.

Not to discount any concerns, but the above behavior is normal, in certain situations.

If the car is not driven often, the vehicle will enter Deep Sleep mode. Mine will enter this mode at the two week mark, wether the car is on a battery tender or not.

If you're seeing the above alarm having only driven the car a few days ago, yes, it's something to investigate further. Any of the suggestions (charging, load test, BMS reset. ) could help confirm or correct problems.

 

[Rocket Man]

normal

 

[Grabber1]

So a few weeks ago, my app informed me that the car was in low power mode and was disabling the remote features due to low power. I had it all checked and it all checked good and hasn’t happened since but my gut is just telling me there’s something off with the charging or something.

Is the car your daily driver? I got my car on 8/22/24 but it was manufactured 5/2024 and sat for 4 months. I had lower voltage readings as I drove the car. I put it on a good battery tender and now it always reads higher voltage numbers when I drive it. It's not my daily and due to the weather I'm not driving it and it's currently on the tender.

 

[decidave8]

It seems fine now

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