Charging system issue

[Jfarquhar]

Hello..major charging system/battery issues. I got “shutting down systems to preserve battery” warning in March. Checked and replaced the battery, alternator output was good, 3 months later “service charging system” siren went on with red flashing alert on the display. Dealer could find nothing wrong, battery and alternator output still both good. “Bring it back if it does it again” was their advice. Last week the “service charging system” warning came back and VERY rapidly a warning for EVERY system came on and the car completely died, no power at all. Dealer says one of the connectors on the battery block wasn’t tight enough. I was an ASE tech (but also human) and I don’t think I failed to tighten the connector AND the dealer had the car in July and should have checked it then too. I don’t think they know what to do, I’ve asked Ford for help as well. Any ideas?

 

[Dale5403]

D id the BMS get reset?

 

[Jfarquhar]

Yes, I did the manual reset myself, the dealer said they used the scanning device, reset the BMS and cleared all codes (which were old). Dealer also claimed 8 hours with windows open and doors closed would automatically reset the BMS. Therefore (theoretically) it was done 3 times .

 

[WaferTech]

In my humble opinion the alarms are based on the battery's state of charge (voltage) and nothing to do with the BMS sensor, I had to change my use of my 2023 ST to stop the warnings. I leave the vehicle running while parked waiting for someone or something (curb side pickups), and I also connect to a trickle changer when it will sit for more that 3 days. After that no preserve battery warnings.

 

[Cdubya]

Are you monitoring voltages with the car running? I used to see some really low voltages that the BMS is putting out. I've never gotten charging system messages but i want my dashcam battery pack to be charging and my sub amp to see a good voltage so i changed my battery state of charge from 80% to 95% using Forscan in BdyCM. My car is old so i don't see 14+V anymore but mine is usually 13.2-13.8V at least.

I do have the Topdon BT200 battery and charging system tester and that says everything is fine.