Hey here's a fun one... please help...

[Heretic404]

'18 mustang.

Had few intended recently of battery just wierdly going flat intermittently for no reason...

Before battery was replaced had a moment when the car was struggling to even idle.

Battery now replaced and using the Windows causes a massive voltage drop (according to on board guage) and the motor rpm dips, (noticed the rev dip when opening and closing the door)

If i actually put them down while running they'll stall the car...

Wtaf?

Also my aux fans on my water air intercooler have stopped working very recently and all fuses look fine don't know if related...

This is doing my head in... i bought a mustang not a bloody alpha...

Rechecking grounds in the morning but if anyone else has ideas that would be fantastic...

Volt guage reads 14.5 must of the time... i think the alts fine... maybe fucky volt reg??? Or whatever the hell else?

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[StangTime]

Did you replace the battery yourself? Did you (or the technician) do a BMS reset? Have you checked your battery cables and clamps?

 

[ice445]

Sounds like a bad main ground or harness corrosion on the battery cables, I'd do a careful inspection of all the cables and do a voltage drop test with the engine running and some accessories on like the lights (engine block to battery negative terminal)

 

[Rapid Red]

Have a look here post 1

https://www.mustang6g.com/forums/threads/bms-reset-no-tools-required.151602/

 

[Heretic404]

I have a lead in a possible solution... i have the terminals off there's a supposed to be a fuse under them that links them... but i can't figure out how to get the damn thing out to check... anyone know?

 

[Heretic404]

Sounds like a bad main ground or harness corrosion on the battery cables, I'd do a careful inspection of all the cables and do a voltage drop test with the engine running and some accessories on like the lights (engine block to battery negative terminal)

Negatives all appear fine. It seems to only have issues if the window are up... do have a possible solution but i can't figure out how to access the fuse to check. .

Someone else had similar problems and this was the issue... i commented with diagram

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