Start/Stop with bad battery stupid question... Plz help!

[RaymondP]

As I understand it for all Start/Stop vehicles, if the battery is too low the vehicle will NOT stop when standing, say at a light. It will continue running until the battery is up to the task (recharged). If you have a bad/dead battery, once the vehicle is started it will remain running as if the Stop/Start feature is turned "OFF".

I have a 2016 BMW 328i, original battery that only activates the stop/start feature after a run of a few miles. For short trips it does NOT stop unless I turn the engine off, so guessing the vehicle's computer is sensing the battery is not adequately charged.

Have been researching and preparing to replace the battery myself. Probably go for a Walmart AGM Platinum (49H/H8), unless others can advise of a better option/price. (Varta currently installed). Have purchased a tool (XTool D7) I am hoping will be able to reprogram the ECM for the new battery when I do replace it. Admit being a little nervous....will see how it goes. Again, any advice on this appreciated.

 

[930.engineering]

.
Exactly. There's no reason to fear a non-starting engine on the road
due to a battery not adequately charged.
Nonetheless I use to to disable start/stop on any new car. Right from
the beginning since I find it disturbing, but not because it'd fear me.
.

 

[dkryan]

Exactly!

That 12v should be for “lighting and interior” only, not “starting, lighting, and interior.”

On Toyota hybrid vehicles an inverter is used to start the ICE. There is no starter or alternator, at least on the Highlander hybrid 2.5L.

Supposedly the smaller of the two hybrid batteries is used to charge the 12v battery, though I have found it lacking in that regard and have to monitor the state of charge weekly.