Battery Chargers

[x119]

A perhaps stupid question on the topic. 
Isn't it possible to simply leave the car running instead of using a charger for most operations such as changing the car configuration (so no firmware flashing or similar)?
With my Mercedes, I have been able to do all coding stuff and also long ECU flashing routines (which can last up to 1 hour) simply with the engine running instead of with the ignition on and a charger connected...

Car configuration changes are a flashing procedure. A SBL is loaded for the CEM and then a CCF.VBF is flashed. As part of the flash procedure ECU are reset. If your engine on it will stall, it doesn’t sound nice. Ask me how I know…