The auxiliary battery must at a greater voltage than the car battery for a current to flow into the car battery. If the battery voltage has dropped, assuming the auxiliary is charged to the nominal 13.8 v a standard lead acid works at, then it will work.
The car will just see 13.8 v so why would the ECU be put at risk?
The fuse protecting the auxiliary socket will prevent the current flowing into the car battery exceeding 10A - even if the auxiliary unit were capable of delivering it, which I somehow doubt.
I suspect the unit will be fine for tickling up the car battery if it drops below the critical voltage which disables the car. And if that gives you peace of mind go for it!
A
|