Hi there everyone,just registered.One question though,does the 12 volts auxiliary battery affect mpg?
Welcome, and yes! I forget exactly how it works but I think when the 12v battery is so low it needs to be replaced, the ICE compensates the 12v in order to power your electronic components including startup functions. Anecdotally, several people with low 12V batteries also have seen decreases in their mileage.
I had to have mine replaced last year and I noticed lower mpg while it was happening. The ICE ran more at stop lights, traffic, etc. due to it compensating for the 12v.
I replaced the 12v battery.The mpg has improved greatly from 34.3mpg with old battery to 55.3mpg with new battery.
Not every way your 12 volt battery can die lowers MPG, but some do. I think when only one cell dies, so you have 10 volts left, the charging system wastes a great deal of energy trying to recharge to 12 volt a battery that can't get there.
