christopherglenn wrote:
Most high output aftermarket alternators are close to 50% output at idle, VS closer to 20% for small stock alternators.
The stock Ford 130 amp alternator in our E450 motorhome's V10 chassis puts out 60-70 amps when the engine is idling, according to Ford's published alternator performance curve for it. This is around the 50% point for the alternator.
I have a permanent ammeter installed in our motorhome and with the engine idling I have seen the alternator dump over 50 amps into the coach battery bank when the batteries have been discharged down to around 50% state of charge. We don't have solar on the RV so often when the batteries get low, I hit them with the idling engine and it's alternator for up to an hour before firing up the little portable generator to finish the charging.
