[bestgenman]

I cannot say whether the terminal changes polarity or not, it is not a function used in new construction. The alternator needs a positive voltage to turn on the regulator for excitation. The alternator used in most Newells is either a Denso or Hitachi as most sets are powered with a Kubota or Yanmar. Older sets may use the Delco.

I'm also not sure about switching while running as it is not a function commonly used, most sets have the excitation terminal tied to the ignition (or run) source so it is on with the engine running. I know of no manufacturer that switches the alternator excitation during operation. Onan does provide the option to have alternator output or not on their quiet diesel sets. Many times the alternator output conflicts with the inverter/charger output.

The genset alternator charges the same battery used for starting and if that is house battery and you want engine battery charging then you have two options. first, change the genset battery feed to the engine batteries or (second), run a seperate conductor from the alternator output (large enough to handle the current output) to the desired battery set.

Kinda wordy, difficult to explain, so I hope this answers your question!