Bob, we used one of those in concert with 6V golf cart batteries and it was very effective. As Richard notes, it isn't a 'smart charger' and so it lacks the 3 stage charging regimen and also can not equalize a bank...but it's a better option than simply relying on the standard alternator that engine
mfgrs. continue - inexplicably - to keep installing on their engines.
To use, you will need to do two basic things:
1. crack the alternator case and wire in the Automac's control wire (in lieu of the installed internal regulator); this allows you via the rheostat to control the amount of excitation of the field, thus controlling the amperage output of the alternator.
2. sort out what amount of charging current
is suitable for the capacity of your bank.