Battery type

[parrothd]

It said in the article that it would not charge both equally in that scenario.

"If the switch is in the “BOTH” position and one battery is nearly at a full charge and one is flat, the alternator will “read” the higher of the two, and the flat battery will never be charged"

I think the better way would be to start the boat with just the good battery as you said, then switch to the other battery while cruising. The alternator will both run the boat and charge the weak battery.

It also says this.. "NEVER use the “BOTH” position except to parallel both batteries if they’re both flat, almost like an attempt to “jump start” your own engine.

But to each their own. I have been more doing it this way for years and have never been stranded.

The author doesn't seem to know how alternators and batteries work. I would carry jumper cables.. lol..