Battery switch danger

[Arminius]

An alternator can produce volts to light a 110 volt light bulb if not firmly connected to a functioning battery. Yes, I proved that as a juvenile experimenter. 110 volts will fry electronics and the diodes in the alternator. The usual "shorting" type switch momentarily hooks both batteries to the alternator as the operator switches from one to the other. However, no valid battery is substituted if the second battery is disconnected or dry, or the switch is turned to "Off" [in really fine print]. This catastrophe can be avoided by buying and installing an AFD (alternator field disconnect) type switch. Here are the instructions for the Blue Seas AFD switch: "Cut the field wire from the alternator to the voltage regulator; connect one end to F1, and the other end to F2."
Gotta ask yourself: Do I really need a 2nd battery?

 

[Stee6043]

You've owned an alternator that tested at 110volts output? I think you've got bigger problems than the switch at that point, Arminius.

The most basic, cheapo Perko switches are "AFD". I can't imagine someone actually deciding not to install a second battery based on this type of silliness...

 

[Arminius]

Asked my friend in the marine electrical business about this. He said that he sees fried diodes when operators try to switch batteries with the engine running and swing the selector through the "Off" position. The NFD leads can't be used with an alternator with an internal regulator. There is a zener diode device to protect Peanuts from his security blanket.

 

[Stee6043]

Asked my friend in the marine electrical business about this. He said that he sees fried diodes when operators try to switch batteries with the engine running and swing the selector through the "Off" position. The NFD leads can't be used with an alternator with an internal regulator. There is a zener diode device to protect Peanuts from his security blanket.

If you can't read....you shouldn't be operating a boat.

 

[Arminius]

Could be wrong on Peanuts; maybe it was Pogo: "We have faced the enemy and he is us."

 

[Wylie_Tunes]

I would not assume your Perko dual bank switch has AFD. Their entry level (basic cheapo) medium duty 8501 is not AFD. Need to step up to the 8504.

Same with Blue Sea. They offer non-AFD and AFD, so dont assume your switch AFD.