Originally Posted by wolfenzee
Changing between banks (1, 2 or both) there is quite possibly no contact until it "clicks" into place and then there is a solid contact ie: there is no power to anything while changing banks (this prevents power surges and shorts).
Contrary to popular belief most every battery switch made in the last 25+ or so years have been of the make before break style. Like the ones linked to bellow:
* Accepts up to 4/0 battery cables
* Luminous label for low light reading
* Ignition protected - Safe for installation aboard gasoline powered boats
* 3/8"-16 tin-plated copper studs for maximum conductivity and corrosion resistance
* Make-before-break contact design for switching between battery banks without power interruption
* AFD (Alternator Field Disconnect) switch
* Meets all American Boat and Yacht Council (ABYC) requirements for battery switches
* Tactile textures indicate knob position by feel only
* Case design allows surface or flush mounting
* Fits all Perko low amperage battery switch hole patterns.
High Performance Battery Switch
Or this one:
Dual battery Selector Switch
- Vaporproof, water-resistant, dustproof, and corrosion-resistant.
- UL and CE rated.
- Ignition protected to conform to USCG safety standard 183.410.
- Functions with alternators or generators.
- Make before break design
If you don't pass through the OFF position with most any 1/2/Both/Off switch you will not fry your diodes unless your switch is really, really old or really, really worn. Still many folks switch through off and toast the alternator. There are a ton of threads on this forums where members have done just that.