Switching Battery Switches with Diesel Running

[silverp40]

This may sound like a silly question but can one switch between "house" and "start" batteries while the engine is running (and alternator charging)?

It is well known that one should never switch the battery isolator switches off while the alternator is charging but do battery switches in general (ours are Guest) have a split second "off" while switching between one and another bank that would burn the alternator diodes?

Thanks for any help...

[Maine Sail]

Provided your switch is a "make before break" design there is no worry moving between 1, 2 or ALL/BOTH just don't pass through OFF.

To test your switch to see if it is make before break;

1- Turn on DC cabin lights
2- Make sure motor is off
3- Rotate switch between 1,2 & ALL (try both fast and slow movements)
4- If you see ANY flickering or the lights momentarily dim or drop out buy a new battery switch as yours is not make before break.

Most all switches from companies like Guest, Blue Sea, Perko, BEP and others have been make before break for many years.

[silverp40]

Great , will try that .

Thank you!

[belizesailor]

Something to consider for a future upgrade, is to ditch the old style "1,2,All" switch and replace it with a battery combiner/isolator or a multi-bank smart charger/regulator. Which route you go depends upon your configuration and preferences, but either of these solutions will charge both banks and isolate them for use. This eliminates the human error factor from managing charge and usage with the old style multi-bank manual switch. You do however want to keep a physical switch in the circuit so that you can shut off power for maintenance purposes or in the event of an electrical fire.