Battery selector switch

[Stu Jackson]

Originally Posted by SanJuanTruant

It seems that a simple test of turning the selector switch between 1, all, and 2 while the lights are on, engine off, and shore power off would answer my question by telling me if power is briefly interrupted or continuous.

Does this sound correct?

Yes, but not always because of the size of the loads, but read and do the other stuff we recommended, too. Maybe at the same time.

The discussion that included a duo-charge was fine, except you don't need a duo-charge for that concept, just a combiner or echo charge or a BS ACR, less expensive and easier to install.

[Mystic38]

it is correct that new battery selector switches are make before break.. but as already pointed out, it doesnt mean that any particular boat has that type of switch..

nor does it mean that the battery selector switch is wired in any particular order...

for example, the battery selector switch in my boat is effectively deciding which bank powers the house electronics, as such 1,2 all, off are all valid positions whether the engine is running or not.. the alternator is hard wired to the house bank...given that is what required 98% of all charging.

30mins with a screwdriver and flashlight would be well spent on your vessel to see how your high current circuits are wired.

Originally Posted by SanJuanTruant

I found this from a licensed marine electrician. His thoughts on make-before-break:

On many older boats, the big 1-2-BOTH battery switch can be either a make-before-break switch or a break-before-make switch. Engineering speak! What it really means is a description of what happens when you turn the switch knob/handle/etc.:
Make-Before-Break
Nowadays, all switches are make-before-break., As you turn the handle from 1 to BOTH to 2, the battery voltage to the boat will never go to zero, i.e., there is never a voltage interruption. If you had a light on while turning the switch, you would see that it doesn't blink, though the light brightness might change, depending on your battery voltages. If this is your switch type, you can switch it while the engine is running.
Break-Before-Make
As you turn the handle from 1 to BOTH to 2, the battery voltage gets disconnected before each new switch position. If you had a light on while turning the switch, you would see it blink off then on. If this is your switch type, don't ever switch it while the engine is running or you could blow out your alternator!
Never switch off the battery switch with the engine running. Doing so will destroy your alternator!

It seems that a simple test of turning the selector switch between 1, all, and 2 while the lights are on, engine off, and shore power off would answer my question by telling me if power is briefly interrupted or continuous.

Does this sound correct?

[Mystic38]

while i agree that a combiner and a relay are other options..they are cheaper for a reason..

a combiner (cheapest) when charging will regularly discharge the start battery into the house battery and leave both banks at similar state of charge... when the house is significantly depleted then its a situation where you may always wish to preserve the high charge of the start battery in isolation so this is unsettling.

charging relays.. mechanical. nuff said.

either though are certainly preferable to manually fiddling with the battery selector switch...

Originally Posted by Stu Jackson

Yes, but not always because of the size of the loads, but read and do the other stuff we recommended, too. Maybe at the same time.

The discussion that included a duo-charge was fine, except you don't need a duo-charge for that concept, just a combiner or echo charge or a BS ACR, less expensive and easier to install.

[Stu Jackson]

Originally Posted by Mystic38

while i agree that a combiner and a relay are other options..they are cheaper for a reason..

a combiner (cheapest) when charging will regularly discharge the start battery into the house battery and leave both banks at similar state of charge... when the house is significantly depleted then its a situation where you may always wish to preserve the high charge of the start battery in isolation so this is unsettling.

charging relays.. mechanical. nuff said.

either though are certainly preferable to manually fiddling with the battery selector switch...

Combiners only work (close) when there is a charging source present and above around 13.0 volts.

The Yandina website has tons of information about this misconception.

[GordMay]

Originally Posted by SanJuanTruant

... It seems that a simple test of turning the selector switch between 1, all, and 2 while the lights are on, engine off, and shore power off would answer my question by telling me if power is briefly interrupted or continuous.
Does this sound correct?

Yes, it does.