Allocation of Batteries

[Mike Thompson]

At the end of last season I did some testing.
I disconnected the red cables from the battery posts.
With the port battery disconnected only the bilge pump works.
With the starboard battery disconnected everything except
the bilge pump works.
(I did not record what happened with both batteries
connected but with the main battery switch on "1" or "2".)

a) When on board, I always have the battery switch on "BOTH"
and on leaving the boat I put it on "OFF". Should I change
this practice?

b) Should I change the wiring?

[Ron Turner]

Mike,

What you did not say about your test last year was what position the selector seitch was in while you pulled the "red" cables off. On the surface it sounds like the bilge is direct wired to a battery, that's a good thing.

[Mike Thompson]

I think it is likely that the switch was in "ALL" when I did the test.
Mike

[Neil Gordon]

a) When on board, I always have the battery switch on "BOTH"
and on leaving the boat I put it on "OFF". Should I change
this practice?

OFF is good when you leave the boat. Only the bilge pump, which is wired directly to the battery, will be drawing current.

Conventional wisdom with two deep cycle batteries and a selector switch is to use BOTH for starting and charging. When the motor goes off, switch to one or the other so that you have starting power in reserve. Switching to 1 or 2 depending on the date is as good a way as any to balance use between the batteries. Note that alternating doesn't work unless you charge in between.

[Mike Thompson]

Thanks Neil

[Mark Yashinsky]

At the end of last season I did some testing.
I disconnected the red cables from the battery posts.
With the port battery disconnected only the bilge pump works.
With the starboard battery disconnected everything except
the bilge pump works.
(I did not record what happened with both batteries
connected but with the main battery switch on "1" or "2".)

a) When on board, I always have the battery switch on "BOTH"
and on leaving the boat I put it on "OFF". Should I change
this practice?

b) Should I change the wiring?

What was this "TEST" suppose to do or prove?
What is puzzling, is that if the "TEST" was done while the battery selector was on BOTH, why does only the the bilge pump work when the port was diconnected??? Power should be available from either battery when on BOTH and only the bilge affected because its connected to the starboard. Do you have a dead battery?
As for changing, what is the issue(s) that causes you to raise this question?

[Mike Thompson]

Mark,
I have a (large) loose leafed book labled "Thing to Fix" which is full of stuff about my boat. The page on which I recorded these findings is not dated but it was probably done last year. After which I forgot about it as the boat was performing well and I had other things to think about especially sailing and painting.

The wiring concerns me as I don't understand it and feel I should!
Now looking at these notes again, I see under STRBD BATTERY DISCONNECTED, under the list of things that WORK, the following note:
(when Master Switch set to "2" or "ALL")

The sheet does not record whether I disconnected the positive
or negative terminals.

[Mark Yashinsky]

Get fresh data on paper and in your head. The electrical systems are really not complicated. Most of these problems, after the problem has been found, are a "OH DUH, OF COURSE".

Another item, the starboard battery "+" connection should have another wire ( the bilge pump fuse) going directly to it (if connecting by threaded post or bolt) or to the battery clamp (if using the automotive large solid posts). Disconnecting a battery cable from the battery (ALL cables/wires to the connector), it does not matter if it is the positive or negative, THE BATTERY IS DISCONNECTED. There is no complete circuit.

Also, when rerunning the test, use 1/2 AND port/starboard labels together. Associate the two.