It's amazing how complicated simple things are when you start thinking
about them.

A little research in Calder's book shows that he, at least, considers
bilge pumps on the battery side common.

But..

I've already decided to run both my batteries as close to parallel as
possible to minimize the depth of the discharge cycles and get maximum
life out of the expensive AGM cells. This goes against the
conventional wisdom of always maintaining a dedicated starting
battery. I'm going against the grain because:

a.. This is a sailboat and I will not be helpless if the engine
doesn't start. I've cruised in boats with no engine at all.
b.. The engine can be hand started, at least in warm weather.
c.. I'm going to be mostly daysailing and short cruising this year.
d.. I have very minimal ship's service loads so it is unlikely that
I'll run the batteries flat.
e.. I can start this little engine with a portable emergency
battery. It's even been done with a handful of flashlight batteries.
So, if I want a dead ship except for the bilge pump, I have to decide
which battery to use. That means that a long run of pumping with the
charger off, as could happen with the boat unattended in a storm,
would drain one battery down. I also would only have half the battery
capacity for bilge pumping under the same circumstances. That is not
ideal. Worse, if one battery did die, I would have to get into the
panel and switch the bilge pump. That's not good.

I guess that, for now at least, I'll just leave things as they are
with the bilge pump wired into the bus. That means leaving the switch
on "Both" when putting the boat away and being sure to turn everything
except the bilge pump off.

A good solution for my situation would be two bilge pumps, one on each
battery. That would provide redundancy. It should be simple to run a
second line and another through hull in this boat. I'll just wire them
into the same float switch. I'm going to take a look tomorrow. We're
doing a lot of through hull work anyway and we'll have the equipment
right there to punch one in above the waterline.

The ramifications just go on. I just realized that the bilge
discharge fitting is 3/4 and the pump hose is 1 /18. That means there
is a reducer somewhere. That's a kludge I'd better track down. That
would be another reason to go to two pumps of the same total capacity.

--

Roger Long



"Doug Dotson" dougdotson@NOSPAMcablespeedNOSPAMcom wrote in message
...
Bilge pump should not be wired though a battery switch. If you have
a
switch that even has a "both" position, then there is a better way.
House bank
should be unique with a separate starting battery. A switch to
parallel
the starting bank to the house bank in the case of an emergency is a
good
idea.

DOug

"Roger Long" wrote in message
...
In that case, you would have to leave the battery switch on both to
leave the boat charging the batteries from shore power. I like the
idea of being able to turn everything in the boat except the bilge
pump completely off when not on it. I would have to rewire the
bilge pump to the battery side to do that.

That's the way I would like it but I will probably be chartering
this boat eventually and I want to keep the set ups simple and
standard.

That's why I'm asking here what is typical.

--

Roger Long



"Phil Lewis" wrote in message
ink.net...
Typically, the chargers are on the disconnect side and not the
battery side. The alternator is on the battery side. there should
also be a large fuse between both and some sytems have a battery
isolator too.