Gary Warner wrote:
And my alternator has
survived since 1991 with a Guest 1/2/off switch.


My understanding is that what can kill an alternator is if the Alt
is putting out power and you switch from, say, #1 to #2. At that
moment when you switch there is no battery connected to the
charging system to take the power thus creating a momentary
surge in power.

It's not a "momentary surge," it's a voltage spike attempting to reach
infinite! From a Buddhist point of view this might be Nirvana but for
the alternator regulating circuit it is a guaranteed trip to the
afterlife


... Some switches are "make-before-break" so
they make the connection to the #2 battery BEFORE breaking
the connections to the #1. (or whichever way you are switching).

But these better type switches can look exactly like the cheaper
type. You have to check the part number (or study it's design
and operation) to determine which type you have.

Yes exactly. Bill's point about using one battery to buffer his
electronics is also worth noting. We have a somewhat similar set-up but
it's accomplished in the breaker panel.




Doug King wrote
Also, you don't mention it but are you putting in a hard wired charger?
Definitely get & use a 3-stage smart charger no matter how you rig it.


Gary Warner wrote:
On such a smally boat with such low electrical draw and only weekend
use do I really need/want a charger? Won't my generator take care of
charging up the batteries?

Depends on how you use the boat & generator... you've got a genset in a
22 footer? If true then you can skimp on the house banks, fer sure.


Other question: I do have a good home based battery charger. It has
both a full charge & trickle charge setting. But I see that trickly charging
all winter is going to kill the battery.

Yes, whereas a smart charger which has a third stage which "floats" the
battery at a full-charge but less-than-charging voltage will greatly
extend a battery's life; usually they also have a desulfating function.

... So are my choices are basically as
follows ??

A: Charge it when taking it out, then leave it all winter
B: Go to the shop every 2 or 4 weeks and charge it for a while
C: Buy a "smart" or "float" charger and leave that running

A trailer boat can be plugged in at home, whether the charger is wired
in or kept on a shelf is a matter of convenience... I'd go for option
"C" since that will pay for itself by extending the batteries working
life and getting you underway with batteries at peak charge every time.



And is it really OK to leave a smart charger running and connected to
a battery for weeks at a time without checking on it? The thought
of that just makes me a little nervous.

It shouldn't. Of course it is a good idea to check the cells every
couple weeks, but a smart charger will not boil them like a taper
charger or trickle charger (which is basically a taper charger with very
low amperage) will... I go several months without having to top mine up.

Our boat had a large & expensive ferro-resonant taper charger (80 amps
according to it's nameplate!!) wired in when we bought it... top of the
line 1970's technology! But it consistently boiled off the batteries
according to the previous owners maintenance log, and the previous
owners were in the habit of buying new batteries every 18 ~ 24 months.
Expensive! One of the first upgrades was a Xantrex smart charger, which
we used to desulfate (or "condition") the old batteries... gave them a
last hurrah...

Fair Skies
Doug King