Lets review:

You don't want to leave both batteries connected at all times
because A) they are different size & capacity batteries
and B) the charging system is 5 amps and so the starting
battery only gets 2.5 amps and would take a long time to
charge back up. ~ While some here seem to disagree, I've
always heard and it makes sense to me that connecting
dissimmilar batts for a long time ain't that good.

You don't want to replace the 1000 battery, I guess because
that battery *does* make sense for trolling. Plus to do it
really right you'ld need two of the identical battery...something
like two dual-purpose batts. ~ I just bought two dual
purpose for about $110. This actually might be a good
option for you. But read on.

You don't want an A/B/BOTH switch because you seem
afraid that either you or people you lend the boat to
(guests) will accidentially leave it in the Both position. ~
While this makes sense to me....you also have to ask
yourself: How likely is this to happen, for how long, and
what damage will be done. If it's not likely and not a
lot of "damage" then maybe who cares?

Maybe just put a red X on the "both" position. Or, as
Tom suggested, maybe you can disable the both position
in some way.

Also consider your statement: "...I figure I can watch the guage
and just flip the switch when the voltage gets too high..." This
seems to assume you will be watching the gague. It seems to
me that you are more likely to forget to watch the gague
after a while (get distracted by the big fish that's biting) then
to accidentially put a switch into the BOTH position. ~ Same
goes for your guests. If they are smart and ware enough to
remember to flip the switch when the gague does a certain
thing....they are probably smart enought to NOT use the
both position.

You may be suffering from the same thing I often do. I think a
problem through TOO much and want the solution to be TOO
perfect. That's not to say I don't get your points. They seem
all or mostly all valid. And the perfect solution might be out
there. But maybe you need to step back and be simpler about
it.

Good luck,
Gary

Your thinking is correct about charging dissimilar batteries hooked in
parallel. You could wind up with one under charged and the other fried. Some
google searching will verify this (for non-believers). I don't think you
will find a marine switch without the both selection. Since you are dealing
with relatively low amperage, you may be able to find another type A/B
switch and then seal it with liquid tape. Just a thought.
--
Bill
Chesapeake, Va


"CCred68046" wrote in message
...
So... rather than replace the old, oddball battery(s), you think a
different
switch is an appropriate fix? Gimme a break!

OK guys, I'm not going into huge detail here, I have done that before with
this
problem. My Johnson outboard has an un-regulated charging system. There
is
really nothing on my boat that uses any current to speak of. Once the
starting
battery is fully charged (very quickly) the voltage go's up to 16+ and
this is
not good. Its much cheaper to buy the switch to let the voltage go to the
trolling motor battery which is usually discharged enough to keep it
"busy"
than it would be to try and put a regulator on it. To further complicate
matters the charging system is only 5 amps so when I used a combiner, both
batteries wound up low (I cant win!). Sooooo, I figure I can watch the
guage
and just flip the switch when the voltage gets too high and let the
trolling
battery have it. At 5 amps it would take it a looooooong time to recharge
the
trolling battery. If anyone else has a better plan I am listening.

CCred68046 wrote:
Does anyone know of a 2 battery switch that just allows for the use of one
battery or another at a time but NOT both? I just want a simple A/B switch.

Thanks.

Most if not all those multiple battery switches include a "both"
setting. They are set up so when you change from 1 to both or both to 2
etc the system never sees "no" connection, as this can damage some
proper alternator charging systems on the spot. particularly if done
when the alt. is running at high output. You can see how it might be
tricky or at least more expensive to create a 1/2 switch with this
protection.

Just get 2 on/off battery switches & position them so it's really
obvious if not physically difficult to have them both in the "on"
position together.

Don't get too fussed about having both batteries connected, the risks
are much overstated by the scary bananas brigade & yes the old OB
charging systems did show some high voltages but remember they never put
out much real power (amps). It takes high volts & high amps together to
murder a battery quickly & OB chargers of the type you've mentioned put
out very low amps even when they do work:-).

K

Don't get too fussed about having both batteries connected, the risks
are much overstated by the scary bananas brigade & yes the old OB
charging systems did show some high voltages but remember they never put
out much real power (amps). It takes high volts & high amps

Thanks Karen,
In spite of the high voltage and all the doom everyone warned me about, nothing
was ever hurt. I just find it interesting that no one I have ever found can
explain to me WHY they would make something that could do this and how mine ran
perfect for years and all of a sudden decided to run at 16 volts. Its only 5
amps so I guess its just a personal thing with me

CCred68046 wrote:
Don't get too fussed about having both batteries connected, the risks
are much overstated by the scary bananas brigade & yes the old OB
charging systems did show some high voltages but remember they never put
out much real power (amps). It takes high volts & high amps


Thanks Karen,
In spite of the high voltage and all the doom everyone warned me about, nothing
was ever hurt. I just find it interesting that no one I have ever found can
explain to me WHY they would make something that could do this and how mine ran
perfect for years and all of a sudden decided to run at 16 volts. Its only 5
amps so I guess its just a personal thing with me

It's cheap:-)

K