I'd like to add a second battery to my existing three battery setup.
Actually it'd be two 6v golf cart batteries wired in series, to be added to
the ships system circuit. I've got a Charles 30 amp AC charger that has 3
circuits; one to each existing battery. There are two engines, each with 70
amp alternators. They're wiring through a Surepower 2 amp, 3 bank battery
isolator.

Can I just add this new bank in parallel to the existing ships system
battery? Do I need to add another isolator? Can I hang that isolator off
the current isolator? As in pull one leg off the existing 2/3 isolator and
split it via another 1/2 isolator. Or do I "have to" use a whole other 2/2
isolator?

Thanks,
-Bill Kearney

On Wed, 20 Jun 2007 19:04:10 -0400, "Bill Kearney"
wrote:

I'd like to add a second battery to my existing three battery setup.
Actually it'd be two 6v golf cart batteries wired in series, to be added to
the ships system circuit. I've got a Charles 30 amp AC charger that has 3
circuits; one to each existing battery. There are two engines, each with 70
amp alternators. They're wiring through a Surepower 2 amp, 3 bank battery
isolator.
Missing a couple of zeros?

Can I just add this new bank in parallel to the existing ships system
battery?
Yes
Do I need to add another isolator?
No so the following is invalid
Can I hang that isolator off
the current isolator? As in pull one leg off the existing 2/3 isolator and
split it via another 1/2 isolator. Or do I "have to" use a whole other 2/2
isolator?

Thanks,
-Bill Kearney

--
Richard

Nb "Pound Eater" Parkend G+S
"Governments are like Nappies, they should be changed often."
(For the same reason)

"Bill Kearney" wrote in
:

Can I just add this new bank in parallel to the existing ships system
battery? Do I need to add another isolator? Can I hang that isolator
off the current isolator? As in pull one leg off the existing 2/3
isolator and split it via another 1/2 isolator. Or do I "have to" use
a whole other 2/2 isolator?


Anytime you are charging, with any charger, all they need is to all be in
parallel and the batteries will sort out how much current each branch of
them wants to charge with. Battery chargers are voltage floating devices
for lead-acid batteries.

My suggestion is to add another A-B-BOTH-OFF battery switch to the
existing house battery + terminal. Remove the + cable from the house
battery and connect it to the common terminal on the switch. Now, add a
heavy jumper from A to the original house battery and from B to the new
monster golf cart series batteries. This switch allows you to isolate
and bad or just dead batteries from the live ones you're running the boat
off of until you can get bad batteries replaced or dead batteries
charged. Under usage, charging or discharging, leave the switch in BOTH
to parallel the banks, or you can discharge them one-at-a-time in A or B.

The charging connection should still be hooked to the common terminal on
the new switch, by default. If you're going to store it on the hook for
over a day or so, pick a battery bank, A or B, to leave the house on,
which isolates them when there's no charging. Hook the automatic bilge
pumps, of course, to the biggest battery bank, DIRECTLY not through an
panel or switches where it can be cut off with a separate fuse double in
size to the load of the pump lifting lots of water. Bilge pumps should
NEVER have OFF positions!....that includes those damned RULE pump
switches with the crappy pushon connectors that belong in the dumpster!

Larry
--
http://www.spp.gov/
The end of the USA and its Constitution....RIP

They're wiring through a Surepower 2 amp, 3 bank battery
isolator.
Missing a couple of zeros?

That should be '2 alternator, 3 bank batter isolator' not amp.

Can I just add this new bank in parallel to the existing ships system
battery?
Yes
Do I need to add another isolator?
No so the following is invalid

No because an isolator won't work, or some other reason?

My suggestion is to add another A-B-BOTH-OFF battery switch to the
existing house battery + terminal.

Yes, the trick being finding an effective location to mount said switch.
The existing battery panel in the port gunwale doesn't have room for another
switch on it. So I'm rummaging around below to find a suitable place to add
this A-B-Both unit.

The bilge pumps are on the starting motors, and are always live (through a
breaker). The starting batteries have a relay that allows bridging across
all three banks should one of the starting batteries be too low to crank
it's engine. Even if both starting batteries were dead the switch will
still pull from the ships system. Thus far I've never had to use it.

I hear your comments re the Rule connectors, pieces of crap.

So I'm still wondering about an isolator and whether this fourth bank needs
one. I have absolutely no desire to get into flipping the A/B switch to
deal with charging. Since there's no good place in the cockpit it'll likely
mean this switch would have to be placed below, in the engine compartment.
All the more reason to avoid changing it.

Tangentally, I found marine 1/0 wire from SkycraftSurplus.com for just over
$2/foot. Quite a bargain.

-Bill Kearney