I'm building a new battery system for my Albin 27 trawler. The boat
previously had a 1-2-Both-off switch and two banks of batteries. My new
engine has two alternators and I'd like to take full advantage of this
set-up. My plan is to install a dedicated starting battery with an
on-off switch, a dedicated house bank with an on-off switch and then
have a third switch to parallel the banks in an emergency. This system
is explained in detail in Calder's book and seems to be a good match
for my boat.

My question is this; Assuming I connect one alternator to each bank,
what happens when I parallel the batteries? Will the two alternators
feeding into the system cause any problems? 99% of the time the two
systems would be totally independent.

Thanks,
Jason

Albin 27 FC- "Tonic"
http://www.people.cornell.edu/pages/jek15/

See the article at http://www.yandina.com/combInfo.htm#Q33 on
alternators in parallel.

I don't like seeing a switch between the battery and the alternator -
if you turn it off while the engine is running you run a serious risk
of damage to the alternator. A zapstop will add some level of
protection and put a warning right on the switch so those unfamiliar
with the danger are informed.

Regards,

Andina Marie Foster,




Jason wrote:
I'm building a new battery system for my Albin 27 trawler. The boat
previously had a 1-2-Both-off switch and two banks of batteries. My new
engine has two alternators and I'd like to take full advantage of this
set-up. My plan is to install a dedicated starting battery with an
on-off switch, a dedicated house bank with an on-off switch and then
have a third switch to parallel the banks in an emergency. This system
is explained in detail in Calder's book and seems to be a good match
for my boat.

My question is this; Assuming I connect one alternator to each bank,
what happens when I parallel the batteries? Will the two alternators
feeding into the system cause any problems? 99% of the time the two
systems would be totally independent.

Thanks,
Jason

Albin 27 FC- "Tonic"
http://www.people.cornell.edu/pages/jek15/

If you connect the switch between the battery and the load, and connect the
alternator to the battery ( or the battery side of the switch, I try to
minimise using the battery lug as a connection point for lots of wires .. )
that will overcome the switching whilst running issue. You also need to
deal with switching the 12V to the alternator, it won't charge without it.
I'd probably switch the 12V to the engine alternator via the normal start
switch, and I'd add a relay driven by this switch to connect the house
battery +12V to the second alternator.
There will be separate "not charging" lights for each alternator, and
presumably separate voltmeters ....
You can build a very cheap audible alarm by connecting a piezo buzzer
between the switched positive to the alternator and the alternator output -
drives you mad until the engine has started. Same thing for the oil
pressure switch.

You can get much more complicated, and I'm only a beginner at this, but I
think it would be simple, cheap, reliable, and easy to fault find. Given
that the least reliable part of the whole thing is probably the battery
isolating and linking switches, I'd consider omitting the "link" switch and
just carrying a jumper cable. If the batteries are close, and the cables
are long enough, you can always swap the cables between the battery + and
their isolating switches. This would let you start the engine from the
house battery PROVIDED the engine isolator had not failed ... in which case
you need the jumper ... or just use the jumper.

I'll let someone else work through the issues of how to handle the -ve side
of things, which battery should have solar cell charging, and whether to
connect the second bilge pump to the house battery or the engine battery
.......
David








"Andina Marie" wrote in message
oups.com...
See the article at http://www.yandina.com/combInfo.htm#Q33 on
alternators in parallel.

I don't like seeing a switch between the battery and the alternator -
if you turn it off while the engine is running you run a serious risk
of damage to the alternator. A zapstop will add some level of
protection and put a warning right on the switch so those unfamiliar
with the danger are informed.

Regards,

Andina Marie Foster,




Jason wrote:
I'm building a new battery system for my Albin 27 trawler. The boat
previously had a 1-2-Both-off switch and two banks of batteries. My new
engine has two alternators and I'd like to take full advantage of this
set-up. My plan is to install a dedicated starting battery with an
on-off switch, a dedicated house bank with an on-off switch and then
have a third switch to parallel the banks in an emergency. This system
is explained in detail in Calder's book and seems to be a good match
for my boat.

My question is this; Assuming I connect one alternator to each bank,
what happens when I parallel the batteries? Will the two alternators
feeding into the system cause any problems? 99% of the time the two
systems would be totally independent.

Thanks,
Jason

Albin 27 FC- "Tonic"
http://www.people.cornell.edu/pages/jek15/

I see no reason to disconnect the batteries from the alternators.

In an emergency you can se a set of jumper cables to crank the motor.

I keep a set of jumper cables in a waterporof bag in the bilge of my bass
boat, although its usually just to swap batteries around.

"Jason" wrote in message
...
I'm building a new battery system for my Albin 27 trawler. The boat
previously had a 1-2-Both-off switch and two banks of batteries. My new
engine has two alternators and I'd like to take full advantage of this
set-up. My plan is to install a dedicated starting battery with an on-off
switch, a dedicated house bank with an on-off switch and then have a third
switch to parallel the banks in an emergency. This system is explained in
detail in Calder's book and seems to be a good match for my boat.

My question is this; Assuming I connect one alternator to each bank, what
happens when I parallel the batteries? Will the two alternators feeding
into the system cause any problems? 99% of the time the two systems would
be totally independent.

Thanks,
Jason

Albin 27 FC- "Tonic"
http://www.people.cornell.edu/pages/jek15/



--
Posted via a free Usenet account from http://www.teranews.com

It's not so much disconnecting the battery from the alternator that's the
issue, it's disconnecting the battery from the load. The diodes in the
alternator should prevent any reverse current flow.
DF

"Bob La Londe" wrote in message
.. .
I see no reason to disconnect the batteries from the alternators.

In an emergency you can se a set of jumper cables to crank the motor.

I keep a set of jumper cables in a waterporof bag in the bilge of my bass
boat, although its usually just to swap batteries around.

"Jason" wrote in message
...
I'm building a new battery system for my Albin 27 trawler. The boat
previously had a 1-2-Both-off switch and two banks of batteries. My new
engine has two alternators and I'd like to take full advantage of this
set-up. My plan is to install a dedicated starting battery with an
on-off switch, a dedicated house bank with an on-off switch and then have
a third switch to parallel the banks in an emergency. This system is
explained in detail in Calder's book and seems to be a good match for my
boat.

My question is this; Assuming I connect one alternator to each bank, what
happens when I parallel the batteries? Will the two alternators feeding
into the system cause any problems? 99% of the time the two systems
would be totally independent.

Thanks,
Jason

Albin 27 FC- "Tonic"
http://www.people.cornell.edu/pages/jek15/



--
Posted via a free Usenet account from http://www.teranews.com