"mark s" wrote in message
I think 1 is a starting battery and the other is a deep cycle w/cranking
amps.
As I understand it, a starting battery is setup to deliver lots
of amps over a short time (as in when starting). A deep cycle
or "house" battery is setup to be better at providing a lower amp
load for a long period of time (as then running electronics without
the engine running). Each can do the other's job, but not as efficiently
and with more damage to the battery. So "deep cycle" with "craking amps"
is, I believe, not quite correct.
1 - why is this system utilized (why not just 1 battery?) and what is
the proper operation of this system?
This system is there so that when you are running electronics without
the engine running (say when fishing, on anchor, or maybe at the dock)
you will be draining the deep-cycle/house battery. This battery is
made for this type of discharge. More importantly, you will not
accidentially drain down your starting battery.
Assuming #1 is starting battery and #2 is the house battery:
Normally Start and Run on "both". This allows both batteries
to remain charged up. Then when you stop the engine switch to
battery #2. This way only #2 will be drained. When ready to
start flipping to both should allow you to start the engine. If not,
you can flip to just #1 to start the engnie. When you are off the boat
flip to OFF.
As others have said, changing the switch position when then the
engine is running could cause problems. This is because the
altenator is putting out power but for a moment when you flip
the switch there is no battery to "take up" that power.
However, some altenator / power systems regulate for this. Also,
you can buy a 1/2/BOTH/OFF switch that is a "make before break"
switch. This means it makes the connetion to the next battery
before breaking the connection to the previous one. Example: When
switching from #1 to #2 it would connect to #2 before breaking
the conenction with #1. With this type of switch it's not a problem.
See:
http://tinyurl.com/27u45
Note that in the description blurb they say "We strongly recommend field
disconnect battery switches (or failsafe diodes) to eliminate the chance
of alternator damage due to inadvertent switching."
Also, some power generation systems do not put out any power
until you reach a certain RPM on the engine. So switching at low
RPMs (idle) may not be a problem.
The safest rule is not to switch with the engine running...but that may
or may not be necessary on your system.
2 - should I always have it switched to "both" so both batteries get
charged when running? what is the preferred switch scenario?
Answered above. Generally:
BOTH when starting & running
#2 when engine is off but you are running electronics
OFF when you leave the boat
#1 only to start if BOTH does not work.
3- which battery is better to run the electronics to? (I imagine the
deep cycle.)
Deep cycle.
Also, many people just use two of the same battery. They get
two "dual-purpose" batteries. This is also good in that both
batteries have the same charging characteristics.
Another note:
As another poster mentioned, there are other things you can add
to your system. I have a "battery combiner" along with my 1/2/BOTH
switch. The Battery Combiner (BC) makes a connection between #1
and #2 when the charging system is putting out 13.3 volts or more.
With this setup I just flip the switch from OFF to either #1 or #2
and then do whatever I want (start the boat, stop, use power, etc.)
When the engine is running the charging system is putting out
13.3 or more volts and BOTH batteries get charged up. If I shut
off the engine I'm only drawing from the one battery. If ever
I drain that battery, I can always switch to the other to start the boat.
This setup means I don't have to remember to flip the switch except
to turn it on when I get in the boat and off when I leave it. I have two
of the same batteries, so I just alternate between whether I flip the
switch to #1 or #2.
Here's a link to a BC:
http://tinyurl.com/2g3ut
Thanks for the advice.
-mark
Hope that helps.
Gary