Onboard battery charger question

In my boat, I have a dual onboard battery charger. One side is connected to
my engine battery. The other goes to my trolling motor battery. With
regards to my trolling motor, what happens if I hook up another battery in
parallel to my trolling motor battery? My trolling motor is 12V and by
hooking up in parallel, I still have 12V.

My question has to do with how the onboard charger from one side would
charge those two batteries hooked up in parallel. Is it possible that if
one battery is not as full as the other, that the charger would "cook" one
battery too long? Keep in mind that I am only talking about the two
batteries hooked up to the second output of my charger. The first output is
hooked up only to my outboard battery.

Thanks,
Jeff

Jeff Durham wrote:

In my boat, I have a dual onboard battery charger. One side is connected to
my engine battery. The other goes to my trolling motor battery. With
regards to my trolling motor, what happens if I hook up another battery in
parallel to my trolling motor battery? My trolling motor is 12V and by
hooking up in parallel, I still have 12V.

My question has to do with how the onboard charger from one side would
charge those two batteries hooked up in parallel. Is it possible that if
one battery is not as full as the other, that the charger would "cook" one
battery too long? Keep in mind that I am only talking about the two
batteries hooked up to the second output of my charger. The first output is
hooked up only to my outboard battery.

Thanks,
Jeff

An interesting question. I just talked to John at Charging Systems
International and he says that this hookup will not hurt the charger,
but the second battery will not be charged. To use a 2 bank charger to
charge 3 batteries will require a double pole double throw switch in one
set of electrical leads to allow you to mechanically switch the leads
from one battery to the other. I don't know what brand charger you have
but this company has a trade in policy for upgrading to a 3 bank unit.

I have no connection with this company, but I live close to the plant
and have been a satisfied customer for many years.

Jeff I did the same... But I never charged the Motor Battery as my engine
always seem to recharge it.I hook up my charger to each Trolling battery. I
have never had to charge my engine battery once,unless your listening to a
radio or have alot of stuff running

Chris S

"Jeff Durham" wrote in message
...
In my boat, I have a dual onboard battery charger. One side is connected
to
my engine battery. The other goes to my trolling motor battery. With
regards to my trolling motor, what happens if I hook up another battery in
parallel to my trolling motor battery? My trolling motor is 12V and by
hooking up in parallel, I still have 12V.

My question has to do with how the onboard charger from one side would
charge those two batteries hooked up in parallel. Is it possible that if
one battery is not as full as the other, that the charger would "cook" one
battery too long? Keep in mind that I am only talking about the two
batteries hooked up to the second output of my charger. The first output
is
hooked up only to my outboard battery.

Thanks,
Jeff

That's a great idea. I had not thought of that. The charger was primarily
for the trolling motor battery because the engine took care of the starter
and accessory battery. Having it charge the engine battery was a bonus.

Thanks,
Jeff

"Chris S" wrote in message
...
Jeff I did the same... But I never charged the Motor Battery as my engine
always seem to recharge it.I hook up my charger to each Trolling battery.
I
have never had to charge my engine battery once,unless your listening to a
radio or have alot of stuff running

Chris S

"Jeff Durham" wrote in message
...
In my boat, I have a dual onboard battery charger. One side is
connected
to
my engine battery. The other goes to my trolling motor battery. With
regards to my trolling motor, what happens if I hook up another battery
in
parallel to my trolling motor battery? My trolling motor is 12V and by
hooking up in parallel, I still have 12V.

My question has to do with how the onboard charger from one side would
charge those two batteries hooked up in parallel. Is it possible that
if
one battery is not as full as the other, that the charger would "cook"
one
battery too long? Keep in mind that I am only talking about the two
batteries hooked up to the second output of my charger. The first
output
is
hooked up only to my outboard battery.

Thanks,
Jeff

On Wed, 31 Mar 2004 16:04:24 GMT, "Jeff Durham"
wrote:

With
regards to my trolling motor, what happens if I hook up another battery
in parallel to my trolling motor battery? My trolling motor is 12V and by
hooking up in parallel, I still have 12V.

Nothing bad will happen--only good. You will have TWICE the amperage,
TWICE the run time.

My question has to do with how the onboard charger from one side would
charge those two batteries hooked up in parallel. Is it possible that
if one battery is not as full as the other, that the charger would "cook"
one battery too long?

If you are precautious like I am, you might want to fully charge the
batteries separately first, then hook them up in parallel, so they
will share the load and be equally discharged before charging them in
parallel.

FWIW, I have a three-bank charger (5/5/3 amp circuits), one 12 v.
trolling motor battery, and a 12 v. starter battery. The engine keeps
the starter battery full, so I have connected all 3 charger circuits
in parallel on the trolling motor battery, for the equivalent of a 13
amp charging current. It's been working fine for 5 years.


batteries hooked up to the second output of my charger. The first
output
is
hooked up only to my outboard battery.

Thanks,
Jeff