battery charger alternative

[rebuilding boat]

I inherited a 40 year old boat that I am rebuilding. I am using 3 batteries. 1 12 v starting for 115 hp merc. and accessories and two 12v in series for trolling. Instead of buying a 2 or 3-bank charger, is there a reason I can't just use the motor to charge the starter battery and use two small chargers to charge each one of the 12 v batteries I have hooked in series?

 

[alldodge]

I inherited a 40 year old boat that I am rebuilding. I am using 3 batteries. 1 12 v starting for 115 hp merc. and accessories and two 12v in series for trolling. Instead of buying a 2 or 3-bank charger, is there a reason I can't just use the motor to charge the starter battery and use two small chargers to charge each one of the 12 v batteries I have hooked in series?

Yes you can do that, but don't use the little maintenance chargers to recharge the 2 Bats. Need to have a charger that puts out enough amps to recharge the Bat it the amount of time you allow

 

[dingbat]

I inherited a 40 year old boat that I am rebuilding. I am using 3 batteries. 1 12 v starting for 115 hp merc. and accessories and two 12v in series for trolling. Instead of buying a 2 or 3-bank charger, is there a reason I can't just use the motor to charge the starter battery

Rarely, if ever do people put enough hours on a boat to fully recharge a starting battery each outing.

and use two small chargers to charge each one of the 12 v batteries I have hooked in series?

Guessing your two batteries in series are ~80 amp hours range.
If you discharge the batteries to 1/2 capacity (80 amps,) your looking a recharge time in hours = 80 amps/charger output

 

[Chris1956]

If your motor is an inline 6, the max charge is likely 9A at high RPM. If a newer motor, it could have a 35 or 40Amp charging system.

If a motor can charge 35 or 40Amps, you may get some charge into the trolling batteries, from the engine.

 

[airshot]

Yes to what others have stated, gotta have a charger to get them filled back up in the proper time....then once full use a maintenence charger while in storage or if your not gonba use them in the next week. I would be very nervous using my main starting battery for my accessories !! I have a small dedicated start only battery for the motor and the charge system keeps it full with ease. Depending on what accessories you have, you might end up with a serious draw down then no starting your motor. I use a group 31 deep cycle just for accessories, fish sonar, sterio, lights, ship to shore aerator for minnow bucket etc. Then my two batteries for trolling motor. If you don't run lots of accessories you might get away with your setup, but I wouldn't make that gamble, way to far to row back in !!

 

[JohnSz]

FWIW: I use a 10X2 on the trolling motor batteries, to make sure they will be fully charged overnight, for the 2nd day of fishing. I use a 5X1 on the starter battery, which is typically still near full charge after a day of fishing. If your batteries are not located together, then two chargers can also ease the pain of running extension cable thru the boat to the starter battery.

 

[rebuilding boat]

Thank you all for the responses. You have talked me into 4 batteries with 3 chargers. 1 starting battery and let the motor charge it. One battery for all the accessories and a 10 amp charger for it. Two 10 amp chargers for the batteries in series for the trolling motor. That still comes out a lot cheaper than a 3 bank charger.

 

[alldodge]

One 3 bank charger can charge the 3 you mentioned, or a 4 bank can charge all of them. Doesn't matter if 2 are in series

 

[airshot]

On my boat, all the chargers are hooked together with a heavy duty extension cord that runs inside all the panels on rhe boat. One small covered acess port has a plug.. When I park my boat in the barn, just plug that one olug into a heavy extension cord and all batteries get charged over nite. I am good for at least two weeks, if I go longer, I will replug the chargers the night befirevto top everything off.. When winter comes, I have small maintenence chargers that will maintain all the batteries over the winter and add length to the life expectancy of the batteries.

 

[Grub54891]

Extension cords are not abyc compliant.

 

[airshot]

Extension cords are not abyc compliant.

They are in my private barn, I do not use/ or charge while underway, would need a really long cord to get 110 three miles out.

 

[rebuilding boat]

One 3 bank charger can charge the 3 you mentioned, or a 4 bank can charge all of them. Doesn't matter if 2 are in series

I can purchase three 10 amp smart fully automatic chargers for $81 total. They will do what a 3 bank charger does but not cost $324.