Need help charging trolling batteries "On the Go"

Submitted: Thursday, Feb 19, 2009 at 20:40
ThreadID: 66112 Views:2098 Replies:5 FollowUps:0
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I would like to charge my boat trolling batteries from the alternator of my outboard. I have a 12 volt cranking battery that is charged from my outboard. I have two 12 volt batteries connected in series to run my 24 volt trolling motor. What type of setup do I need to charge my trolling batteries from my outboard? Any help would be greatly appreciated. Thanks.
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Reply By: Madfisher - Thursday, Feb 19, 2009 at 21:00

Thursday, Feb 19, 2009 at 21:00
I am not an expert in this area, but I think your problem is that outboards do not have much charging power and would struggle to charge three batteries.
cheers pete
AnswerID: 349942

Reply By: Member - Oldplodder (QLD) - Friday, Feb 20, 2009 at 09:12

Friday, Feb 20, 2009 at 09:12
On our trailer sailor we had an outboard that had connections to charge a battery. Put out 10 amps from memory, and we ran some cables to the battery. Read the instructions for the motor? (I know, silly question). We topped up the battery with solar when under sail.
AnswerID: 350016

Reply By: oldtrack123 - Friday, Feb 20, 2009 at 12:59

Friday, Feb 20, 2009 at 12:59
"miguel266 said
I would like to charge my boat trolling batteries from the alternator of my outboard. I have a 12 volt cranking battery that is charged from my outboard. I have two 12 volt batteries connected in series to run my 24 volt trolling motor. What type of setup do I need to charge my trolling batteries from my outboard? Any help would be greatly appreciated. Thanks."
Hi
Depending on amps available , you should be able to put some charge into your troll bats.
However some precautions are necessary..
You will need to arrange the troll bats in parallel ie pos tp pos & neg to neg.
IF the troll bats are flat they will drag the other bat's voltage down & IT MAY BE INSUFFICIENT TO START MOTOR.
The motor should be running before connecting troll bats
THE SPARK WHEN MAKING THIS CONNECTION COULD BE DANGEROUS IF PETROL FUMES ARE PRESENT or gas from batteries.
These problems can be minimised by putting a HIGH CURRENT DIODE in the + line to the troll bats. the batts can then be connected in parallel before starting motor & will not discharge main bat.
The diode will prevent the troll bats reaching max charge, but for short term use should be no problem, just remember to fully charge them asap.
AnswerID: 350048

Reply By: Flywest - Friday, Feb 20, 2009 at 13:20

Friday, Feb 20, 2009 at 13:20
Depends on the OB.

Smaller HP outboards often just have a lighting coil - that unless the OB is at full revs will barely put out any current at all.

Those with 12v elec start tilt and trim usually have a small alternator - maybe 35 amp hours or so and will put some charge back into the batteries, but maybe not as much as a 24V trolling motor uses, if it is continuous use on a heavey boat in windy conditions.

As for the 12V/24V conndrum - sorry no idea!

Cheers
AnswerID: 350055

Reply By: RV Powerstream P/L - Friday, Feb 20, 2009 at 21:14

Friday, Feb 20, 2009 at 21:14
Some smart chargers are built DC to DC and can charge from a 12V to 24V but are not waterproof.

One such unit is under development as a waterproof unit and hopefully willbe released soon it is being deveoped for the Bass boats.

As stated above regardless of this if the outboard is small it may be a waste of time but in the big outboards will be a definate advantage.

As mentioned in a previous thread the Pro Sport Chargers are IP66,IP68 rated waterproof.

Ian
AnswerID: 350147

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