2 bank on-board Alternator Chargers worth it- do they work?

fichtfart

Cadet
Joined
Sep 23, 2002
Messages
16
I have a 98 19.6 PrinceCraft w/98 150hp Ficht (trust me- I got a good one!!) and a 24v trolling motor- great set up- no (major) issues. (looking for wood to knock on)

I?ve been looking at getting one of these MinnKota Dual Bank DC Alternator Chargers (at least 10amp per bank) to tap off the engines alternator to charge the (2) deep cycle trolling batteries while under power of the engine.
I?ve heard both good and bad opinions from friends, bro in law and bar tenders but believe they may be mostly based on how often you?re using the engine vs how often the trolling motor batteries are close to a 120vac outlet (then use a battery charger)
Over the past few years (and for the next several) - I?ve been hitting a river for 2 weeks of every year where:
1) I don?t pull the boat out for the full 2 weeks, (average 300+miles logged per GPS)
2) Its about 150+ foot to run an extension cord to the batteries, (swimmers freek out when they see me doing that) and I don?t feel like humping them out every other night and carry back to camp.
3) the day consists of early morning buzz out to fish- and using the trolling motor to troll or work the shoreline, then tubing/skiing zipping around all afternoon followed by evening repeat of the morning.
So I feel there would be sufficient time to charge each day.
Anybody have runtime with these chargers that can tell me if their good/bad/no difference?

Thanks
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,224
Re: 2 bank on-board Alternator Chargers worth it- do they work?

Maybe I'm dense, but I don't get it. Seems like you could do that with a couple of diodes. Well whatever, you can only get out of a battery what you put in the battery (actually less than). So you would have to calculate how many amp hours your trolling motor is using and compare with what your alternator is capable of producing. Be sure to factor in the normal juice you are using for starting, power tilt & trim, bilge pump, bait well, etc, etc. Generally speaking, the alternator can't supply enough for the trolling motor. Depends on how much you are using each.
 

Vic.S

Rear Admiral
Joined
May 4, 2004
Messages
4,718
Re: 2 bank on-board Alternator Chargers worth it- do they work?

Maybe I'm dense, but I don't get it. Seems like you could do that with a couple of diodes.

Is it because the Minn-Kota battery is 24 volts whereas the main engine alternator's output is only 12 volts.

You could only charge a 24 volt battery using diodes from the alternator if you can break it into 2 x 12 volt ones and charge them in parallel.

I cannot find any useful technical info on the Minn-Kota charger

Success or other wise will depend upon how many hours the main engine is run compared with how many hours the trolling motor is run and what its average power consumption is.
 
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F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,224
Re: 2 bank on-board Alternator Chargers worth it- do they work?

Ah so. 24 volts helps explain things to this dense head.
 

Vic.S

Rear Admiral
Joined
May 4, 2004
Messages
4,718
Re: 2 bank on-board Alternator Chargers worth it- do they work?

Ah so. 24 volts helps explain things to this dense head.

To return to the OP's question then.

Yes it should work ... I'm sure it will do what it says on the tin provided the main engine alternator can supply sufficient current, and provided he is running the main engine for long enough to recharge the trolling batteries at 10amps.

I don't know his main engine electrical output. 35amps ?? if so that should be adequate.

I dont know what trolling motor he has or for that matter sufficient about trolling motors to even guess the average power consumption or how long it will require the main engine to run for say every hour of trolling.

What-ever. For the good health of the trolling battery he should make sure he always fully recharges it after use by getting the battery charger in operation when he returns to the dock. He might consider a solar panel as an alternative to the shore powered battery charger. It'll be slow, a lot slower, but at least does not require the 120 volt AC connection and all the problems that can bring.

BTW Instruction manual for the Minn-Kota Alternator-to-Battery charger here http://store.minnkotamotors.com/media/document/2377137_revH_english_alt_manual_100129.pdf
 
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