For those with on board TM chargers

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Dungee

Dungee

Keeper of San Juan Secrets
For those with on board chargers that charge the trolling batteries while the big motor is running....

Has it eliminated the need for a generator? Any other thoughts/suggestions on one? Any down falls to it? I see SQ always talking about his and loving it. It has gotten me intrigued.
 
On my last trip we used spot lock and jog for at least 10 hrs/day with a 112 lb 36 volt system holding a 24' boat in place. I was amazed that my battery gauge never went below 3/4 charge for the batteries, so this might not mean much, but they would be charged by the time we ran back to camp then returned to the same spot the next day. Which was maybe 15 min each way or about 3/4 back in Moqui to about a mile from the mouth of Moqui. They may have been charged sooner but I never checked them at camp. I am sooper happy with the system and am so glad I don't need to plug it in and listen to a genny.
 
I have an on board charger that starts charging the trolling motor batteries once the engine battery reaches 13.6 volts (Minn Kota). It works great when you have long trips on the water. On days that we caught lots of fish, I have both live wells running and 3 depthfinders on all day. Since the main engine battery is drawn down quite a bit, the on board charger doesn’t kick on Long enough to make much of a difference. So if your main battery doesn’t get drawn down to much it works great
 
We’ve had the on board charger in our last two boats and we never needed a generator, but we don’t fish from sunrise to sunset. It was recommended by a friend who is an avid fisherman and loves his. I will say that he does occasionally need a generator; if he’s been fighting wind all day, or stays close to the HB, so he doesn’t get a couple of long runs in to recharge.
 
I have a 2 bank (10 amps/bank) Minn Kota onboard charger that maintains 2 batteries for a 24 volt trolling motor and 1 battery for a 12 volt cranking system. I usually run the big motor for about 2 hours on a typical one day fishing trip. The trolling motor has GPS capabilities and it is always using spot lock or following/recording tracks stored in the memory. Never need to put the batteries on a generator or a shore powered battery charger.

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To be clear I think? - the topic is about on-board alternators - not on-board chargers. The typical on-board chargers are usually identified as AC plug-in types that save one from pulling out batteries to charge. I think the Minn Kota on-board alternator models are MK-1dc, MK-2dc, MK-3dc. Wouldn't want someone to order the AC plug-in charger thinking it would operate as an alternator.
 
I’m really surprised that the alternator on a relatively small (say under 200 HP) outboard motor would be enough to not only maintain the charge on the starting battery, but also charge two batteries that are used to run the trolling motor.

That is something I would never have expected.
 
Fished 3 full windy days with a lot of spot lock, livewell and electronics running all day and my red light came on the last morning 1 hr in. 24v w/ MK 2 bank charger, 225 Opti, 21 ft Triton. Burned 25 gallons on the trip. Could have easily fished a few more days by burning more gas cruising. I’m sold, my advice is run slow you will save gas and get more charge time. Scenery ain’t bad, enjoy it!
 
P Dub said:
Fished 3 full windy days with a lot of spot lock, livewell and electronics running all day and my red light came on the last morning 1 hr in. 24v w/ MK 2 bank charger, 225 Opti, 21 ft Triton. Burned 25 gallons on the trip. Could have easily fished a few more days by burning more gas cruising. I’m sold, my advice is run slow you will save gas and get more charge time. Scenery ain’t bad, enjoy it!
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25 gal. In three days at Powell, you were definitely burning up the batteries. 🎣
 
Ryan said:
I’m really surprised that the alternator on a relatively small (say under 200 HP) outboard motor would be enough to not only maintain the charge on the starting battery, but also charge two batteries that are used to run the trolling motor.

That is something I would never have expected.
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I totally agree, I’ve always been skittish about over-taxing a small outboard alternator. This Minn Kota alternator tech is new to me.

Visited MK website and read the MK-2-DC (2-bank) product manual, very cool stuff. It first sends charge to the starter battery, then only after starter batt reaches 13.6v does the unit switch to charging the trolling battery(ies).

Input amperages required for the 3 models are as follows: 1 bank = 12 amps, 2 bank = 25 amps, 3 bank = 35 amps.

On our smaller pontoon boat in Parker, we’ve got a 2004 75 hp Merc 4-stroke that runs a stator (rather than an alternator) and it’s rated at 20 amps. So this older, smaller outboard would support only a 12A single-bank MK alternator/charger.

On the other hand, the houseboat runs a newer 115 hp Merc with an alternator rated at 50 amps. This outboard would support all three MK models.

Thinking about installing a 2-bank MK model on the houseboat. Would be great to maintain charge on the 2 house batteries on those long runs up the lake without having to fire up the generator.

 
how do you connect the MK alternator charging system to batteries already connected to an onboard charger (AC)? Do you have to disconnect the AC charger? any issues with leaving the alternator charger connected when at home and plugging in to AC power?
 
PBH said:
how do you connect the MK alternator charging system to batteries already connected to an onboard charger (AC)? Do you have to disconnect the AC charger? any issues with leaving the alternator charger connected when at home and plugging in to AC power?
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You do not need to disconnect the onboard charger.. Both can be connected at the same time, pretty easy installation. The alternator charger only charges the TM batteries when the ignition is on, and the starting battery is fully charged. So when you have your AC charger plugged in, the alternator charger is not connected. And your batteries charge off the AC charger....
 
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