this is probably a pretty basic question but there are tons of products out there. I have a new pontoon, I have a trolling motor to put on the front. I want to use the engine to charge the trolling motor battery and start battery while its running. but I don't want the trolling motor to run down the start battery. minn kota sells all sorts of chargers etc. but none seem to have the simple capability. what do I need for this. I think most guys with trolling motors are just going out for a day and the trolling motor battery is easily charged back up when they get home. for me we are out 3-4 days on boat camping trips, we need to at least add some charge back into the battery during engine run time.

Perko switch. Allows you to use either battery. Hasbeen

I would think charging capabilities on a boat motor are limited.

Similar to an atv.


Maybe buy extra batteries. Swap as needed.

Charge when you return home.

Buy yourself a Sportsman 1000 inverter generator and charge your trolling battery up at night. They'll run eight hours on half a gallon of gas and you can't hear them more than 50 feet away. They weight under 30 pounds and cost under $300. LINK

Love mine. I can even use it at motels where I can't get to an outdoor outlet. I just chain it to my boat trailer.

Solar charger?

I always carry one of these as an emergency starter backup

NOCO Boost Plus GB40 1000 Amp 12-Volt UltraSafe Lithium Jump Starter Box, Car Battery Booster Pack, Portable Power Bank Charger, and Jumper Cables For Up To 6-Liter Gasoline and 3-Liter Diesel Engines

https://www.amazon.com/dp/B015TKUPIC/ref=cm_sw_r_cp_api_i_G37VXTYA27HZDFPWSRJ6

The alternator on a boat motor is not capable of keep up with the charging needs of two batteries. Never use your cranking battery to run a trolling motor unless you main motor is shot and you are using the trolling motor for power.

If your trolling motor is 24 volt, get two batteries just for it. Install a 3 bank charger to be able to charge all 3 when you return to the dock.

^This. Set up your boat with a plug in charger with the appropriate number of banks. Then use AC when available and an inverter generator when necessary. I have one of the little Hondas primarily for this purpose.

Jerry

the boat has a mercury 200L outboard, which has an 85 amp alternator on it. thats more than a lot of cars. so I would think a substantial amount of battery charging could be done while the engine is running. I don't want the hassle of an additional generator, I will have too much crap already on board. any ideas how an hour of run time with that kind of amps could do to top off a trolling motor battery?

There are tons of on/off switches out there.

It'll charge your batteries, but how long are you planning on running around with the big motor to do it? Your batteries won't last a full day running an electric motor. Gonna leave the Merc idling to charge batteries?

I'd want the main motor charging my cranking battery and the trolling motor batteries completely separate, but that's just me.

Once you get it figured out you can take your learnings to Ranger, Tracker, Lowe, Lund, etc and share with them. There has to be a strong market for this...

Yandina combiner. Or yandina Trollbridge if the trolling motor runs off more than one batt wired in series.

The combiner will parallel the starter/ trolling (or house) batteries after the starting battery is recharged/topped off so the trolling batteries are charged. When you shut the main engine off, the switch opens so the trolling motor only drains the trolling batteries, the starter battery remains fully charged. Blue seas has an “ACR” which is basically a copy of the yandina.

You said you need this for extended fishing trips. You wouldn't carry your little generator aboard the boat. You'd have it ashore during the day and hook it up to your boat's normal battery charger at night. You'd have a full trolling battery in the morning for the cost of half a gallon of gas. That's WAY more efficient than running your 200-hp main motor to charge the troll battery.

You could certainly come up with a switching system to charge either your starter battery or your troller battery using the big Merc, but whichever way you did it the other battery would be low. Believe me, this is not the best approach.

Electricity is the weak spot on modern fishing boats but they’ve come a long way in the last few decades. I’ve been using deep cycle AGM batteries for a year or two and I won’t ever go back to flooded. I charged my 2 AGM’s after crabbing in November and decided in March to see how much juice they’d lost during the coldest, snowiest part of winter. I brought them in and put them on the charger. They showed 90% full and were completely topped off inside of 30 minutes. My flooded deep cycle was a year newer and it was almost totally discharged. A Perko switch and at least 2 AGM deep cycle batteries and you are starting from the right position. I use 1 battery for STARTING and my 2nd battery for running electronics and downriggers. Switch to LED for the house lights.

Good luck.

Could consider lithium Lifepo4 batteries if you want much longer run times/capacity

Is your trolling motor 12v or 24v? You can run your trolling motor battery parallel with your motor battery with a cut off switch in line with the hot which would stop you from burning up any of your motor battery while you are using the trolling motor. When running your motor simply complete the switch and it should work. If 24v of course you'd need another set of wires and another switch.

I agree with others here though, you'll use up a lot of battery running that trolling motor. You'll have to run your main motor a while to get it charged up. A solar solution like suggested here might be your best bet.

With the number of little piss-ant problems that seem to plague sport boat electrical systems I don’t think I’ll ever go backwards and use flooded batteries again, at least in boats. I’ve been so impressed with the AGM which is most definitely a HUGE improvement over flooded so I’d be looking towards the newer battery technology with great hope. As time goes by the prices are coming down and the products are infinitely. I bought 3 group 27 deep cycle batteries for $67.50 OTD each which was the same exact price as the same flooded battery by Interstate. They have factory seconds and refurbished units for a fraction of the price of new and I’ve never had an issue with them in 20+ years and dozens upon dozens of batteries. For every AGM I’m getting the performance of 2 flooded batteries of equal size. So effectively if I run 2 AGMs it’s about like running 4 flooded….ime.

You can use the charging system on the main, however it is unlikely you will fully charge the batteries for the trolling motor. Depends on how long you are running the main, how many amps it puts out and how much you are discharging the troll batteries. If you are running the main for a hour each way it will have some value, if only 15 minutes, not so much. Pontoons usually have a roof, if so why no solar panels? For battery isolation, Blue Seas makes a ACR specifically for that, and often can buy with a large amp capacity switch.

Do you think your AGMs aren't flooded?

This is the system I use.


https://www.bluesea.com/products/7610/SI-ACR_Automatic_Charging_Relay_-_12_24V_DC_120A

The question of how fast you will charge your battery bank is just math. You can get fancy and install a shunt with a meter to know what your battery has lost and gained.

I run a agm ×power on my boat and a sreaperate 100ah lithium for the trollin motor......trolling motor, I don't have tied into the charging system I use a solar panel system that I lay out ( 20hrs day light helps lol) never ran the lithium down far enough that I wouldn't be back home to plug iit back in! gif upload

Yep, I'm with you !

& I possibly do a little fishing !!

All I can think of, to help you, is to suggest going to lithium (& probably multiples) for the deep cycle.

Comes at a significant cost increase, too !

Minn Kota has a battery charging system with a separate alternator for trolling motor batteries. Both charge while motor is running.

this is probably what I need. this is for going to lake powell. we normally have about 8 hours of engine run time and 3 days of fishing with, like I am saying 8 hours of run time mixed into that driving around the lake. that should be quite a bit of time to add some extra charge into the trolling battery I would think. we would use the trolling motor to skirt rock outcroppings and hold position. so its not like its constant used while fishing. probably 25% duty cycle with poles in the water.

Lake Powell is exactly where I use my Sportsman 1000. Pull up next to the houseboat in the evening, fuel and start the Sportsman, then head for happy hour. In the morning, the sportsman has run out of fuel, the trolling motor is fully charged, and I'm off for another full day of hauling in smallies, walleye, and stripers. No stress, no troubles, and all for half a gallon a night.

No idea how it worked, but in the 90s the trucking company I drove
for set us up a 3 and 1 battery system. The trucks had 3 starter batteries
and 1 deep cycle. When the engine ran, it charged all 4.
When it was shut down, the electrical system ran off the deep cycle.
That allowed lights, refrigerator, bunk warmer...to be on, but you
wouldn't have to worry about cranking the engine in the AM.


Providing you will run the engine enough, your situation sounds
exactly like what I'm describing.

that would cause a problem for me. the most awesome thing about lake powell is when evening sets in all the boats flee off the water. you get silence and peace and quiet like few people ever get to even experience. you have for a window of time an experience as if everyone on earth is dead but you are the only living life left. its these moments I crave. a generator despite how quiet would royally F this up.

They make a device for RVer's that will automatically disconnect the main battery when it reaches a certain level so that the RV may still be started. I don't remember the name of the device, sorry.

I literally cannot hear this thing running if I park 100 ft down the beach, even at Powell. But you make your own choices, sir.

That will work if you have a 12V trolling motor with one battery. If you have a 24V trolling motor with two batteries connected in parallel you need something like this:

https://yandina.com/troll12X24info.htm

Or this:

Minn Kota Alternator Charger

Jerry

Guys use these (or similar) here for off road lights and accessories on trucks. Charges both batteries and but one battery remains dedicated to the starter.


https://www.waytekwire.com/item/800...KaCUXFns0hXfHrIMIDJoI-PsGiEaAp_LEALw_wcB

Might take a look here.
https://minnkotamotors.johnsonoutdoors.com/battery-chargers/board-alternator

Greg