how to add shore power to onboard battery charger for trolling batteries

CheezyPete

Cadet
Joined
Jan 28, 2019
Messages
8
I've got a Minn Kota Terrova that is powered by 2 12V batteries on a 2001 open Crestliner 1600.

After each trip I remove the batteries from the boat, put them on charge in my garage and then on the next trip I lug them back to the boat .

The boat currently has no shore power hook up.

I want to install a battery charger that can hook up to 1) domestic mains power when trailered on my driveway, 2) marina shore power when afloat in the marina. The marina power sockets looks something like a trailer hitch socket.

I'm totally new to this so a bit stumped how to set this up and what components I need to buy. I can see waterproof marine battery chargers online, but how do I hook that charger up to power it ?

thank you
 

TBarCYa

Senior Chief Petty Officer
Joined
Apr 13, 2005
Messages
781
I just rewired my whole boat, both AC and DC so I know a little about it.

You have two choices. You can wire the boat for shore power and use an adapter for the household connection OR you can get an adapter to convert the 30a shore power connection at the marina to a household plug. The latter is easier but if you want to wire the boat for shore power you will need the 30a shore power connector to install on the boat, a circuit breaker, 3 conductor marine cable and a bunch of marine grade ring terminals.You'll run the 3 conductor cable from the shore power connector to the breaker box and then from the breaker to the charger. It's a bit overkill if all you're running is the charger but when you're at home you can use a pigtail like this to connect to household current. https://www.iboats.com/shop/marinco-...-adapters.html

The easier way would be to get a charger with a 100v 3-prong plug like would plug into your house outlet and get the exact opposite of the pigtail I linked above. It will convert the 30a connection at the marina to the 15a connection you need to power the charger.

I think this would be the pigtail for option2: https://www.iboats.com/shop/marinco-15a-straight-blade-to-30a-locking-125v-p30-15.html
 

harringtondav

Commander
Joined
May 26, 2018
Messages
2,438
My neighbor has a 36V trolling motor. (three 12V deep cycle batteries) He keeps the charger in his boat, and runs an extension cable a looong way down to his dock. You could install your charger in your boat, and use any of TBarCYa 's methods to get the line voltage to your charger, at the dock, or at home.
 

harringtondav

Commander
Joined
May 26, 2018
Messages
2,438
PS: I asked my neighbor if there was a way to purchase or rig up a switch gear that would allow him to use his O/B motor's charging circuit to directly charge his trolling batteries while he is underway, then throw a switch to disconnect them and put his starting battery battery back in the circuit.

He shrugged it off. He is a tournament Walleye fisher, and that big Merc 200 hp runs fast and for short time periods. Probably wouldn't get much charging time from it.
 

TBarCYa

Senior Chief Petty Officer
Joined
Apr 13, 2005
Messages
781
PS: I asked my neighbor if there was a way to purchase or rig up a switch gear that would allow him to use his O/B motor's charging circuit to directly charge his trolling batteries while he is underway, then throw a switch to disconnect them and put his starting battery battery back in the circuit.

I've had a couple people here recommend an ACR which is an Automatic Charge Relay. In the case of running 24 or 36v battery banks for trolling motors, I don't know how that would work.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
There is no mystery here. Install a one, two three or four bank on-board charger depending on the number of batteries you have. The charger has a three prong plug on it just like any appliance in your home. Since you have power both at home and at the mooring you simply plug in an extension cord to shore power and the charger into the cord. Done! The starting battery and a house (auxiliary) battery could benefit from an ACR or dual battery switch but you cannot use the engine to charge a deeply discharged trolling motor battery. You can -- but you would have to run wide open for several hours to top off that battery. Terribly inefficient.
 

fishrdan

Admiral
Joined
Jan 25, 2008
Messages
6,989
I'd opt for a multi-bank onboard charger, enough banks for the batteries in the boat. 2 trolling motor batteries and the start battery, would mean a 3-bank charger. The charger will have multiple output leads, connect each set of leads to individual batteries, no need to disconnect the trolling motor wires from the batteries, just leave everything wired up. BUT, you have to make sure your multi-bank charger has independent outputs, so the series connected TM batteries don't short out through the charger. Pull up the boat to your garage, drag an extension cord to the boat, plug it into the charger, and done. Been doing this for years, works GREAT! Not sure how that works at a marina, no experience there, probably just need an adapter cord...

If you have days between trips a 5 amp/bank charger will suffice, but if you're looking to charge overnight and go fishing the next day, I would opt for a 10amp/bank charger.

You don't "have to" have your start battery on the onboard charger, but it will make the start battery last longer, by keeping it completely charged up, along with the trolling motor batteries.

I wouldn't worry about trying to recharge the TM batteries on the water with an outboard, not enough charging capacity from the outboard. I do this, but have an I/O engine with a 105amp alternator...
 
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