# Charging starting battery?



## Target (Jan 1, 2017)

I just got a new boat with two batteries- one up front for the trolling motor and the other for starting the mercury 4 stroke in the back. The starting battery is an automotive battery. Do I need to charge the starting battery as well as the troll motor battery. I am not sure if he alternator in the motor will charge it like a vehicle or what.. just wondering so I can decide if I need a single or dual bank charger.


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## mbweimar (Jan 1, 2017)

I would say get a two bank charger anyway. If you go any extended periods of time without using your boat the 2 bank charger will help keep he battery maintained. I had a dedicated marine starting battery in my Weldbilt and I never had to charge it for the 2.5 years unused the boat. In my case I would never go more than 3-4 weeks without using the boat so I didn't need to charge it.

But to answer your question. Spend a few bucks more and get a 2 bank charger. Keep it plugged in while not using the boat. Both of your batteries will last longer.


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## Al U Minium (Jan 2, 2017)

The charging system on your motor probably better suited for topping off the charge lost when starting the motor and not much else. It can only provide so much current and no more so using it to charge a trolling motor battery not a good idea.


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## mbweimar (Jan 3, 2017)

That's true. My Mercury 9.9 only charged at 3 amps. I think that was WOT, so at idle it wouldn't do much of anything.


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## richg99 (Jan 3, 2017)

Most all of the answers above say the same thing. 

Unless you run your boat lots and lots of miles every time out, and you go out often...sooner or later your charging battery will get run down. A two bank charger, mounted on the boat, can be a Godsend.

However, I installed one recently and found that it was overcharging one of the batteries. Boiled some of the water out of it. I added a lamp timer in the circuit to only allow it to charge an hour a day. So far, that seems to work. I can adjust the time when I need to.

richg99


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## hawkertech (Jan 4, 2017)

This is kind of a tangent but anything that I don't use during the winter such as a boat, RV, tractor. I remove the batteries and bring them in the warm house and charge them now and then to prolong life. Sub freezing weather like in MI winters with no use or charging is not good on batteries. But if you live in the south that may not be necessary.

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## mbweimar (Jan 7, 2017)

Rich, what kind of charger do you have? That's definitely not supposed to happen.


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## richg99 (Jan 7, 2017)

Marinco 10 SMP two bank


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## moloch16 (Jan 10, 2017)

Google "battery tender junior" I use one of these works great for starting battery.

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