1 12volt trolling motor and 2 batteries

[rndn]

I have 1-12 volt trolling motor 55# Minn kota. I plan on using it a lot more than past and want to have 2 deep cycle batteries for it instead of just 1. I understand I need to connect the batteries in parallel, so + to + and -to-, right?
My question is I want to get an onboard charger and am assuming because of the way the batteries are attached, I can attach the charger to just one battery and it will charge both, right?
Please let me know if I'm on the right track or if this will create issues with the automatic chargers.
Thank you in advance for your help.

 

[Randy169]

Re: 1 12volt trolling motor and 2 batteries

Hey rndn:

Yep. You're correct about the parallel connections for the batteries. (I would add a switch - for protection, charging, and in the event one dies)

The charging is a little different.

The automatic charger will 'see' the two batteries as one and may not charge them to full capacity. You may have to charge each one individually to get them to full charge - hence the switch.

 

[rndn]

Re: 1 12volt trolling motor and 2 batteries

So with a switch you run one battery down, throw the switch and then run the other down? For a charger then I suppose get a 2 bank charger?

 

[Randy169]

Re: 1 12volt trolling motor and 2 batteries

Thinking more on this, as usual, there is more than one way to skin a cat.

Since it is a trolling motor and not your main one, one large battery would be a better way to go. Unless you had a specific reason to use two.

The switch idea works. Each battery would work independently from each other, you would need to charge each one. A regular charger would work - you would need to switch between the two once the first one was charged.

You should put in an isolator that would allow you to run in parallel, and isolate any problems between the batteries. The voltage drop should be negligible.

How muddy is the water now?

PS I run two batteries for my entire boat. One for the engine and the other for everything else. I have an isolator as well as a switch. If the engine battery dies, I can then switch over to the other battery and get home. The isolator allows me to charge both batteries at the same time. To about 90-95%. Works for me.

 

[bullgator99]

Re: 1 12volt trolling motor and 2 batteries

I've got a dual bank automatic charger on my boat. My group 24 cranking battery is on the first bank, and I have two identical group 27's in parallel on bank 2 for the trolling motor. All the grounds are connected together.

I've run this setup for 4 years now with no problems.

 

[Silvertip]

Re: 1 12volt trolling motor and 2 batteries

You will be fine running a large single bank charger on two paralleled batteries. The switch idea works ONLY if you do not simply break the connection between the two. If you run one battery down with the switch open, when you close the switch you now parallel the battery again and you just added a dead battery in parallel with a good one. To make that work effectively you need a dual battery switch so you can run from BAT 1, BAT 2 or BOTH.