one battery or 2

[fishdale]

Question - One of my boats has a 15 HP yamaha electric start and a troling motor. I had a normal battery for the yamaha and depth finder and a deep cycle for the T-Motor. Well the deep cycle battery fried and I need a new one and the other batery may also be on its way out.

Question is since it is small boat can I hook up everything to one batery to save room/weight? Any pros/cons to this and any suggestion on a battery type.

[catchnothing]

I'd go with 2

[harvey lee]

If when you go out you do not troll to much, then one could work.

Preferably I would go with a minimum of two.

I have a 16.5 ft boat and I have 3 in it. I do not like to run out of power for the trolling motor. I also run two GPS/sonar units and the livewell.

[marine_man]

You can and if you do I'd recommend a dual purpose battery instead of a starting battery (trolling motor use will wear battery out quicker) or a deep cycle (motor draw may shorten deep cycle's battery life).... but, be aware of these possibilities:

-You may get interference on the locator from the trolling motor

-If you run the battery down with the trolling motor you'll have to pull start the 15 hp

-You're trying to do two jobs with one battery... which means mediocre performance at both tasks.

marine_man

[jwmiller33]

i'd go with two for sure. when you troll around when your fishing all day, and using the sonar at the same time, chances are there isnt going to be enough juice left to start the motor when you want to go home.. its better to have too much juice then not enough

[fishdale]

Marineman - Thanks you confirmed my thoughts.

Boat is a 14 ft deep that I use to river fish. I think I will go with 2 batteries and maybe mount one towards the front as I need to get more weight up there.

[CAMAN]

i'd go with two for sure. when you troll around when your fishing all day, and using the sonar at the same time, chances are there isnt going to be enough juice left to start the motor when you want to go home.. its better to have too much juice then not enough

Chances are, a small 15hp motor still has a pull cord along with electric start.

If you have the room go with the two batts, but you would be fine with only one, especially if you have a pull cord to start the motor if you draw the battery down too low.

[Larson15]

2 for sure

[Loon]

I have a 50/35 Evinrude with a 55PD Power Drive and 2 sonars with anchor and nav lights along with task lighting and I run all this on one 27 series dual-purpose battery.

I have the voltage displayed on my sonars and monitor the levels. The lowest I've ever had it was 10.4 volts and the motor started right up. Not sure how low would be too low. Maybe 9.5 volts? Hopefully I never find out.

I'm a river fisherman who needs to get through some really shallow water and my boat is a little under-powered already so I need to cut weight wherever I can. This move saved me 50-60 pounds.

Fairness In Conversation Act:

I don't really ask much of my trolling motor. I use it to steer the boat while the current does the bulk of the work. If I go up river from the launch there are no worries. The river will take me back if the motor won't start.

If I go down river and need to get back, then I monitor the battery level closely and don't tempt fate.

I also have a 30 amp rectifier on my motor and I don't know if a 15hp electric start would have anything bigger than a 6 amp if any at all.

I made the switch to one battery and I'm glad I did.

I have never had any noise-induced interference on either sonar.

[jwmiller33]

I don't really ask much of my trolling motor.

some people use their trolling motor a lot more then others... if you start the motor up a couple times and run the sonar for a couple hours, you might not have enough juice left in the battery to use the trolling motor the way you want to use it when you actually wanna use it (especially if you fish rivers).. then, you will use the majority of your remaining juice on your trolling motor, then your graph wont have enough juice to run.. then, when you need to go home, your gonna have to pull start, which isn't a big deal, but if you have electric start, you mind as well take advantage and use it.

like i said, i'd go with 2 batteries for sure. i have two batteries in my boat for the electric start, trolling motor, graph, and lights. it might be a little excessive but i love having the option to switch the batteries around in the boat if the trolling motor battery is losing juice from being out on the water all day. if your out trolling on the river all day, i'd rather be safe then sorry.

it's really a good idea to mount one of the batteries in the front of the boat, which is what i did in my 16 footer, and its really not hard to do at all. it will actually make your boat safer to drive when its just you in the boat. its not good to have you, your gas tank, and your battery in the back of those little 14 footers. it can get scary when your up on plane driving across the lake in any wind or waves

[Ufatz]

Put one battery in the bow.....WELL secured, and you can rest easy. Running around with only ONE is just not a good idea, even though one member finds it works for him.

Why take the chance? It's why a guy came up with the idea of TWO motors on an airplane way back when. Then his pal said "Well heck,if TWO is good THREE should be better."

You know how it goes.

[BobT]

Two is nice but here's my story.

I owned a Lund Rebel 16 for nearly 12 years. I powered it with a 40 Evinrude with electric start. I used a dual-purpose marine battery. I used an Exide size 27, which is rated 575CCA with 160 minutes Reserve Capacity. I powered a 40pd Minkota powerdrive, interior lights, sonar, etc.

I rarely ran out of power but then I didn't use the electric to do much trolling.

The thing was, if I ever did run the battery too far down to start my outboard, my 40 was very easy to pull start so I didn't concern myself.

With a 15hp, I would think you wouldn't have much more trouble and you might be able to get by without the extra weight of a second battery.

Edit: Almost forgot. My outboard did not have a functional charging system for the battery but even if it did, it would have never been adequate anyway using the battery to power everything the way I did.

[marine_man]

Lots of good points here.

The other thing to note regarding outboard motors charging system, is that unless you're running above 1/2 throttle for extended periods of time, you're not going to be capable of recharging your battery with your outboard motor... and even then it might be a stretch.

marine_man

[fishdale]

Thanks for all the info. Might be looking at going the BobT route as I do not use the Tmotor much in fact since the batery was dead last year it never made it on the boat. This boat is used almost always on the river and then it is only a 4 - 5 hour trip.

My other boat has a 3 batery setup and I use that most of the time when I am fishing long days.

I agree 2 is best but want to avoid clutter/weight in this boat.

Thanks for all the info.

[raymondk]

If you have a pull rope for starting as a back up i would go with just one battery just get the biggest one you can get and go with a deep cell not a duel purpose you don't need much to start a 15 hp it would be a differt story if you had a bigger motor you are better off with a battery that will drain slower . Also with a small boat tha extra weight of another battery isn't worth it and the extra cost of another battery .you start to add a little weigh here and there and before you know it your boat will have a problem planing..