Battery, is one ok?

[Drew in B'ham]

I just purchased a new pontoon. While shopping I learned about the multi battery switch and dual batteries. Unfortunately the boat I purchased only has one battery, although is does have an on off switch. I foresee me spending a lot of time on my boat anchored and floating with the stereo going and maybe even the anchor light and interior lights on.
I am thinking of adding a second battery and connecting it in parallel (pos to pos and neg to neg) just to give me lasting power.
Thoughts?
Is there any reason not to do this? Is there any risk of damaging the charging system or anything?

 

[roscoe]

Do not connect the batteries.
Keep one for starting and running lights.
The second for optional accessories.

Connecting them could give you 2 dead batteries with no way of starting the engine and getting home.

 

[Chris1956]

Find a convenient place to mount a battery switch with positions off, 1, 2 and both. Set the switch to both and motor to your anchorage. This charges both batteries.

Now set the switch to 1 and party as much as you want. if the motor won't start, set the switch to 2, start her up and set to both for the trip home.

 

[MercGuy]

Does your engine have the provision to rope start it ? My 1998 2 stroke 115 came with a section of rope and a wooden handle for emergency starts. It's much like an old lawnmower. I've used it before and it's a life saver. Starting a 2 stroke 115 with a rope pull is not difficult.

If you don't have that option and you dont want the expense and weight of an extra battery you might consider a low voltage alarm. In fact, my marine grade am/FM/ Bluetooth radio has a low voltage alarm. I installed it only in the last 2 years, so it's never gone off yet, but it does add a little peace of mind.

 

[Chris1956]

Mercguy, have you ever tried to start a 115HP Merc Il6 with the pathetic rope they give you? I had no chance 30 years ago, when I was strong.

Maybe your newer 115 is easier, as it is likely an IL4. Hopefully the IOP doesn't have a V6.....

 

[MercGuy]

Mercguy, have you ever tried to start a 115HP Merc Il6 with the pathetic rope they give you? I had no chance 30 years ago, when I was strong.

Maybe your newer 115 is easier, as it is likely an IL4. Hopefully the IOP doesn't have a V6.....

Chris,

No, I've never rope started an I6, I've only rope started a late 1950's 35hp Evinrude Lark and my current 1998 I4 115.

I've rope started my I4 115 about 4 times over the last 20 years of ownership. Once when I first bought it just to see how difficult it was to do, and 3 times when I had dead batteries. Each time was simple and effective.

The most difficult time was when I arrived at the boat ramp and found that my battery was dead because I left the accessories switch on. The engine was tilted up for towing, which posed a few problems.

First off, I had to back the boat way deep in the water to get the lower unit underwater. I actually had to leave the back straps on so that the boat didn't float off the trailer while I was trying to start it.

The next problem was that with the engine tiled up I could not pull straight on the rope because the flywheel was at an angle and close to the transom. I had to step out on the little swim platform and pull sideways. I didn't have much leverage that way, but I was able to get it started.

I let it run long enough to charge the battery enough to tilt it down, then shut it off, pulled out of the water and took off the trailer tie downs, backed it back in the water, rope started it again, and backed it off the trailer.

I really wanted to go boating that day...

 

[Drew in B'ham]

Thanks all, all good advice. I wasn't really wanting to swap out the on off switch for a 1,2,both or off switch, but that would be best. My thought of wiring them together was it would have twice as much juice to use before the reserve to crank was gone. I think for now I will just keep my "jump" device charged and take it with me when I go boating.