2002 Mercury 115 ELPTO 2 Stroke electrical output

[Texasmark]

I would guess that your motor has pull start capability. If so, no harm no foul if the start battery goes dead.

Having said that, I see no problem in having two batteries. One for start and one for the house. With a VSR/ACR/Combiner/Isolator/Etc. between the two.

The alternator on your model does not produce enough current to harm anything.

When I bought my first new boat it only had one battery. I wanted and added a trolling motor. One day while fishing I drained the battery to the point where it wouldn't roll the 85 HP Chrysler triple. In the underside of the canopy/hood whatever, was a plastic pouch with a cranking rope.

I got it out, got the engine ready to run like when using electric starting, installed the rope and gave her one big yank.....engine fired right up. After that trip I had 2 batteries. Never saw that again in any of the engines I had after that.