Moving cranking battery to unvented bow storage?

[openseat]

I need to replace my dead cranking battery. So far I've had it in the open splashwell behind the rear bench of my 1752 flat bottom OB jet. I plan to move the cranking battery forward to level out the hull better. The only storage in the bow is a single large dry box. The carpeted lid doesn't fit absolutely air tight, but good enough to maybe trap a pocket of hydrogen when a wet cell battery is charged.

This hasn't been a problem for the two 12v wet cells I keep in that compartment for the trolling motor, because I leave the lid open when charging those batteries. The cranking battery however will get charged by the alternator on the motor when I'm running. Leaving the lid open when running isn't practical. I would rather not install a vent, because it would have to be in the lid surface, as hydrogen is lighter than air.

So, for the cranking battery replacement, I'm thinking to go with a sealed AGM battery that doesn't emit gases when charged. I know its more money and more weight than a wet cell, but that seems to be the lesser of the two evils. I can wait awhile on moving the cranking battery to the bow compartment, but I need to buy something in the next week with MN fishing opener around the corner.

Any thoughts on this? Thanx

 

[DearJon]

I run Optima Blue tops on my 1548 flat jon. I have deep cycles up front for the trolling motor, and a starting battery in the back. They do cost more, but IMO they last longer. They are sealed, vibration resistant, and can be mounted in any direction, even upside down. If you decide to pull the trigger on an Optima, you'll want a 34M for cranking. This quote came straight off their website:

"These batteries are designed for engine starting applications. They are not recommended or warranted for use in deep cycle applications." 34M

 

[openseat]

Oops. Turns out I based my original post above on out-of-date info. Apparently, if you get a decent "no maintenance" style of wet cell battery, they are sealed well enough these days to substantially eliminate the release of hydrogen when charging.

That should solve it for me

 

[lowe1648]

Openseat where are you at in mn?

 

[openseat]

I'm in the north metro area. Mostly run below the Coon Rapids dam, but venture out to other spots once in a while.

 

[lowe1648]

I was out on that stretch tonight for a few hrs. I'm up in coon rapids.