440 Battery Box & Batteries

[wsp2]

I was looking at installing either a new inverter (original one was only like 600W and is 30 yrs old, doesn't appear to even work) or a combination charger/inverter. After looking at info on batteries in general I think I have some other issues and would appreciate any recommendations or feedback. This is on a 1995 440 aft cabin.

For starters, my boat only appears to have two starting batteries in the battery box. These provide power for starting the engines and supply house power. The web site gives no Amp-hour rating for the batters. Will this be a problem running an inverter off the starting batteries other than the fact I could run a risk of draining the starting battery? There are two other batteries - one for starting the generator and one for the bow thruster.

Should I split the batteries and have one dedicated to starting and get a deep cycle for house power? Or add batteries, although I have no idea where I'd put them?

There's a battery selector switch which was set a "Both" when I bought the boat so I've never changed it. Been reading up on how that should work.

Next, my batteries always have some water on the top. I know a few things can cause this, but my battery box is not ventilated at all. I'm also in a high humidity area (Houston, TX). I'm thinking about cutting a hole in the lid and installing some sort of screen, although I sit on the lid when working back there. About how much vent area is needed for that?

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Thanks!

[bud37]

I have rethought and edited the previous post I made, this is the result.... That is a nice box, lets go one step at a time before any work.

Is your boat a diesel ?

Is the water just condensation or the products of charging off gassing ? Have you checked the fluid levels in the batteries.

Considering you mentioned cutting a hole.......Please be aware of the danger of working in an engine compartment with the possibility of combustible/explosive gases......ventilate, ventilate , ventilate, run the blowers continuously and check your explosimeter if you have one. This is especially true when dealing with a gasoline fuelled boat.

[wsp2]

Source of the post I ...

Is your boat a diesel ?

Is the water just condensation or the products of charging off gassing ? Have you checked the fluid levels in the batteries.

It is diesel.

Trying to determine if if it condensation or the product of off-gassing, or if the battery is boiling. I had cleaned off the tops of the batteries and left the cover off the battery box and there's water on the top of the battery the next day. The water appears to be worse over one battery too.
I last filled the batteries about 2 weeks ago. I use a battery jug which stops filling at a certain level. Looking inside some of the cells it appears like it lost some water but not very much considering how much water is on the battery.
Mechanic is coming by to test the batteries so maybe that'll tell us something. I'll need to read up on how to test the inverter to make sure that's not the problem. The charging profile is set to the correct battery type.

If I drill any holes I'll probably just take the lid completely out of the boat and do it. But Diesel should be safer anyway.

[waybomb]

When my charger was baking my batteries, i could smell the gas. When you pulled the cover off, did you notice the smell?

[bud37]

Ok, Diesel.....If you can put some holes or slots at the end side just below where the lid fits....that will allow air movement across the top of the batteries and if you put a nice 1 1/2 " vent at the back corner of the lid , to that.

The off gassing is hydrogen for the most part and is light so will dissipate up the vent naturally. That vent could be hosed and direct the gas to the bilge vents to outside if that is desired. Hydrogen is explosive in the right concentration so ventilate/blowers on etc and be careful while you are getting to the bottom of the issue.

Good luck with it