And yet, another battery question.

therrick · Guest

Ah, my first post to the C-Brats site, and it’s yet another battery question.

I just acquired a 1984 22’ C-Dory. The battery boxes were brittle and I’ve bought new ones. The old boxes were mounted on rotted wooden bevels in the well-drained space in front of the transom.

The battery boxes were not mounted on the level, but leaned aft at about 7-degrees. Holes were drilled in the boxes to allow drainage.

Here are the questions I’ve come up with so far:
1. Why should a covered battery box need to drain? If the battery’s loosing acid, shouldn’t this be kept in the confines of the box?
2. Shouldn’t the batteries be mounted as close to level as possible to ensure that the plates are evenly covered by the acid?
3. If the battery boxes are supposed to be mounted off plane, what is the optimum angle recommended?
4. I was planning on building the battery box mounts out of some mahogany scraps I’ve got left from other projects. Some marine Waterlox over mahogany seems to me like a fairly bullet-proof approach. What do you folks think?

Thanks,

Tom Herrick

CAVU · Posted: Sun Mar 12, 2006 1:48 am Post subject:

Tom,
The first two questions are yes. Normally most C-Dories floors slope a little forward. The previous owner may have been trying to compensate for that, but I don't think it would be anywhere near 7 degrees. I would level the batteries up based on your normal loading. Also consider elevating them a little higher if possible to lessen the chance that water would get over the top of the boxes. Mahogany, or any wood well sealed would work. Plastic lumber (Starboard) would also be a good choice.

Dora~Jean · Posted: Sun Mar 12, 2006 1:50 am Post subject:

Tom wrote:

Sea Wolf · Posted: Sun Mar 12, 2006 4:08 am Post subject:

Tom-

The only things I can offer that are different than Ken and Steve have said are these-

1. Do batteries in boxes "sweat" by going through a daily heat cycle much like gas tanks? If so,here's how it might work:

Heating during the day expands the air inside the box.

Cooling at night causes the air in the box to contract, bringing in new air.

Further cooling causes water to condense on the walls of the battery box., which then runs down to the bottom, under the battery.

Heating the next day begins the cycle anew, but the liquid water at the bottom under the battery is not heated enough to evaporate it.

This daily condensation and pooling cycle results in the need for a drain in the bottom of the box.

This just a theory, of course. The heating and cooling cycle could also be caused by heating and cooling of the battery during the discharge and charging cycle.

Another thought: Your "Classic" '84 C-Dory has a flat bottom of encapsulated plywood, not the rounded and forward sloping floor found in the '87 and later models. Does this make any difference in figuring out what was being done with the sloped boxes?

Keep on investigating!

Joe.

therrick · Guest

Thanks for the considerations. Common sense told me that the batteries should be mounted level, but the previous owner who did or authorized the mounting was supposedly a very experienced boat owner so I questioned my knowledge base.

They're sitting flat now.

Thanks again,

Tom