Surrette, says that they work fine and solve all problems, even during
equalization. Certainly if they don't work during equalization, they're
worth less (not "worthless", just "worth less").

I guess I trust Surrette -- the family has been making boat batteries for a
long time -- but I'll still have a vent above the battery box. I saw a
Hinckley 70 in Bermuda in 1996 that was going back to Maine to be repaired
after a battery explosion. They were gel cells, mounted under a bunk, with
no vent. Wasn't a pretty sight. Lucky there was no one in the stateroom at
the time. Even gel cells need venting.


--
Jim Woodward
www.mvFintry.com


...
"Glenn Ashmore" wrote in message
news:ejgrb.12352$62.2320@lakeread04...


Maynard G. Krebbs wrote:
On 30 Sep 2003 22:21:31 GMT, (BOEING377) wrote:


Do those so called catalytic battery caps actually work? The are
supposed to
use a catalyst recombine outgassing molecules back into H2O which drips
back
into the battery cell. I am sceptical.


I think it's in Calder's boat maitainence book where he says they work
but you should remove them before equilizing your wet-cell batteries
because of the pressure buildup.

The Hydrocaps are basically a large baffeled cap with a small piece of a
catylist in it. The catylist makes the hydrogen recombine with oxygen.
The reaction produces water which drips back into the battery and some
heat. The hydrogen in the water takes up a lot less space than the
hydrogen gas so the pressure inside the battery is slightly lower than
the air outside. This pulls more air in through the baffels so that
there is more oxygen to be combined with the outgassing hydrogen.

Like I said, the reaction produces heat. During normal charging the
heat is radiated off the fins on the caps but during equalizing the
battery produces a LOT more hydrogen. When all that extra hydrogen
starts recombining the caps can get hot enough to melt.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com