Water Miser caps & Hydrocaps [RE-wrenches]

[Windy Dankoff, Dankoff Solar]

<x-flowed>>I am curious to know if anyone has seen the Water
>Miser caps work.  I sold a batch to one customer to
>put on half of his batteries. (One of 2 series
>strings.)  He claimed that both sets used the same
>amount of water.  All I have is his word, and no other
>useful information to verify his conclusion.  After
>this experience I ended up handing out the rest of my
>stock to customers for test purposes.  I guess its
>time to check with them to see how the caps worked
>out.



We had similar experience.

There are 3 sources of water loss from batteries -- electrolysis 
(gassing) of water in to H and O2, evaporation, and spatter/splash. 
Water Miser caps are supposed to help to condense water that tends to 
evaporate and to block spatter/splash, but they are not a true 
catalytic cap like the Hydrocap, and thus do not recombine H and O2. 
Maybe they help in fork lifts where fluid sloshes around all the time 
and temperatures can get high, but in our systems, the primary source 
of loss is the electrolysis.

My 2 cents on Hydrocaps ------

Hydrocaps, unfortunately, work in a narrower range of charge current 
(gassing rate) than we see in our more complex systems. If they are 
formulated to handle high gassing during equalizing charge, then they 
are ineffective at handling low gassing rates that occur more 
normally. If they are formulated to handle the low gassing rates, 
then they can overheat, soften, and flop over sideways during 
equalizing or any other overcharge or high-gassing situation. The 
only way to size them safely, is with too little capacity as a 
less-than ideal solution. To their credit, the mfg. has always been 
straight and strict about this, and that's why they are made to order 
based on data you provide.

Hydrocaps have a place in some systems. They can be loosened during 
intentional EQ/overcharge to bypass the gas, but that's too easy to 
forget. A quick hand-feel of their relative temperatures is a great 
way to check for inequalities of charge or for cells going bad. They 
need to be baked in a home oven every 5 years or so to restore their 
capacity. They're expensive, to the point where they are mostly 
obsolesced now by sealed batteries.

Windy

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