Tom Walker wrote in a message to Roy J. Tellason:

-> ->  TW> Adn incideltly a Gell Cell is a Poor Battery to pick fro a
-> ->  TW> possable
-> ->  TW> deep discharge operation. A Wet Cell is far better suited.

-> -> On what do you base this?

-> TW> Manfacturers Specifications. I have delt with Gel Cell batteries in
-> TW> Critical Medical Equipment. They specificly spec NOT deep 
-> TW> discharging them on a regualr basis.

-> Oh.  Perhaps what you were reading there is a warning against the sort of
-> treatment that some people have figured as being "necessary" with 
-> nicads,  to prevent the "memory effect".  I've seen people do that,  
-> and gel or wet,  deep cycle or not,  it's a good way to ruin a 
-> lead-acid battery.  The way to treat those is to keep them nearest 
-> full charge for as much of the time as possible.

 TW>  Unless they are designed for it YES. 

Designed for it or not,  you don't wanna leave one in a discharged
condition. That's how they get ruined...

 TW> And the problem is the Quest for Maintenance Batteries. In the old 
 TW> days they used Antimony to keep the lead places form flaking when 
 TW> the battery was in the discharged or nearly discharged state. It 
 TW> had the side effect of High Hydrogen production if overcharges and 
 TW> the resulting high water usage. In the quest for the Ultimate 
 TW> sealed Maintenance they shifted to using Lead Cadinum plates. That 
 TW> almost cut the gassing and water usage to zero. BUT the Side 
 TW> effect was that IF the batteries were Deep discharged it was very 
 TW> damaging.

What's your source of info on this?  I had thought they were using
lead-calcium in some of them,  too.

 TW> The Sealed Gell cells are even more susceptable to that damage, 
 TW> Active Material flaking off the plates, then the Wet Cell types. 
 TW> Unless the batteries are specialy built and Rated for Deep 
 TW> Discharge. I get a laugh when unjknowing RV owners don't want ot 
 TW> pay the Price for hte Proper Battery. They get several of those 
 TW> "Crap" batteries form the Coener Auto Parts Store and then Cry 
 TW> when they give out in short order. :-)

Yep.  There's always folks looking to do it cheap,  and they find out that
these things are the way they are for a reason!

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