Lead Calcium Leisure batteries - any info pls ?

[Marauder]

-
I've heard of Lead acid, Flooded, Sealed, AGM, Gel, Lithium, LiFePo . . . . .

But Lead Calcium is a new one to me.

Has anyone any insight to where these fit in the list above ?

or their advantages / features / suitability as Leisure Batteries ?
_

 

[autorouter]

It's a well-known alloy, used instead of the ancient lead-antimony alloy. Sometimes even with a bit of silver too.

Pure lead is fine in a laboratory version of a battery, but is not very strong, thin plates bend very easily. Originally a small amount of antimony was added to make it stiffer. These batteries used to give off hydrogen/oxygen gas as a normal part of their charge and discharge. Such batteries need vents that can be unscrewed to top up the liquid with water.

Then they discovered that the gassing was mostly caused by the antimony, so they switched to lead-calcium alloy. Because much less gas was produced, the batteries could be sealed, with a pressure release valve for safety in exceptional circumstances. So all sealed batteries are lead-calcium, they don't usually bother to advertise this. I'm not sure when this was discovered but it's over 50 years ago. Lead-antimony batteries, that need topping up regularly, are still available, slightly cheaper, and still popular.

 

[Marauder]

-
so if my battery has no screw top-up ports, and says 'zero maintenance', then it must be Lead Calcium ?