Hi; Has anybody any knowledge of the calcium batteries that are now available for vehicles. How does their construction stand up to 4X4 and marine use ? What are the advantages against the old lead acid types. Thanks for any enlightenment. Frank
in article email@example.com, Gene S. Snider at firstname.lastname@example.org wrote on 11/28/03 1:38 PM:
My impression is that he was talking about calcium as if it were an electrode rather than an alloying element. If lithium can be used as a battery anode, why not calcium?
To go on with a follow-up question: Does the presence if calcium in lead reduce the time a (calcium) lead-acid battery can hold its charge? Thinking by analogy, if copper or another metal present in zinc can produce local currents that corrode the zinc, why would that not happen with calcium in a lead anode?
1) Calcium IS a metal (a so-called "light" metal).
2) in your "standard" lead/acid battery at least one of the two "active" electrodes is a compound containing lead. But for a low tech lead/acid cell, you can start with two sheets of pure lead in H2SO4 and start charging.
Early lead-acid battery designs experimented with a variety of allows to strengthen the plates. The positive plate, made from PbO is very brittle material and prone to shattering under the slightest vibration. Early designs commonly used a lead-antimony alloy 'grid' into which the lead oxide paste is formed.. These types of batteries 'used' a lot of water and had removable vent-caps to allow adding more water as needed. A newer design (now 'standard' in automobiles) is the lead-calcium grid.
Lead-calcium have much lower standby losses and can retain their charge for a longer time than lead-antimony. They also use less water. With a larger volume built into the battery above the plates, these batteries can go for years without needing water. The so-called 'maintenance-free' battery with non-removable vent-caps is a lead-calcium design.
But they have a drawback. If they are deep-cycled (deeply discharged) several times, there life is very short. A lead-calcium can be fully discharged only 80 to 200 times before the battery is pretty much crap. The lead-antimony designs, although they use more water, and self-discharge faster, can handle 1500 to 2000 such cycles.
For automotive, engine starting is just a short discharge of less than 20% of total capacity, so the maintenance-free lead-calcium is the clear winner. But for golf-carts, fork-lifts, PV installations, or anywhere you need deep-cycling, lead-antimony have advantages (but require more maintenance).
P.S. They do make a pure lead grid design, with very good standby characturistics, but it doesn't last long in vibration-prone environments.
Wasn't there also batteries for Autos that used molten calcium which had very high energy per unit weight purposed. The problem was that before the battery could be used, the calcium had to be heated to the molten state as I remember it. . . I DO NOT FOLLOW MANY OF THESE NEWS GROUPS To answere me address mail to email@example.com