I think what the bus company is saying about the batteries makes
perfect sense. You get CCA, the ability to put out a lot of power in a
short period, by having more plate surface area. The only way to get
more surface area in the same box size is to have more plates. More
plates will be thinner and less rugged. Reducing the space between
the plates also makes the changes in shape that is inevitable with
deep charging cycles more likely to cause plates to touch.

Self discharge should be primarily a function of surface area as that
is where the reactions take place. More surface area for more fast
output capacity has got to be a trade off for self discharge rate.
The only way to avoid these trade offs is to increase the size of the
box which is effectively what they are recommending when they suggest
increasing the number of batteries.

--

Roger Long



"chuck" wrote in message
link.net...
Hello Glenn,

I am also skeptical. Couldn't find out what the CT-400 is or who
wrote it or why, but the idea that someone would make a
high-capacity Group 31 battery and then recommend it only for
frequent charging use sounds almost counter-intuitive.

After a very quick check of Exide's battery application guide, it
appears that their only Group 31, 925 cca battery carries a 24-month
warranty! Talk about disposable.

They have other Group 31's with lower cca ratings carrying the same
warranty, and they also have Group 31's with lower cca ratings
carrying six and seven year warranties.

But it is probably a true statement that all of the Exide Group 31's
rated at 925 cca will not last long, for whatever reason.

A similar statement could not be made about ALL of the Exide Group
31's with lower 925 cca ratings.

Make sense? Sounds like it might be coincidence.

Chuck

Glenn Ashmore wrote:
It is not all Group 31 batteries. Just the high capacity 925 CCA
type.

Here is the service bulletin they got from their chassis supplier:
http://www.internationaldelivers.com...pdf/dyk128.pdf