In article , Martin Evans wrote:


In the application they are designed for the batteries ought to
last for a good 10-15 years. Abused as they are by incompetent design
I am surprised they even manage to give service beyond a few weeks.


Are you sure? The following is from a Yuasa tech document for their
SLA batts.

NP batteries are designed to operate in standby (float)
service for approximately 5 years, based upon a
normal service condition in which float charge voltage
is maintained between 2.25 and 2.30 volts per cell in
an ambient temperature of approximately 20C (68F).


Thats 5 years at an ideal 20C. How many UPS are operated at that? In my
experience, none. All UPS get hotter than that, I just checked three here
and found that one was 25C, another 28C and a third 34C, and that's their
internal temperature without the invertor running.

Surely that must reduce the battery life, though the document doesn't say by
how much.


--
simon at sbarr dot demon dot co dot uk
Simon Barr.
'97 110 300Tdi.