[OZAPRS] SOT : Lead Acid battery reconditioning

[Terry Collins]

Chris Hill wrote:
> Hi Damien,
> 
> The UPS can maintain full load (1300W) for just over an hour (when the
> batteries are healthy, that is).
> 
> They were designed to keep a GSM cellular basestation going for 8 hours
with
> no mains power.

Err, these two statements contradict.
If a system is designed to run for 8 hours, its one hour capacity is 
probably something like 4x at best. No linear relationship in discharge 
rates.

More than likely/let us assume, it was designed for 1300W (108Amps) for 
1 hour, which explains the glass matt batteries. (Are the internals 
three parallel strings each of two batteries in series?. )

So, the GSM base station would have drawn less than 100/8 and probably 
gone longer.

Basically 6 x 50AH = 300AH, which is 3600Watts.

With  deep discharge lead acid, that gives 1800W usable (50% rec).
Max discharge rate of 50AH DDLA is about 5 Amps (max life rec)
So from 6 DDLA, you could get 30Amp or 360W, but no one recommends 
putting that many in parrallel.

Reading the brochure, it says unlimited discharge rate (guess that is 
why you pay for glass matt) asnd talks about C/4 recharge trate at 100%.

So 1300W is within the capacity of three parallel strings of two 
batteries in series and they would be just about totally flat after an
hour.


Frankly, most UPs are not designed for anything more than a few minutes 
to provide ordered shutdown so that files are not corrupted.

If you need to run for hours, then you really need an autostart 
generator that kicks in and takes over the load. Now, that is a real way 
of frying batteries {:-)



-- 
Terry Collins {:-)}}}}}
Email: terryc200605 at woa.com.au Web: http://www.woa.com.au/terryc
Bicycles, GIS, Technology, Natural Environment.
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