Smart-UPS: seemingly abnormal battery power consumption - repair?

[A.Iakovlev]

Hello,

I've diagnosed with my APC Smart-UPS 1000 the following problem, when
it runs on battery:
- with the load of about 20%, the average current consumed from the
battery (2x12V) is about 25A
- with the load of about 40% - about 50A.

Consequently, the batteries (30A*h) cannot hold up to the task, but I
tend to think that this is not the batteries' problem, but a UPS's.

It the above power consumption (corresponding to less than 30%
efficiency of the UPS) abnormal? If so, how could one proceed to
diagnose the problem?

Thank you.

-- Andy

 

[Jerry G.]

Try another set of batteries first. If the nominal voltage output is less
that spec, the current pull will go very high to try to compensate for the
inverter. The battery performance is very critical in these. If you do not
have the proper battery-test loading evaluation equipment to test the
battery, your best test is to try another one.

As for servicing the electronics. APC will service their UPS products, but
they will not sell, give away, or sell replacement parts for outside service
of any kind. The only thing they will provide for outside service are new
batteries, the user instruction manual, or the interface cable.

We are using many of the APC UPS's for our clients. I found them to be very
reliable. When we have any type of problem, the first thing that is changed
is the battery. It fixes the UPS over 95% of the time.

If you order the batteries under their generic equivalent from an
independent battery dealer, you will find the cost to be about 1/2 of that
from APC. When changing the batteries, don't forget to transfer the
adhesive attached thermo protector fuse. You will have to clean its rear
surface, and need several inches of high temperature rated adhesive two-way
tape. You can use some contact cement, but you want to be able to change
this again in a few years.

The expected battery life is about 3 to 5 years maximum. I have however,
seen some batteries to last longer, but this is rare.

--

Jerry G.
=====


Hello,

I've diagnosed with my APC Smart-UPS 1000 the following problem, when
it runs on battery:
- with the load of about 20%, the average current consumed from the
battery (2x12V) is about 25A
- with the load of about 40% - about 50A.

Consequently, the batteries (30A*h) cannot hold up to the task, but I
tend to think that this is not the batteries' problem, but a UPS's.

It the above power consumption (corresponding to less than 30%
efficiency of the UPS) abnormal? If so, how could one proceed to
diagnose the problem?

Thank you.

-- Andy

 

[Andy Iakovlev]

Try another set of batteries first.

I have tried two sets of batteries. The results are pretty much the same.

If the nominal voltage output is less
that spec, the current pull will go very high to try to compensate for the
inverter.

For 22% UPS load, the battery's pack (nominal - 24V, about 27.5V )
voltage shape is the following: decrease by 0.8V, then holes of 1.2V
even lower - with the 50Hz frequency. This seem to correlate well with
my evaluation of the internal battery impedance of 0.04Ohm.

 

[Andy Iakovlev]

Correction:

For 22% UPS load, the battery's pack (nominal - 24V, about 27.5V )
voltage shape is the following: decrease by 0.8V, then holes of 1.2V
even lower - with the 50Hz frequency. This seem to correlate well with
my evaluation of the internal battery impedance of 0.04Ohm.

From the 25 or so volts w/o load, under the load the voltage shape is:
decrease by 0.8V, then holes of 1.2V even lower - with the 50Hz
frequency. I've measured approximately that peak current - it's
110-130A. Which gives the internal battery impedance of less than
0.01Ohm. 25A is the average current.

Thanks.