UPS function

[Procrastinator71]

Hi,
I'm using a 700W UPS (localy made) with a 120 Ampere battery to run
three ceiling fans (150W each), a tube (40W), and my laptop (70W?) and two
energy savers (18W each) to cover load shedding time which is mostly for one
hour several times a day. The problem is if all tree fans are running for
some time, they begin to slow down considerably. Is the battery responsible
for this or the UPS.
If I add another battery in parallel will this solve the problem. I intend
to add another fan to this. Also is there a way to test what is the actual
strength of the UPS? It is common here to sell UPS that are lower in power
than what is printed on them.

Thanks

 

[James Sweet]

Some car batteries are connected in parallel. Especially larger trucks with
diesel engines.

Mike

Those normally use a battery isolator which is really just a couple of
large diodes. Most RVs and larger boats have a setup like that too.

 

[ian field]

The 700 W rating is the maximum load that can be used from the UPS
without any damage to it, or it with it being over-loaded. Normaly, the
maximum load should not exceed about 60% of the maximum capacity of a
UPS.

In the instruction manual for the UPS, they usually give a chart of how
long it will supply power with different loads. The effect of the load
may not be exactly linear because the load is being run from an
inverter. This inverter itself uses a certain amount of base current to
operate. It's efficiency may not be very linear.

In theory, a 120 Amp Hour battery should be able to put out 120 Amps for
one hour. Normaly, when a battery is under load, when the voltage of
the battery has decreased to about 10% below the nominal rating of the
battery voltage, the battery is considered weak.

Most battery manufacturers specify Ah capacity for the 10 hour discharge
rate - a 120Ah battery loaded at 120A will be discharged in somewhat less
than 1 hour.

 

[JosephKK]

Most battery manufacturers specify Ah capacity for the 10 hour discharge
rate - a 120Ah battery loaded at 120A will be discharged in somewhat less
than 1 hour.

If they are working to US SAE specifications it is 20 hour discharge.

 

[JosephKK]

Some car batteries are connected in parallel. Especially larger trucks with
diesel engines.

Mike

Actually the batteries are in series to run the starter motor, and
isolated otherwise.

 

[Eeyore]

Hi,
I'm using a 700W UPS (localy made)

Just out of interest, of what value is the information "(localy made)" <sic>
when you don't mention what part of the world you live in ?

Or is it the 'world' called the USA ?

Graham

 

[PeterD]

Just out of interest, of what value is the information "(localy made)" <sic>
when you don't mention what part of the world you live in ?

Or is it the 'world' called the USA ?

Graham

I'd say he made it himself...