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Re: UPS made by MGE?

On Thu, 31 Jan 2002 16:34:00 -0500 (EST), Mike Dresser wrote:

>On Wed, 30 Jan 2002, Gary Turner wrote:
>> Does any UPS mfg offer ampere-hour ratings? 
>Well, at least with the APC's, you can find out, by looking at what the
>replacement batteries are.  I believe they say there the AH ratings.  The

I looked at some APC's--in the box--and there was no info on the
exterior, whether about batteries or watt-hour ratings.

>280-500 backups and backups pro use 7.2ah 12v cells, the 650's are a 12ah,

If they are 12V (nom) gel cells then the inverter rating *is* the key,
since you can use a larger battery (bank) for longer service times.  The
limit will depend on not overtaxing the inverter.  So, if the system
draws 2A cont. @ 120V, you need about 325-500 VA rating, for a 50-100%
safety factor.  And, if you want it to keep you up for an hour, you'll
need a 30-40 Ah battery, allowing for inverter overhead and safety.

>APC does have some kind of table you can put your load in, and it will
>tell you roughly how long to expect it to last. How accurate that is, I
>don't know.

Probably as accurate as the values you plug in.
>As well, the TYPE of load can make a difference a well, even if it's the
>same "wattage".  A monitor will drag a ups down differently from a
>computer, for example.  Power factor is what it seems to be called.

The monitor will have some clear power consumption values in the specs.
Just divide the wattage by the voltage (120Vac nom.) to get amperage.
The box is problematic.  Best to put a meter to it or just go by the
power supply rating (max value).  If the fans and discs are on
continuously, the load will be essentially constant.

By comparison, a radio might draw 200W transmitting, and 10W
standby/receive.  The transmit to receive ratio is about 50-50.  The
power factor transmitting data or tty is 100%, CW (morse code) is 50%
and voice is 25-30%.
>As for your 60ah gel cells?  Sure, some ups's could take it.  I don't know
>which ones off hand though :)

Any should.  The only problem could be a fully discharged battery and no
current limiting on the charger circuitry.

And thanks, Mike.  Just knowing that standard V batteries are used will
make for educated decision making.

Yes I fear I am living beyond my mental means--Nash

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