kc8qln said:
I have a small 3 year old APC backup I was just using on a cheap TV. The model number is ES-725. The spec for the ES-725 shows 1 Hour 20 Minutes with 50 Watts. But, I am sure the scanner is less than 5 watts.
So I expected 8 or 10 hours of use (as least as much as AA batteries would last), if not a lot more. So I plugged my Uniden 996T scanner into it, and let it "run out" to see how long it would go on the APC battery itself.
It went 2 hours and died!!
Does this mean my APC is basically dead? Or am I not doing something right?
If it should last 1:20 on 50 watts, I would expect a lot more from just a scanner.
You have several things working against you for getting 8-10 hours of use.
First, look at the power supply for the 996. What is the amperage output? (It should be expressed in milliamperes, or abbreviated as "ma". And the voltage? The one for it's closest digital relative, the BCD396T, is rated at 800ma, or .8 amps. At 6 volts nominal operating output, that might be 5 watts output. But wall warts are not 100% efficient. Some of the power comsumed is lost as heat. Your hand will tell you that. So actual power consumed will be more.
The 996, I presume, takes a 12v output adapter. Multiply the power output (in amps) by the nominal voltage, presumably 12v. I'd add at least 25% to that figure for inefficiency. I would imagine it's power requirement is greater than the 396, as it has a more robust processor, greater audio volume, and a larger display (with more backlighting).
Your APC supply is also not 100% efficient. It stores power in one or more battery cells. But to turn that back into usable ac current, it has to use an oscillator to convert the dc power from the battery into ac, so that the voltage can be stepped back up to normal ac line voltage. Again, some of this energy is lost as heat in the process.
Lastly, at three years old, it's likely that one or more of the battery cells may not be holding their full charge anymore. This you could address by purchasing replacements at a battery specialty store or from an APC dealer.
For another thread along this line, with a couple of alternate suggestions. see
this.