So I picked up a used APC Back-UPS 250 at yard sale for $5, not a bad deal if it worked I thought. I've finnally thought I'd test it... plugged it into an outlet and plugged a 25w lamp into the UPS. It charged overnight, and the next day I unpluged the UPS from the wall and the lamp went out. Is this UPS dead?
Testing a UPS
- Thread starter mleonard
- Start date
thescreensavers
Diamond Member
- Aug 3, 2005
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I found a Replacement Battery that matches everything except the amps. The battery I pulled out is 12v 7.0Ah, while the link is 12v 7.5Ah. Does this matter?
The higher the Amp-Hour figure, the longer the battery will run before it stops because it needs to be recharged.
Make sure it will fit (dimensions) in your UPS.
You can't test a ups by unplugging it. You need the ground. Mine has software that lets me test capacity.
Bill
Bill
Very interesting!
Do you have any references or links where we can read about this?
I frequently test my UPS (APC) by pulling the plug. I have actually once found a weak battery in a newly purchased unit and after calling APC and explaining to them how I tested it, they shipped me a new one (under warranty). They never told me that the UPS needed a Ground connection to provide a voltage at its output.
Really?
When I had a problem with my APC Smart-UPS 1400, I called APC since it was under warranty. You know what the APC tech had me do? Unplug it to test it. He said it was just fine to unplug it to test.
As has been pointed out, that's wrong. Of course your system is no longer grounded if you unplug it, but the PC components are at the same potential as the UPS still. The UPS only cares about lag of ground if it's actually connected to a power source, and it'll still work then but have an alarm light or sound because of it.
Most UPSes do have a test button, so installing their software isn't necessary. It's may be a separate button, or just pressing the single power button in a certain way, like 3 times in 3 seconds or just tap it once.
Rubycon
Madame President
- Aug 10, 2005
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Grounding is necessary for proper surge suppression.
What's even scarier is I've seen a UPS that would shock you if you unplugged it and touched the plug's prongs. Turns out the relay was faulty and the inverter was connected to the line side when running!
What's even scarier is I've seen a UPS that would shock you if you unplugged it and touched the plug's prongs. Turns out the relay was faulty and the inverter was connected to the line side when running!
An actual power failure looks like a near short across the hot and neutral wires to the UPS (you all can think on that), so that is the optimum way to test. You'd need an SPDT switch to do that: one t hrow connects to the wall, the other throw connects to neutral. I'm not sure what test buttons do - maybe just disconnects the hot line or maybe works like I outlined.
.bh.
.bh.
I'm not sure why but Tripp-Lite is the company that insists a UPS should be plugged in (and thus grounded) at all times. APC does not seem to share this philosophy (which is fine with me). I've tested plenty of UPS's by pulling the plug (though I admit most were APC's).
As for the OP, the battery is very likely dead, especially if it hasn't been replaced, since APC has not made a 250VA UPS in quite a few years. I recommend getting a replacement from here. I suggest Panasonic or Yuasa batteries.
As for the OP, the battery is very likely dead, especially if it hasn't been replaced, since APC has not made a 250VA UPS in quite a few years. I recommend getting a replacement from here. I suggest Panasonic or Yuasa batteries.
So, if I flip the circuit breaker switch, which could be one cause of a power failure, it looks like a short? Please explain how that is! Unless my understanding of short and open are way wrong, that is an open!
No tripping a breaker causes an open circuit just like unplugging. That is one fault mode. UPS should trip in both fault modes. In a true power outage, what the UPS sees is the secondary winding on the transformer on the power pole - a low resistance.
.bh.
.bh.
Partially wrong.
Popping the breaker or switching it off still maintains the ground of that circuit.
Rubycon
Madame President
- Aug 10, 2005
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Actually when the power mains fail the "load" that's seen on the line is all the other devices on the circuit and surrounding circuits.
This is why it's so popular to hook a large generator up to say a 50A circuit feeding a range or condensing unit, remove the fuse to that appliance and the generator will power whatever circuits you turn on at the panel. It should be stressed though you must always open the main breaker when operating like this as the "unused" power will feed back up the drops to the pole pigs and those transformers will indeed work in reverse. Even a small amount of current on the secondaries can energize the primary windings and distribution feeders causing linemen working to restore power to be electrocuted. :Q
This is why it's so popular to hook a large generator up to say a 50A circuit feeding a range or condensing unit, remove the fuse to that appliance and the generator will power whatever circuits you turn on at the panel. It should be stressed though you must always open the main breaker when operating like this as the "unused" power will feed back up the drops to the pole pigs and those transformers will indeed work in reverse. Even a small amount of current on the secondaries can energize the primary windings and distribution feeders causing linemen working to restore power to be electrocuted. :Q
- Mar 4, 2000
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I have never had a UPS that did not have a test button on the front panel. ??? This was mentioned before but seemingly ignored.
Anyway, I modded my current UPS with a heavy duty power cord with an inline switch. It shows in the picture on the right side - lets me turn off the power without unplugging the UPS - that maintains the ground.
UPS]
Anyway, I modded my current UPS with a heavy duty power cord with an inline switch. It shows in the picture on the right side - lets me turn off the power without unplugging the UPS - that maintains the ground.
UPS]
It's a very unlikely scenario that the ground circuit would ever be broken in a household situation - except for unplugging from the wall. Failure modes are hot is open (breaker trips, plug pulled from wall etc.) or short between hot and neutral (power outage).
.bh.
.bh.
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