BACK UPS 750 (BE750G-CN)

[Anonymous user]

I recently purchased two BE750G-CN units.  I have started to test them this weekend.  I have a number of questions and since this is the first time using backup systems like this, please excuse my ignorance on the subject.

1. When using the powerchute program, sometimes it will register that on backup is proving four watts of back up power (router and modem) however other times it says there is zero load.  Is the load too small for the program to pick up on?

2. Regardless of the load, once main power is removed the battery levels starts to drop quickly.  Is this normal without a load?

3. When I was on the APC website, I went to UPS selector, indicated a load of 4 watts and a minimum run of ten hours on back up.  The first and least expensive option was the BE750 and the website showed 1177 minutes.  I assumed that 1177 minutes was how long it could last running 4 watts.  Am I wrong?

4. The second BE750 unit is going to run a VOIP phone in case of a blackout and one LED lamp.  My question is, can a normal LED table lamp run off this unit or will it damage it somehow?

Any other advice on using these units is also appreciated.  Thank-you for your time 

[Anonymous user · Accepted solution]

The metering hardware in your BE750G-CN isn't going to be all that accurate with a very small load attached to the unit. It may not sense a very small load.

If the batteries in your BE750G-CN have been sitting idle for a long period of time, they may have discharged significantly. Without at least eight hours of charging time, they could be partially depleted. This might explain the sudden drop in percent of charge.

No inverter is 100% efficient, especially under a very light load. Power from the battery also has to keep a microcontroller and other circuitry within the UPS operating while the inverter is running, so a little more energy is lost there. You won't get a ten hour runtime on battery as a result of these losses, which I don't think the APC UPS selector tool takes into account. Realistically I think the best you can hope for is two or three hours at most, and less as the battery wears out over time.

When running from its battery, your BE750G-CN outputs a waveform quite different from that supplied by your electrical utility. While it should be safe enough to test your LED lamp, it may have trouble starting, could flicker noticeably while in operation and might emit a buzzing sound. None of this is likely to damage the lamp or shorten its life in any appreciable way.

If your application absolutely requires a ten or more hour runtime, the only recommended option would be an APC Smart-UPS XL, or extended run model. The smallest of these is a 750VA model. These XL models support the attachment of external battery boxes. They are not cheap, but they will do what you want and as they output a true sine wave (same as your electrical utility) you can run just about anything from a Smart-UPS so long as it doesn't overload the unit.