APC Back-UPS BX 1400VA - BX1400U-GR not working on generator

[Anonymous user]

Hi, I am off-grid and have solar panels providing our electricity. Occasionally, we use a generator to top up the batteries, or when we need to use something that is power-hungry.

I bought the Back-UPS system for my computers, so that if the solar batteries drain completely, I have a buffer to prevent them shutting down immediately.

My problem is that when the generator is supplying power to the house, the UPS starts making a clicking sound every few seconds; after a while, this changes to four beeps on the same schedule, every few (approx five) seconds. Eventually, it will trip the generator. I have had to remove the UPS because it is preventing me using the generator at all. 

The generator produces a smooth output suitable for sensitive equipment. This is it: https://www.justgenerators.co.uk/hyundai-generators/hyundai-dhy6000selr-long-run-silenced-5kw-diesel...

Does anyone have any idea what might be causing this issue and how to resolve it?

Thanks.

[BillP · Accepted solution]

Hi Fiona,

Going by the description of the UPS behavior, the clicking could be the UPS AVR is kicking in, trying to either step the output voltage up or down, in order to provide a regulated output to the equipment connected to the UPS. If the voltages are outside the AVR threshold, or if high or low transfer points are met, the UPS would transfer to battery, this is indicated by four beeps every 30 seconds. If the four beeps repeat in a shorter interval than 30 seconds, it is possible that the UPS is continuously switching between on-line and on-battery.

As discussed in this article, one possible cause here could be the size of the generator. While 5kW is a generous size to power this Back-UPS and load connected to this UPS, if there are other equipment connected to the generator, then these may also be drawing power. In general, the generator should be at least three times the size of the total load attached to the generator, not just the load attached to the UPS. Due to wide differences in output impedance for generators however, it is not possible to specify an oversizing factor that guarantees compatibility with all systems. 

Powerchute Personal Edition allows setting the UPS sensitivity to low, and the high and low transfer points to their highest, respectively lowest values, increasing the chance the UPS will stay online while supplied by the generator.

[Anonymous user]

Hey Szabi,

Apologies for the delay in responding. Adjusting the settings using Powerchute as you suggested fixed the issue.

Thanks a million for your help.

Fiona