Home UPS Overloads

sinner_93 · April 2017

My solar home system has a 200Ah LA battery, three 135 Wp panels in parallel, a MPPT charge controller, 900 VA Home UPS. I use it to light bulbs all over my house that has three floors, and sometimes charge my phones and laptops and run the internet router and the ONU device 24/7. Multiple times a day the UPS goes into overload without any huge loads. It happens during broad daylight when the battery is fully charged or at midnight when the battery is discharging or during the early morning when the battery is at it's lowest SoC. There's really no pattern to it.

But once I turn the UPS off and on back again it works without removing any devices plugged in although the overload led blinks for a few times before turning off completely. I've had the house wiring checked, battery gravity checked and the UPS serviced by the UPS company but to no avail. What could be the problem? Thanks in advance!

Estragon · April 2017

One of your phones wouldn't be a Samsung note7 would it? Seriously though, it would help to establish if the overload is real. Do you have something like a kill-a-watt to check actual load?

sinner_93 · April 2017

Haha, no. I like my house not on fire.

The whole house when lighting every single bulb and all the devices running is 200W - 250W and out of that I only light a fraction of the bulbs and run a few devices. I don't have a similar device but wouldn't the overload happen every time I turn the UPS on if that was the case?

One thing I did notice yesterday was that when I was charging the battery from the AC mains and when I turned the AC mains off the UPS went into overload again. It was late evening and the house was lit.

mike95490 · April 2017

Power Factor could be the cause.
A 5w LED bulb often has a cheap driver circuit and likely consumes 10VA . AC power is measured in Volt Amps, and totals the real power the devices use. The batteries only need supply the peak power, but the inverter has to be able to supply the real power.

Estragon · April 2017

The PF is one reason I suggested measuring actual loads rather than adding up rated amp on devices.

As well, maybe something got plugged in and forgotten about, or maybe something is drawing more power than it should, like a bad/failing wall wart. Some of those things seem to have internal heaters as undocumented features.

Johann · April 2017

Some UPS do not like to be powered from the battery for an extended time. They are designed to draw power from the battery for a little time at a time and an extended use could overheat the electronics inside them, After all, you just powering an el cheapo build-in internal msw ( modified sine wave ) inverter that is designed to just run long enough to shut your computer down when there is a power failure.. Most UPS in my eyes are a bad choices to run electronics on them while they are running on battery power, they will eventually burn the electronic items up, like a msw inverter would.

I extended my battery to an 42 ahr capacity on my 1100 VA UPS and once a month I test the system which will be powered for 24 hrs from the extended battery capacity. While in test-mode the plastic casing of my UPS is getting very hot and I ended up to cut extra air slots in it to help it cooling it down. When in normal AC mode there is almost no heat what-so-ever, because you are just charging the battery with very little power and the standby power is very small also and will not develop a lot of heat.

Maybe you are dealing with an internal over temperature.

sinner_93 · April 2017

mike95490 said:

Power Factor could be the cause.
A 5w LED bulb often has a cheap driver circuit and likely consumes 10VA . AC power is measured in Volt Amps, and totals the real power the devices use. The batteries only need supply the peak power, but the inverter has to be able to supply the real power.

How can I find out what bulb or device has a higher power factor and thus a higher power draw?

sinner_93 · April 2017

Estragon said:

The PF is one reason I suggested measuring actual loads rather than adding up rated amp on devices.

As well, maybe something got plugged in and forgotten about, or maybe something is drawing more power than it should, like a bad/failing wall wart. Some of those things seem to have internal heaters as undocumented features.

I've tried it with all the devices connected and then running solely off of the battery, nothing happens then. I now suspect it is faulty wiring from the UPS to the wall sockets or the bulbs but I am not sure.

sinner_93 · April 2017

Johann said:

Some UPS do not like to be powered from the battery for an extended time. They are designed to draw power from the battery for a little time at a time and an extended use could overheat the electronics inside them, After all, you just powering an el cheapo build-in internal msw ( modified sine wave ) inverter that is designed to just run long enough to shut your computer down when there is a power failure.. Most UPS in my eyes are a bad choices to run electronics on them while they are running on battery power, they will eventually burn the electronic items up, like a msw inverter would.

I extended my battery to an 42 ahr capacity on my 1100 VA UPS and once a month I test the system which will be powered for 24 hrs from the extended battery capacity. While in test-mode the plastic casing of my UPS is getting very hot and I ended up to cut extra air slots in it to help it cooling it down. When in normal AC mode there is almost no heat what-so-ever, because you are just charging the battery with very little power and the standby power is very small also and will not develop a lot of heat.

Maybe you are dealing with an internal over temperature.

Mine is a Pure Sine Wave UPS and this problem wasn't there when I first got the system installed or when I was charging my battery solely through the AC mains while I waited for the panels to get delivered. I would rule out heat as a cause because the UPS fan rarely kicks in when it's on and running off of battery when it's not overloaded. I got the control board changed under warranty just in case.

BB. · April 2017

Some UPS systems will not turn on if the AC neutral is not bonded to Ground somewhere in the system (such as at the main panel or you use a smaller AC genset that has full floating AC output)... I .e., you have significant voltage between Neutral and Ground). Many of the ones I used required a manual button press on the front panel to "turn on" if the AC power cord was not plugged in.

-Bill

Estragon · April 2017

A $20 investment in a kill-a-watt meter (NAWS sells them) might be a big help in chasing this down. It can tell you consumption both at a point in time and over a period of time.

Also a multimeter to check for the ground/neutral mentioned by Bill. Intermittent problems like this can be hard to isolate without the right tools.

Home UPS Overloads

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