Works when plugged it but not on battery

[Anonymous user]

Over the last few hours I've been searching the forum and although people seem to have similar problems, they don't have the exact one I'm having.

I've currently got a sump pump plugged in to my Smart-UPS 1400. If my calculations are correct, the 5.7 amp pump should use about 684 watts. Which should be no problem for the 950w max that the 1400 supports.

When the unit is plugged in and the pump starts, the overload flashes for a brief 1/10th of a second, and then turns off after the pump starts (while running the 2/5 lights are lit up). However, when the unit is not plugged in and running on batteries, the pump is never able to get past it's startup and stalls.

I started with a Smart-UPS 1000 which peaks at 670(ish) watts, so I went out an bought a 1400 thinking I was maxing out the wattage.

Is the 1400 overloaded too or do I have a battery issue or a configuration issue?

Thanks for any input you guys can offer

[BillP]

Hi:

It sounds like the inrush current of your sump pump may be a bit too much for this UPS to handle. While your current calculations for this do sound correct, that is likely the current draw while the pump is operating. The draw when it is first powering up is likely much higher. You might try contacting the pump manufacturer about what the max inrush current is when the pump starts up, then size the UPS that way. Let us know if we can be of more assistance!

Thanks

[Anonymous user]

Thank you for your speedy and informative response. I will try to contact the pump company or do some research to find out the initial draw.


If I am exceeding the UPS's limit, why would it supply power just fine when it's plugged in but not when it's on battery?

[Anonymous user]

From what I've tried to find, it does look like I'm exceeding the UPS's limit.

But, if I am exceeding the UPS's limit, why would it work when plugged in but not on battery?

[Anonymous user]

When the pump starts (on batteries or plugged in), the overload light quickly blinks, then all 5 lights are on.

When the UPS is plugged in, the pump starts. When the UPS is on batteries the pump tries to start, then doesn't get over it's initial starting phase and doesn't start pumping the water. If I monitor the 110v plug on the back of the UPS, it dips way down around 40v... (according to the pump manufacturer, it doesn't start properly unless the voltage is above 108v).

Thank you for your response.

[BillP]

hmm ok. so as the amperage draw goes up, the voltage should go down, which seems to be what we are seeing here.

so while that voltage draw is 40v, are all 5 load LEDs still on even though the pump hasnt fully started?

[BillP · Accepted solution]

how many load LEDs are present on the left hand side of the UPS while the UPS is online and then while on battery?