EP500 Outgoing A/C Power Measurement Accuracy

I’ve was measuring the overhead of the EP500 in UPS mode and put a Kill-a-watt on both the A/C wall plug and the EP500 plug feeding my entertainment center.

The readings are identical, though that may not be the whole story. The battery level slowly creeps down and the system occasionally powers up the 560w charging circuit to keep the battery at 100%. I’d speculate that the onboard logic is powered off the battery so there’s an extra load there that’s hard to measure (I’ll have to do a longer test over a day or two and compare the total power used - I guess I could do that w/o an A/C load and just measure the power pulled from the grid).

The A/C Load watts measured on the unit appear high. With the Kill-a-watt showing 67 watts the BP500 is reading 105w for the AC load (I tried two different meters). That seems like a pretty significant discrepancy. Has anyone else looked at this? I need to check some higher loads and see if the error is fixed (38 watts) or a %.

I also did some power loss tests in Standard UPS “Off Line” Mode. Seemed to work fine (for my TV and some other components). I put a scope on the output power lines and I saw about 25ms to switchover (close enough to the spec).

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I’ve been using the customized ups setting so I can set up the max charge and discharge percentage.

My observations on running the refrigerator from the EP500, no grid connection:

EP500 on (light on), AC only, there is a 30W constant electricity draw. Refrigerator runs on average 1/3 of the time and the average use is 40 watts over an hour. So with my calculations adding 40w and 30w, I can closely estimate refrigerator run time.

This 30w means the unit on, providing AC only, uses approx. 720wh/day. A considerable dent in capacity. Early on I asked about standby losses and was given two figures from Bluetti in the comment section, I think the first one was more accurate (I got 29.9w more or less for the EP500).

Please check the below data:

  • Power On, Standby: 8.7W
  • AC ON and DC ON: 35.6W
  • Only DC ON: 11.5W
  • Only AC ON: 31.5W

According to the latest test, the data of power consumption as below:

  • Power On, Standby: 9.1W
  • AC ON and DC ON: 23.12W
  • Only DC ON: 12.89W
  • Only AC ON: 17.9W

The 30w was close to the observations of one or two online reviewers who looked at standby losses.

At the low wattage my refrigerator runs (usually 110w or 120w when running) the fan only kicks in during the last minute or two. So fan draw would be minimal.

Strangely, when charging, I saw less wattage being used on my killowatt meter than was displayed by the EP500. Charging was roughly 87% efficient, losses partly due to 30w for every hour it is charging (light is on).

My first refrigerator run went from 90% to 22% charge (68% of battery, or ~3482wh) but only 1.98Kwh of that was for the refrigerator, according to the killowatt meter. The balance was the 30w over ~50.42 hours of runtime, or ~1513wh.

I’m sticking these figures here in case they help with your calculations. Because of the problem I am having with the GFCI breakers tripping, I will only run the EP500 (right now) when the power is out or I am testing.

I plan to charge with solar but have a lot of research to do before I can do that.

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Wow, that 30w does add up and eat a good chunk of the battery. Probably 1/3 of what I’m getting from the 4 jury rigged solar panels (since my rooftop system is dead weight during a grid failure).

Did you measure it? I’ve been using “Off Line” mode and it seems like I just see 0 watts with bursts of 550 when it tops off the battery.

It does seem like my fridge run time is a lot shorter then I expected.

So if you were trying to get maximum run time on a fridge, you might be better off manually cycling the battery switch. Maybe 1 hour on, then 2 hours off to save that 30 watts. It would be hard to justify that much trouble.

I’m still curious…

Can someone tell me what they see on the EP500 AC reading (watts) vs a Kill-A-Watt meter (plugged into the load).

I’m wondering why my EP500 is reading so high.

Sounds like my AC200P, watts out always reads way higher than the external meter. The external meter is closer to the truth since doing a full discharge I get the expected KWH out of it.

That is a solution I thought about too. I would only do this if I was in in desperate straights.

When I did my refrigerator test, the watts the EP500 showed being used were about the same as what the killowatt meter was reading.

One of the reasons I got the EP500 was how impressed I was with a brand new EB240 I was able to test out of the box. Charged to 100 and discharged as much as it would let me. I recorded 41 hours run time and refrigerator energy use of 1.64 Kwh. This is the same ~40w/hr for the fridge. If the EB240 had a cap of 90% discharge, that would make 2160 wh available - 520wh unaccounted for for the 41 hours, and perhaps standby losses of 14w per hour. I thought this was pretty decent.

I wish the EP500 was more efficient.

Damn, I need to start looking for a new Fridge. My 20ish year old side-by-side beast is pulling 2.16 kWh/Day.

What do you have? How old is it?

I have a 30 year old 18 cu’ GE refrigerator. I don’t know how well the current crop would hold up but imagine they are widely available at a price lower than shown online.

The space I have for a refrigerator limited the size I could buy - but I also like the efficiency. Your personal electric use would depend on house temperature, number of people in the house, and how it is used (frequency of opening, temperature of items when refilling, etc.).

I think the current ones are a little smaller, probably because they added more insulation. This should be cheaper at a place like Lowes during sales.

I’m sure the refrigerator would be considered too small for some families.