Lack of capacity?

I did a capacity test with the Bluetti EP500 Pro. I discharged the EP500 Pro with about 200 watts. Of the 5120 Wh only 3564 Wh remained. So only 69.61 % !

Even if you use the formula described in the manual: 5120 * 0.9 (because of DoD 90%) * 0.9 (because of inverter efficiency) = 4147 Wh this is still only 85.94 % of the promised energy.

Is there an explanation for this or should I return the EP500 Pro?

It seem to be very common concern, but maybe normal.

One factor to keep in mind, the highter the inverter capacity, the less efficient.

I haven’t tested my ac200max but from what I have read, it will be worse then 10 percent. Hopefully improvement are found in latest firmware update.

The firmware play a role. Compare Victron inverter, they have taken a different approach to improve efficiency by putting unit in another state and wakes up as needed. Smart inverters!

Turning off AC mode and using DC mode would improve the efficiency.

The inverters are heavy on power, even when doing nothing. The more intelligent the inverter the better the results. Who sells dumb inverters?

Bluetti approach is simple, eco mode, shut down after x amount of hours.