B300S: Real capacity - what is it?

Product Discussion Expansion Battery
1

I wonder what is the REAL capacity of the B300S.

I have the system AC500 + 6 x B300S.
Shall be: 6x 3072 Wh = 18432 Wh.
.
For calibration I drained my system to 0% and then charged to 100%.
Charged from grid: 17300 Wh.
Charging time ca. 8h which means self consumption must be taken into account.
How much? Minimum 100 W per hour I think.
Then we have ca. 17300 - 800 = 16500 Wh.
.

Another question is how much is usable because of inverter loss.
Next time when I start calibration I will meter it.

2

This depends a lot about the load. The real capacity of a new battery is probably very near to 3.072 kWh.
Most power is lost by the inverter when AC output is on. I got an AC300 and I get 2.174 real usable kWh out of my 3.072 kWh B300 battery. This is with a load of 290 to 360 watt. The lower the wattage, the higher will be the relative power lost in the AC500 and inverter. The AC500 is a bit more efficient than the AC300 that I have so it should be a bit higher on similar circumstances.


You should measure the real usable capacity by putting a power meter on the AC output of your AC500 and then run your load from your battery from 100% until it shuts down. Be sure to record the final measurements before it shuts down because most power meters will not keep their measurements after a power cut.

3

Try the Kill A Watt EZ, model P4460. It shuts off when power to it is cut, but remembers its last data. It turns back on and displays that data as soon as it’s plugged back into an AC outlet. Doesn’t clear the data until it’s reset by the user.