I’m a new Bluetti user and have what I hope is a simple question. I have the AC200L + B300K expansion battery for a total of 4,812 kwh. Does it take several recharge cycles before the batteries reach their full potential?
I have a refrigerator, a freezer, and some networking related items connected. The unit shows everything pulling ~191W-194W pretty much every time I check it. At this draw, I only get about 18 hrs of power from the batteries (from an actual test and also what the unit reports as expected runtime). Per my calculations, this is roughly 3,492kwh (194*18). As the AC200L shows the expected runtime based on current load, I unplugged the networking gear which reduced the power consumption to 147W. At that draw, it reported that it expected to run for 23.5 hours or 3,454 kwh which is very close.
I don’t expect to get the full 4,812kwh, but the reviews I’ve seen show this combination typicially getting around 90% efficiency for better. At 3,600kwh, that’s only 74.8% efficiency which seems pretty poor.
Can I expect the batteries to get closer to that 90% efficiency level?
@mikeparks Around 10% of the total watt hour capacity is kept for battery protection. There is also self consumption when the power station is on which can be around 15 to 18 watts per hour. Also, if you are using the AC output, the inverter uses additional battery capacity. Even with the AC output turned on but with nothing plugged into it, the inverter will also continue to draw battery capacity.
In addtion to the great summary of @Erebus , the unit is more efficient when you use it shorter. For example:
You want to charge a 500Wh battery. If you charge it with 500W, it would be finish within a hour. You draw 500Wh + 18Wh for selfconsumption. On the other hand, when you charge it with 250W, it will take 2 Hours and the self consumption is 36Wh.
So you will get less useable power if you run the unit for longer. To be more efficient, you can use DC instead of AC where possible and also charge at a higher rate if possible.
Hi @mikeparks, Please note that,
1/ The total capacity of the AC200L+B300K combination is 4812.8Wh. To protect the battery and avoid over-discharge, the battery is not drained 100%. The discharge formula is: capacity * DOD * n ÷ (load + self-consumption). DOD is calculated at 95%, and n is 93%.
The self-consumption when the AC is on is 18W. Your load power is too low, so the effect of self-consumption is quite noticeable. We recommend using a load of 1000W-2000W to test.
2/ What is the ambient temperature where the machine is placed? Extremely high or low temperatures can have an impact.
Thanks to @Erebus and @Selfmadestrom for the helpful insights, these have been very useful.