@AndreyTavrel , Have a read on this thread. https://community.bluettipower.com/t/elite-10-discharge-too-quickly/42300
The power station’s self consumption when using low loads can often be higher than the actual load. (This is not displayed). The display you see on the App or Unit is the power being provided to the device and is slightly more than what it draws, this is a part of the efficiency factor. This is also affected by turning on both DC and AC load buttons, even without anything plugged in. Here both DC and AC loads will display zero, but there are background loads just for the power station to be switched on, i.e. bluetooth, wifi, inverter and the display itself.
All this in general making sense… unless we will come to real figures, if 17W load will cause 9.4 hours of powering, that means I have 159.6 Wh available capacity, and all internal consumption takes all other capacity from 320Wh available? So, internal components consume 50% of energy? Is that normal efficiency? Why same laptop connected in the same minute to another power station from Allpowers (also not perfect), by the AC inverter as well shows 36W and 8 hours which is equal to it’s 288Wh capacity? I do have another Power station from BigBlue, CellPowa 1000, it is always shows correct consumption and remained time (means it calculates right capacity). So, I still thinking it is incorrect BMS behavior… and we are ignoring first issue - 99.9 Hour charging time always.
And even more… Let’s exclude AC inverter, and keep it on DC only - so 12 Volts (or 24 via StarGear adapter) output to Starlink mini
With consumption 21W - remained time 10.7 Hours on 97% capacity. So, what is the battery capacity we have: 21Wx10.7 hours = 224.7 Wh, even with 97% of capacity from advertised 320 = 310 Wh must be available.
So, I what conditions I can get 320 Wh from this device?
Most power staions (PS) operate as do Bluetti PS. Here is the simple point…
The 320 Watt hours advertised and indeed written on the PS (Premium 30) is the capacity of the battery inside it. It is not the energy (Wh) available to your devices. This is industry standard practice as it creates benchmarking. Most LFP batteries note a C rating at a specific load i.e. A C rating of 0.2 of a 100Ah LFP means if you draw 20 amps for 5 hours you get 100Ah. Conversely if you draw 100Ah for 1 hour you might only get 60Ah due to the high load or more than 100Ah for light loads, but they are batteries only. (Unless they are smart, ie. have Bluetooth) That said;
To protect the battery from total discharge Bluetti limit battery discharge to 90% of capacity i.e 32Wh in the case of yours. This is not shown on the SOC or time remaining i.e. when it shows zero SOC there is still some charge there to allow it to power up for recharge.
Self consumption on small PSs is approx 15W, so with a 15W load, you are using 30W or 200% of actual load. However if you draw 150W with a plugged in device, self consumption is only 10% added discharge.
The 3rd point is when using the inverter, there is a 10 to 15% efficiency loss plus the self consumption.
The calculation I use to give me a closer actual capacity is; rated capacity less 10% i.e. 320-32=288, then multiply that by the 85% inverter efficiency loss i.e. 288x0.85 = 244.8. This for AC use is worst case and I would safely hope for around 240Wh and any extra is a bonus. However, for DC only loads using your 17W load, actual load is 17+15 (self consumption) = 32W. Then divide 288 by 32 = 9 hours (up to and maybe less due to environment) If you use both AC and DC loads simultaneously, then this starts to complicate the math.
This does not mean that Bluetti have a problem as every use scenario is different. It was a learning curve for me. I found the best way to assess time of use was run the PS as I wanted for 1-2 hours, checking use at one hour and again at 2 hours to get a consistent use per hour, then a simple math calc to tell me actual expected runtime. I then assessed that as being enough or not. If enough, great, if not, I expanded capacity with either a bigger PS or useing Charger 1, powered from a 100Ah LFP deep cycle battery. (I’m fortunate to have 7 power stations, I can “piggy back” if needed) Hope this explains
