I have a new Bluetti 2000L. As a test I tried to see how long the battery would last trickle charging (float voltage) lead batteries via a smart charger. The start bluetti capacity status was 73%, the output to the charger was 16W, and after 24 hours the capacity showed as 26%. So simple math says that 384W went out, but the capacity meter would suggest that 73%-26% times 2048Wh is 963Wh. I realize the efficiencies arent 100%, but the lead batteries only received 384Wh out of 963 Wh. Am I missing something? Do these LiFeP batteries need to be cycled or equalized before use?
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Hi @BRGrant, We do recommend that customers recalibrate the power station before testing after receiving it. This is because during long sea shipments and storage in warehouses, the power station will gradually discharge. Irregular periodic charging can lead to inaccurate SOC readings. Additionally, if you log into Bluetti and find new firmware, please upgrade to the latest version.
Furthermore, when testing, we recommend using a load of over 200W, as the AC200L itself consumes some power. Using a low-power load will significantly affect the test results.
Lastly, please note that the battery retains a certain discharge depth to avoid over-discharge. You can use the following formula to calculate the load time.
Running time = Battery Capacity (Wh) x DoD x η ÷ (Load Power + AC200L Self-consumption)
DoD refers to Depth of Discharge and η is local inverter efficiency. For AC200L, DoD and η are 95% and 93%. The self-consumption of AC200L is approximately 12W. If you run a 1,000W microwave oven with it, the running time will be:
2,048Wh × 95% × 93% ÷ （1,000W +12W）≈ 1.78hrs
Note:
- The formula is NOT suitable for inductive loads with compressors, like refrigerators, air conditioners, etc.
- The above data is for reference ONLY.
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If you are running a small load, use DC power whenever possible instead of AC power. DC power is more efficient.
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I will hopefully clarify @Bluetti_Care’s comment re microwave use.
My RV microwave is stated as a 700W output unit, however it’s rated power input is 1200W.
During testing, I found that from the Grid it drew 1,152W. From my AC180 the load on the AC180 showed a power use of 1,372W. I put this down to 2 things, 1. The grid voltage when operating the M/W was 241VAC, from the AC180 the voltage was approx. 223VAC, and, 2. Unit efficiency loss.
I set the microwave to full power for 6 minutes, or, 1/10th of an hour, the AC180 was at 100% charge. After 6 minutes the AC180 showed a charge of 86% = a net 14% used. The calculated 1/10th of 1372 is 137W used by the microwave. The calculated 14% of 1152Wh of capacity is 161W = 24W of self consumption and this is 14.9% of it’s use or an efficiency of 85.1%. This is well within the stated/rated efficiency of the unit.
I have also noted that the efficiency becomes a bigger % of the total power used, the lower the power value. In other words if I used 137W instead of 1372W I might still use close to 24W of self consumption, which is over 20% of the total. It’s not an exact science, but it really helps if you occasionally calibrate the system.
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Yes, I recognize my idiocy. The self-consumption was approximately the same as the load. When I consider the 12W self-burn rate, things make more sense. The enlightenment for me is the potential losses from phantom loads; the 24 hour losses are significant, especially when the inverter self loads and efficiency are considered. Leaving the Bluetti on overnight with a TV etc consuming 15W or so plus a 12 watt self loss is not an efficient use of stored energy. I’ll be conscious of turning it off when not needed and using my house batteries for the lights and fans.
Thanks, I’m awake now!
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Hi @BRGrant, Thank you for getting back to us so quickly.
Self-consumption is indeed unavoidable. We recommend maximizing the use of free solar energy so you don’t need to worry about energy loss.
Here are some suggestions for storing the unit.
- Never store the battery empty, even for only a few days. LiFePO4 batteries might be unrecoverable if stored empty.
- Storage temperature: 0-40℃. Don’t store the battery in a humid environment. Keep it away from fire as well.
- The optimal state of charge for long-term storage is 50%.
- The battery will slowly self-discharge over time. The battery should be recharged every 3-6 months.
- Don’t store the battery on its side. Keep it up straight.
- Don’t stack things on top of the unit. Don’t block the fan.
Regarding the recalibration we mentioned, please follow these steps:
- Please discharge all the power (charge AC & DC appliances with the power station) until the SOC is 0%, turn off the machine, and leave it for 3 hours till it cools down.
- Please charge it again, please do not load any device when charging it, and do not interrupt it while in charge.
You can click this link for reference.
Please feel free to contact us if you need more help.
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Hi @Mandp, Thank you for your detailed analysis, your calculations are very close to our laboratory data. You’re clearly an expert in the field of solar energy!
You’re absolutely correct—our machines have self-consumption, and the smaller the load, the more this affects the test results. For this reason, we recommend customers use a larger load when testing the station’s capacity.
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Thanks for the feedback. Perhaps not an expert, lol, I am a retired mech/elec designer and have an interest re home solar, grid back up and off grid camping.
If there’s one thing I have learned, it is, to have redundancy in whatever is used. i.e. My Bluetti PBs are the redundancy for grid failure and off grid camping, as options for recharge are with vehicle DC-DC, solar or last resort a petrol generator. If one fails, there are options. 
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Hi @Mandp, That’s great! Having more options is always a good thing, no matter what the problem is.
I completely agree with you. Personally, I prefer solar power as well because it’s cleaner, quieter, and more environmentally friendly.
Please feel free to contact us if you need more help.