AC200max shows wrong watt (+90 !) in AC output

I just received a new AC200max and I’m already thinking of returning the device.

Unfortunately the control display shows constantly wrong watt when using AC output. I used a separate measurement unit to compare values. With real power of 10w, the display of the AC shows 100w. with real power of 150w, the AC shows 230w.

This is annoying if you want to estimate remaining usage time. I would accept +/-10-15% deviation, but 90w is unacceptable (at least in my opinion).

Three questions

  1. is this a known error, or is this a defect specifically with my AC200max?
  2. is there a way to re-calibrate the device?
  3. is there a chance that this will improve after a few load cycles

Thanks in advance

Hi @rj2000 , Please do a firmware update, load other devices and see if the situation still occurs?

Thanks for the advice

The firmware seems to be up-to date. I don’t see an option to update anything in the iPad app

This is my status
DSP 4005.07
ARM 4008.03
BMS 1017.02
HMI 6037.03

After using the device for one day, the display shows only 5% remaining capacity (starting at 100%) even though I just consumed 0.9KWh (measured by a separate device).

Do you have any other advise or do I need to return the AC200max?

Regarding the other topic, I tested another device

at 240w (separate meter) the AC240max shows 350w, at 30w (separate meter) it shows 0w
at 450w and above, the AC200max shows quite similar values (+/-5%).

Overall the measurement is totally wrong. The powerstation turned off with 0% capacity even though I just consumed 980w using a separate meter (starting at 100% capacity)

Basically the watt meter is not very accurate at low wattage. Below 50W it often reads zero and @BLUETTI has stated in other places that it does not work reliably below 50W.

Also, when you measure with your watt meter (assuming it is accurate) there is an additional draw from the AC200MAX since it has to take the DC power in the battery and convert it to AC. There is some loss that happens here.

Finally, you cannot consume 980W … Watt is a measure of instantaneous power usage. Consumption is power over time, measured in watt-hour(wH) or kilowatt-hour(kWh).

You should, theoretically get about 85% of the rates capacity taking into account the loss discussed above, so the AC200MAX has a 2kWh capacity, so you should be able to draw about 1700kWh out of it before it reaches zero. Remember that when you are not drawing power and the device is still on, you are still drawing power to keep the screen and the bluetooth, etc, on.

I have a fridge that draws ~1.7kWh per day and with a AC200MAX and no extra B230 batteries I can get about 24 hours with no solar input.

Hope that helps.

Hi dr_toch

Thanks a lot for the input and clarification. To clarify, of course I wanted to say 980wh as accumulated capacity running from 100% to 0%. In the other direction, the same meter accumulated 2100wh to load from 0% to 100%.
This would mean that I only was able to get approx 50% of the theoretical capacity.
I used it to run multple PCs (iMAc, Windows and a Notebook with Montitor), adding up to approx 120w in total (measured by the separate meter) . As the AC200max was showing around 200w for this load, it seems like that the AC conversion consumes additional 50-80w. Taking the overall loss into account, I can imagine, that with 100w constant AC load, you have to add additional 70-90w waist. This would explain why only approx 50% of theoretical capacity can be used.

For me the only question would be, is this by design and acceptable or is this poor performance a bug with my specific AC200max which needs to be corrected.

Hi @rj2000 , please provide your AC200MAX SN code and are you using US 120V?
After we get your SN code, we will first have our engineers push you a firmware update. You update and reboot, then load other devices and try again

Hi, thanks for the support.
The SN code is 2236000180141
Please let me know when I have to act

@rj2000 , Our technical engineers have pushed the update for you (AC200MAX US 120V), please open the app and update it.

Hi, I installed the firmware update.
The difference between external meter and display of the AC200max is still approx 70w (external meter 100w vs AC200max 170w)
I’m using EU 230V

… maybe I received a wrong firmware update. I have the EU 230V version, not the US 120V.

After confirming with the engineer, the BMS version is compatible with either 120V or 230V. What is the load you are connecting? Suggest connecting another large loads to try

I run home office equipment via the AC200max. Mulitple PCs (iMac, Windows and a Notebook with Montitor), adding up to approx 120w in total (measured by the separate meter) . The AC200max is showing around 190w for this load. So it seems like that the AC conversion consumes additional 70w.
Is this within expected range for this device?

I have the same issue with incorrect actual power consumption display. I have EU 230V version with serial 2234002000139

ARM 4008.03

DSP 4005.07

BMS 1017.02

The load you are connected seems low, and may be connected to a large load to be able to display properly. You can try to connect a 600W or more.

Thanks for providing the SN code. You are expected to receive a push notification of the firmware update within 24 hours.
Please keep an eye on the app and keep it updated at that time, thank you!

Why do the firmware updates not come down automatically through the app and have to be sent individually ?

Also is there a list of the latest firmware versions that each device should be on ?


I also run my home office with 115W and my AC200MAX use 180-200W.
ARM 4008.03
DSP 4005.07
BMS 1017.02
HM1 6037.03

Got it start observing lower numbers of actual consumption. Can see not only 90W but 70’s as well

It seems that the AC200 max AC output reading is in VA (volt-amps), not watts. If you put a resistive load like a heater or hair dryer on it should read pretty accurately. If the devices you are feeding have a low power factor the consumption will appear higher on the Bluetti screen. Feeding the small loads you mentioned continuously will be very inefficient. I have found the self consumption to be just under 70 watts during 24 hour (watt in - watt out) tests with small loads. Neither my AC300 or 200 max read ac loads below 50 watts consistently, but they are pretty good above that, but again, the reading is in VA, not watts.

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