New AC200max jumped from 97% to 4 % when switched off

Hello. My brand new AC200max came with 36% charge when I unpacked it. Then I charged it from power outlet up to 100%. Plugged in the car cigarette lighter adaptor and connected to Wifi router for a constant use. Slowly the charge indicator sank to 97% and then it was stuck for 3 days. Having used a Jackery unit before for the same purpose I knew that was not normal. The charge needed to decrease by 2 or 4% per day. It did not.

Last night I switched off the unit before bedtime. This morning, after switching on, it shows 4%. I guess this is as wrong as 97% yesterday. So, what can I do? Does the unit need “calibration”? Shall I leave it on now with the constant 7 watts drain through the Wifi router until it reches the real zero percent and switches off by itself? And then charge it to 100%? Will the unit then “learn” its real status? Thanks for inspiring me! Cheers from Germany

Welcome to the forum @German !! I would say yes, I would “cycle” the unit completely. Keep the draw on the unit until the output shuts off and the unit hits 0%. Then unplug all loads/ keep outputs “off” and charge the unit via the AC charger until it hit 100%. These SOC indicators can be a little finicky sometime and need this “calibration” to reset them. Honestly, I’ve had to do this complete “cycle” a few times repeatedly before getting it to really set with some units. ( not specific to just Bluetti ) The displays are awesome to have to give a general census, but I have found them to not be the most accurate sometimes. Eventually, once you get a good feel for your units, you wont even really “need” them.

Hope this helps, but please reach out if you have any questions.

Here is a video explaining what a calibration of the battery meter is, how to do it and when you need it.

And to add to that, you may want to find a heavier load than just a router that draws 7 watts. I used a 700-watt heat gun. It goes much faster, and you can monitor the process. the goal is an uninterrupted draw down and then charge up.

Wow, thanks everybody for rhese very useful hints and tips. I will soon try this. Btw the first of my two ordered E230 batteries will be delivered soon. Do you suggest to the same thing of full drain and recharge again when attached to the AC200max unit? Cheers from an electric (!!!) train!