backchannel: bluetti recalibration

from a reddit post

I’ve been using a Bluetti as my power source for in my van for the last seven months… It works quite well. But, bluettis have an issue with their SoC needing to be calibrated often

OP wants to go to a DIY setup because of this issue. Unfortunately, all coulomb-counting schemes drift and will need to be regularly recalibrated. One major factor is the shunt or sensor has to withstand the largest current that will flow through it (including the inverters surge rating). Those that can survive Big Current are typically less sensitive/accurate for small currents like phone charging.

The other problem is that there will be no State of Charge indicator (battery monitor) in the DIY system unless he puts it there. IMO DIY setups are generally a better solution but I am also a fan of “run what ya brung” (use what you have). I am completely opposed to spending more time/effort on a different solution that is unlikely to fix the “problem”.

This means discharging to 0% at a constant rate, then charging to 100% at a constant rate and doing this several times without using the power bank. This is an absolute pain on the road.

OP didn’t say which power station he has¹ but reading his posting history says it’s an AC200max (superseded by the AC200L?).

Neither the manual nor the FAQ for the device describe the described procedure; perhaps it came from support or some other source. Some of it makes sense and some does not.

• charging to 100% or discharging to 0% will likely reset the counter, depending on internal logic.
• constant rate doesn’t add value here – could they be thinking about the Time Remaining calculation?

This official Bluetti video discusses the 0%/100% approach with no mention of constant load.

1. par for the case on /r/vandwellers, and particularly common with power station fanciers. ↩