[RE-wrenches] Internal BMS vs external capacity meter

[Jay]

Hi all,

A common question I see and have around lithium is figuring out SOC. 

I have to assume that the internal BMS is as accurate as one can get. 
That said, does anyone have real world data that compares accuracy of internal BMS SOC to external SOC meters, such as bogart, Schneider, OB, magnum?

The companies that list how to set up a external 3rd party SOC meter have them set up in a way that seems unlikely to be that accurate, especially in PSOC and in low SOC conditions. 

For most of my clients, they don’t want a computer/phone view only SOC meter.
Having a easy to read and understand SOC meter on the wall is important to them. 

So wondering if folks have answers?

Thanks
Jay