has anyone ever used these inline power meter thingy's
https://powerwerx.com/watt-meter-analyzer-inline-dc-powerpole?gclid=CJGMibCsm9QCFUtufgodnDMJVg

this item looks like a re-branded item as it sells for ~$20 via other names.

i have seen some testing via u toob, they seem ok, but looking for opinions. my use would be to monitor voltage and amps of two 12v 100Ah batts in series.

 

I have used one that was sold on a RC site for monitoring motor current, it works fine.
Max.