Blue Tooth meter, amps, volts, amp hrs, watts. $24 eBay

i'm trying to find an excuse for getting one of these
maybe the 100a or 200a and put it on the inverter leads
or maybe the 50a and but it on the solar charge leads
yeah yeah i can already monitor the Grape 40 via BT
but hey redundancy is nice

looking around on ebay
i found 200a 300a and 500a versions

same thing, different amps, different seller names