Review on Geekworm X728-A2 Stackable 18650 2-Cell Battery Holder (Without Batteries) For Raspberry Pi X728 UPS by Josue Porter

This UPS meets most of my needs, but I would like the python2 scripts to control it to be updated from the manufacturer and if possible compatible with newer operating systems. After overriding a few things from the .py scripts provided on the wiki, it works enough with OpenWRT to query the battery percentage and do a controlled shutdown before the battery hits the low voltage cutoff, but I left it on "good enough", so I haven't got any power failure detection working there yet or 1 or 2 power button functions. One odd thing I noticed about this UPS is that the battery percentage fluctuates when running on AC power. When I first put in (brand new) cells I noticed that they were 100% charged, then the controller went into a kind of discharge cycle that brought it down to almost 90% before charging it back to 100% and repeating. again and again. From what I've read lithium should be fine in that range and hopefully daily repeated cycles won't wear the battery down to just the top 10% charge after thousands of such cycles. Maybe the charge controller needs a full discharge/charge cycle to know the capacity? More research is needed, but they are all brand new balanced cells. I've had a few brief power outages over the past few months, but it wasn't enough to test full runtime on 4 connected 18650 cells. I expect to get a few hours out of this just running the Pi and a couple of USB network adapters. There are a few other UPS solutions for the Pi that can be scheduled to start up at specific times, but for a routing device this seems pretty reliable so far. Love the selective 18650 modular holders with mounting holes and posts!