ARK lithium batteries are 100% made in China. The wooden crate they ship in has no English writing on it. My second ARK battery even had all Chinese script on the BMS instead of English.
Unfamiliar with Miller Tech or rhinovoltz. But would bet they are 100% Chinese sourced too. Amish and Mennonite tribes in the Midwest just flipping batteries for a profit just like every other company out there. Folks being mislead, “oh it’s Amish it’s got to be good stuff”. Not really. Marketing geniuses, yes.
FWIW I added some Zooms series sets into my battery bank. 2 sets of 4-100AH with stand alone series balancers. They outperform the ARK batteries, hands down. I load tested my 10kwh worth of Ark vs 10kwh worth of Zooms. I got .75kwh more capacity from the Zooms.
Both sets of Zooms with DC combiner, 1/0 wire, breakers, balancers etc. Were only +/-$200 more than current price of a single ARK 5kwh pack.
Another observation is my ARK batteries have different internal resistance from each other and one pack is 4 pounds heavier than the other. Not consistent on build quality either.