The nationality of battery manufacturers is complicated. Powersonic is really a trading company with little manufacturing capability. Up until the early 2000s, every Powersonic battery I purchased said "Made in Japan" on it. They were one of the best AGM batteries out there. In the early 2000s, the batteries changed to "Made in China" and I felt the quality degraded: shorter life and a few did not meet their specs when new. For the next couple of years I bought Panasonic batteries ("National" or Matsu****a in much of the world), then they too started coming "Made in China", and quality fell off. Same with Yuasa. Price pressure has forced them all to China, with similar results. Manufacturing in China is unlike what you might be used to in the USA or Japan in many ways large and small. I used to buy a lot of small AGMs to feed my large motorcycle collection so my sample size is relatively large. Currently the best AGM batteries are made by Lifeline here in the USA (part of Concorde, I think), but they do not make small sizes.

Nearly 100% of lithium cells are made in China, so you don't get much of a choice in country of origin. There are a range of qualities though, and the integrator that assembles them into a battery makes a difference. Powersonic was recently purchased by a venture or hedge fund group, often not a good thing, time will tell. The battery I just bought and tested seems to be a good product.

On Saturday, September 12, 2020 at 8:27:37 AM UTC-7, Craig Reinholt wrote:
Panasonic quality is a thing of the past. I've purchased 2 SLA 12v 20ah bats in the past couple of years and, after testing each bat multiple times, neither were any better than some generic brand batteries that I've purchased and worse than others.

Regarding Panasonic as an American company here is a quote from Wikipedia..
Panasonic, then Matsu****a Electric, was founded in 1918 by Kōnosuke Matsu****a as a vendor of duplex lamp sockets. In the 1920s Matsu****a began regularly launching products. In 1927, he produced a line of bicycle lamps that were the first to be marketed with the National brand name.
Craig
Had to chuckle on this one. Ever wonder where the strange PowerSonic
name came from? It's shockingly similar to Panasonic, which actually
makes quality SLA batteries. I hope PowerSonic makes better lithium
batteries than their SLA batteries.