Bought a brand new Shimano battery recently from a warehouse retailer. Arrived in genuine packaging with a build date of Oct 23, charged it with a Shimano and went on first ride, bike rode great for first 15 miles but then motor cut out 6 times for the last 10 miles of ride, resetting every time when I stopped.

I then fitted the original battery which had been used for 3900 miles and everything was good again. Could this be aged related? Safe to continue to ride? Reached out to retailer. Cheers