My 2 batteries worked fine for a month.  Then the BMS on one died.  After a week of email exchanges, wattcycle agreed to send a return label.  It took a week to send it, then a week for the battery to get back to California, then several days to ship the replacement and a week for it to arrive.  The new one is working now.  I went a month without a battery and I worry that the replacement may also fail.But I was pleased that Wattcycle did provide the replacement.