Late to the party, but my USB werk failed less than a week into a tour, after some prolonged rain. Not sure if rain was the cause though.
It never recovered, even when fully dried out weeks later. Returned to spa cycles. They sent off to B&M who have agreed it's fooked. Refund imminent.
Does it work?
Was considering USB werk
https://www.bike-discount.de/en/buy/busch-mueller-usb-werk-ac-64473?currency=3&delivery_country=190&gclid=EAIaIQobChMI08vix9au1gIVzLDtCh2T-QFREAkYASABEgKQE_D_BwE