Bests & Worsts Reviews from Amazon

I purchased the NOCO Genius G7200 from Auto TrenDs in late October 2016. I "repaired" an old battery that was in a work truck that had been sitting for over a year. The battery is still working to this day so the NOCO did the trick. However, when i got the charger out to charge my boat battery the first week in May it didnt work. There was a high pitch sound coming from the NOCO. It wouldn't charge the battery. I got one use out of this $90 charger. I am attempting to return the unit to the Amazon seller Auto TrenDs, so far they have not responded.