I would like to know more about the details of those stories. Tenders are designed to remain on the battery. I use a Battery Tender brand tender and have not had any issues.
Kooks 1-7/8 LTs; Calico coated w/HFCs, Solo Mach XL catback w/J-pipes, VMax TB, C.A.I. Intake, JRE Tune, RX Catch-Can