Amazon with GOOLOO has the GOOLOO S10 6V/12V 10-Amp Smart Battery Charger and Maintainer Full Automatic 10-Stages Trickle Charging with Clamps for $80 - 10% off coupon (check "Apply coupon" box_ - $36 off with coupon code 9CWCBKMT [Exp 7/27] = $36 with free shipping.