Northern Tool offers the Schumacher 10-amp 6/12-volt Fully Automatic Battery Charger
, model no. XC10, for $39. Coupon code "244935" cuts that to $34
. Opt for in-store pickup
to avoid the $6.99 shipping charge. (Beach Audio via Rakuten
charges the same.) That's the lowest price we could find by $26. It features automatic voltage detection to work with 6-volt and 12-volt batteries and reverse hookup protection. Deal ends February 20.