Goirish , this come in handy up here in the frozen waste land . I have lots of toyz that need the batterys maintained over the winter, I have 4 of them ,that I rotate on the motorecycles, boat , 4 wheeler and trucks. I dont drive my Tahoe in the salt in the winter but leave a battery tender on it , the Battery in it is 8 yr.s old and shows no signs of dieing any time soon. lol They pay for themselfs in the first winter.
HarborFreight has them for under 10 bucks , but I never bought ant thing electronic off them.