I have 3 of the battery tender plus. the radioshack ones would fry my atv battery. never had a problem with the tender plus and they've been hooked to my boats, tractor, lawn tractor, atv and jet ski....

 

I don't want to be the guy who pisses on everybody's rainbow but I had some trouble with my battery tender (the original one when they first came out). Got it fixed under warranty 2 times. It's been running ever since. Pretty annoying to have that much trouble out of one unit. Bought the Jr. model some time back, never had any problems.

 

Schumacher has been making float chargers about as long as they've been around. You can buy two of them at WalMart for the cost of most battery tenders, and they include quick-disconnect fittings, alligator clips and a cigarette lighter attachment. I think I own four of them and they all are tops...