I've bought 4 of 5 of these goddamned Magsafe1 to Magsafe2 adapters, and they ALL fail over (a very short amount of) time. Sorta non-sequiter, but god it's terrible.
With what you've spent in adapters by now, you could have bought an actual M2 brick. Just sayin' ;)
(In 4 years I had to buy two bricks. Those thin cables are shocking. Still, Magsafe is such a nice connector, I wish they were all like that... instead of these large phallic daggers that will inevitably break their precariously-soldered ports.)