External MacBook Battery Charger

What I'm looking for is a means to charge a MacBook battery when it is not inserted in the laptop itself. Is there such a device?
subatomicsoul wrote on :

Hi,

Having two batteries for the MacBook (or any laptop, for that matter) is a great option to have beyond the obvious travel convenience. For me, if I'm on the living room couch and the power runs down, I don't need to lug it back to the den to recharge it; instead I can swap the batteries and I'm back in business.

But now what do I do with the now depleted battery? Right now I play this battery hot potato game of re-charging and re-re-charging the laptop so that I can always have two fresh batteries.

But that's not an elegant solution.

What I'm looking for is a means to charge a MacBook battery when it is not inserted in the laptop itself.

Is there such a device? I searched the web in vain.

Thanks, Roland Thomas