AAA battery upsizer to AA battery

Hello,
I just watched a video on Youtube where a guy had what he called a battery upsizer. He put a AAA battery into a container with contacts at each end that was the size of a AA battery. then he used the AAA battery in the light that uses AA batteries. Has anyone seen this thing? Is it good or bad for the circuitry in the light? Where can you get them?

Here is the video I saw.
http://www.youtube.com/watch?v=HJi0ON53ADE

Thanks,
Jack

Hi Jack. Yes these adapters are around. Many of the Far East vendors supply them.

The only real problem that you may run into using these, is that an AAA cell of any chemistry, only has about one third the capacity of an AA cell. This will pretty much also apply to how well the cell will perform under load, as well.

In applications where the current draw of the device is high, an AAA cell is likely to fall flat on it's face and not perform very well. Concerning rechargeable cells, this will also contribute to early failure of the cell. For applications where the current load is acceptable for an AAA cell, it would work fine, however the runtime will still only be about one third, or less.

Dave