Quote Originally Posted by typhoon_driver
The cells in a laptop battery aren't A123s they are lithium ion (lipo). A bit confusing but basically the internal chemistry is different hense the difference voltages even though they are both technically lithium batteries.

You are allowed to use Lipo's in featherweights yes but I certainly wouldn't advise using laptop batteries. They are designed to be used in a low discharge capacity ie running a laptop for a long time requiring an amp or two. If you try and discharge them quickly chances are they will catch fire. It may be spectacular, it may not but either way I wouldn't bother. Just take them along to your local battery recycling center and hand them in.
That'll explain it then. Just that they are in a 'can' which as you say is slightly confusing.

Andy