RE: mini laser brushless
torquerolln; For the Hacker B20-18L I would probably use 3S3P of the new Kokam super high discharge 340 mah cells. This setup would be much lighter than any other current lipoly setup for that motor, but it would also cost more. It would only have a total capacity of 1020 mah but it would be almost two ounces lighter than either a Thunder Power or E-Tech lipoly pack, which is in the neighborhood of 40% less weight (weight is very important). The reason for this is that the super high discharge Kokams can run at 20C, versus 5C to 8C for the Thunder Powers or the E-Tech's, so you don't need to "parallel up" as many cells to obtain enough current for your application. If you want more duration you can parallel up more Kokams or use Thunder Powers or E-Tec's.
The key to selecting lipoly batteries is to know how much current your motor/application will pull, and then select lipolys that will handle that amount of current. Depending on the gear ratio and prop, you could pull as much as 18 amps with the B20-18L.
The Thunder Powers and E-Tech's are great cells, and I use both, including Thunder Powers in a [link=http://www.katmandew.com/images/RC/Electric/Lexx%20-%20holding.jpg]61 inch Lexx[/link] and a [link=http://www.katmandew.com/images/RC/Funtana/fuse%20bones%20and%20covered%20wings%20%20top.jpg]78 inch Funtana[/link] But the new 20C capable Kokams are in a different league. I believe the the 20C Kokams are only available in the 340 mah size at the moment, but once Kokams, and other 20C lipolys are available, it's going to blow electric flight into a whole new realm.