batterys are a funny one. i go off the actual energy stored. and it's charge time.
eg makita. 18v 3AH 18 x 3 = 54 watt hours. thats how much actual energy is stored in the battery. but the batterys ablity to deliver that power is just as inportant. general rule for all batterys is the faster it can be safely charged the more current it is capable of supplying.
the makita will charge in 22 mins ( it pulls in about 9 AMPS ) so it can safely absorb power at a rate of 162 watt's per hour, guestimation say it should be abel to supply at about twice that rate so it proably has the potential to run a 250-300 w motor. thats what really matters. big motors are cheep and easy to make. makeing light compact batterys to run them isn't. and none of the manufactures tell you anythign about the ablity of there batterys to give power.
but as a general rule of thumb. you want 18v or more. 2-3 AH at 18v is fine. as voltage goes up you dont need as meany AH ( volts x amp hours for stored energy ) YOU WANT LITHIUM BATTERYS THEY ARE SERIOUSLY WORTH THE MONEY. they charge fast, they have long service life and no memory effect ,(you can top up half full batterys or take off and use before theyve finished charging without knackering them)
the milawakie job also looks a bloody good bit of kit, and a 28v li ion battery will give some serious punch prob more than the makita ones
