hi guys
The motor is being switched from a 12v car battery
the heatsink is only slightly larger than the mosfet (supplied by maplins)
the motor is from an electric battery drill - i do not know its spec
the arduino is providing the pwm
the current the motor pulls i guess is down to how hard it is working
can you take a look at this mosfet - http://www.irf.com/product-info/datasheets/data/irl2203n.pdf
rated at 116 Amps at 10V or 400 Amps pulsed !!
is this one any good ? - http://www.ebay.co.uk/itm/New-1pcs-G80N60RUFD-G80N60-80N60-80A-600V-TO-3P-IGBT-/190508662045?pt=LH_DefaultDomain_0&hash=item2c5b337d1d