I run mine off the speed battery connections. I see many people running 2x25mm fans on the cars, but I'm sure they don't realise that its would be far better to use 1x40mm fan.
The advantages with a single 40mm fan over 2x25mm fans:
- Single 40mm fan draws less milliamps
- Single 40mm fan is lighter
- Single 40mm fan seems to have more air flow