Why did I blow 2 20A fuses in a row?

[friggerand]

I just got my kit yesterday. Hooked it all up, battery charged... take it for the maiden voyage....everything's good, good torque....for about 200 meters, then dead. The 20A fuse leading to the battery pack (36V 12ah lead acid) blew right away. So I put in another 20A fuse and I go again, this time I go real easy on the throttle, it lasts a good 5 minutes this time but blows again.....
...What happened, is the controller supposed to draw more than 20A from the battery at any time?

I had to go to work at 2:30 in the morning and my car has a dead battery, a flat, and no insurance, so the bike was it, (plus I spent all day mounting it to a Giant Stiletto bike which isn't your typical bike shape or install)... so I put in a 30A fuse and left it at that, woke up, pounded the 20Km to work out in no time, and was satisfied with the torque (it's a 20" wheel, surprisingly small tire too) and nothing blew and the controller never felt hot at all. I then went the trip home in rush hour traffic, and it didn't blow the fuse and the controller wasn't hot...

Am I ok with the 30a fuse?

Any help would be great.

[OneEye]

A 30A fuse should be the right size.  Having a 30A fuse won't damage anything.  the controller will pump 20A to the motor without causing any harm to the motor or controller (motor is 500W continuous, so its peak rated power is in the 700+ range).  The controller will protect itself, so the fuse is just to protect against short circuits.

[myelectricbike]

Ditto.