The batteries 'store' energy and the controller 'gives' it to the motor. The 750 watt motor needs a controller that can give it that much power otherwise you wont go very fast at all. A 40 amp draw on the 36v 12ah battery pack will give you about 3 minutes of max power~ (40/12) but that would be accelerating uphill under full throttle without pedaling, so in reality you get about 30 minutes of wide open riding at 30mph without pedaling. so about a 15 mile range on flat ground with no pedaling.
I'm building one of these things for myself, and I'm just wondering why you need a 40 amp controller with 12AH batteries. Is it because 12AH each adds to 36AH so you just got a 40 amp controller? Just wondering if you need a controller with more amps than your batteries give.
12AH is a capacity rating. It means the batteries SHOULD put out 12 Amps, for 1 Hour. Generally on Sealed Lead Acid batteries, you would assume the rated discharge would be 1/2C, so 6Amps MAX. If you're drawing 40A, you're going to run into issues with Peukert's effect, and likely will only get about 6-7Ah out of the cells. And a 40A controller ALLOWS 40A to pass into the motor, it doesn't always take the current limit. I would expect this to draw 8-10A wide open on level ground, 40 min runtime.
The batteries 'store' energy and the controller 'gives' it to the motor. The 750 watt motor needs a controller that can give it that much power otherwise you wont go very fast at all. A 40 amp draw on the 36v 12ah battery pack will give you about 3 minutes of max power~ (40/12) but that would be accelerating uphill under full throttle without pedaling, so in reality you get about 30 minutes of wide open riding at 30mph without pedaling. so about a 15 mile range on flat ground with no pedaling.
q5quint 3 years ago
I'm building one of these things for myself, and I'm just wondering why you need a 40 amp controller with 12AH batteries. Is it because 12AH each adds to 36AH so you just got a 40 amp controller? Just wondering if you need a controller with more amps than your batteries give.
th3muff1nman 3 years ago
12AH is a capacity rating. It means the batteries SHOULD put out 12 Amps, for 1 Hour. Generally on Sealed Lead Acid batteries, you would assume the rated discharge would be 1/2C, so 6Amps MAX. If you're drawing 40A, you're going to run into issues with Peukert's effect, and likely will only get about 6-7Ah out of the cells. And a 40A controller ALLOWS 40A to pass into the motor, it doesn't always take the current limit. I would expect this to draw 8-10A wide open on level ground, 40 min runtime.
ericspda 2 years ago