Volts&watts?

[Amish David]

Good morning everyone I just purchased a full set wheel hub and Battery recently I'm fixing to hook it up today. My question is is this I have a 48 volt 20 amp hour battery with a 1000 watt rear wheel hub. Is a 20 amp fuse going to be okay from the battery to the wheel hub in case there is ever any issues it will not fry the battery box or my wheel hub.

 

[harryS]

No, a 20A fuse will be too small. I can get 20A peak out of a 36V 4AH battery powering a 250W motor. It's the controller, in my case a 20A controller, that controls current flow.

Look at your controller label and see if it says max current. That will give you fuse info. Most people don't use fuses. It adds complexity, and if the fuse is poorly installed/wired in, it will get hot and waste power if that happens.

The amp hour rating of a battery is a rating of its capacity. 20AH is capable of 20A for 1 hour, 10A for 2 hours, 2A for 10 hours, etc. You would have to know how the battery is actually made to know its max current potential. For example, A 20AH lead acid battery is different from a 20AH lithium battery. And for lithium batteries, you have to look at the number of cells in parallel, and their brand.

 

[Amish David]

The battery pack actually says 250 volt fuse only on the battery Bank. And it OS Lipo, I put the fuse on there for safety reasons when I was installing the setup. I know that it's correct now so what you're saying the best thing to do is to delete the fuse and just go with a straight wire. I was just concerned if there was ever any issues that it would blow the fuse instead of arming the battery or the control module or the wheel hub. Thanks.

 

[harryS]

You used the 20A fuse to set up the controller and test the motor, but not yet run the bike on the ground yet? That would make sense. A motor spinning freely doesn't use much amps.

It's nice to know they want a fuse rated for 250V, but they let you figure out the value? By the way, the voltage rating means you could go up to a 250V battery and the fuse will blow safely if the rated current is exceeded. You don't want a fuse exploding when it fires. Some fuses are glass, for instance, with a fusible link inside.

Well, it's up to you. A fuse is nice if you're thrumming up a hill and overcooking the motor, but you don't want it too small so it blows when you need power to accelerate out of the path of a car or crazy dog.

 

[Amish David]

Thanks again. I will be using a lot of pedal assist I live in the mountains so at my age it's harder to get up to the house when I go to town. So perhaps maybe I should leave the fuse in but go with a 30 amp? And thank you for your reply, and your knowledge of e-bikes