CEF50 External battery build

[mike_kelly]

Not possible. The Bafang charge connector is only designed for 2amps, the wires are not big enough to handle the current to drive the motor.

 

[hamncheez]

Not possible. The Bafang charge connector is only designed for 2amps, the wires are not big enough to handle the current to drive the motor.

My proposal is to leave the frame completely unmodified, and the auxiliary battery would connect directly to the charging port, which is again unmodified, so the power goes into the main battery.
I've tested mine with the supplied charger, the motor still turns on and runs when external power is supplied.

 

[mike_kelly]

All you are going to do is charge the main battery from the external, slowly, from the external battery. Not going to help much in a ride. For a 360whr 36v battery 360/36= 10amps 10/2=5 hours or more considering the external battery voltage will drop and as soon as it is lower that the main battery it will stop transfering energy.
If the charge port is simply in parallel with the main output port you risk all the dangers, with the exception that the small 2 amp charge wires would probably act as a fuse as they catch fire and burn.

 

[hamncheez]

All you are going to do is charge the main battery from the external, slowly, from the external battery. Not going to help much in a ride. For a 360whr 36v battery 360/36= 10amps 10/2=5 hours or more considering the external battery voltage will drop and as soon as it is lower that the main battery it will stop transfering energy.
If the charge port is simply in parallel with the main output port you risk all the dangers, with the exception that the small 2 amp charge wires would probably act as a fuse as they catch fire and burn.

So what you're saying is I should have ordered the 700wh battery!

 

[mike_kelly]

yep. If you are riding for two hours after work every day the 360whr is fine and lighter. if you want to do epic all day rides you need more juice.

 

[hamncheez]

yep. If you are riding for two hours after work every day the 360whr is fine and lighter. if you want to do epic all day rides you need more juice.

I got the custom 410wh battery, which sounds fine compared to the competition, but I ride at 5am and on my natural bike I like to do at least 2,400 feet of climbing, sometimes over 3,000. I was hoping to go even bigger on an ebike, but this motor in B mode reports a consistent 580+ watts, so if you do the math you aren't even getting 45 min before you hit the 20% cutoff to Eco mode. At first I was a bit frustrated, but physics is physics.

 

[mike_kelly]

I got the custom 410wh battery, which sounds fine compared to the competition, but I ride at 5am and on my natural bike I like to do at least 2,400 feet of climbing, sometimes over 3,000. I was hoping to go even bigger on an ebike, but this motor in B mode reports a consistent 580+ watts, so if you do the math you aren't even getting 45 min before you hit the 20% cutoff to Eco mode. At first I was a bit frustrated, but physics is physics.

Yes the motor is not designed to be used in boost except for short steep climbs. Bafang warns against using it for continuous boost riding and 700whr or larger batteries designed to enable this type of riding. Just not the right motor.