Actually Im not sure. I didn't check motor or battery temps. But nothing didn't overheat. I'm sure that cold air+snow helps with cooling. And I think that the motor would have burned without cold air and snow
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10kW 72v Electric mini bike build
- Thread starter Jacka98
- Start date
Cool videos! Watched some of your other videos in your channel. Is the battery pack in the 72V 10kW minibike soldered with copper strips? Reason I ask is that I have a heavy duty soldering iron but no battery spot welder. I know how to solder but no experience spot welding if I ever want to build a pack.
Thanks! Yes it is soldered. I used ladder type 0.2mm copper strip.
SlowCo
1 MW
Its getting pretty cold in here-30C
That's really too cold. I hate it that it will start freezing (-1 to -3 degrees daytime) here from tomorrow for a few days.Enjoy your "winter sports" on the mini bike!
I'm upgrading the battery. There is a little video of that if anyone is interested. Previous battery was 20s 7p and the new one is going to be 20s 8p. So I can take more power
Lets see what is qs90 motor limits. And also I'm upgrading controller to fardriver 72680
Looks like you spot welded this one. How did the last one (that was soldered) hold up?
I'm upgrading the battery. There is a little video of that if anyone is interested. Previous battery was 20s 7p and the new one is going to be 20s 8p. So I can take more power
it was ok. I put it to the other project. Battery cells started to be were pretty old (3-4 years old) so the voltage drop started to rise littlebit.
I used my QS260 Hub 60V5000W 1 with a ND72680 and burnt the phase wires. After changing the phase wires from 13.3mm² to 16mm² 205C I could turn up the power to 22kw.Also I did upgrade the qs90 phase wires. Old ones were starting to melt
The windings also looked fine.
Don't forget to add a temperature sensor , if your motor does not have one.
Yea I also installed ntc 10k temp sensor, so I can monitor the temps
Be carefull with the phase amps.
I melted my AWG 6 wires in a few minutes driving uphill with 18kw.
The fardriver can do around 600A continous not peak and normaly the fardriver is set to use field weakening. This will produce much more heat when you try to get faster. I had a separate temperature sensor in between my phase wires with the sabvoton SVMC72150 I had installed before and there I already reached 180C driving uphill.
I melted my AWG 6 wires in a few minutes driving uphill with 18kw.
The fardriver can do around 600A continous not peak and normaly the fardriver is set to use field weakening. This will produce much more heat when you try to get faster. I had a separate temperature sensor in between my phase wires with the sabvoton SVMC72150 I had installed before and there I already reached 180C driving uphill.
I will probably turn off field weakening for most of the time. It reduces the efficiency. I have always been confused about fardriver rpm % settings. I have to learn how all the settings affect the performance. I will only do short bursts. If I put full power continously it will 100% burn. Also I have to upgrade the motor when it burns or I get tired of overheating.
The rpm % settings are percents of the max phase amp value.
If you set max phase amps to 400A and set 100% at the lowest rpm value you will get 400A phase current from zero rpm.
In the factory setting is set 100% at the lowest falling to 0% at the highest rpm after you have done auto learn.
That gives you a smooth acceleration.
If you want faster acceleration you can raise the values in the lower rpm range.
I have set my first 4 values to 100% that gives me the 1400A phase current I have set as a max value.
With this setting my controller draws 400A at 30kph (30kW), which gives the fastest acceleration I can reach with 400A battery current.
The field weakening is only used when you are near top speed and the controller is not able to reach the disered phase current.
If fw is not needed then it won't waste any energy.
You can see it in the raising yellow line on the graph near top speed. This was from the ND72680 with the QS60V5000W 260 hub motor, where the topspeed was raised from 107kph without fw to 120kph.
When I was driving constantly with 90-100kph fw was not used only when I was accelerating, to get more power.
If you set max phase amps to 400A and set 100% at the lowest rpm value you will get 400A phase current from zero rpm.
In the factory setting is set 100% at the lowest falling to 0% at the highest rpm after you have done auto learn.
That gives you a smooth acceleration.
If you want faster acceleration you can raise the values in the lower rpm range.
I have set my first 4 values to 100% that gives me the 1400A phase current I have set as a max value.
With this setting my controller draws 400A at 30kph (30kW), which gives the fastest acceleration I can reach with 400A battery current.
The field weakening is only used when you are near top speed and the controller is not able to reach the disered phase current.
If fw is not needed then it won't waste any energy.
You can see it in the raising yellow line on the graph near top speed. This was from the ND72680 with the QS60V5000W 260 hub motor, where the topspeed was raised from 107kph without fw to 120kph.
When I was driving constantly with 90-100kph fw was not used only when I was accelerating, to get more power.
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thanks for the good explanation. If I remember right with "weak response" setting you can turn on or off the field weakening?
Fardriver still needs a littlebit of tuning.
SlowCo
1 MW
More smoke than a two stroke...
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