Precharge resistors

[fechter]

are you guys mainly putting the resistor on the battery pos. or controller pos. side?

I don't think that will matter. Either side. It's a series circuit.

It's an easy test to try a 10 or 100 ohm resistor and see what the controller voltage comes up to and how hot the resistor gets. I'd lean more toward the 10 ohm side.

 

[ebike11]

Hi
The qs10 connectors have a 5.6Ohm built in resistor but its too fast for a large 96V controller with large caps. Would 10ohm work though?

 

[fechter]

At 96v, the peak inrush current would be 9.6A with a 10 ohm resistor. The contacts should be able to handle that no problem.

 

[999zip999]

In between

 

[ebike11]

In between

In between what?

 

[Jonndeka]

Hello guys,
Could you please guide me about precharge resistor calculation?
I searched in google. some mentioned a capacitor. But in my application I don't have capacitor.
What parameters do we need to calculate precharge resistor?

My reference was here.

 

[larsb]

One thing to add here is that you need to add all consumers to the precharge current calculations. Let’s assume there is a dcdc converter pulling 50W that’s connected always ON in the main power circuit, could be if there are lights that are always on, could be the consumption of some auxiliary circuit, then your precharge resistor needs to be low enough to supply current both for that and for the charging of the controller capacitors.

100v system and 50w, 0.5A needed for that - so max precharge resistance would need to be less than 200ohm, on top of that the current to charge the capacitors within a reasonable time.

 

[Jonndeka]

One thing to add here is that you need to add all consumers to the precharge current calculations. Let’s assume there is a dcdc converter pulling 50W that’s connected always ON in the main power circuit, could be if there are lights that are always on, could be the consumption of some auxiliary circuit, then your precharge resistor needs to be low enough to supply current both for that and for the charging of the controller capacitors.

100v system and 50w, 0.5A needed for that - so max precharge resistance would need to be less than 200ohm, on top of that the current to charge the capacitors within a reasonable time.

Thanks. Do we need to consider capacitor of converter for calaculation?

 

[larsb]

Yes, i think mxlemming explained it well in his previous post in this thread.

 

[eee291]

The controller is seeing some power because it beeps faintly and the Cycle Analyst screen with random flashing and display Low Volts etc because the main leads arent connected

Well there's your problem, you have it powered on while precharging, by the time you plug in the anderson plug the caps have already discharged.
The cycle analyst needs to be off or disconnected, the controller also needs to be switched off.