What draws more current as more power is applied other than the motor?

[TECH_GEEK10]

I have a new bike build I am setting up with a cycle analyst 3, grin phaserunner 6, std wind grin rear all axle hub motor, erider torque sensor, 72v 20ah 80A battery, 400w dc-dc converter powering ca3. I have finished assembling it and it spins the wheel when unloaded, but when I ride it I think the ca3 resets. The dc-dc converter says that as power is going to the motor, the more goes in the more the ca3 draws. I've seen it go to 400ma at times, maybe more. the ca3 is hooked up to run on 12v from the dc converter and has a 200v 1000uf capacitor on the 12v out put to smooth it. Any ideas why it is resetting when I apply power? My guess is something is over loading the ca3 's power supply. I know at 12v it is only able to supply like 750ma or something.

 

[amberwolf]

if the torque sensor runs on the 10v supply, then it might be overloading the ca regulator. this might only apply when running off battery voltage, as i haven't dealt with this issue in a while, but there is a note either on the cav3 info page at ebikes.ca or in the ca manual aboutt it that shoudl clarifiy.

12v is pretty low to power the ca with, too, usually 15v or more is recommended iirc. if so any dip in voltage could reset the ca. so if your dc-dc glitches from voltage sag or other noise on the battery input line, it might be enough to reset the ca if the cap between them is drained back by the dc-dc, or is otherwise drained by anything else in the system running off that 12v line.

if your 12v dc-dc is "automotive" 12v, it will be 13.6-14.4v or so. some go as high as 15v, most don't.

at 72v battery range you can often use regualr ac-input wallwarts with battery voltage fed to the ac inputs, and goodwill and other thrift stores often have lots of old laptop power supplies that run at 19v, which should run the ca easily enough.

 

[offGridDownUnder]

a cycle analyst 3, grin phaserunner 6, std wind grin rear all axle hub motor, erider torque sensor, 72v 20ah 80A battery, 400w dc-dc converter powering ca3

Wanting to understand.

I have a 48V battery connected to a V4 Baserunner, to CA3 & motor. No dc-dc converter.

What is the converter for in your set up? My set up has no requirement for that.

 

[amberwolf]

At least some versions of hte CAv3 have a current limit on the 10v supply (used for some torque sensors) that drops the higher the voltage battery is used. If your sensor draws more current than that it can blow up the CA's power supply. I have an old thread where i started trying to learn how to repair this damage when it happened to me (because there is no warning label on any of the parts to tell you this).

I think hte manual has a note on this somewhere.

If hte sensor runs on 5v and has no 10v connection it's probably not an issue (as long as it doesn't draw more than the CA's 5v supply can handle).