Field weakening: Experiences, settings and tweaks topic

Hey all, just joined. We (I) need a better understanding of fieldweakening.
Just couple of thoughts:

  • When to apply? Higher DC range, mid, or from 0?
  • How much?
  • Other parameters under FW tab
  • Effect on tune and temperatures/ battery consumption
  • Effect on torque
  • How safe/ consistent is it? Eg. can it fail and put us in nosedive territory instantly?
  • How does FM apply this?

Curious if any can be documented for the next gen;)

Just to recap my own experience so far in the short period i use it:

  • DC tiltback with FW always 80%. Without FW i have it on 85% but do not dare to go there with FW active cause of the nervous DC needle and my fragile bones;)

  • I started off activating around 65-70% dc, now down to 50%. All at 30A.

  • Regularly hit speeds > 31mph pre-tiltback. Without it i hit tiltback at or before 28mph, 85% dc. Tire= Enduro@ 13psi, rider 155lbs.

  • Torque has been solid off/on trails

  • Board feels a little looser with FW which can be weird around topspeeds. Dont know how to stiffen it there without sacrificing the buttery feel at lower carve speeds.

  • Operating temperature of lfoc3 and Hypercore are slightly higher as is the battery consumption.

  • Higher drops and bonks need special attention since ERPM can reach 15000+ in freespin in a heartbeat which makes landing pretty tricky.

This is what i can think of currently, hope this thread fills up with good and useful tips.

  1. DC Tiltback
    Obviously the duty cycle is increasing slower with FW and you had more room left at the same 85% DC. I just did it the other way round. I had it usually at 80% and changed the DC Tiltback with FW to 85%

  2. Freespin for Drops and Bonks
    I use RPM limit to control the top Speed limited at 15000 RPM which is resulting in a freespin at 32 mph. Attention! This will also cause a NOSEDIVE at that speed.

Hey Hannes,

What dc do you use to start FW? Did you manage the board to behave more like an FM board with bonks limiting ERPM to 15000? I tried this but notice have to go much lower more like 12000 to get that kind of behavior. Maybe i missed some important settings causing it?

Interesting bit of info from @MaddMax here:
image

Yes, it is. Im using 50% for some days now and it feels better but as you say sometimes we’re occasionally delivered to the mercy of placebo (maybe i got used to the “feel”). Playing with ramptime sounds good, will try this.

Is there any reason the consensus is to set Field Weakening to use max 30A? I get people are used to 30A with stock packs, would it not be okay to set it higher if you’re using a higher discharge rate pack, such as a CBCSO (35A), CBSP (45A), TORque Pack (90A :flushed:), etc.?

There’s likely to be diminishing returns with higher amps but it wouldn’t hurt to try - I use 35A on my 18s board and I think Hannes uses 40A

It may help to think of Field Weakening like shifting to the next gear (though electrical vs mechanical), since it will give you increased top speed but at the cost of torque. When tuning it however, there a few items to consider:

  1. if you enable it to fast (esp under higher load), then the nose of the board dips slightly AND suddenly - it will usually hold, but is quite un-nerving.

  2. if you enable it to soon, then you loose torque (acceleration) before getting upto speed (though this is really only noticeable for racing - for normal cruising you could probably enable it as low as 10-20% and never notice).

  3. if you ramp it to slow, then it might not fully kick in before you reach PWM limit. Meaning you could hit premature pushback.

So, with this in mind (and a bit of ride testing) a trigger of ~50% lets you get full torque upto ~15mph (for avg weight rider), and 1000ms ramp makes the transition (into next gear) smooth whilst giving enough time for it to fully engage before hitting pushback limit (usually set at ~85%).