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Firewheel mainboard cutout


esaj

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Now, we probably pretty much all know that Firewheel and most other wheels have the dreaded BMS-cutout problem. This can be solved by shunting the BMS, as mentioned in numerous places, and the instructions are, once again, here:

BUT, this topic isn't about the BMS-problem, but about the mainboard ("overspeed") cutout in Firewheel. Hobby16 thinks it's tied to the RPM of the motor, and so did I, until I noticed that I was sometimes getting the overspeed-warnings at lower speeds when the battery had less charge left. Today, I've had the "last" warning that says "Take care" at 26.5km/h (somewhere after 10km on the trip) and at 24.5km/h (about 18km on trip). Once I got home after riding little over 19km, I didn't put the wheel on charger and instead waited a while, added the kilometers to my signature, and zeroed the values on the bike computer. Then I took the wheel outside, and turned it on, the battery indicator was showing 25-26% stationary.

What followed was a series of "lift-tests", meaning I turn the wheel on and lift it off the ground so it can run free. I've done this test before, but with full battery, and was getting constant values around 39-40km/h before the wheel would shutdown the motor and start saying "Please restart the unicycle" (I think the variation depended on what point the the sensor-magnet was when the shutdown occurred, ie. higher speed if the magnet just had passed the sensor before shut down, otherwise the last "fastest" round of the wheel would seem slower to the computer).

This time however, I was getting low values at first (around 29km/h and once 19km/h), as the wheel would shutdown the motor very fast, if tilted more, it could even shutdown so fast that the bike computer didn't get a full turn to record any value (0km/h). After more tries, I got the wheel to run a bit longer at a time before the mainboard would shut the motor off, by tilting it very, very slightly forwards, so the acceleration wasn't as fast. I was constantly getting values around 35km/h.

So this leads me to believe that the Firewheel mainboard cutout is NOT (only) tied to the motor RPM, but (also) to voltage and/or current. I'd like to ask @hobby16 to perform similar tests with his FW F260 (lift-test with full battery and lift-test with battery much less full), if he could confirm this.

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Also, if @dmethvin could do the lift-tests with full and near-the-end battery charge also (do you have a bike computer on your Firewheel?), that would give us more data to work with. Or anyone else who has a Firewheel (any Firewheel, F132, F260, F520, F779) and can measure the shutdown speeds fairly accurately... Thanks  :)   

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@esaj

just tried it with a 25% battery with no load and 15% during lift-test. No warning at low speed, only the usual thresholds (beeps at 18km/h, "you're speeding" voice at 25km/h, "take care take care" voice at more than 30km/h. I have the feeling it's very hard to lift-test above 25km/h without triggering rapidly the cut-off, much harder than when the battery is full. So not exactly the same behavior than your FW. BTW, my board is from March, so more recent than yours, maybe this explains that.

I will try another lift-test at 0% battery this evening.

I wonder if asking directly Firewheel will give you better information, since the successive mainboard & firmware versions may render our comparison moot.

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@esaj

just tried it with a 25% battery with no load and 15% during lift-test. No warning at low speed, only the usual thresholds (beeps at 18km/h, "you're speeding" voice at 25km/h, "take care take care" voice at more than 30km/h. I have the feeling it's very hard to lift-test above 25km/h without triggering rapidly the cut-off, much harder than when the battery is full. So not exactly the same behavior than your FW. BTW, my board is from March, so more recent than yours, maybe this explains that.

I will try another lift-test at 0% battery this evening.

I wonder if asking directly Firewheel will give you better information, since the successive mainboard & firmware versions may render our comparison moot.

​Thanks! Yeah, it could be different behavior between different mainboard revisions, and even when the mainboard design isn't changed, they could still change the firmware between different batches of same board design. But thanks for testing anyway :)   The second warning on mine says something like "Warning, ..<never heard the rest clearly enough>...", I've never really heard it clearly, but I'm pretty sure there's the word "Warning" somewhere.

Edit: I always reset the max speed recorded on the bike computer after each test, so I can read the recorded max speed after the wheel shuts down, and don't need to try to see what the highest value was before the shutdown while it's running. It's tricky to get it to max speed with lower battery during lifting, you need to hold it pretty precisely level, so the acceleration is slower, otherwise it will shut down before the actual max speed. I didn't notice it giving any of the voice-warnings to me during the lift test (I seem to recall it did play the first "beeping" warning, but not the "Warning..." or "Take care"-messages), might be that the cutout is too fast for it to have time to playback those.

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Also, if @dmethvin could do the lift-tests with full and near-the-end battery charge also (do you have a bike computer on your Firewheel?), that would give us more data to work with. 

I don't have a bike computer but would be interested in getting one. What do you have?

The control board I have is relatively new since they had to replace the original one that was fried. ​

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I don't have a bike computer but would be interested in getting one. What do you have?

The control board I have is relatively new since they had to replace the original one that was fried. ​

​I have cheap(ish) Sigma 1200 -bike computer (cost around 20€, so about $22.50), that I took from my bike, probably you could get similar for much cheaper too (I've seen wireless bike computers for less than $10 in eBay or something similar, this one's wired), but I just bought mine from a local supermarket. I did a "temporary" installation by taping the magnet to the wheel rim and the sensor on the side of the shell, then taped the wire to the side and attached the computer stand (the computer itself is detachable from the stand) with some rubber bands. It's seen briefly at the beginning of this video:

 

Not the most optimal place, as it's pretty hard to read it at first while riding, after a while I learned to do a quick glance down to see the current speed. In the longer run, I've thought I'd get one with wireless sensor, so I could attach the actual computer to either inside my visor or on the backplate of my wristguard.

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I don't have a bike computer but would be interested in getting one. What do you have?

The control board I have is relatively new since they had to replace the original one that was fried. ​

​I've installed a wireless one, "Sunding" brand, but it's so imprecise because of RF transmission problem that I have removed it.

Now I have this wired version, it works flawlessly.

DSCN1442.jpg

See more details about installation in my pictured tutorial here : http://trottinetteselectriques.heberg-forum.fr/sutra21627_montage-compteur-kilometrique-v2.html#21627

The idea is to use 2 rigid wires as connexion AND as support frame.

I have some prepared bike computers, with all parts ready to install. If you want one, please PM me. The first one was very very long to fine tune so I made several copies for those to want a bike computer without all the hassles I had.

DSCN1606.jpg

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Thinking of getting this wireless bike computer, it has great reviews and the price is good. Maybe I could wear the readout like a watch? It might be easier to see it, looking down at the wheel while I'm moving is not a good thing.

Yeah, I've looked into the CatEyes, they have wireless version(s) with backlit display, which would be good for helmet visor -mount (it's dark inside ;)) or night riding...  ​Though hobby16 makes a good point above that I hadn't thought about:

I've installed a wireless one, "Sunding" brand, but it's so imprecise because of RF transmission problem that I have removed it.

If the wireless computers use radio-frequency transmission, the motor of the wheel and other sources of RF-"noise" may cause enough interference to make it almost unusable  :wacko:

Unless he was just referring to that specific brand just being low quality...

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Unless he was just referring to that specific brand just being low quality...

​No no, even the most costly wireless bike computer is not usable if the sensor-screen distance is > 1m, so don't even dream of having the screen on your wrist. The transmission distance is so low that when I put the sensor near the Firewheel's pedal (to avoid dismounting the housing), no transmission occured as soon as the wheel is on ! I have tried 2 wireless bike computers without success. But you can look up the problem on bike forums, the wireless transmission is very susceptible to electromagnetic noise (eg problem when riding next to powerlines), and EM rules in monowheels.

t's not hard to understand, the wireless transmission is not very powerfull to preserve the sensor battery, hence the problem.

I will have more pictures of French users installing my system which is, IMHO, the most streamlined I've seen so far, I'll post an English tutorial some days.

 

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@esaj

I just checked again the lift test with battery level at 0, even with no load (so a really empty battery).

No change, the 5 buzz occurs always at 18km/h and impossible to have the "take care" voice since the wheel accelerate rapidly until cutoff.

So on my Firewheel version, I can conclude the warnings are at fixed speed, a predictable behavior exactly like I want.

 

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@esaj

I just checked again the lift test with battery level at 0, even with no load (so a really empty battery).

No change, the 5 buzz occurs always at 18km/h and impossible to have the "take care" voice since the wheel accelerate rapidly until cutoff.

So on my Firewheel version, I can conclude the warnings are at fixed speed, a predictable behavior exactly like I want.

 

​Ok, good to know. With my lift tests, the cutouts occurred too fast to tell when (or if, I don't recall if they even played) the warnings played, maybe have to check that again, right now the magnet isn't on the wheel rim, as the taping failed, have to redo it. Also, I was wondering if I'd maybe hit some bump or something when getting the "Take care"-message in (at least seemingly) lower speeds, the wheel would have to turn a bit faster to re-balance after such, but it might be too fast for the bike computer to notice if it's just a short burst. The bike computer is the kind which seems to measure the number of signals (magnet passing the sensor) per second it gets, instead of measuring time difference between two signals (as it was doubling the speed when I had the problem where the sensor would get two signals right after another, when the magnet was in wrong position). Although to go from something like 24.5km/h to around 28km/h in short burst sounds like a lot... Or then it's simply just different with the older board.

But I don't have much use for the warnings anyway, what I'd really like to know is can it shutdown on me with lower battery in lower speeds than with fuller battery. Of course there's always to option to simply try it by riding... :rolleyes:  Time to learn running to stop from around 30km/h? ;)

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But I don't have much use for the warnings anyway, what I'd really like to know is can it shutdown on me with lower battery in lower speeds than with fuller battery. Of course there's always to option to simply try it by riding... :rolleyes:  Time to learn running to stop from around 30km/h? ;)

​Don't know on your version but I can certify mine never ever shuts down at low battery without forcing you to climb down by pedals tiltback.

When I climb a steep hill and I can't reach 18km/h, there is no sound warning. Here is what happens : battery full => I climb faster, battery low => I climb slower, too much forcing by too much body incline, I fall. A totally predictable behavior, and none of this bloody cut off.

Yeah, try to flirt with 30km/h or above, on a nice, large and straight road, ignoring the warning voice. You should have the warning-by-acceleration. I have it several times per trip (but only on the roads I know perfectly well, on new trips, I ride at more reduced speeds).

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Given your feedback about wireless bike computers I don't know that I'll get one, wired or wireless. I don't think I'd use one that was fixed to the wheel. Also it's starting to get crowded down there because I have a mount for my camera as well. I need to figure out how to chop up the video so you can see my wipeout.

 

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  • 8 months later...

You could always calculate the hole placement and drill a small hole on center. Then all you have to do is drill it to the desired diameter. As long as you take your time and don't push hard it should come out looking pretty nice. Of course you'd wanna remove the motherboard first to be safe.

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