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The Inmotion V8 tried to kill me 5 times. One time it almost succeeded.


enGate
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I just noticed that the Light effects rolled back to the DIY settings I made about 2 hours ago.(I changed it to one of the original effects before the ride)

 So seems like the firmware crashed and couldn't save the settings.

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Thanks for the write-up. We just had a situation (though a bit different) where the V8 suddenly went crazy (here).

Sudden changes in behavior of wheel = very likely a bad board (can't think of another explanation). Also a big warning sign to stop riding it when that happens, but it may be hard to judge with only very rare occurrences.

Would be sad to write it off after only 4 months and 200km. Where did you buy, do you have warranty? You can get it repaired (new board) or returned (if you have trust problems now, or want to upgrade anyway).

Not remembering settings may be another symptom of bad board.

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I sorry to hear of your bad falls.

After your crash was the wheel still powered on? I ask as it looks like WheelLog continued to record some data after the rapid deceleration. I'm guessing any kind of power loss (bad connector to the board) would have terminated WheelLog data at the same time.

Like @meepmeepmayer says this is likely a bad board. You seem to have been maintaining a constant speed below the max limit and the current draw on the cells was within the 20A max for the V8s 2 parallel pack. At 10C with a 94% battery I wouldn't have expected any kind of overload issues from the cells.  Were you on a hill at all? Do you always fully charge your battery or do you perform partial charges below max capacity? Can you freely rotate the wheel when it is powered off?

I've never felt this 'wobble' in the 700km I have ridden my V8. I'm starting to wonder if such behavior is a portent of a future catastrophic failure. A hint that something isn't right.

Doesn't the V8 have a diagnostic section in the app? Try running it.

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I am not so sure about "just" having a bad board.....

For the boards -mainly they work or they dont- perhaps some of the batteries are dead that lead to shutoff by BMS, can also be a reason.

We no to less of the design of the IM BMS, to say that it is without flaws.

 

Before retiring it i would go and measure each of the cells individually. If just one or two of the cells measure at a lower voltage than the rest you might have found the culprit.

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On a semi-unrelated note, does anyone have any idea just how useful/effective the Inmotion 'Diagnose' scan is?

I always make it part of my v5f+ 'pre-flight' check along with tire pressure and scv correction.........although as someone with zero electrical/sensory knowledge, I'm intrigued as to whether this is indeed thorough or more of a basic placebo scan that is only ever going to pick up trivial things like communication problems between phone and wheel.

Edited by Paddylaz
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One thing as a general note: the french forum has a much larger number of V8 riders than we do and is a good place to visit for info on these issues. 

Interestingly, the french forum not only has a higher number of V8 owners, but the V8 is also a more popular model there than it is here relative to other brands.  At least that's my perception.  Maybe it's because most french EUCers are city riders.

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I did a test ride about 15 minutes ago with proper protection this time and speed limited to 15km/h. Full cutout at 9km/h. The front light was on and everything went dark for about 1 second and then came back. The front light didn't turn on ofc.

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5 minutes ago, meepmeepmayer said:

Well, at least you know now there's a definitive problem. :efee8319ab:

I'd return it if you can, no excuse for such a new wheel to fail like this. Can you?

It will be difficult to return it to china.That's why i'm trying to fix it myself.

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So do you occasionally leave the wheel on charge for a few hours after the light on the charger has gone green? If not this would be the first step to allow the BMS to balance all cells in the pack. I'd do 6-8 hours once green considering the severity of your issue. Once disconnected allow the pack a few hours to rest. Using WheelLog take a note of the voltage at this point. Then take a test ride.... Carefully! 

Edited by WARPed1701D
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Just now, WARPed1701D said:

So do you occasionally leave the wheel on charge for a few hours after the light on the charger has gone green? If not this would be the first step to allow the BMS to balance all cells in the pack. Try this and then test.... Carefully! 

Yes,after about every 3th charge cycle. Actually one time the charger couldn't charge it all the way up.The LED was green but on the EUC battery level it had only 4/5 bars.That was before the first crash.

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Have you tried contacting Inmotion? Thankfully I have never had to but i did blow my IPS wheel up and they were really helpful in getting me to test this or that to diagnose the issue so they could send out the correct new parts. Worth a try.

Gotta say the not charging full thing sounds like a duff cell or three...

Edited by nute
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I would say a battery that cannot accept a full charge is indicative of one or more bad cells. What is beyond my knowledge level is how this would affect the charging indicator when there are two packs in parallel. If one was fine and one was compromised I would have thought the wheel would still report a full charge based on the good pack voltage but the V8 BMS is connected to the main board so maybe they are inspected independently with the lower pack voltage driving the reading shown on the display. I do know that any voltage below 82.5v is considered < 100% charge level on the V8. I also am not sure why having one compromised pack (with BMS shutdown) would cause complete power loss when the other pack is likely fine. Sure capacity would be halved, as would the max deliverable current, but your earlier failure showed current draw around 5A (well below the 10A max of a single cell bank) so you shouldn't have been dumped. There are many battery experts here who can likely provide more help in this area than I.

Out of interest, what kind of range have you been getting from a full charge?

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2 minutes ago, WARPed1701D said:

I would say a battery that cannot accept a full charge is indicative of one or more bad cells. What is beyond my knowledge level is how this would affect the charging indicator when there are two packs in parallel. If one was fine and one was compromised I would have thought the wheel would still report a full charge based on the good pack voltage but the V8 BMS is connected to the main board so maybe they are inspected independently with the lower pack voltage driving the reading shown on the display. I do know that any voltage below 82.5v is considered < 100% charge level on the V8. I also am not sure why having one compromised pack (with BMS shutdown) would cause complete power loss when the other pack is likely fine. Sure capacity would be halved, as would the max deliverable current, but your earlier failure showed current draw around 5A (well below the 10A max of a single cell bank) so you shouldn't have been dumped. There are many battery experts here who can likely provide more help in this area than I.

Out of interest, what kind of range have you been getting from a full charge?

About 20-30km

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17 minutes ago, WARPed1701D said:

also am not sure why having one compromised pack (with BMS shutdown) would cause complete power loss when the other pack is likely fine. Sure capacity would be halved, as would the max deliverable current, but your earlier failure showed current draw around 5A (well below the 10A max of a single cell bank) so you shouldn't have been dumped. There are

If the packs are real paralleled and one shut down it depends on the BMS working what happends...

On good wheels real parallel packs where each has an BMS, these should communicate...

Can be quit pe dangerous if not (DIY paralleling..)

I would suspect the V8 only to have one BMS for the 2 parallel systems...so it is possible the complete pack shuts down on one cell failure..

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11 minutes ago, KingSong69 said:

What and how did you check?

EACH of the 40 individual cells?

Nope. That would be more difficult. It's in a group of 2 cells. So I checked every single group. By going from the right to the left (B1,B2,etc) if the output voltage increased by 4 then the cell group is good.

Edited by enGate
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Get the battery pack out. use it to power a few parallel light bulbs, totaling 800W( or 8 ohm resistance in total ) to simulate the power draw of motor. Measure the voltage or each cell while the current is flowing. Pay attention to voltage drops because that indicates larger than normal internal ohm of a cell.

One 100w light bulb in 220V is 100/220*80 w under 80V voltage. You need about 20 of these light bulbs in parallel to simulate 800W power draw.  Probably you can just do a 400W power draw using 10 100w light bulbs. If it is 110V in your country, then 5 light bulbs will do.

OR If you know someone with V8, take his battery pack to test.

 

Edit: Just as @Chriull said, the cold the ohm at cold can be much lower than the ohm of a light bulb when hot. So, start with fewer light bulbs, measure the electric resistance. Aim for 10 ohm to get 400w power draw.

Edited by EUCMania
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54 minutes ago, EUCMania said:

Get the battery pack out. use it to power a few parallel light bulbs, totaling 800W( or 1 ohm resistance in total ) to simulate the power draw of motor. Measure the voltage or each cell while the current is flowing. Pay attention to voltage drops because that indicates larger than normal internal ohm of a cell.

One 100w light bulb in 220V is 100/220*80 w under 80V voltage. You need about 20 of these light bulbs in parallel to simulate 800W power draw.  Probably you can just do a 400W power draw using 10 100w light bulbs. If it is 110V in your country, then 5 light bulbs will do.

OR If you know someone with V8, take his battery pack to test.

@enGateJust care should be taken in because of the (much) lower cold resistance of light bulbs! So using less at the first try could be not the worst idea.

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It's very hard to regain confidence in a wheel once it's done what yours has. I have a cheapo generic that dumped me when I went down a 2cm ledge. Bloodied my hands. I've never ridden it since.

Maybe use this opportunity (if you can) to upgrade to a new more powerful wheel. KingSong or Gotway. You probably want to anyway :D

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