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V8S: Overload when just departing


marcelsamyn

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I'm starting to really get the hang of riding the unicycle with 1400km under my belt! It's so much fun.

The following happened for the third time this morning and I'm curious to hear what you guys think or if anyone else has had this: with a fully charged battery I was just taking off, say 150m from my house, when the wheel started tilting back with "overload, please get off." Today it stopped relatively quickly but previous times it'd go on for 5 minutes and wouldn't balance even when turning it off and on. It was cold-ish today, between 0 and 5 degrees (Celsius).

Do EUC's have much less power in their first few minutes after being turned on? Or would it need to warm up a bit?

I like accelerating of course but don't know if I'm really going too hard often. Of course when accelerating on a hill I expect that this might happen; otherwise I've only dipped the pedals once when I was trying to see how quickly it could accelerate (so also to be expected there).

Does this mean I'm already riding too close to the limits of the V8?

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When you ride downhill you are charging the battery using regenerative braking. If you are at 100% Battery when you set off and immediately go downhill this will cause the wheel to potentially overcharge*. To protect the wheel, depending on age, make and model it will either cut out or in most cases warn you and tilt back. To stop this happening either ride around flat ground to drain the battery slightly or if you can't do this, only charge the battery to 99% or so. 

Edited by The Brahan Seer
*sorry- overvoltage according to mrelwood.
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1 hour ago, mrelwood said:

That I don’t know. But you trying to find out by experiment is really not a smart thing to do, on any EUC. Also be careful when approaching the maximum speed, as the tilt-back can be a surprise at those speeds, and it may not catch you if you are accelerating hard past the limit.

Wow, thanks for your detailed remarks!

Maybe that first message sounds like I'm very careless which is not the case, but still good to be reminded of the dangers. I've got my speed alarm at 30km/h so that's even 4 below what Inmotion deemed the maximum. In my experience so far, tiltback has been coming quite gently and it seems to be helping me well in getting a feeling for that 30kph (or less when the battery is at a lower charge).

I do start on a decline but it's a very short one, like 20 meters less than 10 degrees (on cobblestone). (Haven't measured it)

Good point on the storage. I store and charge it inside so at that time it would probably still be pretty much at room temperature.

Will start logging next times and see what the app is saying when it'd happen again!

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31 minutes ago, marcelsamyn said:

 

I do start on a decline but it's a very short one, like 20 meters less than 10 degrees (on cobblestone)

That would be enough. I had exactly the same thing happen to me on my V11 a couple of days ago. when the battery is really brimful even very little recuperation is apparently sufficient to trigger the alarm and cut-off.

Edited by mhpr262
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I used to get overvoltage beeps on my 16S when braking at higher medium power after 200 meters on flat surface. Regeneration can create a lot of temporary voltage.

Edited by mrelwood
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Hmm, now the wheel woke me up at 5AM while charging asking me to get off 🤷‍♀️ Stopped after a minute once I pulled it out of the charger.

Checking in EUC World for half a minute showed the voltage at 87V (max 87.3V) which I think is too much? Seeing the M50T at 4.2V charge current in other places, but this would have them at 4.35V. Don't know too much about battery science though.

Would the charger just be keeping charging even though it's going too far? Sounds very odd to me that that could happen.

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23 minutes ago, marcelsamyn said:

Hmm, now the wheel woke me up at 5AM while charging asking me to get off 🤷‍♀️ Stopped after a minute once I pulled it out of the charger.

Checking in EUC World for half a minute showed the voltage at 87V (max 87.3V) which I think is too much? Seeing the M50T at 4.2V charge current in other places, but this would have them at 4.35V. Don't know too much about battery science though.

Would the charger just be keeping charging even though it's going too far? Sounds very odd to me that that could happen.

That sounds very bad! I wouldn’t store the wheel inside until you get to figure this out. If the charger is faulty and charged the wheel up to 87V, the battery is in a seriously dangerous state right now.

 Do you have a multi-meter you could use, borrow or buy to measure the charger output?

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  • 4 months later...

Thought I'd follow up here with the newest developments of the story, so the information is out there :)

I don't recall exactly, but the charger output was neatly around 84V when measured with a multimeter.

The response from Inmotion France was "don't worry; if it's a high voltage at standstill, and the system check doesn't notice anything wrong—it's okay." Wasn't terribly convinced by that so I continued charging the wheel only until EUC World showed 84V. The charger never turned green.

Thinking the charger might be faulty I got one of the EUnicycles smart chargers. Yeah they work for both the V8S and V11 even though the contacts on the connector are rotated.

There's a huge discrepancy between the voltage measured by the charger and the one measured by the wheel, 5-6V! So when the charger measured around 81V (and still quite some charging left to do), the app showed 87V and the wheel went into what I assume is the overvoltage alarm. (overload, please get off)

MSP_9537.thumb.JPG.50c9e3145ce2df0f66c34c9d4165dc41.JPG

So now this is starting to sound more like a poorly calibrated voltage meter in the wheel or something. I'll follow up with Inmotion support and see what they say.

Edited by marcelsamyn
pics or didn't happen
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11 hours ago, marcelsamyn said:

So now this is starting to sound more like a poorly calibrated voltage meter in the wheel

I agree, so far it points to that. Your seller can arrange a date with Inmotion where they calibrate the wheel's voltage metering remotely. That difference is definitely too large, as it will engage the wheel's overvoltage protection where it shouldn't.

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  • 1 year later...
  • 9 months later...

Same issue after fully charged. Should I be worried? The 'poorly calibrated voltage meter' idea sounds reasonable to me. I have to say that I asked my dealer who reccommend to change the battery. He didn't not provide any color though and I'm not so sure, also because the  650€ he asked me! If I charge till all green bars are on and the disconnect the charger, the weel does not ask to get down.Should I be worried? The 'poorly calibrated voltage meter' idea sounds reasonable to me. I have to say that I asked my dealer who reccommend to change the battery. He didn't not provide any color though and I'm not so sure, also because the  650€ he asked me! If I charge till all green bars are on and the disconnect the charger, the weel does not ask to get down.

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