V8f Bricked - HELP

[Carey]

My son's V8f bricked when he tried to start it after a class at college. It had had no problems for the six months since I bought it for him. Now, when the power button is pushed, the battery level light bars illuminate from bottom to top, then fade out, with the bottom two bars being momentarily visible, and then all the lights are gone.  The wheel does give an extremely brief bit of motion to straighten up the wheel, then powers off and rotates back to its original position. There was no crash before this event, and he has never had a bad wipeout, but he has had numerous beginner falls at low speeds. The wheel won't connect to the App, it won't turn on, and if you try to turn it on, get the up and down lights show described above, and then try right away to turn it on again, you get nothing, no lights, no attempt at self correction, just nothing. 

I bought the wheel on Amazon on 10-2-22. It is past the 30 day return/service period. I submitted a review detailing the problem and to my surprise, was contacted by InMotion through the Amazon App and offered a full refund. I accepted the full refund on a reply message, but then received a followup message that indicated instead of a refund, I was to contact their service department through email. I have to say, if they hadn't offered a refund, I wouldn't have been surprised, but since they did offer a refund and then reneged on it, I am quite unhappy with InMotion.

Can anyone help me figure out what is wrong? 

Thanks, 

Carey

[gon2fast]

The InMotion website states that they offer a 1 year warranty on their products sold by authorized dealers. You should be able to send it in and get it repaired/replaced under the warranty, but that process can a take while once the wheel is sent out. 

 

[Carey]

Thanks!

[alcatraz]

Same thing happens on my V8. I just power on a couple of times until it stays on.

[amishpsycho]

Similar thing going on, i have to wait a couple minutes before it will even attempt to illuminate the battery bar.

in motion told me it needs a new battery.

i’m going to keep troubleshooting. Hopefully I can figure something out and I’ll let you know.

[redsnapper]

2 hours ago, amishpsycho said:

Similar thing going on, i have to wait a couple minutes before it will even attempt to illuminate the battery bar.

in motion told me it needs a new battery.

i’m going to keep troubleshooting. Hopefully I can figure something out and I’ll let you know.

Check the batt voltage with a DMM - if the voltage is as expected (@84v) the issue is not batt... if voltage low then charge and retest. If machine  within warranty then return.  There are lots of tear down vids for v8 to reach the board etc.

[mrelwood]

13 hours ago, redsnapper said:

Check the batt voltage with a DMM

Note that the battery cables on Inmotion wheels do not carry the full voltage when detached. The BMS needs a wake up call from the board in order to give out the full battery voltage.

[redsnapper]

59 minutes ago, mrelwood said:

Note that the battery cables on Inmotion wheels do not carry the full voltage when detached. The BMS needs a wake up call from the board in order to give out the full battery voltage.

Thx @mrelwood - so this has to be probed on the board itself (at batt+ batt-) while batt connected? Also make sure DMM is set to DCV - I was checking a batt once while distracted and had not noticed meter was set to measure current duh!!). Shorting the batt jarred me from my torpor as the sparks flew and my probs melted! Take away - be thoughtful and deliberate around the high current potential of EUC batteries!

[mrelwood]

37 minutes ago, redsnapper said:

so this has to be probed on the board itself (at batt+ batt-) while batt connected?

Yes. And as you already learned, it’s easy to mess up as is, let alone when probing a live mainboard.

[amishpsycho]

That’s good information I didn’t know that.

battery was 50% when it started the issue. 
when I disconnected from the main board it is 2 volts.

i’ll reconnect it and try again, maybe have a couple coffees first LOL.

[alcatraz]

Probing a live board doesn't have to be super dangerous. Ground/minus probe in one place and then move the other probe around being careful not to bridge anything. (VDC mode on the multimeter.)

[alcatraz]

If you suspect battery problems then I can inform you that the V8 battery is easy to open up to expose all the terminals for direct probing. Sure you need to remove one layer of heatshrink but because there's an external enclosure it's relatively safe to put it back without the heatshrink. You could use shrinkwrap if you're worried. The only slightly tricky part is to carefully get the cables through the enclosure hole, without damaging them. The insulation is quite sensitive and can tear if you pull too hard. 

[alcatraz]

It's possible that you've got a few low cell voltages, and a bms that won't balance (it happened to me). I fixed it by manually charging the discharged groups. This assumes that they aren't below the 2.5v limit where permanent damage occurs. V8 prevents turning on if a group is at 3.0v or below. That leaves a window of 2.5-3.0v where it's safe to bring the voltage back up. You need a single cell charger for that. A bad bms means it eventually will happen again later and that the wheel is compromised. For someone with a bit of knowledge the wheel can still be ridden for many many years.