[EcoDrift.ru] Ninebot Z10: A Diagnosis of Common Issues

[mrelwood]

 

Quote

I'm not sure - but imho changing to green is when the charger shuts off?

Not any of my chargers. They keep giving the maximum voltage, and Charge Doctor keeps showing (diminishing) amps flowing into the wheel. I don’t remember exact amps, but I think it was somewhere around 0.5A where the charger turns green. Balancing is not at all finished at that point.

 

[Planemo]

1 hour ago, mrelwood said:

 

Not any of my chargers. They keep giving the maximum voltage, and Charge Doctor keeps showing (diminishing) amps flowing into the wheel. I don’t remember exact amps, but I think it was somewhere around 0.5A where the charger turns green. Balancing is not at all finished at that point.

This is very interesting and you have kind of proven what I have thought for some time.

I wonder how many peeps see the green light pop on and think all is done, thus never actually balance charging their wheels.

My wheels alway stay on charge for a good couple of hours after the light comes on. Dont know why I did it but always thought it couldnt do any harm as the bms would always protect overcharging.

[ir_fuel]

1 hour ago, mrelwood said:

 

Not any of my chargers. They keep giving the maximum voltage, and Charge Doctor keeps showing (diminishing) amps flowing into the wheel. I don’t remember exact amps, but I think it was somewhere around 0.5A where the charger turns green. Balancing is not at all finished at that point.

 

So it switches to green when it goes into constant voltage mode.

[Marty Backe]

15 minutes ago, Planemo said:

This is very interesting and you have kind of proven what I have thought for some time.

I wonder how many peeps see the green light pop on and think all is done, thus never actually balance charging their wheels.

My wheels alway stay on charge for a good couple of hours after the light comes on. Dont know why I did it but always thought it couldnt do any harm as the bms would always protect overcharging.

My wheels can often stay on the charger for day before I remember to unplug them.

[mrelwood]

2 hours ago, ir_fuel said:

So it switches to green when it goes into constant voltage mode.

Not immediately, as the current has already come down to 0.5 amps or so. I should monitor the Charge Doctor more closely to confirm or to have exact numbers.

[Chriull]

9 hours ago, Planemo said:

This is very interesting and you have kind of proven what I have thought for some time.

I wonder how many peeps see the green light pop on and think all is done, thus never actually balance charging their wheels.

My wheels alway stay on charge for a good couple of hours after the light comes on. Dont know why I did it but always thought it couldnt do any harm as the bms would always protect overcharging.

Since i just posted a bit about charging here a link:

 

15 hours ago, Chriull said:

Balancing happens at the constant voltage part of the charge - the last and longest part. 

That was imo wrong- the CV phase is only longer with >~0.5C charging....

[mrelwood]

Today I checked. MSX was charged with a 3rd party 5A charger through Charge Doctor v2.

The charger light turned green when the charge current got below 0.65A. The charge current trickles down very slowly, so a good amount of charge was added still after the charger led turned green.

[Planemo]

Very interesting. So as you said, quite a bit more goes in after the green light. I imagine the amount varies between chargers and bms', but for sure I imagine all wheels and chargers do it to some extent. For this reason, I think all owners should leave the charger connected for a few hours after green light, even if its only 1 in 5 charges, in order to get the cells fully balanced.

[mrelwood]

Somewhere every tenth charge was recommended for the balancing charge. But it might well be that due to the variances in chargers and bms, precise recommendation can’t exist.

”Every now and then” would perhaps be a good start.

[Ziiten]

On 6/25/2019 at 7:38 PM, Leonardo Deleon said:

Is that a common problem on the z10? Is happening to me after I've used it for 3700km. What should I do?

Are you still getting this message. Mine has got pretty severe. Yesterday went for a ride and had this message popping up constantly. And whenever it shows up, the wheel cannot be ridden because there will be a steep tiltback if you go over 7 km/h. I am thinking my battery is just about finished, after 3000 km. If I look at Ninebattery cell voltages whenever I get this message, I can see a voltage difference of over 1 V between cells 1 and 2 of battery 2. Also the charge percentage can drop 20% in a second. If I turn the wheel off and on the difference in cell voltages and charge% goes away for a while, but may or may not return soon. Sometimes I can ride long times without issues.

Edited August 6, 2019 by Ziiten

[Planemo]

 'Cell' is not quite the correct term. Its really a 'string' as there is more than 1 cell in each of the 14 strings. But yes, it does look like you have a duff cell/s in string 1.

Might be worth checking the charger - assuming your pic is taken from a full charge - even the good strings havent hit full voltage (my Z6 ones were just shy of 4.2v).

[ir_fuel]

6 hours ago, Ziiten said:

Are you still getting this message. Mine has got pretty severe. Yesterday went for a ride and had this message popping up constantly. And whenever it shows up, the wheel cannot be ridden because there will be a steep tiltback if you go over 7 km/h. I am thinking my battery is just about finished, after 3000 km. If I look at Ninebattery cell voltages whenever I get this message, I can see a voltage difference of over 1 V between cells 1 and 2 of battery 2. Also the charge percentage can drop 20% in a second. If I turn the wheel off and on the difference in cell voltages and charge% goes away for a while, but may or may not return soon. Sometimes I can ride long times without issues.

I would NOT ride that wheel anymore and replace or (if you have an expert nearby) fix battery pack 2 asap.

Also know that undervoltage/overvoltage Li batteries can be a fire hazard.

[Ziiten]

10 hours ago, Planemo said:

 'Cell' is not quite the correct term. Its really a 'string' as there is more than 1 cell in each of the 14 strings. But yes, it does look like you have a duff cell/s in string 1.

Might be worth checking the charger - assuming your pic is taken from a full charge - even the good strings havent hit full voltage (my Z6 ones were just shy of 4.2v).

Yes, that pic is after practically a full charge even though the percentage of battery two shows 77% at that moment - the next moment it showed ~99% again. I wonder if the "cell" 2 is bad as well showing such an overvoltage when compared to the rest. I am using stock charger - do you mean it might be giving an under spec voltage?

[Ziiten]

7 hours ago, ir_fuel said:

I would NOT ride that wheel anymore and replace or (if you have an expert nearby) fix battery pack 2 asap.

Also know that undervoltage/overvoltage Li batteries can be a fire hazard.

Thanks for the heads up. I was just yesterday shopping for a new battery. According to this Aliex seller the batteries are fresh from Ninebot. Sure. Who knows what you get, possibly the same crappy cells. 800€, not cheap.

[Chriull]

27 minutes ago, Ziiten said:

Thanks for the heads up. I was just yesterday shopping for a new battery. According to this Aliex seller the batteries are fresh from Ninebot. Sure. Who knows what you get, possibly the same crappy cells. 800€, not cheap.

Seldomly it can happen that one gets some badly matched cells. Was reported here already from time to time.

By the "vampire drain" many Z10s get delivered with discharged batteries - so the chance to get a wheel with already stressed cells is much higher. Although they could have been good at the factory!

In your case in battery #2 cell pack #2 with 4.7V is in great stress and danger! Li ion cells don't like it at all beeing overcharged!

I'd assume your wheel is out of warranty or no battery warranty from aliexp?

Buying a new original ninebot battery should bear much less risk, as they never got discharged like this. "Vampire drain" justs starts once they are in the wheel...

[Ziiten]

1 hour ago, Chriull said:

Seldomly it can happen that one gets some badly matched cells. Was reported here already from time to time.

By the "vampire drain" many Z10s get delivered with discharged batteries - so the chance to get a wheel with already stressed cells is much higher. Although they could have been good at the factory!

In your case in battery #2 cell pack #2 with 4.7V is in great stress and danger! Li ion cells don't like it at all beeing overcharged!

I'd assume your wheel is out of warranty or no battery warranty from aliexp?

Buying a new original ninebot battery should bear much less risk, as they never got discharged like this. "Vampire drain" justs starts once they are in the wheel...

I bought it from a Alidealer. I assumed no warranty when making the purchase. And even if they had given it some kind of warranty, the shipping costs for such a product would probably be so high it would not make much sense. And it being a high risk li-battery special shipment would probably be needed.

[Ziiten]

2 hours ago, Chriull said:

In your case in battery #2 cell pack #2 with 4.7V is in great stress and danger! Li ion cells don't like it at all beeing overcharged!

When I charge the battery to full, there isnt initially this kind of over or undercharged cells. It only occurs randomly and often right when I start riding. Also many times the issue goes away after one or two such events. However, at times, especially lately, I keep getting the imbalance warning constantly. Yesterday, I rode practically with no issues.

[Mike Sacristan]

9 minutes ago, Ziiten said:

When I charge the battery to full, there isnt initially this kind of over or undercharged cells. It only occurs randomly and often right when I start riding. Also many times the issue goes away after one or two such events. However, at times, especially lately, I keep getting the imbalance warning constantly. Yesterday, I rode practically with no issues.

Have you tried riding the battery out as low as possible and then charging it for a long time (48 hours) to let it balance properly.
Somewhere where it doesn't risk burning down the house.
I can believe that one of the cells is 3.4V but I have trouble believing the one that is 4.7V.

[Ziiten]

1 hour ago, Mike Sacristan said:

Have you tried riding the battery out as low as possible and then charging it for a long time (48 hours) to let it balance properly.
Somewhere where it doesn't risk burning down the house.
I can believe that one of the cells is 3.4V but I have trouble believing the one that is 4.7V.

That was actually something I had thought of doing next. I have usually left the charger on for some time after the led turns green just in case there is still balancing going on. I think somebody indicated that this might be the case for some chargers.

[Chriull]

1 hour ago, Mike Sacristan said:

Have you tried riding the battery out as low as possible and then charging it for a long time (48 hours) to let it balance properly.
Somewhere where it doesn't risk burning down the house.
I can believe that one of the cells is 3.4V but I have trouble believing the one that is 4.7V.

 

35 minutes ago, Ziiten said:

That was actually something I had thought of doing next. I have usually left the charger on for some time after the led turns green just in case there is still balancing going on. I think somebody indicated that this might be the case for some chargers.

You should look while charging that cell pack #2 does not go as high...

Stop once it reaches ~4.3V and drive a bit, charge again, and so on.

Theoretically (according to my personal theories) this cell #2 should drop voltage faster than the others.

So this could work out. Just cell #1 coupd make probs

Best to keep an eye on the cell voltages while driving and charging - so you maybe can work out a strategy to get them equalized again.

[Nic]

Balancing cannot fix cells that have lost capacity ... these will always go out of balance when discharging/charging as they will do this faster than the other healthy cells. If you've got the skills, I would try replacing the faulty cell ... at least you now know which one it is.

[Girth Brooks]

8 hours ago, Ziiten said:

Thanks for the heads up. I was just yesterday shopping for a new battery. According to this Aliex seller the batteries are fresh from Ninebot. Sure. Who knows what you get, possibly the same crappy cells. 800€, not cheap.

I just got mine from We Unicycle on eBay. They also have an Alli store as well. I got a new battery from them for my Z10 with no issue. It was at 96% on both batteries upon arrival with both LED lights flashing blue.

[Ziiten]

3 hours ago, Girth Brooks said:

I just got mine from We Unicycle on eBay. They also have an Alli store as well. I got a new battery from them for my Z10 with no issue. It was at 96% on both batteries upon arrival with both LED lights flashing blue.

Ok, thanks for this. I sent an inquiry to the seller about this. Let's see if he responds.

[Girth Brooks]

@Ziiten the BMS board failed in mine so I didn't have the option to fix any dead cells. I don't think I would have if I could have though. I would be too scared that I'd create a fire hazard. I am not a battery expert either by any means though.

[Ziiten]

56 minutes ago, Girth Brooks said:

@Ziiten the BMS board failed in mine so I didn't have the option to fix any dead cells. I don't think I would have if I could have though. I would be too scared that I'd create a fire hazard. I am not a battery expert either by any means though.

Yeah, my thoughts exactly.