E+ Battery died on me while riding

[noisycarlos]

So I was riding today, maybe 8mph at the time. Battery was around 50-55%. I hit a bump and um, involuntarily dismounted. Anyway, at first I thought I had underestimated the size of the bump, but when I tried to put the E+ upright, I noticed it was dead. I tried to restart it but no luck.

I came home and plugged it, thinking it might be a BMS thing (which would also suck), but no. The bot turns on when it's plugged to the charger, but as soon as I pull the plug it turns off (see video). If I put any load, it also shuts off (probably because it's not receiving any current from the battery, and the charger doesn't have enough amps).

Anyway, just wanted to report and share the video of me demonstrating the problem below. If any of you have an idea of what else could it be let me know, but my generic sucks, so I'll probably buy a replacement battery soon (@FORWARD california do you have battery packs? I couldn't find them on the website, but I'd rather buy from you than ninebotUS.com).

 

Here's the video:

 

[Hunka Hunka Burning Love]

Open up the side boxes and inspect the battery and wires for damage.  Did you secure your battery as it's usually loose inside resulting in frictional wear.  Could be a broken wire?  I've seen people's Ninebot battery wires worn through from friction, but I can't find that thread.

 

[noisycarlos]

Oh yeah, I forgot to mention that, thanks.

I did open it, checked the cables, it all looked good. I disconnected and reconnected them just in case, but it made no difference. 

I should also mention: About 300 miles ago, I opened the battery compartment to check it, and I used double-sided tape to secure the battery pack to the body of the unicycle inside the casing (which removed the famous 'ninebot rattle'). I doubt that had something to do though, since it kept working for 300 miles or so.

[Radislav]

Maybe your battery had bad cells? (Max charge level less than 100%)

 

[Hunka Hunka Burning Love]

How old is the battery?  Can you take a voltmeter reading on it?   Does the battery charge up at all if you leave it plugged in for a few hours?   Is it still under warranty?  It looks like the battery is charging as the green indicators are about 3/4.  Could be a fried control board I'm thinking if the balance is cutting out that easily.  Do you know anyone with a Ninebot to try a battery swap to rule that out?  Did you check the yellow connectors to make sure they are attached to the wires well?  When I unplugged my battery, I discharged the capacitors by turning on the bot with the battery disconnected.  When I went to plug it back in there is a noticeable spark sound when connecting.  That might be a simple test to see if the connectors and wiring are sound to the control board.

[noisycarlos]

The battery (and the NB) are about one year and one week old, so i'm out of luck with the warranty. (The warranty is 1 year for the ninebot itself, but the battery is only in warranty for 180 days).

I don't have a voltmeter, I'll try to get one. But I did notice something strange with the battery: 

I plugged the charger on, the light went red as normal. After a couple of hours the light turned green, as usual. So that must mean that the battery pack is actually sending some current back, right? According to the charger and the NB app (when I turn it on with the charger plugged), the battery is at 100%.  So I'm confused. It looks like it's ready the charge correctly, just not actually receiving any power from it.

[Hunka Hunka Burning Love]

Well there are two separate pairs of wires going to the battery.  One yellow and black thin pair with black connectors are for the charging circuit from the charger.  The thicker wires with the yellow XT60 connector feeds power to the control board.  In your video when you power it up it looks like the green indicators show more than 50% charge so I think the battery is charging correctly.  Unless there is a few cells going bad I would think the unit should at least still turn on with battery power.  That's why I think it might not be the battery, but maybe the control board itself or I guess it could be the battery BMS going bad.  If you can detect power level from the app the control board should be getting power readings from the battery.  Does the wheel spin like normal with the power off?  Do you have access to someone else's battery to try?

Where did you get the bot from?  Maybe check with your dealer to see what they suggest.  If it's just one week out of warranty they might grant you a little leeway depending on who they are.  If you bought it on a credit card some cards will extend the warranty by double.  I just replaced a faulty iPhone 6, and my credt card covered the replacement cost.

[noisycarlos]

The wheel does spin normally with the power off. 

What I think is happening is that the pack is indeed charging and measuring charge properly like you mentioned. It looks good in the app too.

However, I still think the problem is on the battery pack (but I'm happy to be corrected) because, if the control board was the problem, I think the unit wouldn't turn on and function normally like it does when the charger is plugged. Does that make sense?

I guess I'll have to get a voltmeter to test the pack.

[Hunka Hunka Burning Love]

That loss of balance is kinda weird though.  Maybe if the battery BMS is cutting power off due to increased current load it could be the battery pack?  Try to see if any other botters in your area can maybe do a quick test by swapping in their battery to rule things out.  A new battery pack is not cheap!

[noisycarlos]

Yeah, thanks. I'm looking for other riders. I'm gonna try to use the Find Riders Nearby feature in the app.

I'm also hoping maybe @FORWARD california can hook me up with a good deal for a new pack ;-)

[FORWARD california]

Hi Carlos,

 I agree with Hunka. Please test the battery if you can. That will determine if its the battery or the control board. Its either one of the two. Can you send me the video in a file to Jake@forwardca.com I can send it to the head engineer at Ninebot inc. and see what he thinks.

[noisycarlos]

Awesome. Just emailed you a downloadable link. Meanwhile I'm still trying to find someone with a battery.

Thanks guys!

[Hunka Hunka Burning Love]

Why don't you post up your location here - maybe there's someone who can offer some help who lives close by.  @TwixFix was selling a battery, but it got sold.  I think they go for around $350-400 brand new.

Edit:  There is a sale on for $265 fromNinebotus with free shipping:

http://www.ninebotus.com/320wh-battery-replacement-battery-for-ninebot-one-e/

[noisycarlos]

Oh for some reason I thought I had mentioned my location in the original post. Oops.

I'm in Los Angeles :-)

Yeah, that's the one I was looking at. Just wanted to make sure that's the problem first, but I might just order it and hope for the best. Worst case I lose the restocking fee and I have to order a control board.

[noisycarlos]

UPDATE: I got a new battery pack and my ninebot is up and running again :-D

A shout out to Jake from @FORWARD california for the great service and quick response.

And @HunkaHunkaBurningLove for the advise ;-)

Now I can finally go buy groceries again, I was getting tired of the fast-food chain within range of my x3 clone :-D

[Hunka Hunka Burning Love]

Glad to hear you're up and running again!  That's interesting to note the behaviour was related to the battery pack.  I wonder if the BMS board was the problem, and the cells might still be useable or whether it was a couple of cells going bad that might be replaceable.   Were you able to get a voltage reading from the charged up old pack?  I thought these packs normally last a bit longer than one year.

I do recall some people posting photos of their BMS boards with a fried component on them melting through the plastic covering.  It would be interesting to see why your pack failed.

[noisycarlos]

Yeah. I thought it was too soon for the battery to die as well. Per my estimation I've gone through 200-250 charge cycles, which is half or less than the 500 they're supposed to last.

I'm visiting an electrician friend on Sunday. It's a birthday party, but I'll bring the pack and try to sneak out and borrow his voltmeter for a little bit. I'll post if I find something on the post mortem.

[HEC]

4 hours ago, noisycarlos said:

Per my estimation I've gone through 200-250 charge cycles, which is half or less than the 500 they're supposed to last.

Sadly 200 - 250 charges is the threshold where battery could be towards end of its life unless treated really well - meaning avoiding deep discharge and full charge state if / whenever possible. In general keeping battery between 15 to 20 and 80 to 90% of charge max will greatly increase it's life expectancy. See some more info for example here: https://www.ewheels.com/ewheels-fast-chargers-rock/ and here: http://hobby16.neowp.fr/category/charge-doctor-en/ / http://hobby16.neowp.fr/2016/02/07/charge-doctor-v2-auto-shutdown-function/

Basically - as almost with any other EUC spec - you'd need to divide them almost by 2 to get a "real life" values  

[noisycarlos]

Well @HEC, that makes me feel a little better in one sense and a little worse in another.

I treated them fairly well though. The charger is on a timer that I'd set to my (admittedly rough) estimation of how long it'd take to top up. Meaning, if the battery was 80% or less I'd set it to charge for 1hr (or I just wouldn't charge it until after the next trip unless I needed all the charge). 50% or less - charge for 2 hrs, etc.

I only discharged it to less than 25% once or twice because i hated traveling at 7mph, and both those times where a couple months ago.

But I guess that's the nature of these batteries. I just wish they wouldn't fail just like that. Some warning of some sort would be nice.

[HEC]

1 hour ago, noisycarlos said:

I treated them fairly well though. The charger is on a timer that I'd set to my (admittedly rough) estimation of how long it'd take to top up. Meaning, if the battery was 80% or less I'd set it to charge for 1hr (or I just wouldn't charge it until after the next trip unless I needed all the charge). 50% or less - charge for 2 hrs, etc.

It seems that you've paid a bit more attention to your batteries that most of the normal users though using timer is really just basic precaution. For the more precise control / more expensive battery packs it's worth considering purchasing the Charge Doctor (or build your own ) as it will repay itself eventually due to the prolonged battery life.

[Hunka Hunka Burning Love]

I wonder with the timer charging method whether you might not be giving the BMS a chance to balance charge.  From hobby16's site:

"Important : a full charge is still required occasionnaly, e.g. 1 every 10 or 20 charging sessions, to ensure the BMS ( (battery management system, the embedded battery controler board) would trigger charge balancing. Balancing, whose importance is most often exagerated, is still necessary on Lithium batteries. So plan some 100% full charges from time to time if you decide to mostly charge to 80% or 90%. "

It's a long shot, but maybe try charging up your old pack to full and let it continue charging for another couple of hours to see if it might bring some life back?

[HEC]

2 hours ago, HunkaHunkaBurningLove said:

It's a long shot, but maybe try charging up your old pack to full and let it continue charging for another couple of hours to see if it might bring some life back?

Excellent point! Definitely worth a try.

[Rotator]

As far as I know, ninebot BMS lacks the balancing circuit.

[Chriull]

1 minute ago, Rotator said:

As far as I know, ninebot BMS lacks the balancing circuit.

It's not using external components for the balancing. But it (hopefully) should use the internal balancing circuit's of the IC's - they are not as "capable" of balancing but still can balance (a bit).

But since @noisycarlosgot already a new pack he maybe could open the plastic wrap and measure the individual cell voltages and look at the BMS for anomalies?

If the BMS looks fine and just one (some) cell(s) show undervoltage one could try to charge them individually, so they maybe can reach the normal voltage again - but with proper safety precautions in case they vent/explode...

PS.: After opening the plastic wrap one should be very carefull to not short circuit anything and repack it (somehow) safely again afterwards!

[Keith]

1 hour ago, Rotator said:

As far as I know, ninebot BMS lacks the balancing circuit.

With the relatively small capacity of Ninebot's, I really cannot believe that Ninebot have no balancing.

It would make Ninebot, the crappeast EUC out there and loads of people would be getting very poor battery life. I'm pretty sure Ninebots must have balancing within the BMS, This is very easy to prove, if the BMS has one wire/connection  going to every single series cell - it will have balancing.

9 hours ago, HunkaHunkaBurningLove said:

I wonder with the timer charging method whether you might not be giving the BMS a chance to balance charge.  From hobby16's site:

"Important : a full charge is still required occasionally.

@HunkaHunkaBurningLove, is spot on, 90% of the charge happens very quickly but it is that last 10% that takes several hours to complete and includes the balancing as most BMS do not actively balance during charge they simply clamp the first cells to reach full charge whilst the others catch up. The pack absolutely needs an, at least occasional, full charge plus an hour or two after the charge LED goes green.

If @noisycarlos used a timer for every charge (or at least did an awful lot of them on a timer with very few full charges) then i guarantee the weaker cells would have dropped to lower and lower discharge voltage until they became damaged. In fact not failing until after 200+ cycles is impressively good. So, in this case it is possible that you were so careful you did a lot more harm than good. 

By the way, the best way to identify weak cells is with the battery discharged, not charged, depending upon the way they are failing they can, if properly balance charged reach a full 4.20 volts, they may, if left resting, drop down a little further than others but not by much. Possibly jus a few tenth of a volt. Only if they have failed in such a way that they are self discharging will they be a clearly lower voltage - if left to rest for a few days. However it is if the pack is discharged that their voltage will likely fall further, by (say) an indicated 50% charge they could be 0.5V lower. If the pack has failed as a result of not being balanced then there may be only one or two faulty cells that could be replaced and the rest still good. Whether it is worth putting new cells with ones that have had 200+ cycles though is questionable.