Kingsong KS-18XL only charging to 85% / faulty battery pack

[Tadas]

I received my KS-18XL in June 1, 2019. This is my first wheel ever, amazing fun, been riding it for a month, 727 km done on it.

I started reading about battery packs and how to keep it fresh for a long time. Should I charge to 100% or just 80%?

Only then did I notice that my wheel would only charge to 85%, it would stop charging at 80.7 V, then later settle down to 80 V. Started debugging, maybe it's a faulty charger?

KS-18XL has two 20s3p battery packs connected in parallel. I noticed that if only one is connected, the wheel charges normally to 84 V, if only another is connected, it only charges to 80 V and shuts off, the charger shows green light.

The voltage would indicate that only 19 cells out of 20 are working. After communication with the seller and seller communicating with Kingsong we decide to try to rebalance the cells.

I didn't know the cell balancing connectors are in the corner, so I removed the whole cover. If someone needs to balance their battery back, you don't need to open it all.

I noticed the board had physical damage and first assumed it was me who had somehow damaged it during the disassembly. I was all dismayed so didn't document this part very well. Later after thinking more and more I realised it couldn't have been me, it had to have happened in the factory.

19 cells out of 20 were all showing equal voltage (3.8V), but the 13th cell was showing 0 V, exactly the same cell who's BMS had been damaged.

Kingsong has told the dealer they would be sending me a new battery pack, so I am happy with the service, however it will just take a long time to reach me so the riding season might be over Will update if I do receive it or not.

This story does sound awfully similar to @FrankFilmer incident. His wheel only charged to 70%, which I think is a huge red flag and indicates battery problems (maybe only 18 cells working out of 20).

Finally, I think that our wheels are inherently very dangerous and had my board been damaged in another spot, or had I kept riding the wheel without paying attention I would have eventually gotten a cut-out or a fire in my home. The wheel doesn't have any advanced battery management system, it should watch the health of all cells and it should warn the user that the battery is malfunctioning, but there is no such warning for the user.

I was riding with 19s3p and 20s3p battery backs connected in parallel. That can't be good.

Always make sure that the wheel charges to 100% and actually check that it reaches the voltage it should be reaching. Just because charger shows green, doesn't mean all cells are working.

 

Edited July 8, 2019 by Tadas

[meepmeepmayer]

Very good report (and detective work)! Replacing the pack is the only safe option so it's good to hear that KS went with this right away.

[Tadas]

I am happy with Kingsong's service, but it goes to show that the rider is responsible to understand the wheel and stay safe.

There is space in the board for the smart BMS connector, so they have thought about it, let's hope it makes it info the future models of the wheel, would make it much safer wheel.

 

[ir_fuel]

On 7/5/2019 at 6:18 PM, Tadas said:

Always make sure that the wheel charges to 100% and actually check that it reaches the voltage it should be reaching. Just because charger shows green, doesn't mean all cells are working.

That's a good point. We should all be aware we are not dealing with bullet proof systems here (Lithium batteries always carry a risk, that's just the way they work) and we should make sure to regularly check if all is ok, just as we are supposed to check we are not riding with underinflated tires.

[esaj]

8 hours ago, ir_fuel said:

That's a good point. We should all be aware we are not dealing with bullet proof systems here (Lithium batteries always carry a risk, that's just the way they work) and we should make sure to regularly check if all is ok, just as we are supposed to check we are not riding with underinflated tires.

Agree, probably the best bet is checking that the battery charges to full voltage (as said above), and if it doesn't, figuring out whether it's a faulty battery or a charger with too low voltage. Unfortunately at least with most wheels checking the battery pack health further isn't easy for a layman (even trying to decipher whether the voltage values are normal or not may not be easy), and not many people will want to unwrap the pack and start measuring individual cell voltages. Even less exchanging faulty cells. There should at least be some type of internal monitoring that can warn the user (through app or blinking lights or warning sound or whatever) if the battery voltage/behavior seems abnormal (ie. very little or no current running through the motor but the voltage drops faster than expected, tracking charge and discharge to detect energy "disappearing" from the pack or something...). Hopefully this will change in the future.

Edited July 8, 2019 by esaj

[Seba]

On 7/5/2019 at 6:18 PM, Tadas said:

Always make sure that the wheel charges to 100% and actually check that it reaches the voltage it should be reaching. Just because charger shows green, doesn't mean all cells are working.

+1 and one more thing - verify this voltage with mobile app, not by reading your charger voltage meter! The latter will always show 84 V, even if battery voltage is lower. And it's worth to remember that KS-18L/XL may be connected via BLE to monitor battery voltage during charging with mobile app.

[Tadas]

So I received a new battery pack from Kingsong. Pretty happy with their service!

[mrelwood]

 

On 7/8/2019 at 3:03 PM, ir_fuel said:

we should make sure to regularly check if all is ok, just as we are supposed to check we are not riding with underinflated tires.

Just want to add two cases to further underline the importance of the quote above.

I loaned my spare wheel to a friend whose wheel was out of comission. We had noted that the battery doesn’t last as long as it should, but did not investigate further.  We didn’t check the voltage after charging. Until the wheel gave out without a warning, and sent my friend to hospital to be stitched. Only after that I measured the cells, and one pair was indeed dead.

Yesterday I was on a late night ride on my own. Behind a shallow curve, a bush and a tiny hill on a downhill cycle/pedestrian way there were perhaps five people with dogs. Nobody had any lights, reflectors, or white clothing, so I couldn’t see them. And then one of the dogs start running towards my path. I start braking quickly, but the wheel starts to wobble badly enough that I couldn’t slow down any further. Luckily there was room to circle around them through the grass. No crash, no collision, and no-one got hurt but my throat from the speed that my heart jumped to it with.

Now, I know how to tame wobbles. I’ve been riding for about 19000km, of which 7000 with this wheel. Still the surprise behaviour caught me off guard. I started to test emergency braking, and indeed the behaviour was dangerously wild. The tire pressure had only dropped from 2.5 to 2.2 bars. Pumped it back to 2.5 bars and the wobbles were pretty much gone.

- Rehearse emergency braking in downhill!

- Check the tire at least every two weeks, even if it holds the pressure!

- Check the voltage of the battery after charge!

[Christophe]

Hello Tadas,

I've exactly the same problème of you. My KS18XL have only 200 km ( only 3 month ) and refuse to charge more 85% first, then 80% and now 70%.

Can you help me please ???? I'm desperate .... 

I don't really understand if your problem is because of your battery or your BMS ?

Is it OK now for you ?

What do you finaly change ? Your BMS or your battery ?

[Christophe]

 

You take this photo to show us the Physically damage BMS. 

 

After you said you received a new battery pack from Kingsong.

Where is this piece damaged on your photo ? In the batterie pack ???

[mrelwood]

@Christophe, the photo you posted is the BMS, and it is tightly interconnected and wrapped together with the battery. No matter if your wheel has a failure in the BMS or the battery cells, the faulty battery pack must be replaced. Your wheel is still quite new, so it absolutely should not develope a failure like that. Contact your seller, it’s their responsibility to sort you out.

But based on the little you wrote about your issue, your charger might also be the broken one:

1) Do you have a multimeter you can use to check the output voltage of the charger? Or 2) try to carefully use the charged wheel just a few minutes then continue charging. 3) Does the charger led turn green when the charging stops? Or 3) can you check from the app wether the wheel voltage drops a bit immediately after the charging stops?

Since your battery might be faulty, ride carefully!

[Christophe]

@mrelwood thanks for your reply.

I 've just buy this KS18XL at somebody Who bought it at GREEN FASHION on internet in Chine. I 've ever contact GREEN FASHION  and they ask me to return the batterie to test them.

But I don't know what to do ... It's the reason I explain you my problem on  Electric Unicycle forum because I'm alone.

1) I don't test with multimetre the charger but I have two different new standard charger KINGSONG 1,5A . I test it with the 2 different charger and there is always the same problem.

I don't think that the charger is the problem.

2) The wheel run well but the problem is that i can't charge it at 100%. Now I can only charge it at 70% after it's worse and worse. Tomorrow it will be at 60 % because more I charge the battery more its capacity become low.

After first charge the batterie are maximum 85% with  81V , then after 80km the second charge 80% whith 79V and now after the next charge it's 70% with 77V instead of 100% and 84V.

It's a disaster.

3) Yes the charger led turn green after only 70% now.

4)  the wheel voltage drops a lot immediately after the charging stops. It pass 75% to 70% immediatly after green led of charger.

 

[mrelwood]

13 hours ago, Christophe said:

@mrelwood thanks for your reply.

I 've just buy this KS18XL at somebody Who bought it at GREEN FASHION on internet in Chine. I 've ever contact GREEN FASHION  and they ask me to return the batterie to test them.

Based on your answers the most likely cause for the issue is a faulty battery pack. The packs are quite expensive, so a replacement under warranty might be the best solution. Unless you can get the seller to cancel the sale, since the wheel is faulty.

13 hours ago, Christophe said:

1) I don't test with multimetre the charger but I have two different new standard charger KINGSONG 1,5A . I test it with the 2 different charger and there is always the same problem.

I don't think that the charger is the problem.

I think you are correct.

13 hours ago, Christophe said:

2) The wheel run well

While it may behave normally during easy riding, if some of the battery cells are indeed dead which they appear to be, the wheel will have a lot less max power. If you ride aggressively, the wheel is a lot easier to overlean, and the ”overpower” warning will be played too late. Be careful!

If you can’t get the seller to cancel the deal, what I would do next is to open up the wheel, disconnect all cables going to one of the battery packs, tape the disconnected battery’s main connector shut, then recharge the wheel with one pack only.

IMPORTANT: You can NOT have both packs connected at the same time again!!! Unless you get the both packs to exactly the same voltages first (0.1V difference only). If you connect a full pack and a half empty pack at the same time, you WILL get a huge spark, molten battery connectors, burnt fingers, and may even get an aggressive battery fire.

If the wheel now charges to 100% with one pack, you have disconnected the faulty pack. I believe the wheel will even be safer to ride this way.

If the wheel still doesn’t charge above 70%, FIRST disconnect the other battery as well, tape the connector shut, and only then reconnect the first battery pack. Then charge the wheel. It should now charge to 100%, and you have identified the faulty pack.

[Christophe]

I've just do What you tell me to do.

Whith one batterie I can charge only 70% and whith the other one only 85%.

So the two battery seems to be destroyed. 

My KS18XL has only 200km !!!! 

Chen Yanming of Green Fashion propose me to send the batterie to test them.  So I don't know What I must to do. It's not easy to send battery to Chine ...

 

[Meserias]

Do you try to send a detailed video to seller showing how do you test what and where you measure and with your multimeter
then upload this video to OneDrive/ZippyShare/GoogleDrive/Box/Copy....

You smiled probably on good price when you bought your wheel now it's time evaluate again your actions and what is the benefit buying from near buy seller (even with higher price !)

[Christophe]

Just now, Christophe said:

 

I did not buy the wheel directly at Green Fashion. I bought the wheel from someone who bought it on the internet.

I do not really understand what you mean in fact ?

 

 

[Chriull]

7 hours ago, Christophe said:

Chen Yanming of Green Fashion propose me to send the batterie to test them.  So I don't know What I must to do. It's not easy to send battery to Chine ...

You know/have some local "battery repair shop"? Could be easier and cheaper!

[Christophe]

I ask at one "battery repair " this morning and they told me that they don't repaire this type of batterie. They told me that 84V is so much for them .

You think it's possible for me to find battery repair shop you could repaire this sort of cell ?

[Chriull]

26 minutes ago, Christophe said:

You think it's possible for me to find battery repair shop you could repaire this sort of cell ?

Yes. Maybe you'd get some recommendations in the french forum https://www.espritroue.fr/ ?

[Christophe]

Yes thanks. I know it inevitably. I already explained my problem before coming here. I just spoke with a specialist in battery repair. He told me that the batteries on the 18XL were very powerful. It is necessary to change all the cells for the batteries to refurbish. It would be as expensive as buying a new wheel. In China, batteries cost significantly less than in France.

[Seba]

52 minutes ago, Christophe said:

Yes thanks. I know it inevitably. I already explained my problem before coming here. I just spoke with a specialist in battery repair. He told me that the batteries on the 18XL were very powerful. It is necessary to change all the cells for the batteries to refurbish. It would be as expensive as buying a new wheel. In China, batteries cost significantly less than in France.

Contact https://www.1radwerkstatt.de/, maybe they will help you at a significantly lower cost compared to buying a new wheel. And don't forget that there are two batteries in KS-18L/XL. If only one has defective cells (what is most probable), you need to repair just one battery.

[mrelwood]

 

Quote

Whith one batterie I can charge only 70% and whith the other one only 85%.

That is unbelieveably bad luck! I’m so sorry. Sounds like the previous owner managed to destroy the batteries somehow.

On another thread a person repaired his battery in a e-vehicle battery repair shop in Spain for very cheap. Unfortunately I don’t remember the shop’s name, or even the discussion thread title.

[Christophe]

I will be very happy to know the address of your repair shop in Spain to find out what they think.

A battery specialist in France told me that anyway it is useless to change only the cells that do not work because all the cells are now damaged. It is therefore necessary to remake a new battery with new cells and this is overpriced.

[Chriull]

1 hour ago, Christophe said:

A battery specialist in France told me that anyway it is useless to change only the cells that do not work because all the cells are now damaged.

They are not damaged! Just the ones in parallel with the bad cell(s)- all the others in series are still fine!

Just the long term ability to stay balanced by the balancing capabilities of the BMS depends strongly on perfectly matched cells! So since you have some slightly used ones and they would be combined with new ones they'd "drift" apart earlier as preselected cells from a battery manufacturer.

But with your max charging up to ~70% there could be about 2 cells dead, together with their paralleled ones - so 2*3=6 to change. The other battery with 85% has presumably 3 dead cells. So you'd need some 9 to 12(?15?) cells plus ?1 to two?) working hours.

That could be some ?200-300€? for a not perfect but still very suitable battery!

Imho a better "chance" than sending them to china or buying new packs!

... If it's hopefully not damaged BMSs...but afaik 1radwerkstadt also has BMS?

[Tadas]

On 11/18/2019 at 10:07 AM, Christophe said:

Whith one batterie I can charge only 70% and whith the other one only 85%.

 

 

Sorry for late reply. Sorry to hear that, that is bad news. At least you know the problem....

Perhaps the previous owner deeply discharged the wheel and left it at 0% charge for days/weeks/months. In this case both battery packs would not be safe, better not use it at all. The risk of fire is not worth it, these things can burn the house down...

Maybe buy 2 new battery packs from kingsong?  Unfortunately, this will not be cheap