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KS-14S not charging (charger voltage OK)


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EDIT: It now charges! I just disconnected and reconnected all the battery related connectors multiple times. Should have done that first.

 

Hello everyone,

Been a while since I last posted but a lot has been going on for a year or so, busy is an understatement. Hope all are doing well!

But my lack of posting hasn't meant I've not been using my wheel, I've continued to use it as part of my commute and generally getting around (except during winter).

The wheel is proving to be about as reliable as my old Peugeot 306 when it comes to electronics though, for now it suddenly won't charge.

I last charged it perhaps a week ago, and I'd been riding it from time to time. The battery is now around 70%. Today I planned to head into the centre on it and went to give it a charge before I did - nothing. Green charger light stays on.

Charger is a Wate 3A charger that I bought on recommendation from others on the forum a couple of years ago after the KingSong charger blew up. I measured 67.4v on its output connector.

So I ripped the wheel apart, luckily still muscle memory after replacing two motherboards and two headlamps since getting the wheel in 2018, so it was apart in record time. The last time I opened the wheel I put copper grease on every screw thread. Wow what a difference, thanks past self! The voltage gets to the connector on the motherboard, so it's something on the board that's died. I would guess either the main charging IC or maybe some MOSFET that enables the charging when the wheel is off, I don't know.

I don't think I can face the massive hassle of getting yet another motherboard from KingSong again, so I'll probably try to fix this one. Any pointers are welcome, if someone has experience of this problem. I have good soldering iron and hot air rework station so it's not a problem in that regard. Do I have the patience at the moment? That's a different story!

The wheel still functions so absolute worst case scenario is that I hack on some sort of multi pin connector to bring out the balancing wires from the batteries and use an external charger that handles the balancing also - if I can implement it cheaper than getting yet another motherboard.

The wheel has a bit of a toy look and a bit slow for me nowadays, but the battery is in otherwise good condition and it works. And it wasn't cheap new. So I don't really want to give up on it yet, but I have to say at this point selling it for parts and just forgetting about the whole thing is quite appealing.

I've just started a nice long holiday from work and it's buggered again. This is exactly what happened last time the motherboard failed with charger related problems. Time to buy a cheap bicycle I think.

So yeah, any pointers welcome, or anyone with a motherboard to sell cheap within the EU give me a shout. ✌️

Edit: Actually I realised there isn't any balancing going on. There's just positive, negative.. something else (blue wire).. (that doesn't measure any voltage) and a very thin wire which I feel is likely for a temperature sensor. Does anyone know if it's possible to just connect the charger output directly to the battery packs if no balancing is going on?

Edited by cgi
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Glad to hear you got it working!

Battery cell balancing like a few other functions as well are controlled by the BMS boards that are located inside the battery packs. They have connections from each cell (group).

 The thin wire between the packs tells the other pack to stop receiving charge as well, in case one BMS must interrupt the charge due to cell overvoltage etc.

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13 hours ago, cgi said:

EDIT: It now charges! I just disconnected and reconnected all the battery related connectors multiple times. Should have done that first.

These connectors might be dirty. I had a case with my charger where tips of the plug had melted and got damaged. Good reminder that if there be any "sparks" likely cleaning connectors is due time.

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7 hours ago, mrelwood said:

Glad to hear you got it working!

Battery cell balancing like a few other functions as well are controlled by the BMS boards that are located inside the battery packs. They have connections from each cell (group).

 The thin wire between the packs tells the other pack to stop receiving charge as well, in case one BMS must interrupt the charge due to cell overvoltage etc.

 

Makes sense, thanks for the info. Well, it doesn't charge again. I charged it to 90% last night with intention of topping it up to full before I left today for the meet but no go. It's been a while since I charged it to 100% and left it to balance so is there perhaps a possibility that a cell imbalance is upsetting one of the BMSs?

Update: After going on a long group ride today and draining the battery to something like 40% it started charging right away.

Edited by cgi
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If you haven’t charged to full for a while but still have been charging, cell imbalance could well be sneaking in after all. Letting it charge to full and waiting for an hour will hopefully solve the problem, but you might have to do it a few times. Meaning, charge to 100% + 1 hour, ride a few km, repeat.

 If it still doesn’t get above 90%, the imbalance could be bad enough for the BMS to cut the charging before it even gets to balancing.

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Yeah, I charged it right up and left it to balance. I rode it about 12km today and now home - it's charging right away. So it seems that may have been the issue. I'll let it charge all the way up again and then go out for a night ride.

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Ok so I let it charge until the charger went green, then left it around an hour. Checked status in EUC World and it reports 95%.

Well, whatever. It's now consistently charging.

photo_2021-07-05_22-11-12.jpg

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Most wheel have 2 battery pack. If one of you (1x 18650)battery in these packs are disconnected (or breaks, etc), your wheel will not charge to 100%. In most wheels you can disconnect the one battery. Then charge the wheel as normal - > if it charges then that pack is healthy / if not then you can try connecting the other and disconnecting the one you tested. If one of these battery pack charges higher than that 65.4V then you know which one is broken. Broken will not charge higher than that 65.4V.

You might need to discharge wheel or contact where you made the purchase so you will not lose warranty to do the test.

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27 minutes ago, Tasku said:

Most wheel have 2 battery pack. If one of you (1x 18650)battery in these packs are disconnected (or breaks, etc), your wheel will not charge to 100%. In most wheels you can disconnect the one battery. Then charge the wheel as normal - > if it charges then that pack is healthy / if not then you can try connecting the other and disconnecting the one you tested. If one of these battery pack charges higher than that 65.4V then you know which one is broken. Broken will not charge higher than that 65.4V.

You might need to discharge wheel or contact where you made the purchase so you will not lose warranty to do the test.

Warranty is the last thing on my mind, I've had that wheel apart so many times now. Yeah, I figured that might be what's going on, and yes, it has 2 packs so I could do the test. In the past I've had to disconnect the battery packs and discharge them with a light bulb while waiting for a new motherboard from KingSong, so that's not alien to me either.

But at the moment I'm just going with the option to not care about it. The battery packs are so expensive it's not worth replacing them!

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That is dangerous route. Be aware you battery packs will not balance now. Sooner or later a new more bigger problem will arise.

The risks of battery packs that are not balanced at all, is another topic. Maybe others members can explain that better.. or ask it in new topic?

 

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3 minutes ago, Tasku said:

That is dangerous route. Be aware you battery packs will not balance now. Sooner or later a new more bigger problem will arise.

The risks of battery packs that are not balanced at all, is another topic. Maybe others members can explain that better.. or ask it in new topic?

 

It could easily have been this way for a much longer time. The last time I used an app to look at the full battery voltage was probably 2 years ago. Otherwise I'm quite familiar with the risks involved, but still not going to do anything about it for now. If the wheel lasts until the autumn when I'll stop using it for the year anyway, it's lasted the 3 years I was hoping it would in order to be satisfied enough getting enough value from it. It's likely to be both my first and last EUC, I always knew the battery would determine its lifespan.

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If it now charged to 95%, and last time only to 90%, it seems that the balancing is working and the packs are being salvaged successfully!

Charging after every ride (to max + 1-2 hrs) is important right now, so that the batteries can get every bit of balancing they can get.

 It is a good idea to keep checking the charge level after a charge or before a ride (the same way every time), so that you can monitor for any changes, and can ride more carefully (ie. stay away from my group rides! :P) if the packs start going worse.

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The 90% I mentioned before was what it got to when I manually stopped it. I just didn't want to leave it sitting on the charger all night. Whether it improves over the 95% might tell something, but if the fully charge voltage is now indicative of a single cell failure I don't think it will recover. But let's see! In the morning I'll put it on charge again and see where it gets to.

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Already waiting next results as if it is x-mas and I get to open new chocolade from calendar :whistling:
Edit: Also the voltage is better indicator than the %. Screen captures work just fine too.

Edited by Tasku
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...Actually I just tried to put it on charge to see if it would charge and no, it doesn't, so it seems the voltage has to drop more before the BMS permits charging. Currently 62.2v. I'll ride it tomorrow more and then charge again, but I already can tell it's just going to be the case from now on that it won't charge unless the battery has drained enough.

photo_2021-07-06_01-30-43.jpg

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55 minutes ago, cgi said:

The 90% I mentioned before was what it got to when I manually stopped it.

I’m sorry, in that case I was overly optimistic.

 

55 minutes ago, cgi said:

if the fully charge voltage is now indicative of a single cell failure I don't think it will recover.

It most definitely will not, you are right. What @Tasku was pointing out about the dangers of the situation might indeed be very real. If any li-ion battery cell drops below 2.5V, the cell should be discarded and not charged ever again. Charging a bad cell group is not an instant bomb detonator, but it does increase the fire hazard quite substantially.

 If it turns out that a cell group has indeed died, it would be best to disconnect the faulty battery pack, just like @Tasku mentioned. The output power of the wheel will then drop substantially as well, so it might not be able to save you at sudden bumps. Especially at speeds closer to the wheel’s maximum speed.

In both cases the net damage can be quite huge, which is why a bad battery situation always awakens many a warnings all over the forum.

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9 hours ago, cgi said:

Actually I just tried to put it on charge to see if it would charge and no, it doesn't, so it seems the voltage has to drop more before the BMS permits charging. Currently 62.2v.

62.2V is in average 3.9V per cell - far away from full 4.2V!

Only condition for charge input cut off from the BMS is single cell (group) overvoltage - which mormally triggers somewhere around 4.3V.

A cell group triggering this alarm gets discharged "quite fast" (some low hours count in maximum) by the balancing resistors.

If this specific cell group is alread very weak, it could get recharged very fast and reach this cut off threshold withon short time.

Did charging start at least for some time (minutes) when you tried or did the led just stay green?

Main problem of such a back is that this weak cells that get (over)charged first get discharged first, too. So if you drive your wheel to low charge percentaged this group can easily get down to around some 2V which damages them even more.

Our used 18650 cells are surprisingly good in taking such beating, but sometimes it's enough for them and the take the while pack on fire with them...

Edited by Chriull
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54 minutes ago, Chriull said:

62.2V is in average 3.9V per cell - far away from full 4.2V!

 

That's its 70% voltage. I went for a ride to discharge it after the last charge, and that's where it's at. It charges up to "95%" which is 65.4v.

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(Edited the post for typos and gave some options that I can think of)

The one faulty battery sounds again possible theory. The test I mentioned would solve what battery pack is faulty. (charging only one pack, and see if you reach the full 100% with only one pack)

Taking off the faulty battery pack is safety. Riding with only 1 battery pack would set ~45% performance what you are used to. No fast accelerations. Top speed x 40%. Just my safe estimate.

In ideal world you would just take the faulty battery pack to professional. Then it gets opened. (In your case that one might be fallen off the  connector or such, usually easy to detect, then measure it. If not they would have to test until they found it) Changing that one faulty "18650", I assume. Yet replacing it one close enough to state of the others.. (or the ~3(?)group of em paralel just to make sure they do not break next, most battery stores have used ones, measured and tested). Then spot weld it back in, get the heat wraps around it. They charge some time, like hour or 2 maybe. A full change of all battery could go to 300€ for electric bicycle, so maybe more for EUC battery that usually have more batteries.  

If it turns out one battery pack is not charging to full: Good thing you came to ask about it, there is a risk involved with the current state.
You need to choose:

1. Ride with healthy 1-battery-pack at even lower speeds.

2. Dispose device

3. Fix the broken battery back to get to normal.

4. Order new battery pack might be cheaper than fixing it locally, or not. Your custom battery-pack might take month to arrive, there is that..

You live in Helsinki area with wide range of services. Searching the area in finnish: "akkujen kennotus helsinki", revealed multiple companies that offer services that you might use now. If they accept the task to change the damaged ones and replace em.

There is reason why they want to change all the batteries usually, if some wanna explain that..

Edited by Tasku
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4 hours ago, Tasku said:

The one faulty battery sounds again possible theory. The test I mentioned would solve what battery pack is faulty.

Taking off the faulty battery pack is safety. Riding with only 1 battery pack would set ~45% performance what you are used to. No fast accelerations. Top speed x 40%.

In ideal world you would just take the faulty battery pack to professional. Then it gets opened. (In your case that one might be fallen off the  connector or such, usually easy to detect, then measure it. If not they would have to test until they found it) Changing that one faulty "18650", I assume. Yet replacing it one close enough to state of the others.. (or the ~3 of em paralel just to make sure they do not break next, most battery stores have used ones, measured and tested). Then spot weld it back in, get the heat wraps around it. They charge some time, like hour or 2 maybe. A full change of all battery could go to 300€ for electric bicycle, so maybe more for EUC battery that usually have more batteries.  

You live in Helsinki area with wide range of services. Searching the area in finnish: "akkujen kennotus helsinki", revealed multiple companies that offer services that you might use now. If they accept the task to change the damaged ones and replace em, you would only know if you call and check.

I've repaired laptop Li-ion packs in the past by replacing bad cells - although got someone else to do the actual spot welding of the tabs (taking foolish risks with technology is nothing new to me). I used to be very active in the hackerspace back in Scotland, and although I'm also a member of the local space, I tend to use my own workbench mainly. But welding the tabs is always the problem. If I were to go the route of fixing the pack I'd probably start up a discussion with the others at the hackerspace as I know some of them have worked on Li-ion packs. But there's an element of I simply can't be bothered putting much more time or money into that wheel. I hate batteries. If only there was some standard packs that were easily swapped out, common to many EVs, and so more readily available at reasonable prices. But I know that implementing such a design while keeping the power density high enough, and with optimal weight distribution, is problematic.

I've put another 10 km on the wheel and now charging it up as far as it will go (after leaving it to rest for 20 mins), I'm expecting it will stop at the same 65.4v voltage, but let's see.

The likely course of action is that I'll continue to use it as-is with caution until the end of the summer, and if it hasn't put me in hospital, over the winter I might start investigating the packs properly and consider repair.

Update: Yup after charging again, 65.4v.

Edited by cgi
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Three years is a long time to hold off upgrading, congratulations! I would echo others in urging caution, especially when charging. I’d personally keep it in a place where if it were to decide to self combust, it wouldn’t harm anyone or burn anything valuable down. And I’d keep an eye one it while it was charging.

Hopefully it lasts through the summer, then you can part it out!

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4 minutes ago, Tawpie said:

Three years is a long time to hold off upgrading, congratulations! I would echo others in urging caution, especially when charging. I’d personally keep it in a place where if it were to decide to self combust, it wouldn’t harm anyone or burn anything valuable down. And I’d keep an eye one it while it was charging.

Hopefully it lasts through the summer, then you can part it out!

I earn enough to live comfortably but not enough to save up and make large purchases over 1000 € too easily, so I tend to try to get as much use of anything I buy as I can. For example I use smartphones for 3-4 years until they're really useless before I upgrade.

I wouldn't settle for anything less than an Inmotion V11 if I was upgrading, but I wouldn't want to buy one used unless it had very low use (I'd want as much battery longevity as possible), so ultimately I just can't afford to upgrade as things stand. And anyway after a few years the battery will fail in that also, and the wheel will be obsolete! (although one could argue it's more worthwhile paying the price for battery replacement in a more expensive wheel if it's still in good working order) The EUC market is so rapidly advancing all of the time. I don't like having credit cards or finance either, so it's not an option for me - I would guess credit is the only way many people manage to buy wheels. It's been really fun riding the wheel and I'll really miss it once it breaks for sure, but I'll probably just buy a cheap bicycle and rent the city e-scooters like everyone else after that :).

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Batteries are not a two year death sentence though. For example, I sold my MSX this summer after two years and 14000km. I still didn’t notice a decrease in range. I let it balance the cells after every charge, and stored at around 50% during off months. Nothing more to it.

Li-ions deteriorate to 70-80% capacity in about 300-500 full cycles. A full charge on an EUC is less than one cycle. A 1600Wh battery gets to 300 cycles at around 25000-30000km. A small battery on the 14S of course much sooner. But still, the issue in your battery doesn’t come from age or too much use, it comes from insufficient balancing, be it from usage or design.

 Anyway, a quality wheel is not limited to 2 year usage. It’s just that at that point the improvements on new wheels are so fundamental that they’re hard to resist. Like suspension was for me a year ago.

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These are not your wheel, but maybe give insight how difficult the fire can be. Atleast start to consider where you charge and store the device. Fire blanket is something I hope you have if you need to throw the device out.

If you indeed continue 'as it is', in your own private housing that is understandable. But if there are anyone else in the house, I hope you reconsider. Fire is rare, but when you increase the change with faulty product on repeated manner it more likely everytime.

Even half battery value in use, it would be safer, without the faulty pack. If indeed it is the case.

As you did not test the invidual battery packs charging level, we do not know what the deal is. But at this point I would assume one of the battery packs will charge to 100% max voltage where as faulty one does not.

Personally I would not risk it, running with the faulty pack.

Edit: I also assume/believe/make a guess, that the batteries in the device are in half condition so if taken out they would still work. So safe to say it has value still even disposed. Even you did not say, how many kilometres traveled, I would assume so based on average rider km with these  devices. These numbers I pull of my hat, watching what others say they use theirs, in this forums and based on conversations.

Edited by Tasku
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