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KS16s 840Wh problem. Board / batteries / cables?


Pedro Capitão

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22 hours ago, Pedro Capitão said:

However today it was possible to register the csv log while the problem occurred (touching charging port) for a short period of time but not during the riding. 

Ek6DaYl.png

Here the chart of the part while you touched the charging port with the standing wheel.

Curernt, CPU Load, Inverter Load (whatever this number means in detail ;) ), temp seem absoltely normal.

Just voltage breaks down to ~53,5V. This is about 54V/16=3,34V. 3,3V*16=52,8V should, if i remember right and nothing changed with the new firmwares, to lower limit (0% charge) for KS16S. Just took a look at the logs again - battery % breaks down to ~22%. This would fit to 3,15V final voltage (0% charge) for FW2.01 for KS16S, too?!

The voltage sag within the charge % limits could be just coincidence? Or not fully to be seen by the sampling frequency?

Wheel functionality seems not be stopped by the voltage sag - as @Pedro Capitão reported while driving still tiltback and low voltage warning accured?!

And it seems the voltage sag is not caused by some excessive load (inverter, motor wires, any other temporary short circuit...).

The longest voltage sag is about 1.5 seconds - as they happen here without any load (just motherboard running - not motor burden) this could be in the range the capacitors are able to support supply while the battery is disconnected by short loose contacts?

How will this workout with the voltage sags while driving? A log from this occurance while riding would be great - but i would no dare to and strongly recommend you to not ride with it anymore!

Exists the possibility of loose contacts not really loosing the contact but just increased contact resistance?

However - @Pedro Capitão you have to solve the problem of the jammed wires (cut insulations), bend fuses. As there are till now already (at least) two versions of the KS16S out, maybe you have the wrong button/charge port - so they do not fit together with the motherboard within the cover? Or just somehow wrongly assembled!

Although the fuses were already bent once you acquired the wheel there is some force on the wires/connectors/board once you push the charge port - so there is a severe mechanical problem causing some kind of "contact loss"/supply voltage sag.

If you solved this "problem" (no more faults by touching the charge plug, enough safe spacing between the components) it's up to you if you trust your board enough ... If this is not only the "bend fuses" or something aroung there that has bad contacts when "pushed" such faults could happen anytime in the future by some mechanical burden...

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Ps.: Bending back the fuses could worsen the situation. If the sockets on the mainbaord were not influenced by this and neither the board itself (check severly with goid lighting and magnifying glass) it could together with repairing the wire insulation and the abovemention measures _eventually_ solve your problem?

One cannot (easily) check for 100% - most presumably this are multilayer pcbs (one can't check the inner layers), one cannot check the connectors/sockets/components for internal structural damage...

Ps.: And i'm curious for the additional inputs here - what i missed or seen wrongly..

 

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On 5/9/2020 at 9:34 AM, mrelwood said:

IMG_20200221_234606_2.thumb.jpg.1a953002bbe03c1911d3d5dd82716ef6.jpg.b7b021023b16ff33d5f8366e9ea05acc.jpg

Do I see a damaged shielding on one of the battery cables? (Circled in yellow.)

I wonder if the top cover is close enough to the mainboard that if the cables are not placed carefully when putting it back together, the cables will bend the fuses and press on the mainboard. Or maybe even damage the cable shielding and cause a shortcut through the charging connector.

 

Today I'll try to check the fuses and damaged cable, I'll reporte how it goes! I focus just the components on the middle of the mainboard that are a kind of yellow and lose the varnish protection...

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Update: Today I did 55 kms ride at night, running average 26 km/h, but first 40 kms at 29 km/h - no problem at all...

https://euc.world/tour/586587449733140

 

Edited by Pedro Capitão
Kms ride (misse the word ride)
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  • 3 months later...

New update, from July, 14 2020:

The Ks16s did some runs without problems but they happened again and again, randomly...

Brought a Ks16s new board from Kingsong factory brand new v1.5 hardware version with 2.02 factory installed firmware and changed the old one with problems v.1.2 (hardware version) and 2.01 firmware.

It's now riding super smoth, absolutly no issues at all and 65Kms autonomy! FINALLY!

Now days I am riding a KS18L with the same firmware, 2.02 from factory with 2200w motor, 1036wh battery! My kid is going on Ks16S. Aug 2020 selled Inmotion V5F!

Thanks you guys the enfort applyed trying to help to solve this problem, really appreciated!

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  • 2 months later...
On 5/8/2020 at 12:57 PM, Seba said:

It's used to synchronize BMS charging circuitry. Shouldn't cause any problems during a ride, regardless of it's connected or not.

Hi @Seba and sorry for bumping this old thread.

I am having problems again with the damn battery:

  • The battery stops charging at about 66V,
  • If I disconnect a battery pack, the wheel keeps charging, so it would seem like the battery left in it has no problem.
  • If I ONLY disconnect this "BMS Sync" cable, the wheel keeps charging.
  • If I measure black - red-sync-cable on the wheel it gives me 12V
  • If I measure black - red-sync-cable on the battery, it gives me 0.4V

I have measured all voltages on the BMS of the "faulty battery" and they are all around 4.1V, some at almost 4.2V, so it looks like it is in great shape.

What could happen if I charge the wheel without the red sync cable connected?

If I use the wheel and deplete the battery a little bit it charges nicely until those 66V, where it stops suddenly. So when the balancing should kick in it stops working. any ideas?

Thanks :)

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13 hours ago, Struck said:

I am having problems again with the damn battery:

Which problems did you have before?

Quote
  • The battery stops charging at about 66V,

To which voltage did it use to charge up to before?

Does charging really stop (no charge current anymore) or just the led on the charger change the color?

Quote
  • If I disconnect a battery pack, the wheel keeps charging,

Up to the same voltage, it used to charge up before?

Quote
  • so it would seem like the battery left in it has no problem.

Yes.

And the other, disconnected one seems to cause the BMS to prematurely cut of charging due to single cell overvoltage (happens with misbalanced packs)

Quote
  • If I ONLY disconnect this "BMS Sync" cable, the wheel keeps charging.

Yes. Without this sync cable the misbalanced battery still cuts off its charge input, but cannot signal the other pack to cut off charging. Since both packs are connected at the output side (to the motherboard) the misbalanced battery now gets still charged. And the single cell which triggered the overvoltage alarm gets now overcharged whithout limit.

A very dangerous situation as li ion cells are sensitive to overvoltage!

Quote
  •  

I have measured all voltages on the BMS of the "faulty battery" and they are all around 4.1V, some at almost 4.2V, so it looks like it is in great shape.

Ah! Great - so they are just "slightly" misbalanced.

Should be possible to get them balanced again by some "top" charge cycles. Just make short rides to get battery a little bit down and then charge full. Either until the BMS cuts off charging (no current) or 1-2 hours after the charger led changed color.

For a 840Wh , 16s4p -> 14Ah battery the threshold current to consider fully charged should be about 3%*14A ~ 400mA.

Quote

What could happen if I charge the wheel without the red sync cable connected?

As written above some cells could be serously overcharged, so they lend in a thermal runaway.

As in your case, with just slightly misbalanced cells this should not happen.

However, i'd prefer the above described "top" charge cycle for balancing.

Or, since your battery is already open, charge every cell with a single cell li ion charger to 4.2V!

Quote

If I use the wheel and deplete the battery a little bit it charges nicely until those 66V, where it stops suddenly. So when the balancing should kick in it stops working. any ideas?

Thanks :)

Seems to be this single cell overvoltage cut off of the BMS.

The first cell reaching ~4.25V triggers this cutoff.

So with your mixture of 4.1x to 4.2x cells this could be a probable case.

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Thanks a lot for your reply!

 

I'll reply better once I'm in my computer.

But just a little question: those 12V in the battery sync cable mean "go ahead", and the 0.4V mean "stop"/"overcharging danger"?

 

Thanks again!!

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22 hours ago, Struck said:

12V in the battery sync cable mean "go ahead", and the 0.4V mean "stop"/"overcharging danger"?

It wasn’t clear to me from your earlier tests, but since the batteries continue charging without the cable, it makes sense that 0V is “ok”, and only when the cable is there to provide 12V from the BMS that has cut off charging, the other one will also stop. So 12V must be the “Danger, stop”.

Edited by mrelwood
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I totally had the opposite feeling 😅

Anyway, after a couple of times emptying the battery a little bit and charging again, the cell balancing kicked in, and today the battery has been balancing for about 10h already. It has been falling from the 1.3A nominal to almost nothing without any abrupt change.

Right now is drawing 0.01A, which is the minimum my device can measure, but more than zero which is what it previously had.

I don't understand why this worked. What I will do now is certainly balance the cells much more frequently

 

Best,

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