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Why fast charger doesn't go over 82%? :/ (MCM5 V2)


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Strange things.
I got this wheel from a friend and he included a fast charger too (thanks mate!).
 

Theorically the charging with a fast charger should go quick up to 80% and then charge in classic mode the remain part (that's what I've head, I'm not sure about this).

When I plug my MCM5 V2 fast charger is very quick to reach the ~80% of the full charge but then... it seems it doens't charge anymore.
Yesterday, before going to bed, I've checked the wheel. When turned on it showed on EUC World a 96% for a moment and then when immediately down to 82%).
So I decided to leave it charging all night long. 
The result is that today when turned on the battery was showing once again ~82%

What's wrong?
Thanks 

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19 minutes ago, Snowball said:

What's wrong?

Either the charger or the battery.

Does it charge fully (also voltage at quite max value) with the normal charger?

Btw - some (fast) chargers have switches or similar to limit charging to some 80-90%...

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1 minute ago, Chriull said:

Either the charger or the battery.

Does it charge fully (also voltage at quite max value) with the normal charger?

Btw - some (fast) chargers have switches or similar to limit charging to some 80-90%...

Thanks for your quick reply.

I cannot tell you about normal charger because I don't have it. I just got the fast charger.
Now I will take the charger, take a few pics and post here.

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1 minute ago, Snowball said:

Thanks for your quick reply.

I cannot tell you about normal charger because I don't have it. I just got the fast charger.
Now I will take the charger, take a few pics and post here.

And the no load output voltage of the charger measured with some Voltmeter could give some hint.

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42 minutes ago, Chriull said:

And the no load output voltage of the charger measured with some Voltmeter could give some hint.

Here we are.

https://imgur.com/a/yE2KFeU

I think all the info are here. Not for me,I'm not an expert :)

BTW of course MCM5 V2 shows 6 leds (out of 8) like it is really 80% charged.
And, one more thing, I think the battery drains too quick. I rode for about a kg and it seems to have 5% less.

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17 minutes ago, Snowball said:

Here we are.

https://imgur.com/a/yE2KFeU

I think all the info are here. Not for me,I'm not an expert :)

Seems charger works ok (no options/switches, output voltage seems right)

Leaving some cells of the battery packs beeing degraded/dead as most probable cause.

You know the battery configuration of your wheel? Would be great if it has 2 battery packs inside - chances are high that only one pack is degraded and this can be checked easily by charging the packs individually.

If and once you open the wheel to look for the batteries you could measure the single battery pack voltages. 82% should be about 80.7V... 

Could theoreticly be, that the voltage meadurement on the mainboard is way off and batteries are fine - one will see.

Some links in for much more details:

 

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9 minutes ago, Chriull said:

Seems charger works ok (no options/switches, output voltage seems right)

Leaving some cells of the battery packs beeing degraded/dead as most probable cause.

You know the battery configuration of your wheel? Would be great if it has 2 battery packs inside - chances are high that only one pack is degraded and this can be checked easily by charging the packs individually.

If and once you open the wheel to look for the batteries you could measure the single battery pack voltages. 82% should be about 80.7V... 

Could theoreticly be, that the voltage meadurement on the mainboard is way off and batteries are fine - one will see.

 

Thanks for your answer.

So looking at the picture, you say that the charger should be ok, correct?
I spoke to my friend and later today he's going to give me the classic (not fast) charger. He says he could fix the problem. I don't get how since the problem seems related to batteries (not charger) and as I said before in a short ride early this morning I consumed about the 10% of the remaining charge. Really strange.

I will do my best, helped by him I hope, to try to figure out if those packs inside are degraded...

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7 minutes ago, Snowball said:

UPDATE

I got the original (not fast) charger.

Sadly using it I cannot go above 84%. And while is plugged now, the led is green (as it says "ok, it's fully charged).

What I could do to isolate the problem?

This is 84V 800Wh version? If so, then I would open the wheel and measure the voltage of both physical packs to see if one is lower than the other.

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19 minutes ago, houseofjob said:

This is 84V 800Wh version? If so, then I would open the wheel and measure the voltage of both physical packs to see if one is lower than the other.

Correct. 84v and 800Wh.

So I should misure both battery (the one under the handle and the one on the side, correct?) with the electrical tester? How do you do it? Any tutorial?

Thanks.

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I've found this video that maybe shows how to solve the issue.

https://www.youtube.com/watch?v=fQgr_-r2jGM

I commented it in order to be sure i got it right.
If so I should ride for a while (at least 50% of the charge), charge it again to full (using the classic charger, not the fast one), chech if the number is above 83%, do the same process again untill I reach 100%.
It makes sense to me. What about you? :)

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On 10/9/2020 at 11:01 PM, Snowball said:

I've found this video that maybe shows how to solve the issue.

https://www.youtube.com/watch?v=fQgr_-r2jGM

I commented it in order to be sure i got it right.
If so I should ride for a while (at least 50% of the charge), charge it again to full (using the classic charger, not the fast one), chech if the number is above 83%, do the same process again untill I reach 100%.
It makes sense to me. What about you? :)

Didn’t watch the video, but that method is the last straw, and not at all a solution as it tends to work only when the degradation is minor, like 1-2V. Your pack stops charging at 80.7V, which is 4.3V short of 84V (Edit: :blink1: I might have to recalculate this some day...). Coincidentally (not) one cell group accounts for 4.2V, and 0.1 is easily covered by rounding errors and measurement tolerances.

 The symptoms are very clear and familiar, you have a dead cell group in either of the batteries. When they get to 0V, they won’t take any charge, and they decrease the range and power of the whole wheel. The only solutions available are to dismantle the pack and replace the dead cells, which is a laborious and demanding job even for experienced engineers, or to buy a fully working battery pack.

 Since those are the only options, I wouldn’t buy the wheel. And in the future, check the fully charged voltage as the first thing before buying a used EUC. If it charges to 100%, everything else is fixable with (much) less money and effort.

Edited by mrelwood
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5 minutes ago, mrelwood said:

Didn’t watch the video, but that method is the last straw, and not at all a solution as it tends to work only when the degradation is minor, like 1-2V. Your pack stops charging at 80.7V, which is 4.3V short of 84V. Coincidentally (not) one cell group accounts for 4.2V, and 0.1 is easily covered by rounding errors and measurement tolerances.

 The symptoms are very clear and familiar, you have a dead cell group in either of the batteries. When they get to 0V, they won’t take any charge, and they decrease the range and power of the whole wheel. The only solutions available are to dismantle the pack and replace the dead cells, which is a laborious and demanding job even for experienced engineers, or to buy a fully working battery pack.

 Since those are the only options, I wouldn’t buy the wheel. And in the future, check the fully charged voltage as the first thing before buying a used EUC. If it charges to 100%, everything else is fixable with (much) less money and effort.

Thanks for your opinion. Sadly your theory makes sense. I will check just in order to be sure (doing a few cycles) and let you guys know.
By the way, is there a tutorial that explain how to put the shell back (I mean the one the goes around the wheel). I'm going crazy fixing it with all that plastic.
Last thing: my friend sold me that wheel for a very friendly price (same he paid) just to avoid me to wait for a new wheel. The wheel was almost new. I will try to find a solution with him. We were unlucky :(

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1 hour ago, Snowball said:

So I should misure both battery (the one under the handle and the one on the side, correct?) with the electrical tester?

Yes and yes. 

1 hour ago, Snowball said:

How do you do it? Any tutorial?

Just like you did measuring the charger pin, unplug the XT60 connectors where the arrows point below, the right is the top pack, left is the bottom side pack.

After disconnecting the connectors to measure, make sure to drain the board of any remaining charge by pressing the power button until the wheel does not turn on. 

oOvbKMi.jpg

48 minutes ago, Snowball said:

If so I should ride for a while (at least 50% of the charge), charge it again to full (using the classic charger, not the fast one), chech if the number is above 83%, do the same process again untill I reach 100%.

No!, please don't ride the wheel with this issue until you can isolate the problem. We had a local rider who had a bad pack and his wheel started a fire like this.

26 minutes ago, Snowball said:

By the way, is there a tutorial that explain how to put the shell back (I mean the one the goes around the wheel). I'm going crazy fixing it with all that plastic.

Yes, I've done this 1,000 times now, and there is a trick to that piece:

  1. Pinch/squeeze in and attach/slide the bottom hooks into the wheel first. 
  2. Then, rest the other hooks so that they are in the grooves/seams of the openings where they need to go into
  3. Then, resting the wheel on the floor on that center plastic piece from bottom, let the weight of the wheel push the hooks in fully, you might have to push down on the wheel some. Slowly rotate the wheel to fully upside down to get the top hooks in (you will hear snaps with each hook attaching).
  4. Last, the few bottom hooks near the tire might not have been pressed in, so you will need to just use your hands to firmly press them in.
Edited by houseofjob
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14 hours ago, houseofjob said:

Yes and yes. 

Just like you did measuring the charger pin, unplug the XT60 connectors where the arrows point below, the right is the top pack, left is the bottom side pack.

After disconnecting the connectors to measure, make sure to drain the board of any remaining charge by pressing the power button until the wheel does not turn on. 

oOvbKMi.jpg

No!, please don't ride the wheel with this issue until you can isolate the problem. We had a local rider who had a bad pack and his wheel started a fire like this.

Yes, I've done this 1,000 times now, and there is a trick to that piece:

  1. Pinch/squeeze in and attach/slide the bottom hooks into the wheel first. 
  2. Then, rest the other hooks so that they are in the grooves/seams of the openings where they need to go into
  3. Then, resting the wheel on the floor on that center plastic piece from bottom, let the weight of the wheel push the hooks in fully, you might have to push down on the wheel some. Slowly rotate the wheel to fully upside down to get the top hooks in (you will hear snaps with each hook attaching).
  4. Last, the few bottom hooks near the tire might not have been pressed in, so you will need to just use your hands to firmly press them in.

Thanks so much for adding the picture. Later tomorrow I will be able to get the electric tester and I will make some measurements.

So tell me if I got it right. Measuring package one I will get a value. Measuring package two I will get a different value. The package with the lower value is the bad one. Correct? :)

One more thing. I know I'm a pain in the ass.
Sometime the fan/s (the one that starts when you turn the wheel on) make/s a very strong noise. Like it is damaged or there's something wrong with it (maybe it is touching something or whatever...). I've opened as you see in the picture just the side with the batteries, but whatching a teardown video I don't see any fan on the sides of MCM5. Where are those? How can I reach them?

Thanks, you guys are pure gold.

 

EDIT:

1) While I'm writing this message I'm recharging the wheel (normal charger). I want to be sure that the trick shown on Youtube (to drain and charge a few times the wheel) doens't fix the issue and let the battery go back to 100%

2) Today I went out for a ride (not a fast one). I started my ride with 69% of battery. Rode for about 16 km and came back with 40%. 29% for a 16 km ride?! :/

Edited by Snowball
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2 hours ago, Snowball said:

EDIT:

1) While I'm writing this message I'm recharging the wheel (normal charger). I want to be sure that the trick shown on Youtube (to drain and charge a few times the wheel) doens't fix the issue and let the battery go back to 100%

 

EDIT 2

I've completely recharged the wheel and it went up to 85/84%. So no big changes at all.

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Ok, so I don't know how this works, and I'm guessing here, but:

84%-85% (which app?) corresponds to ~79.75V (assuming the normal algorithm where 3.3V per cell = 0% and 4.1125V and above per cell counts as 100%).

19 * 4.2V = 79.8V which is the same number.

So it looks like you may have one bad cell in series somewhere, so you get 19*4.2V = 97.8V = 85% instead of 20*4.2V = 84V = 100% = as it should be. (If this is how this works, I'm not sure.)

So: bad pack with a bad cell somewhere.

Can you charge the wheel with only one of the packs connected, for each pack, and see if you get to 100%? Then you know which pack is bad (I think the MCM5 has two packs) (Be careful re-connecting packs with different voltages!!)

edit: I just saw that @mrelwood already made the same argument. I don't think it's likely to be anything but a bad cell causing your troubles.

Edited by meepmeepmayer
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2 hours ago, meepmeepmayer said:

Ok, so I don't know how this works, and I'm guessing here, but:

84%-85% (which app?) corresponds to ~79.75V (assuming the normal algorithm where 3.3V per cell = 0% and 4.1125V and above per cell counts as 100%).

19 * 4.2V = 79.8V which is the same number.

So it looks like you may have one bad cell in series somewhere, so you get 19*4.2V = 97.8V = 85% instead of 20*4.2V = 84V = 100% = as it should be. (If this is how this works, I'm not sure.)

So: bad pack with a bad cell somewhere.

Can you charge the wheel with only one of the packs connected, for each pack, and see if you get to 100%? Then you know which pack is bad (I think the MCM5 has two packs) (Be careful re-connecting packs with different voltages!!)

edit: I just saw that @mrelwood already made the same argument. I don't think it's likely to be anything but a bad cell causing your troubles.

Thanks for your help.
Tomorrow I'm going to make two different test:

1. Trying to open the wheel and use the Electric Tester on those cables (in the above image) following the instruction of @houseofjob
2. Do what you suggested me and charging the single pack (yes, they are two) and see which one doens't charge to 100%  (*)

(*) Concerning this step, would you be so kind to tell me step by step how to proceed not to make a disaster? You mentioned the risk to reconnect packs with different voltages and I'm scared now :)

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6 hours ago, Snowball said:

(*) Concerning this step, would you be so kind to tell me step by step how to proceed not to make a disaster? You mentioned the risk to reconnect packs with different voltages and I'm scared now :)

There should be a Y-connector somewhere where the two cables from the two packs come together. From there it's one cable to the board. That connector is where you work.

  1. edit There should be some thinner cables between the battery packs, with two tiny plugs. Disconnect those and then forget about them (never re-connect). I forgot those earlier.
  2. Disconnect one pack (A), keep the other (B) connected (speaking of the main power cables with the big yellow plugs).
  3. See how far the connected pack (B) charges.
  4. Disconnect it (B)! No packs are connected to anything now.
  5. Connect only the other pack (A) and see how far that one charges.
  6. Now you know which pack is damaged: the one that doesn't charge to 100%.
  7. If one pack charges and the other doesn't, you can't connect them together again!!

Sounds more complicated than it is. You merely individually connect pack after pack (each alone) and see if it charges, and you never connect differently charged packs.

If you electrically connect different voltage packs in any way, power will rapidly (and uncontrolledly) flow from the higher voltage one to the lower voltage one as they try to balance out. Possibly give a spark, melt some cables, produce a short that fries the entire wheel, or make the lower voltage pack go up in flames (worst case).

So charging both packs individually assumes one of them is damaged and will never be used/connected to the other again. And if you ever need to connect two working packs with different voltages, charge them individually in the wheel, to the same voltage (just charge them to 100%), before making any connection between them.

I hope for you that the big pack is ok and only the small one damaged. Chances are 1 to 2 so *knock on wood*:)

(For the same reason, be very careful not to accidentally short a pack when using the electric tester by having the test probes touch when they shouldn't.)

(For the same reason, when you connect any pack (some voltage) to the board (no voltage), do it quickly so there is no chance for a spark. This is not a big concern, but helpful to know.)

TLDR: Do not make any electrical connection between battery packs with different voltages. They must be roughly the same voltage before they may connect. No need to be scared, just to be aware how electricity behaves on a basic level:) (I'm certainly no expert!)

Edited by meepmeepmayer
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5 hours ago, meepmeepmayer said:

There should be a Y-connector somewhere where the two cables from the two packs come together. From there it's one cable to the board. That connector is where you work.

  1. Disconnect one pack (A), keep the other (B) connected.
  2. See how far the connected pack (B) charges.
  3. Disconnect it (B)! No packs are connected to anything now.
  4. Connect only the other pack (A) and see how far that one charges.
  5. Now you know which pack is damaged: the one that doesn't charge to 100%.
  6. If one pack charges and the other doesn't, you can't connect them together again!!

Sounds more complicated than it is. You merely individually connect pack after pack (each alone) and see if it charges, and you never connect differently charged packs.

If you electrically connect different voltage packs in any way, power will rapidly (and uncontrolledly) flow from the higher voltage one to the lower voltage one as they try to balance out. Possibly give a spark, melt some cables, produce a short that fries the entire wheel, or make the lower voltage pack go up in flames (worst case).

So charging both packs individually assumes one of them is damaged and will never be used/connected to the other again. And if you ever need to connect two working packs with different voltages, charge them individually in the wheel, to the same voltage (just charge them to 100%), before making any connection between them.

I hope for you that the big pack is ok and only the small one damaged. Chances are 1 to 2 so *knock on wood*:)

(For the same reason, be very careful not to accidentally short a pack when using the electric tester by having the test probes touch when they shouldn't.)

(For the same reason, when you connect any pack (some voltage) to the board (no voltage), do it quickly so there is no chance for a spark. This is not a big concern, but helpful to know.)

TLDR: Do not make any electrical connection between battery packs with different voltages. They must be roughly the same voltage before they may connect. No need to be scared, just to be aware how electricity behaves on a basic level:) (I'm certainly no expert!)

Thanks so much for your time mate. Appreciated.
Evenif you told me it is not as hard as it seems, I think I have to do this work with a guy that knows this stuff more than I do (almost nothing) to avoid any big damage to the wheel.
One thing I find very interesting from your walkthrough it that if you find that one battery charged to 100% and the other one charges to 70% (so it's the bad one) you cannot go back and connect them again as they were before. So it is a one way road.
Having not a spare battery package, doest it mean that I should use just a single package untill I don't get a new one, I charge them both to 100% and then I reconnect them together?

Thank :)

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18 minutes ago, Snowball said:

Even if you told me it is not as hard as it seems, I think I have to do this work with a guy that knows this stuff more than I do (almost nothing) to avoid any big damage to the wheel.

You only plug in or unplug one of two yellow connectors (going to one or the other battery pack). It's not more complicated than that. Only thing you should not do is re-connect both packs if they have different voltages (= charge states).

18 minutes ago, Snowball said:

One thing I find very interesting from your walkthrough it that if you find that one battery charged to 100% and the other one charges to 70% (so it's the bad one) you cannot go back and connect them again as they were before. So it is a one way road.

That is what I meant to convey.

Though you could ride with only the one working battery connected until that battery is back at 85%, and then you can again connect the other, damaged battery. They will have the same voltage so plugging them together is ok, and charging will be limited to 85% again because it's limited by the weakest pack, but then you would be back to where you are now.

But riding with a damaged pack can be dangerous, so you already lost one of the two packs.

18 minutes ago, Snowball said:

Having not a spare battery package, doest it mean that I should use just a single package untill I don't get a new one, I charge them both to 100% and then I reconnect them together?

Yes exactly.

Edited by meepmeepmayer
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I forgot, between the batteries there should also be thinner cables with two tiny plugs. These also need to be disconnected, of course, before you charge one battery but not the other.

So disconnect those two tiny plugs before you do anything else, and never connect them again, they are not needed now.

(I edited that into the bigger post above as the new first step.)

Edited by meepmeepmayer
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Here I made a schematic how things should be (I think - I'm going by my ACM and assume the MCM5 is the same). It's an MCM5 800Wh right? Two battery packs, one big, one small?

-

  • 1 are two tiny connectors, from thinner cables only connecting the two battery packs directly (they are wires for fine balancing, I think, and also the charge cables.). Disconnect those two tiny connectors first, and then keep them apart.
  • 2 and 3 are the big yellow plugs for the main power cables of the battery packs. You disconnect one of them, see if the other pack charges, and vice versa. Just don't have both plugged in at the same time if a battery pack has been charged to 100%. Only one pack at a time may be plugged in then.

That's all:) The mess in the MCM5 may make it look more complicated than it is. The Y cable may not immediately look like one, in my wheel one end is much longer than the other and goes to the other side, but you only need to find the two battery ends of this cable.

If your wheel looks somehow different than this picture, then we have to look what is different. But I think this is how the relevant connections are made.

And just remember what you are trying to do: you disconnect all but one battery pack, test if the one connected pack is good by seeing if you can charge it to 100%, and you do that for every pack (two here, but would work for however many packs you have). While you do test the packs individually this way, you just need to be careful never to have two packs with different voltages (= charge states) electrically connected.

edit: I'm a bit confused where the charging cabling comes in play. This schematic might not be completely right. I think I confused myself;) I'll figure this out some other time.

mcm5.jpg.9edc539b6b2bc58cab87d08cc5ae15d8.jpg

Edited by meepmeepmayer
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