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1 hour ago, alcatraz said:

That's what leads me to think there must be a charge circuit that cuts charging to all the packs.

Well, there isn’t. IIRC it’s ust a single wire between the packs that lets the other pack know if the charging has been terminated.

1 hour ago, alcatraz said:

The bms should signal battery malfunction to the control board and the control board turns on the fans and stops the wheel.

“Should” is a word that doesn’t very often teach us how things actually are. ;) Again, the Z10 is the only wheel thus far that has communication between the battery and the controller. The firmware analyzes the individual cell group voltage, and if it finds a big difference, it will tilt back and force the rider to stop riding. Unfortunately something in that system has s tendency to fail, since some riders are getting it intermittently without a direct know cause.

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I know some solutions are just wishful thinking. :) If only an euc engineer could comment, that would be great.

As the wheels pack more and more power, they do need to consider more possible situations. An euc on fire in the news is not going to help sales.

Generic bms just cut charging and output and thus the cells are protected. On an euc it's different so there must be some way to stop the vehicle and prevent riding or charging on a system level.

The big question is. All of you gotway riders (me included). How is it charging stops when one pack issues a charge cut? Does the other pack continue to charge? How can it if they are connected in parallell? From observation it appears both packs stop charging when one cuts the charging. This is good. But, then where is the charge circuit? How do we connect additional packs to it?

Edited by alcatraz
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4 hours ago, alcatraz said:

The big question is. All of you gotway riders (me included). How is it charging stops when one pack issues a charge cut? Does the other pack continue to charge? How can it if they are connected in parallell? From observation it appears both packs stop charging when one cuts the charging. 

As you wrote, if one BMS cuts off the charge input by this patallel circuitry he will still be charged through the output.

With (newer) gw/ks (ks since ks16s?) It is prevented by

4 hours ago, mrelwood said:

Well, there isn’t. IIRC it’s ust a single wire between the packs that lets the other pack know if the charging has been terminated.

So if one single cell group goes over 4.2V the BMS cuts off his input and signals to all other BMS to do the same! So no charging anymore for any pack.

4 hours ago, alcatraz said:

This is good. But, then where is the charge circuit?

The charging circuit is in the charger - he provides the constant current up to some constant voltage and then he (should) cut off at some current threshold to prevent trickle charging.

Whats in a BMS:

Reverse voltage protection at the input (all but GW? Or does gw has this too already?)

Cell overvoltage protection at the input

Charge ocercurrent protection (z10, some newer ks with some firmware version start the buzzer if current gets too high - so this seems to be a mainboard and not bms feature)

Short circuit/overcurrent protection at the output (all but gw)

Some have temperature sensors. Afaik not ks and gw.

4 hours ago, alcatraz said:

How do we connect additional packs to it?

Depends how this signal wire between the packs was designed to work. Has to be looked at and analyzed.

In the simplest case this wire just goes to every BMS. So for example for "normal" state its held by pull down resistors at every BMS at some low level. If one BMS wants to cut charging it pulls it to some high level -> all others stop to charge too. Should be latching until the charger is unplugged.

One just needs the right BMS pcb then to connect it to the others.

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6 hours ago, alcatraz said:

If they have charge terminals then thats ok. I don't see any on planemo's mod though so that pack isn't protected.

Don't let the serial add-on packs on my wheel confuse you even more. Leave that out of the equation for the minute :)

Everything Arbolest and mrelwood is correct.

I don't understand why you are focusing on having to cut ALL packs when one has finished charging. Sounds like the opposite of what we actually want tbh.

PS both my serial packs ARE protected in that they both run BMS'. You are correct that they do not have distinctly separate charge/power leads (like all main packs) but tbf neither you nor I know how the serial BMS's have been wired/designed. I do however suspect that they are not just a simple 4S BMS, and that there is something else going on inside, designed specifically for the job they are doing.

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2 minutes ago, Planemo said:

I don't understand why you are focusing on having to cut ALL packs when one has finished charging. Sounds like the opposite of what we actually want

Its not to cut all packs once one has finished, but to cut them once one cell (group) has reached the overvoltage threshold!

With the now mostly used parallel configuration of the packs this safety measure can only be reached by this signal/synchronisation wire between the BMS's

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Sorry buddy I don't know if it's a lost in translation thing but I don't understand. I don't get why you would want to cut anything (other than the current to a fully charged string).

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26 minutes ago, Planemo said:

Sorry buddy I don't know if it's a lost in translation thing but I don't understand. I don't get why you would want to cut anything (other than the current to a fully charged string).

The BMS cuts off charging input once a cell reaches the overvoltage threshold (some 4.2xV) as safety measure. By the by now used parallel connections of the battery packs this pack will still be charged through the output connections!

So that's a inherently unsafe situation overcharging a cell without limitation!

So all BMS have to cut off charging to prevent "unlimited" cell overvoltage.

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16 minutes ago, Chriull said:

So all BMS have to cut off charging to prevent "unlimited" cell overvoltage.

I do get this. I am just struggling to see where you are aiming your comments at. Is it wheels in general, Gotway packs in general or specifically my serial packs? :blink1:

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1 hour ago, Planemo said:

I do get this. I am just struggling to see where you are aiming your comments at. Is it wheels in general, Gotway packs in general or specifically my serial packs? :blink1:

This came from the discussion with @alcatraz. So it's a bit/quite offtopic here... Sorry.

Afaik GW and KS have implemented them like this by now.

I did not really look into details on your "serial" packs - but i'd assume they are "daisy chained"? As KS had their packs before... (Ks16b)

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26 minutes ago, RagingGrandpa said:

it could trip and become very difficult to reset without opening the wheel.

As i know it from overcurrent conditions, the voltage has to be taken from the Aux Pack for the BMS to reset. Then it has to be charged seperately and can only be reconnected to this system. One has to ensure again, of course that they packs have the same voltage.

The single cell overvoltage condition could just be temporary - the cell voltage will settle over time and with some delay the protection will could reset. This could lead to dangerous situations if the other two packs get by charging a much higher voltage inbetween - once the protection of the aux pack resets itself one has an absolutely not nice uncontrolled "charging". With good luck some cell triggers the overvoltage protection again to save the wheel and the surroundings..

Should be checked if and how this protection works and can be reset/resets itself. The above scenario could end very dangerous - if the cell overvoltage protection works like the overcurrent protection it would be more safe, but much more challenging to recognise that the pack has turned off and to reactivate it...

PS.: great schematics!

Edited by Chriull
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31 minutes ago, RagingGrandpa said:

Good discussion here.

Let's apply this topic to your MSP upgrade.

Not sure if you have me mixed up with someone else.. I have an MSX and my serial aux packs charge directly from the port (not from the output of an 84v pack like your diagram).

Still trying to digest the rest of your diagram and the explanations, but just thought I would point out the above to start with :)

 

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17 minutes ago, Planemo said:

Not sure if you have me mixed up with someone else.. I have an MSX and my serial aux packs charge directly from the port (not from the output of an 84v pack like your diagram).

Ah, oops, I was referring to the OP's MSP work. Carry on :)

On 4/14/2020 at 1:31 AM, Chronic said:

 lithium battery protection board W LED balance indicator
https://a.aliexpress.com/_dSHFnZE

Edited by RagingGrandpa
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On 4/14/2020 at 7:31 AM, Chronic said:

This could eventually have been a not so good decision from @Chronic? As far as i can understand the description with google lens translation the overcharge protection gets triggered at 4.25+-0.03V and gets released at 4.19+-0.05V automaticly again. ... but the information on the aliexpress site is quite sparse... :(

So if @RagingGrandpa's schematic was used this could eventually lead to bad situations sometimes...

If this aux pack gets a bad cell while the two main packs are still in normal condition whilst charging one of the aux packs cells will trigger the overvoltage protection and cut off it's charging input. The two main packs will continue charging until they are full. Once the one cell's voltage of the aux pack settles slowly below 4.19V the input protection will be released and the pack solidly connected to the two main packs with the higher voltage! But then the overcurrent protection should be triggered (hopefully) fast enough to prevent desaster. And this protection should stay triggered until the aux bms is disconnected....

Edited by Chriull
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Posted (edited)
On 4/14/2020 at 5:38 PM, alcatraz said:

20-30mA balancing current is low. 

Also the bms doesn't communicate with the control board to stop charging if a cell group goes over the maximum voltage.

It's good if you check voltages after charging once every few months.

For others considering this mod you can either get a gotway bms (about the same price ~30usd last I checked) or you can open an existing pack, solder balance wires and piggy back your added pack onto the original bms. Then you get charge protection and probably a little more than 20-30mA balancing current.

Because this is the concept of a supplementary battery, it's just need to do a parallel connection

The GW originally battery protection circuit is a normal PCM circuit with no bellance function

It only has a wire that controls the amount of current

Charging and discharging are the same and there is no problem because the BMS current in the extended battery is 50A

What's important is that there's no need to worry because each battery pack controls charging and discharging

I've done a lot of these things, and there's been a lot of trial and error before. Thank you for your interest

628099797__2020_03_29_18_23_IMG_3877.jpg.bd185747e3ee88841e316311cda05205.jpg

1998937801__2020_03_29_18_31_IMG_3879.jpg.69d3f642a6c78875e7d1f656a1f77687.jpg

 

9 hours ago, RagingGrandpa said:

Good discussion here. Re: @Chronic's MSP upgrade:

Your pack's protection works differently from what Gotway uses... but I think it's ok because your BMS can disconnect the entire pack from the system at any time.
Gotway's BMS cannot! (And therefore theirs needs the extra, pack-to-pack charge stop request wires that I showed in red.)

Your design might be a challenge if your pack ever disconnects itself and then becomes unequally charged, vs the Gotway packs... it could trip and become very difficult to reset without opening the wheel.

fUvK_1gtwL9ck4dxrbGu8YQZUKClm96jqtXF5noS

it's exactly 

Edited by Chronic
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Generic bms can cut charging/output if you use those terminals. In the pictures of this thread (add pack) those terminals look unsoldered.

Planemo doesn't risk faceplanting if the bms cuts the power because he has other packs.

I'm not convinced he does have charge cutout unless output is always cut during charging (to avoid charging through the output). If that is the case what happens when you stop charging and a possible voltage difference between the packs exist when output opens and current rushes for a split second? Could it fry the bms? What happens when you descend or emergency stop and high peaking currents rush into the pack through the bms? 

If I had to use a generic bms I would probably try to piggyback all packs off of one bms instead of running multiple in parallell. I'd make sure the charging terminal on the bms is used, but the output I don't run through it.

If I had to go parallell I'd try to use a gotway bms. Or solder balance leads to an existing pack and piggyback the add pack onto that bms. (without its own bms). That seems more like a long term solution

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To Planemo my advice is not to worry. Check the levels every 3 months and you'll be fine. If you sell, tell the buyer there is a home made pack, or sell it separately. Done.

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3 hours ago, alcatraz said:

To Planemo my advice is not to worry. 

I don't. I know this setup works because it's the same as virtually every other 1865wh 100v MSX in existence. I say virtually because I know of one 1865wh MSX that has used the original 100v 1245wh packs as part of the conversion and added a 100v 620wh pack in parallel. It's the only one I am aware of though. And it wasn't supplied by a wheel dealer.

3 hours ago, alcatraz said:

Check the levels every 3 months and you'll be fine. If you sell, tell the buyer there is a home made pack, or sell it separately. Done.

Well it's not a home made pack. It's come from an EUC specialist who built and supplied these packs for the numerous other 1865wh wheels as mentioned above, nearly all of which were supplied by respected EUC dealers ;)

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  • 4 months later...

Bonjou Everyone I'm new to the site I just received my 1800wh MSP and I will add an extension thanks to this forum to start here is the wiring of the bms that I want to do you think what tomorrow I would put the photo of all the material received But how to attach a photo thank you

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  • 2 months later...

Hi all,

I'm new here but thinking of making an extra pack for my MSP.

I looked up the BMS that was used here but how are all the connections of the BMS wired (B-, C- & P-).

I'm sorry for the silly question, but I'm completely new to this.

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  • 2 weeks later...
On 10/27/2020 at 8:49 PM, Kevin Sebrechts said:

Hi all,

I'm new here but thinking of making an extra pack for my MSP.

I looked up the BMS that was used here but how are all the connections of the BMS wired (B-, C- & P-).

I'm sorry for the silly question, but I'm completely new to this.

Show me your bms picture.

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On 11/10/2020 at 10:07 AM, Chronic said:

Show me your bms picture.

I ordered 2 BMS:

1 => https://nl.aliexpress.com/item/4000553283387.html?spm=a2g0s.9042311.0.0.149e4c4d4SASzA => 24S Li-ion BMS 50A

2 => https://nl.aliexpress.com/item/4001218262806.html?spm=a2g0s.9042311.0.0.149e4c4d4SASzA => 17-24S 50A peak 70A

My main confusion is with the first one where there are pictures showing all 3 mentionned connections while also showing wiring diagrams without the P- connected.

Just want clear everything up before I accidentally connect things wrong.

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17 hours ago, Kevin Sebrechts said:

I ordered 2 BMS:

1 => https://nl.aliexpress.com/item/4000553283387.html?spm=a2g0s.9042311.0.0.149e4c4d4SASzA => 24S Li-ion BMS 50A

2 => https://nl.aliexpress.com/item/4001218262806.html?spm=a2g0s.9042311.0.0.149e4c4d4SASzA => 17-24S 50A peak 70A

My main confusion is with the first one where there are pictures showing all 3 mentionned connections while also showing wiring diagrams without the P- connected.

Just want clear everything up before I accidentally connect things wrong.

Both products have the same charging and discharging specifications.

It's charging and discharging of C-P- are the same. That is common.

You can work according to the product's manual.

regards.

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