Show me your JK BMS mounting solutions

[Zwy]

Why are you so negative on WAGOs?

They have a place, usually low amperage AC. I would not run high current thru the Wago, but that isn't a concern with your application

For a small wire like a balance lead, I can't see how it would have a good connection. For a critical component like a balance lead, I would not use a Wago.

Up till now I have used several duzend of cheep "lousy" spring-connectors from China. Then I switched to the WAGOs because of their superior design. Since then I used more than 200 such WAGO connections with zero problems.
Even more I did a pull-test on the WAGOs with wires, ending up with close to 5 kg!!!
The overall resistance (measured) of a WAGO connection is much less than 1 milliOhm. This is nothing compared to a typical balance wire with 50 milliOhms. It guess it is more likely that a wire gets loose from a crimped ring terminal than from a WAGO. Should do a pull test......

It is better to check resistance of a circuit using voltage drop under load. Resistance tests simply mean that a connection exists. The only thing an ohmmeter tells me is there is some type of continuity between 2 points.

Can you please explain to me, how the 3.2 V may lead to some imbalance on cell number 1?

It's simple, the ampacity will be much lower across a point of resistance with lower circuit voltage voltage. On a 16S pack, the voltage at cell 16 is 48V nominal, cell 1 will be 3.2V nominal. Apply Ohm's Law.

Can cell balance still be achieved? It can, but the time may increase and it may not be perfect balance. It would also depend on the balancer whether it is active or passive. The battery is charged to a set voltage point and that pack voltage is the sum of all series cell voltages. Some may be higher and some lower than average.

 

[Checkthisout]

Double-sided 3M tape. Have to use piano wire if you want to take off.

 

[740GLE]

They have a place, usually low amperage AC. I would not run high current thru the Wago, but that isn't a concern with your application

For a small wire like a balance lead, I can't see how it would have a good connection. For a critical component like a balance lead, I would not use a Wago.



It is better to check resistance of a circuit using voltage drop under load. Resistance tests simply mean that a connection exists. The only thing an ohmmeter tells me is there is some type of continuity between 2 points.




It's simple, the ampacity will be much lower across a point of resistance with lower circuit voltage voltage. On a 16S pack, the voltage at cell 16 is 48V nominal, cell 1 will be 3.2V nominal. Apply Ohm's Law.

Can cell balance still be achieved? It can, but the time may increase and it may not be perfect balance. It would also depend on the balancer whether it is active or passive. The battery is charged to a set voltage point and that pack voltage is the sum of all series cell voltages. Some may be higher and some lower than average.

So two amp max? I hardly see the wago turning into liquid due to heat build up of a bad connection, but your mileage may vary

Would I use one? I couldn’t drop the coin on them, they are what $0.45 a pop?

 

[Zwy]

So two amp max? I hardly see the wago turning into liquid due to heat build up of a bad connection, but your mileage may vary

Don't have good reading comprehension skills?

"They have a place, usually low amperage AC. I would not run high current thru the Wago, but that isn't a concern with your application"

Would I use one? I couldn’t drop the coin on them, they are what $0.45 a pop?

 

[740GLE]

I was more focused on the fact you said you wouldn’t use one, even after you said they are fine for low current applications (maybe I glossed over the AC part?)

So which is it? Or is 2a not a low current application in your world?

 

[Skypower]

The last time I did balance lead connection extensions I used non- insulated butt connectors using a crimper with fold in dies. Then covered with highest quality adhesive lined shrink tube. I can’t imagine a better low profile connection. I just don’t trust crimping insulated terminals and connectors, bad experiences. As for household wiring, I’ll stick to the old fashioned wire nuts that I’ve got more than a lifetime supply and I’ve never had a failure of any that I’ve installed.

 

[Zwy]

I was more focused on the fact you said you wouldn’t use one, even after you said they are fine for low current applications (maybe I glossed over the AC part?)

So which is it? Or is 2a not a low current application in your world?

I would not use a Wago in a critical circuit such as a balance lead.

I don't recall saying I never used one as I know I have. I also do have some on hand. I can say I won't use Wago's on balance leads.

 

[OffGridForGood]

The last time I did balance lead connection extensions I used non- insulated butt connectors using a crimper with fold in dies. Then covered with highest quality adhesive lined shrink tube.

I wish they just made the balance leads a few inches longer - or offer it as an option to get longer leads with the JK.
seems just the four farthest cells ever need an extension...so I cut the the four closest leads shorter and use them to extend the four farthest ones.
Duck (here come the comments - "all the leads need to be the same length") no they don't, the JK figures out the wire resistance on every lead (not sure how it does this) and the cells balance fine, I have 80 DIY cells running and they are all within a few millivolts in each pack at the top voltage.

 

[Zwy]

I wish they just made the balance leads a few inches longer - or offer it as an option to get longer leads with the JK.
seems just the four farthest cells ever need an extension...so I cut the the four closest leads shorter and use them to extend the four farthest ones.
Duck (here come the comments - "all the leads need to be the same length") no they don't, the JK figures out the wire resistance on every lead

(not sure how it does this)

Voltage drop under load.

and the cells balance fine, I have 80 DIY cells running and they are all within a few millivolts in each pack at the top voltage.

 

[Skypower]

I wish they just made the balance leads a few inches longer - or offer it as an option to get longer leads with the JK.
seems just the four farthest cells ever need an extension...so I cut the the four closest leads shorter and use them to extend the four farthest ones.
Duck (here come the comments - "all the leads need to be the same length") no they don't, the JK figures out the wire resistance on every lead (not sure how it does this) and the cells balance fine, I have 80 DIY cells running and they are all within a few millivolts in each pack at the top voltage.

Heads! Incoming, frag-out! Kidding!
Your right. JK bms’s and Neey active balancers can have different length leads.. within all reasonable probable scenarios. Both automatically measure the lead resistance and make adjustments accordingly.

 

[OffGridForGood]

But the same basic problem - "HEY JK - offer us some longer leads!! not everyone is connecting with the BMS on top of the cells, or using skinny 100Ah cells in a 16s pack ya know!"

 

[Zwy]

26 AWG wire

1 foot= .041 ohms

1A load at 3.2V DC

1 foot = .082 voltage drop, volt reading at end is 3.118V

1.2 feet= .098 voltage drop, volt reading at end is 3.102

My Batrium runs balance on one battery of B grade cells and delta on those is lucky to be under .06V

 

[OffGridForGood]

is lucky to be under .6V

0.6v ?? ie 600 mv?! What!?

 

[Zwy]

0.6v ?? ie 600 mv?! What!?

0.06V delta at full charge.

That is 64 cells all together in 4 16S packs. The real problem is the 18650 store grade B 304Ah cells where one is always low. There are some 280Ah cells B grade I'm planning on taking those off the Batrium once the new cells arrive and use a JK 2A active balance on them. As for that 304Ah, I might buy one cell someday and replace it.

18650 tends to put in one odd cell in a shipment to get rid of them from my experience. One thing I have noticed with that 304 cell is at the bottom it holds up quite well and doesn't run to the bottom.

Edited my other post, good catch.

 

[brb58]

Not a JK but a JBD BMS. 3D printed enclosure.

 

[Checkthisout]

You guys do 16 cells in one long string?

 

[OffGridForGood]

You guys do 16 cells in one long string?

On a shelf some do,
I build packs in the size of a 6U server rack, eight cells in two rows.
Cases end up 17-5/16 wide x 27 deep x 10 tall.

 

[Skypower]

Mine are all 16 cells, 8 up and 8 back

 

[OffGridForGood]

18650 tends to put in one odd cell in a shipment to get rid of them from my experience. One thing I have noticed with that 304 cell is at the bottom it holds up quite well and doesn't run to the bottom.

I had this exact same situation, one cell that was always the runner coming up to full charge.
Drove me darn near mad. Charging up 15 cells all within a few millivolts of one another, at 3.40 but nooooooo one cell (cell #11) running off 3.5...3.55...3.60...erg damn that cell #11
But one day I got it in my head - gonna see if I can deal with that stupid Cell #11,
I charged until #11 hits high voltage cut off at 3.60 pack shuts down.
I pull that pack, and take the top off the case.
put a car fog light clamped across cell #11 and go do something else for a bit, come back and it is down near the other cells so I used a set of jumper cables from the pulled pack - back to the main ESS that was still charging up.
I left the fog light on Cell 11 put the jumper cables on and let er go, watching the cell voltages with my phone,
I felt like this was going to be a tug-o-war but no way I not going to give up!
Yeah I played with that pack for about 2 hours, and beat that Cell #11 into submission.
In the end what seeemed to work best was pulling the voltage on the problem cell a few millivolts lower than the others, because when I took the load off, even without charging current, that cell would come up nearly to where I had started again.
So damn it all to hell, put the fog light across cell #11 and leave it there, pulled that sucker down a good 10-12 millivolts lower than the others, take the light away, and up it comes, but this time not quite as high, repeat many times.
Finally after two hours of battle, all the cells sitting at 3.5 and holding steady.
OKAY I figured, put the pack back into service and see - been good ever since.

 

[Checkthisout]

I had this exact same situation, one cell that was always the runner coming up to full charge.
Drove me darn near mad. Charging up 15 cells all within a few millivolts of one another, at 3.40 but nooooooo one cell (cell #11) running off 3.5...3.55...3.60...erg damn that cell #11
But one day I got it in my head - gonna see if I can deal with that stupid Cell #11,
I charged until #11 hits high voltage cut off at 3.60 pack shuts down.
I pull that pack, and take the top off the case.
put a car fog light clamped across cell #11 and go do something else for a bit, come back and it is down near the other cells so I used a set of jumper cables from the pulled pack - back to the main ESS that was still charging up.
I left the fog light on Cell 11 put the jumper cables on and let er go, watching the cell voltages with my phone,
I felt like this was going to be a tug-o-war but no way I not going to give up!
Yeah I played with that pack for about 2 hours, and beat that Cell #11 into submission.
In the end what seeemed to work best was pulling the voltage on the problem cell a few millivolts lower than the others, because when I took the load off, even without charging current, that cell would come up nearly to where I had started again.
So damn it all to hell, put the fog light across cell #11 and leave it there, pulled that sucker down a good 10-12 millivolts lower than the others, take the light away, and up it comes, but this time not quite as high, repeat many times.
Finally after two hours of battle, all the cells sitting at 3.5 and holding steady.
OKAY I figured, put the pack back into service and see - been good ever since.

Why can't the balancer do this?