Heltec (JK) 200A Smart BMS with 2A Active Balance

[Sanwizard]

OK wtf.

Put some new washers on all my cells, just steel, nothing exotic, little bit of carbon grease also because that's what the store had, noticed a few connections were just a little loose so gave those a twig up with the crimper also now I'm missing half my cells even though I have tested continuity between each balance lead terminal and the plug into the BMS and it's fine.

I can also confirm I have a voltage reading on each pin on the BMS loom plug when referenced to the main battery neg. As you test each pin, voltage climbs by the cell value all the way up to cell 16 and full pack voltage as you'd expect, there's no bent pins either.

Pack voltage is perfect also. What gives?

Its obvoiusly a connection issue somewhere. Pins bent on connector on the BMS? Loose crimps? Check resistance on each wire. Either that, or your bms may have an issue.

 

[lincomatic]

OK wtf.

Put some new washers on all my cells, just steel, nothing exotic, little bit of carbon grease also because that's what the store had, noticed a few connections were just a little loose so gave those a twig up with the crimper also now I'm missing half my cells even though I have tested continuity between each balance lead terminal and the plug into the BMS and it's fine.

I can also confirm I have a voltage reading on each pin on the BMS loom plug when referenced to the main battery neg. As you test each pin, voltage climbs by the cell value all the way up to cell 16 and full pack voltage as you'd expect, there's no bent pins either.

Pack voltage is perfect also. What gives?

test the voltage at each lead and make sure it's ascending. i think you might have swapped a pair

 

[UV-PWRD]

test the voltage at each lead and make sure it's ascending. i think you might have swapped a pair

Forgot to add I checked this and it ascends by ~3.3 on each pin at the connector end as you would expect, so we know voltage is making its way to the connector at least.

I only removed one lead at a time so there was practically zero chance of swapping them plus the cables are cable tied in such a way that it's very obvious which wire goes where.

Its obvoiusly a connection issue somewhere. Pins bent on connector on the BMS? Loose crimps? Check resistance on each wire. Either that, or your bms may have an issue.

I had no reason to remove the connector for pins to become bent, I just removed the main neg and pos terminals from the pack to power down the BMS, but I did check them when I removed the connectors to check the pin voltages and they look fine to me.

Similarly, the terminals within the connectors themselves appear to be seated correctly as I was able to prob the underside of the connector where you can access those terminals with the multimeter without issue.

I can't get a resistance measurement out of my Fluke 325 because it doesn't go that low it can see a very easy path of continuity and gives me a continuity beep instead, on the 325 continuity and resistance are on the same setting, you'll only get a resistance reading if it's above 30ohm

All I can think of to test beyond this is remove the cover on the BMS and ensure the voltage is reaching the pins on the PCB itself which rules out the connector/pin arrangement, but beyond that there's nothing more I can think of?

 

[lincomatic]

Forgot to add I checked this and it ascends by ~3.3 on each pin at the connector end as you would expect, so we know voltage is making its way to the connector at least.

I only removed one lead at a time so there was practically zero chance of swapping them plus the cables are cable tied in such a way that it's very obvious which wire goes where.

Sorry, didn't see where you said the voltage was ascending on the balance leads in your first post. But I'm puzzled, you said the pack voltage is perfect.. how many cells do you have in series? The pack voltage depicted in your screenshot is correct based on the number of cells it sees, but it's not correct if cells are missing. Is it a 16S pack? I would advise checking the setting for that, just in case it somehow got changed.
Also, the leftmost lead of the left balance connector should be wired in parallel to the wire for the highest voltage cell, and both of them should be connected to the positive terminal of the pack.

 

[UV-PWRD]

The setting in the app is 16 as it's a 16s 277ah pack, pack voltage at the time of the screen shot was around 54.4v, float voltage on the DMM. The inverter, just an MPP 7248 also sees pack voltage perfectly when I bypass the BMS and run it direct.

It does default to 24 when you "reset" the BMS through the app, but I changed that back immediately/rebooted etc still nothing on those cells.

Cell 16, which is the main pack positive does have 2 leads on it.

Remember this is a pack with a 100 cycles on it, all I've done is remove 1 wire at a time, replace a washer, add some carbon grease and put it back together.

 

[lincomatic]

The setting in the app is 16 as it's a 16s 277ah pack, pack voltage at the time of the screen shot was around 54.4v, float voltage on the DMM. The inverter, just an MPP 7248 also sees pack voltage perfectly when I bypass the BMS and run it direct.

It does default to 24 when you "reset" the BMS through the app, but I changed that back immediately/rebooted etc still nothing on those cells.

Cell 16, which is the main pack positive does have 2 leads on it.

Remember this is a pack with a 100 cycles on it, all I've done is remove 1 wire at a time, replace a washer, add some carbon grease and put it back together.

OK, but your screen shot above says 37.44V. Sorry, I'm out of ideas. The only time I've seen missing cells was when I was, like you, redoing some connections, and I inadvertently swapped 2 of the balance leads.

 

[UV-PWRD]

OK, but your screen shot above says 37.44V. Sorry, I'm out of ideas. The only time I've seen missing cells was when I was, like you, redoing some connections, and I inadvertently swapped 2 of the balance leads.

Yes it shows low voltage because it's only seeing 11 of the cells to calculate voltage.

I will quadruple check the leads to ensure they are in the right order, but given I am missing 5 random cells, I doubt that's it, it would make sense if all cells after a given point were wrong, but it can see the other cells.

 

[UV-PWRD]

OK, but your screen shot above says 37.44V. Sorry, I'm out of ideas. The only time I've seen missing cells was when I was, like you, redoing some connections, and I inadvertently swapped 2 of the balance leads.

Oh and in your case were you missing a number of cells? or Just 1 or 2 from having swapped wires?

 

[Sanwizard]

The setting in the app is 16 as it's a 16s 277ah pack, pack voltage at the time of the screen shot was around 54.4v, float voltage on the DMM. The inverter, just an MPP 7248 also sees pack voltage perfectly when I bypass the BMS and run it direct.

It does default to 24 when you "reset" the BMS through the app, but I changed that back immediately/rebooted etc still nothing on those cells.

Cell 16, which is the main pack positive does have 2 leads on it.

Remember this is a pack with a 100 cycles on it, all I've done is remove 1 wire at a time, replace a washer, add some carbon grease and put it back together.

Its either a bad BMS then, or the grease you used is non conductive, and causing the issue. Shut it down, clean everything with Isopropyl alcohol, and then reconnect without the new washers. Back to the way it was when working. Try MG Chem 8463 silver conductive grease as an alternative. I tested it, and it works better than No-Ox-ID Special.

 

[Sanwizard]

Question, the connection wires look larger than the harness that came with mine. Did you get a special connector?

 

[UV-PWRD]

Connector is standard.

The product is listed as carbon conductive grease, sold from an electronics store. Given I have continuity and voltage at each pin without any issue, I am confident there's not a conductivity issue.

I will check the order of the leads but I'm not going to spend another hr+ removing/cleaning each connector to get the same result. I did try mostly removing the grease from 1 terminal and removing the washers/nuts and simply held the terminal firmly against the stud on the cell, no change.

If there's continuity and voltage on each pin, that should be more than good enough. Remember the BMS does the ability to throw a fault and say resistance too high if that's the case. It's also not showing any resistance on any cell.

My guess is it's kicked the bucket being turned off/on.

 

[UV-PWRD]

I've just been over every wire again to confirm they are definitely in the correct order and I have individual and collective voltages on each pin on the connector depending on the negative it is referenced against (individual cell or main pack neg) so those balance leads are carrying everything I would expect them to.

Nothing from the supplier, reading messages but no replies as yet :/

Any idea on warranty?

Surely longer than 6mths and 100 cycles

 

[labeeman]

I've just been over every wire again to confirm they are definitely in the correct order and I have individual and collective voltages on each pin on the connector depending on the negative it is referenced against (individual cell or main pack neg) so those balance leads are carrying everything I would expect them to.

Nothing from the supplier, reading messages but no replies as yet :/

Any idea on warranty?

Surely longer than 6mths and 100 cycles

Did you disconnect the balance leads on the BMS before you redid the connections? If not you may have fried the BMS all you need is to touch another battery terminal to do that while it is connected to the BMS.

 

[UV-PWRD]

No, my order has always beem remove main pos/neg (BMS powers down). Then do any work I'm doing and reconnect pos and neg when done.

I was only removing one lead at a time, I didn't remove the connector.

Are you suggesting a loose cell wire had touched another cell and that's enough to kill it?

I've had those cell wires off plenty of times in the early days.

Thanks for the reply

 

[labeeman]

No, my order has always beem remove main pos/neg (BMS powers down). Then do any work I'm doing and reconnect pos and neg when done.

I was only removing one lead at a time, I didn't remove the connector.

Are you suggesting a loose cell wire had touched another cell and that's enough to kill it?

I've had those cell wires off plenty of times in the early days.

Thanks for the reply

Afraid so any time you mess with the cell wires you need to pull the plug any momentary touch to another cell will fry your BMS

 

[UV-PWRD]

Afraid so any time you mess with the cell wires you need to pull the plug any momentary touch to another cell will fry your BMS

Hmm. Well it's a possibility I guess. Usually if something touches something it shouldn't there's generally a clear visual indication lol

 

[labeeman]

Hmm. Well it's a possibility I guess. Usually if something touches something it shouldn't there's generally a clear visual indication lol

Yep sometimes there is smoke but sometimes there is not.

 

[UV-PWRD]

I'll keep that in mind. The supplier has finally replied so we'll see if I can wrangle another one for testing.

I will make a point of making sure I remove the balance lead loom completely in future, just in case that's happened here.

 

[MrM1]

Sorry jumping in here late, seems I saw someone post it somewhere, but now I can't find it...

Is there a "most recent" manual for this bms?

And a "best version" link to the current Android app

 

[upnorthandpersonal]

This is the manual:

User Manual for Heltec/JK BMS with Active Balance

Smart BMS 1A/2A Active Equalizer Balancer Battery Protection 14S ~ 24S 100A 150A 200A 300A Phone APP Lifepo4 li-ion LTO RS485 Model #s 20S 0.6A 100A, 24S 1A 150A, 24S 2A 150A, 24S 2A 200A, 16S 2A 300A

diysolarforum.com

This link has as far as I know the latest version of the app:

http://qr17.cn/BApbC0