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

[GXMnow]

This looks like what happened to me. In my case it was the pins in the balance lead at the BMS. I think it was a combination that the crimp was not done well, and a tiny bit of corrosion and when just one lead goes open, it shows up as two cells at zero volts. In your case, it looks like you have 3 dead connections. The +2 and +4 for sure, and maybe +3. Those are the 3rd, 4th, and 5th leads from the right end. Try some contact cleaner on the pins and plug the BMS harness in and out a few times to clean the contact, and then also tug and wiggle on the wires. I ended up using one of the higher cell pins since there are 10 I don't need with a 14S pack. It may also help to use a little dielectric grease on the pins so they don't corrode.

 

[UV-PWRD]

Seems I need to ship the BMS back to them for review/repair/replacement so I will be without it for a few months I'd have to think.

In the meantime I have a Heltec 5a balancer coming, locally, should have that in a week or so.

That will keep the pack balanced and I've got the inverter set conservatively for HVD/LVD charge rates etc.

 

[MrM1]

I just got 2 Heltecs. Can't even test them til my batteries arrive in a few months. But they seem to be a bit of a learning curve, having to "jump start" them with a 9v and all. Wish the Overkill units came in hi amp models. I have 3 8s units. Super simple.

 

[UV-PWRD]

If you search for me you'll see I made an incredibly simple jump start loom with a battery, moment switch, some alligator clips, etc.

I made a similar one for soft starting the inverter/pre-charging caps to stop big inverters fooling the BMs into thinking theirs a short.

 

[Samnarly]

I am starting a thread specific to he Heltec 200A Smart BMS with 2A Active Balance. 200A max charge. 350A max discharge
I have 4 of them and I bought them from the Alibaba Heltec store here - https://www.alibaba.com/product-detail/14-24S-200A-Smart-BMS-with_62544207027.html

edit: I forgot to mention this BMS is the same as JK brand. In fact the JK site has more up to date software that can be downloaded from play store or Apple. Check here for more info - https://www.jkbms.com/

Someone asked me to do a review of this BMS. I am not really ready to do a full review because I am new to DIY batteries and it takes me a long time to test these BMSs thoroughly. I actually have only used one so far. I am just getting ready to set up a second one.
And, I just wanted to start a place specific to this BMS so I can add my thoughts as I learn new information.
Of course I also want to hear from others using this BMS

My highest discharge current so far has only been about 70A and that was for a short time. My highest charge current was about 100A.
I hope to test a sustained discharge rate of at least 100A someday. My planned system would need changes for me to test higher than that and it could be years before I come to the conclusion that I need more amps. I don't expect that day to come but as I said I am new to this so I may change my mind someday.

I am very satisfied with this BMS so far.

The software is great.

The active balance is really cool. I had heard that 2A wouldn't be enough but my findings are that 2A is extremely useful and for my purposes I doubt 5A or 10A would be any better.
2A takes a long time but it keeps cells balanced perfectly. I can use 80% of battery capacity and be confident it will stay balanced. But, a passive balancer could probably do that too.

I love how it balances the cells perfectly whenever charging stops. It does even better when ever I am floating above the balance trigger.
Sometimes it can't completely keep up when charging / discharging high amps.
Sometimes it can't keep up in the knees. But so far it can always keep up enough so I am balanced if I only use 80% capacity and stay out of the knees.

A Newby to jk bms, I have just purchased 16 x 280ah eve batteries and trying to work out which jk bms to use. Can anyone help with the factors for choosing 0.6a/1a/2a and 100/150/200.
I run a 5kva victron inverter and rarely use to full crank. Cheers

 

[UV-PWRD]

A Newby to jk bms, I have just purchased 16 x 280ah eve batteries and trying to work out which jk bms to use. Can anyone help with the factors for choosing 0.6a/1a/2a and 100/150/200.
I run a 5kva victron inverter and rarely use to full crank. Cheers

150 or 200a

2A active balance only, or better yet, 0.6 active balance model, turn it off and get the heltec 5a active balancer instead to stand alone which is what I do now.

I have the 150/2a and IMO 2A is not enough even with having top balanced my cells for 2 weeks prior to commissioning.

 

[time2roll]

150 or 200a

2A active balance only, or better yet, 0.6 active balance model, turn it off and get the heltec 5a active balancer instead to stand alone

I have the 150/2a and IMO 2A is not enough even with having top balanced my cells for 2 weeks prior to commissioning.

Even the 5 amp is not going to pump near 5 amps unless the balance is quite bad.

 

[UV-PWRD]

Even the 5 amp is not going to pump near 5 amps unless the balance is quite bad.

Yes I know, and to be fair the 2A does 2A at all times in my testing.

But I see my biggest imbalances under large loads at the bottom end of the pack capacity and at that time, I want the 5a cranking to keep the lowest cells from trigger a LVD.

Design your system how you like and depending on your use case

 

[ArthurEld]

A Newby to jk bms, I have just purchased 16 x 280ah eve batteries and trying to work out which jk bms to use. Can anyone help with the factors for choosing 0.6a/1a/2a and 100/150/200.
I run a 5kva victron inverter and rarely use to full crank. Cheers

I am happy with the 200A with 2A active balancers and I think one would work well for you.
As long as you stay well within the knees it will keep you balanced. Simple as that.

 

[ocular]

A Newby to jk bms, I have just purchased 16 x 280ah eve batteries and trying to work out which jk bms to use. Can anyone help with the factors for choosing 0.6a/1a/2a and 100/150/200.
I run a 5kva victron inverter and rarely use to full crank. Cheers

2A 200A JKBMS would be my advice.
The active balancer is really only needed to fix up a non perfect setup. In the real world resistance variation by the bus bars and cell internal resistance can put cells out of balance. This is aggravated by large current flows. The JK active balancer in the balancer/bms combo can be adjusted so that balancing occurs above a set cell voltage. I use 3.4V and this means active balancing below 3.4V does not occur which is good because active balancing below 3.4V can unbalance the pack and increase the need for top balancing. The standalone JK active balancer and many of the addon capacitance active balancer dont have the ability to limit active balancing to a voltage range at the top end. The only add on active balancer that I know of that can limit balancing to above 3.4V is the new model of the Neely 4A active balancer sold by Hankzor. So if you are not charging your Tesla car @ 70A 3-4hrs per day and there is a daily period of 2-3hrs where the system is near float to allow top balancing then 2A can easily cope to keep delta V down to 10mV.

 

[Samnarly]

2A 200A JKBMS would be my advice.
The active balancer is really only needed to fix up a non perfect setup. In the real world resistance variation by the bus bars and cell internal resistance can put cells out of balance. This is aggravated by large current flows. The JK active balancer in the balancer/bms combo can be adjusted so that balancing occurs above a set cell voltage. I use 3.4V and this means active balancing below 3.4V does not occur which is good because active balancing below 3.4V can unbalance the pack and increase the need for top balancing. The standalone JK active balancer and many of the addon capacitance active balancer dont have the ability to limit active balancing to a voltage range at the top end. The only add on active balancer that I know of that can limit balancing to above 3.4V is the new model of the Neely 4A active balancer sold by Hankzor. So if you are not charging your Tesla car @ 70A 3-4hrs per day and there is a daily period of 2-3hrs where the system is near float to allow top balancing then 2A can easily cope to keep delta V down to 10mV.

Thankyou for the advice, I've been trying to purchase or chat with someone from Hankzor and I can't reach anyone, it doesn't seem like the chat icon is an active link. Does anyone have a direct link to purchase the 2a 200 amp bms from Hankzor?

 

[upnorthandpersonal]

Does anyone have a direct link to purchase the 2a 200 amp bms from Hankzor?

This one? https://www.aliexpress.com/item/1005003104573871.html

 

[Samnarly]

This one? https://www.aliexpress.com/item/1005003104573871.html

Thanks mate, ordered ?

 

[GXMnow]

I have the 200 amp 2 amp balance unit on my 360 amp hour 14S Li NMC pack. I intentionally discharged a group of 4 cells by about 10 amp hours. The JK-BMS immediately went to work, pulling from each of the other cells and then pushing into the 4 low ones. It pulled 2 amps, then pushed 2 amps, picking the highest cell, then the lowest cell. It does only work on just one cell at a time. But it does move 2 amps, even with just a few millivolts difference. By the next morning, all 14 cells were again balanced within 3 millivolts. This thing works perfectly as described.

But any cell balancer has limits. If your cells are not well matched, then the balancer can't fix it. Let's say you have one weak cell that is 90 amp hour, and the other 15 are 100 amp hour. That is a 10% lower capacity cell, which is pretty bad, but only one weak cell. As the cells charge at say 50 amps, that cell would be full in just 1.8 hours vs 2 hours for the rest. This is a total worst case, going from completely dead, 0% charge to 100% charge. To keep that weak 90 amp hour cell from over charging, we need to pull 10 amp hours of charge out, in just 2 hours. That would require a 5 amp balance current 100% of the time. But the JK-BMS balancer, and even the stand alone 5 amp version, only works on one cell at a time. So at best, it can pull 2 amp for half the time, and push those 2 amps into other cells, half the time. So in the 2 hours, if that one cell was always the highest voltage, the 2 amp balancer could pull out 2 amp hours. The 5 amp one, in 2 hours would pull 5 amp hours. And again, this is only one cell out of spec. With a second cell out of spec, it can only move half the amp hours in the same time. The best balancer can't correct for batteries that don't match. When I started working on building a home brew battery bank, my plan was to use a few extra small cells to parallel with the main cells to balance the capacity of each cell group. As long as they are the same chemistry, this should work, but I have not actually tried it. The cells I did end up going with are so wll matched, my balancer hardly ever kicks in.

 

[Dacflyer]

I just got my Other BMS's in the otherday,, They came in way sooner than i thought.
I'm still having issues with SOC meter. I even did a full charge and full discharge, reset and all, and still no correction.
No one seems to know what the deal is.. Everything else works just fine..

 

[SolarPrep]

I have the 200 amp 2 amp balance unit on my 360 amp hour 14S Li NMC pack. I intentionally discharged a group of 4 cells by about 10 amp hours. The JK-BMS immediately went to work, pulling from each of the other cells and then pushing into the 4 low ones. It pulled 2 amps, then pushed 2 amps, picking the highest cell, then the lowest cell. It does only work on just one cell at a time. But it does move 2 amps, even with just a few millivolts difference. By the next morning, all 14 cells were again balanced within 3 millivolts. This thing works perfectly as described.

But any cell balancer has limits. If your cells are not well matched, then the balancer can't fix it. Let's say you have one weak cell that is 90 amp hour, and the other 15 are 100 amp hour. That is a 10% lower capacity cell, which is pretty bad, but only one weak cell. As the cells charge at say 50 amps, that cell would be full in just 1.8 hours vs 2 hours for the rest. This is a total worst case, going from completely dead, 0% charge to 100% charge. To keep that weak 90 amp hour cell from over charging, we need to pull 10 amp hours of charge out, in just 2 hours. That would require a 5 amp balance current 100% of the time. But the JK-BMS balancer, and even the stand alone 5 amp version, only works on one cell at a time. So at best, it can pull 2 amp for half the time, and push those 2 amps into other cells, half the time. So in the 2 hours, if that one cell was always the highest voltage, the 2 amp balancer could pull out 2 amp hours. The 5 amp one, in 2 hours would pull 5 amp hours. And again, this is only one cell out of spec. With a second cell out of spec, it can only move half the amp hours in the same time. The best balancer can't correct for batteries that don't match. When I started working on building a home brew battery bank, my plan was to use a few extra small cells to parallel with the main cells to balance the capacity of each cell group. As long as they are the same chemistry, this should work, but I have not actually tried it. The cells I did end up going with are so wll matched, my balancer hardly ever kicks in.

GXMnow: Hope this is a hijack....

I have a pile of 8s prismatic modules (NMC) where about 16 of them are very closely matched in voltage, but have not yet been fully charged and set up with a BMS to arrive at a fully balanced pack. They had very little prior use (supposedly) There are another 6 modules, same model, but from another group, and they all consistently test at a lower voltage than the larger group. Again, not yet fully charged, and not assembled with a BMS. Both groups show very close consistency within their group. IE: nearly all 3.71 or similar for first group, and 3.42 for the second group. Would this make you worry about placing them all in service together, and using a BMS such as the unit discussed in this long thread?

My plan was to use a bench supply to get them all charged up to about 4.1, and then put them in parallel. Do you see any problems with that approach?

How about a 2a active balance? These are 60ah modules.

Just one more question while on this topic: with modules such as these, do you feel there is any significant disadvantage to using them in a 24v system, rather than 48? These modules were all in a high voltage cabinet originally, in series pairs 16s. A lot of equipment is more readily available in 24v than 48, and siome of it is UL approved. Fuses and wire would cost more, but in a refrigerator sized cabinet, they are all very close to each other, so I'm not worried about that. Thanks!

 

[Sanwizard]

GXMnow: Hope this is a hijack....

I have a pile of 8s prismatic modules (NMC) where about 16 of them are very closely matched in voltage, but have not yet been fully charged and set up with a BMS to arrive at a fully balanced pack. They had very little prior use (supposedly) There are another 6 modules, same model, but from another group, and they all consistently test at a lower voltage than the larger group. Again, not yet fully charged, and not assembled with a BMS. Both groups show very close consistency within their group. IE: nearly all 3.71 or similar for first group, and 3.42 for the second group. Would this make you worry about placing them all in service together, and using a BMS such as the unit discussed in this long thread?

My plan was to use a bench supply to get them all charged up to about 4.1, and then put them in parallel. Do you see any problems with that approach?

How about a 2a active balance? These are 60ah modules.

Just one more question while on this topic: with modules such as these, do you feel there is any significant disadvantage to using them in a 24v system, rather than 48? These modules were all in a high voltage cabinet originally, in series pairs 16s. A lot of equipment is more readily available in 24v than 48, and siome of it is UL approved. Fuses and wire would cost more, but in a refrigerator sized cabinet, they are all very close to each other, so I'm not worried about that. Thanks!

My JK's have been perfect so far. My delta stays around .008v consistently on my 16s pack of 280ah cells, of which I currently have two banks of same in parallel, each with its own JK 200 amp 2 amp active.

 

[GXMnow]

GXMnow: Hope this is a hijack....

I have a pile of 8s prismatic modules (NMC) where about 16 of them are very closely matched in voltage, but have not yet been fully charged and set up with a BMS to arrive at a fully balanced pack. They had very little prior use (supposedly) There are another 6 modules, same model, but from another group, and they all consistently test at a lower voltage than the larger group. Again, not yet fully charged, and not assembled with a BMS. Both groups show very close consistency within their group. IE: nearly all 3.71 or similar for first group, and 3.42 for the second group. Would this make you worry about placing them all in service together, and using a BMS such as the unit discussed in this long thread?

My plan was to use a bench supply to get them all charged up to about 4.1, and then put them in parallel. Do you see any problems with that approach?

How about a 2a active balance? These are 60ah modules.

Just one more question while on this topic: with modules such as these, do you feel there is any significant disadvantage to using them in a 24v system, rather than 48? These modules were all in a high voltage cabinet originally, in series pairs 16s. A lot of equipment is more readily available in 24v than 48, and siome of it is UL approved. Fuses and wire would cost more, but in a refrigerator sized cabinet, they are all very close to each other, so I'm not worried about that. Thanks!

With NMC cells, you should run 7 in series for a 24 volt system, and 13 or 14 in series for 48 volts. My own personal rule is to keep the normal running current under 100 amps. So a 24 volt system, running up to 2,400 watts seems reasonable. Surge power to 4,000 watts is not too bad, but if you need any more than that, I would go to 48 volt.

Getting all of the cells matched to within 0.01 volt would be great to let the JK-BMS active balancer finish the job. Going to just one decimal place is not ideal though, 4.10 to 4.19 is a fairly wide spread. But if you charge at a slow rate, the JK could still balance that out. Set the balance delta low and let it work, it will eventually bring them all to the same volts, just needs time.

 

[SolarPrep]

My JK's have been perfect so far. My delta stays around .008v consistently on my 16s pack of 280ah cells, of which I currently have two banks of same in parallel, each with its own JK 200 amp 2 amp active.

Sanwizard: that is really a good result!

 

[SolarPrep]

With NMC cells, you should run 7 in series for a 24 volt system, and 13 or 14 in series for 48 volts. My own personal rule is to keep the normal running current under 100 amps. So a 24 volt system, running up to 2,400 watts seems reasonable. Surge power to 4,000 watts is not too bad, but if you need any more than that, I would go to 48 volt.

Getting all of the cells matched to within 0.01 volt would be great to let the JK-BMS active balancer finish the job. Going to just one decimal place is not ideal though, 4.10 to 4.19 is a fairly wide spread. But if you charge at a slow rate, the JK could still balance that out. Set the balance delta low and let it work, it will eventually bring them all to the same volts, just needs time.

GXMnow: Thanks for the advice. By the way, I didn't mean to say I hope this was a hijack....I don't know maybe on some level...