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Failed JK BMS

Horsefly

Solar Wizard
Joined
Dec 12, 2020
Messages
1,820
Location
Denver, mostly
I have two JK model b2a8s20p BMS. One is still great, one - the more recent one - has completely failed with very little use. NOT GOOD.

Background:

I had built an 8S 230Ah system for our cabin (see here) with a JBD BMS. I already had since built 3 other JBD based batteries and was pretty happy with them. The app was pretty crappy, and the passive balancing was pretty pathetic given the size of the systems we were building. Still, I was OK with all that. (Flavor of the month, I guess)

I had been reading here about the JK BMS, and it was pretty compelling: Much better app, and really good active balancing. Everything else was positive. Early in 2022, I decided to build a second 8S system (see here) and decided to use the B2A8S20P from JK. I was really impressed. Great BMS, great app. I was so impressed, I decided to order a second JK-B2A8S20P in (I think) early May, to replace the JBD that I had installed at our cabin. Unfortunately, the order could not be placed because they were changing the design to add heating control (which I did not need) to the BMS. I decided it was still worth the wait. I eventually ordered the BMS, and although I specified (and paid) for without the heat control, the one I got came with the heat control.

Skipping the details, I set up and installed the JK-B2A8S20P (new, with heat control) as a preplacement for my JBD BMS on one of my trips to the cabin. The morning after the switch, the sun came up and started charging the battery, and it was clear something was wrong. The Schneider Conext SW4024 Inverter/Charger (connected to the same battery) started making very strange arcing / hissing noises. I've posted about it in the board, but can't find the thread. I immediately switched back to the JBD (with no issues), and all was well.

I put the new JK BMS on my newer 230Ah 8S pack, and on my next visit to the cabin tried to plug that pack in in parallel with the JBD pack. Through a few days of testing, whenever the JK pack was connected the same arcing / hissing noise came from the Schneider equipment. When the JK pack was disconnected, all was well.

I PM'd @Nami about this issue, but of course never heard anything in return.

The 230Ah pack with the newer JK BMS remained on a emergency backup system at my home in Denver, on a hand-truck with a MidNite Solar 3000W inverter/charger (thanks to Lithium Solar channel on YouTube for the idea). I've partially discharged the battery twice this fall, and changed it up to about 70% again two weeks ago.

Yesterday, I connected the JK app on my phone to the BMS just to check the status. It went crazy, alarming continuously and reporting that none of the cells matched the configured voltage, and allowed no discharge or charge. I replaced the BMS with my original JK-B2A8S20P (pre-heater-function) and it immediately said all was well, cells were within 1mV, and pack was at 26V.

So the newer heater-enabled BMS is crap. Lots of line noise (potentially damaging), and the whole thing crapped out. I had it for about 6 months, but in truth it had been through perhaps 4 charge / discharge cycles. Rubbish. I'm really sad. Turns out, JK BMS was truly just the BMS flavor of the month.


I'm not as active on the forum any more (too many other things), but I assume @Nami has gone the way of Michael B Caro.
 
Nami is just a sales rep who also took on a more supporting role.
She & many others just got out out of an extended Covid Lockdown (China has a zero covid policy and they lock down at the 1st hint of an outbreak).
HankZor and others are just resellers and NOT the actual Manufacturer of the products they sell. They do have "some" influence with the manufacturer but no control over QC. Do keep that in mind.

That being said, JiKong has indeed dropped the ball and it is not shouldering responsibility leaving it up to the vendors which inflicts injury on the brand - terrible business model, really. Also the old axiom of never buying Version 1.0 or first production model is still very much true ! regardless of sector. Always best to wait till at least V 2.0 of X product. For example ATM there have been 5 useless versions of the JKBMS Droid App (don't know about their IOS APP) that does not install on Droid up to V.12 of Droid because the Dev is incapable of doing Prerelease Testing prior to Release. An idiot that would have been fired by me QUICKLY if he had been working in my IT Dept when I was running it.

@Nami has returned from lockdown but I do not think they are checking here at this time - I suspect there is a reason (the anti-vendor shtick) that pushed them all out of here which does not help our membership. It is also SAD that even Manufacturers who engaged with us and acted on our feedback while trying to meet our needs were also "pushed away" and there was a few of them but not many because most will not engage with the end-users as it is quite difficult.

I would suggest that you try and contact NAMI through their site IF you bought from them to see if the unit can be replaced. I can tell you that I've had almost no issues at all with the units I use for 24V/8S but I am using the JK B2A24S15P and just took out the leads for B9-B23 from the connector to make a cleaner install. There is no heat function and that model is stable.

Hope it helps.
Steve
 
I suspect there is a reason (the anti-vendor shtick) that pushed them all out of here which does not help our membership. It is also SAD that even Manufacturers who engaged with us and acted on our feedback while trying to meet our needs were also "pushed away" and there was a few of them but not many because most will not engage with the end-users as it is quite difficult.
Yes this is a strange reaction especially as SS are very prominent here if not for all good reasons !!!!
Even more odd is the threads with holes in them where a "vendor" has had everything deleted.
 
One such example when this board started was how the main dev-eng from Chargery BMS Co was here, interacted & worked with a few of us, developed gear with our involvement and went forward with our input to develop even better and higher quality product series which are now coming available (covid issues slowed stuff up badly) but he also was shoo'd away on a broomstick and then more happened. It's really a shame that such self-injury just happens. BUT to be fair, there were also "some - a Few" bad players that did ruin it for those that were genuinely here to interact & listen/hear & help the membership. It's too bad that a "few" can wreck things but that is the 21st century and the way it is these days...

You'd be surprised at the CRAP I got chucked at me for fixing manuals & docs for some products and trying to make peoples lives a bit easier... even conspiracy crap & why I never asked for anything in return for doing so. I am NOT a Ferenghi and not profit driven just an old timer Freeware Opensource dude... I've come close to quitting here several times because of some asshats.
 
Man I keep hearing about these JK I think they are using cheap BMS, Andy from offgrid garage actually blew up one, partially, during his review video.

My JBD have been working solid.
 
Great, I just received my JK bms B2A8S20P yesterday, mine does not have the heating option. I am going to replace my JBD with the new JK bms sometime today or tomorrow when my garage warms up. I will keep you posted as to how it goes. The JDB is ok just does not have the active balancer that the JK has. I also watch Andy on youtube and he is happy with the new versions of the JK bms. Wish me luck..
 
Andy also fried other BMS' and learned some lessons along the way.
The ones that are "exposed" are also subject to Static Electricity damage and just how many pay attention... it is Fine Electronics and rarely does anyone handle them properly. At least the JK's are encased but still should be handled properly.
 
Success, I completed the install of my new JK bms today and everything is working properly. It is nice to see it balance with about 2 amps, I have always had one cell that would act up on charging, it has been that way from the beginning.( over two years). the new JK bms is keeping that cell inline. I would contact your seller and request a replacement bsm, I purchased mine thru Aliexpress in the Hankzor store.
 
He was pushing the BMS way over its operating limits to see how much it takes so a bit unfair characterization.
I had wished Andy would follow up on that test.
He drove the BMS hard and popped a FET.
Anyone remember if it failed open or closed?
I wonder how many inexperienced users would have even known there was a problem.
If the FET failed open, then the other FETs have to work harder and may subsequently fail.
If the FET failed closed, then the BMS can no longer disconnect a current path leaving the battery un-protected.
@Off-Grid-Garage ^
 
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So the newer heater-enabled BMS is crap. Lots of line noise (potentially damaging), and the whole thing crapped out. I had it for about 6 months, but in truth it had been through perhaps 4 charge / discharge cycles. Rubbish. I'm really sad. Turns out, JK BMS was truly just the BMS flavor of the month.

I would really like to see the newer versions - I only have older ones (and they've been rock solid). I've been thinking there are quality issues, in part because of the component shortages. I never get around to ordering new ones because I don't really need them, so if you're selling your broken one, PM me.
 
I would really like to see the newer versions - I only have older ones (and they've been rock solid). I've been thinking there are quality issues, in part because of the component shortages. I never get around to ordering new ones because I don't really need them, so if you're selling your broken one, PM me.
The version I bought earlier (before the heat port was added) is still rock solid. No issues. It's the newer one that crapped out.

I'd be happy to give the thing to you, but I'm not sure how to get it to Finland. I'll send you a PM.

Before I saw your post, I took the heat sinks off both sides of the board, thinking that there may be some obvious failure, but I don't see anything obvious.
IMG_20221119_152817759_HDR.jpg
IMG_20221119_152828102_HDR.jpg
 
I've been using the newer jkbms since August without any issues whatsoever. This is the one with the heating pad port, but I'm not making use of it.
 
One of my H versions of the B2a8s20p has developed a similar fault
Yesterday, I connected the JK app on my phone to the BMS just to check the status. It went crazy, alarming continuously and reporting that none of the cells matched the configured voltag
I removed the display and it will re-initialise without the alarm. I assume it is working now but can't access it to find out. It is putting out power as I can switch off the other bms and the inverter still runs.
My impression is that the balance leads aren't connected properly as if I press the JST connector it stops the alarm and was how I eventually managed to get it to work.
I am struggling to get replacement 10 pin connectors in the UK so need to order some from AliExpress but the holidays kind of got in the way.
I'm somewhat loathed to fiddle at the moment because it's the worst part of the year for solar and I'm only just holding sufficient charge for lighting and water pumping.

I'm less than impressed with the JK and am looking for an alternative replacement.
I'm also less than impressed with Hankzor who could only offer me an address in Italy to send the faulty unit to. Italian post being what it is, and with no details on who I would be sending this to I imagine that I will never see my bms again nor hear from the recipient.

I'd rather replace it and carry out some tests on the faulty unit to see if I can resolve the issue. My initial thought is to solder directly to the pin-outs. I have had to do that with the switch for the other unit which had a badly soldered, non functioning, jst socket when it arrived. It was easier to solder direct than remove the heatsink to refit the socket.

The JK may have some wonderful specs but the build quality is definitely lacking and there's zero customer support from Hankzor (unless you include posting to some random address or the rose emoji they so love to use) and no response contacting the JK store direct.
 
One of my H versions of the B2a8s20p has developed a similar fault

I removed the display and it will re-initialise without the alarm. I assume it is working now but can't access it to find out. It is putting out power as I can switch off the other bms and the inverter still runs.
My impression is that the balance leads aren't connected properly as if I press the JST connector it stops the alarm and was how I eventually managed to get it to work.
I am struggling to get replacement 10 pin connectors in the UK so need to order some from AliExpress but the holidays kind of got in the way.
I'm somewhat loathed to fiddle at the moment because it's the worst part of the year for solar and I'm only just holding sufficient charge for lighting and water pumping.

I'm less than impressed with the JK and am looking for an alternative replacement.
I'm also less than impressed with Hankzor who could only offer me an address in Italy to send the faulty unit to. Italian post being what it is, and with no details on who I would be sending this to I imagine that I will never see my bms again nor hear from the recipient.

I'd rather replace it and carry out some tests on the faulty unit to see if I can resolve the issue. My initial thought is to solder directly to the pin-outs. I have had to do that with the switch for the other unit which had a badly soldered, non functioning, jst socket when it arrived. It was easier to solder direct than remove the heatsink to refit the socket.

The JK may have some wonderful specs but the build quality is definitely lacking and there's zero customer support from Hankzor (unless you include posting to some random address or the rose emoji they so love to use) and no response contacting the JK store direct.
I had tried plugging in and unplugging the button (mine came with a button instead of the display), and unplugging / reseating the balance lead JST connector. Nothing seemed to help. I think mine was more of a hard failure.

I shipped the thing to @upnorthandpersonal for him to play with. Maybe he'll be able to figure out what happened.

I never even tried to contact Hankzor. Based on the comments I've seen here, I made the decision that I didn't need to raise my blood pressure any more.
 
Thing is, Hankzor was really good, fast replies, etc. and then basically from one day to the next it wasn't. I've done extensive tests and analysis on the older BMS versions they have and they're really good - I've been running my house on them for three years now without any issue what so ever. It seems that something changed in the mean time, but I don't know what. Hopefully I can do some more analysis and draw some conclusions based on the one @Horsefly sent me - once that arrives.
 
Thing is, Hankzor was really good, fast replies, etc. and then basically from one day to the next it wasn't.
From the experience I have had with them, I wonder if they understand the translation into Chinese. My neighbour is Malay and speaks several dialects of Chinese but she couldn't make sense of the messages because you can translate with different meaning and some technical words are nonsense without context.
The Ali store translation is different from Google and messages frequently get truncated.
I've had some apparently rude responses that my neighbour translated differently, so I wonder what they read when I send messages.
When I pointed that out to Hankzor they send the ubiquitous "Rose" emoji but made no effort to clarify things.
Hence most responses are to 'download software or info' or the bloody rose emoji. I suspect their success has become overwhelming and they just don't want to be bothered about the few failures.
Hopefully I can do some more analysis and draw some conclusions based on the one @Horsefly sent me - once that arrives
I look forward to your findings, as it will give me a route to follow with my unit once I decommission it and find a suitable replacement.
I'm just in the process of ordering some 10pin JST connectors along with a replacement BMS, when I can decide on brand - another gamble on JK or try JBD which are substantially cheaper. Andy OGG runs different brands in parallel with no issues so I figure I have little to lose in trying a similar approach other than the 2A balance - and once the sun returns in a few weeks, power won't be a problem for 9 months.
 
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