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JK BMS Not activating (JK-B2A8S20P)

ahnatiw

New Member
Joined
Jul 5, 2022
Messages
3
Location
Ottawa, Canada
Hi folks,

I recently got the JK 4s—8s BMS (JK-B2A8S20P), but it did not ship with the manual push button switch. Is there another way to turn it on/activate it. I have it hooked up in a 4s configuration and raised the charge voltage to 20V and nothing happened. I was hoping to see the red light start blinking. The power switch does not look very complicated, is there a way to make one manually?

appreciate your help

Al
 
Connect the positive side of the 9 volt to the negative end of the cells, the B- lead of the BMS. Then connect the negative side of the 9 volt battery to the P- lead of the BMS.

Just touching it for a fraction of a second should get you the beep from the BMS and it will turn on. You might want to use a resistor in series (or a light bulb), especially when there are more packs in parallel.
 
As above is what I do with mine.

I made a loom with a 9v in series, a moment switch and 2 alligator clamps, I just clamp it on the main bat neg and the output side of the BMS, hit the button and remove.

Similarly, if the inverter is being cold started I have a resistor wired up the same way so I can pre-charge the inverter caps. Otherwise the BMS sees the inverter trying to start as a short and disables discharge.

I posted some pics on here somewhere.
 
Thanks for the help - unfortunately it did not work. I did manage to get it working, but I had to connect V+ to a 20V power supply that was grounded to the battery main negative. Applied the 9v and got the red light and beep. The tricky part was then taking the V+ lead and reconnecting to the battery main positive without interruption…not sure why it was not working at 14V (ie connected to the battery) . Applying 20V (ie charging at 20V) also did not work, also tried the 9V signal while 20V charging and no luck. Hopefully the seller will send me the switch.

cheers

Al
 
@Nami , would be able to help. I saw a number of post that you provide great information.

thanks

Al
I have received your message. You bought an old version, which can only be used on 7S and 8s batteries,
 
I have two JK-BMS, and I can’t get mine to start, either. I’d welcome comments. (I know they are set-up perfectly - history is given below – so it is an activation issue.)

My BMS spec says that it needs a 5V difference between the charge input (SCC) and the battery pack (12V nominal, 13.4V actual). Having no 5V sources I applied a small 9V battery (smoke alarm type, PP9/3LR12) across the BMS: C-/P- (PP9 -ve) and B- (PP9 +ve) – this is what the manual suggests. Nothing happens. My school physics tells me the BMS would have seen a battery pack at 13.4V and an apparent SCC voltage of 23.2V (MPPT at 14.2V plus PP3 at 9V), so this is well over the 5V needed to start the BMS.

Does anyone have any ideas, and could ahnatiw describe using the 20V p/s again, please? As I read it, the p/s negative was applied to B-, I would have thought that this would have meant that there was 20V across the batteries and nothing across the BMS (C-/P- & B)? I’m reading that the only way to make it start was to disconnected the SCC +ve?

History:
I know my packs are set-up correctly because each of the BMSes has started spontaneously on its own, in all cases without the application of an externally-applied voltage across P-/C- & B-. I cannot nail down the reason they started so that I can replicate it. In a couple of cases I have been messing with the MPPT outputs to see whether turning them on and off might supply a “surprise” voltage – this was the only time I managed to get both BMSes to start, within about 1 second of each other. On two occasions I have managed to get one BMS to start (no idea how) and left it for a week, and the second one has sat idle and not jumped in to service. Most recently, I managed to get the “idle” one started but the one that had worked for two separate one week periods did not start.

When the BMSes activate, they are visible on the ENJpower app and happily charge/discharge.

The BMSes’ 48V booster is shared between the two BMSes and is live even when the BMSes are not activated - the booster is on the part of the circuitry which can draw from the SCC. The only time there is the possibility that it isn't live is when I am messing with the outputs of the MPPTs but, oddly, the only time I got both BMSes to fire semi-simultaneously was when I was messing with the MPPT outputs, on/off.
 
I have spent some time trying to get my brand new JK-B2A8S20P to activate on a 4S setup, only to find out there are at least 2 versions of the JK-B2A8S20P both called JK-B2A8S20P, the early version is made for an 8S setup only, the latter or updated version is designed for 4S and 8S setups.

I just received batteries and a new JK-B2A8S20P from Docan Technology, expecting it to be the updated version to suit battery setup shipped; it was the early version thus would not work on a 4S setup
,
Docan Technology are blaming JK for sending out old versions, while not wanting to accept any responsibly for sending me the wrong unit.

My view is there have been a number of changes made to the new version to get it working on 4S and 8S setups thus trying to make the old version work on a 4S setup is most likely going to end in tears.
I suspect there are many customers that have ordered an JK-B2A8S20P expecting they were getting the new 4S-8S version and have been sent the old 8S version,
See picture of BMS box label, if yours looks the same the bet is it’s an old 8S version
 

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Mine is not in Chinise but on the last line it says 4s-8s whereas yours says 8s. ?
Hopefully Docan will make it right. I almost bough one from them but with the shipping it was about 50% more expensive than other souses.
You can make that one work by using a boost converter to get 24v on the last sense wire.
Here is a video from Off-grid garage showing how it works.
 

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Mine is not in Chinise but on the last line it says 4s-8s whereas yours says 8s. ?
Hopefully Docan will make it right. I almost bough one from them but with the shipping it was about 50% more expensive than other souses.
You can make that one work by using a boost converter to get 24v on the last sense wire.
Here is a video from Off-grid garage showing how it works.
Wish you well in getting Docan to come to the party, I have sent multipe emails to them on my unit and they just want to blame the issue on JK.
 
I have not seen any emails regarding Docan sourced JK BMS's that have had problems with Docan after encountering a problem. @CulfearneTech is the first post I have seen that actually reported receiving a JK form Docan. I have seen many Hankzor performance issues with little or no response including mine.
Before Hankzor started selling the 4s version and up till a week after I received my units with significant damage, I was able to contact @Nami anytime I had a question. Now that I have a dead unit, Hankzor has gone dark as far as answering my questions.
 
I have not seen any emails regarding Docan sourced JK BMS's that have had problems with Docan after encountering a problem. @CulfearneTech is the first post I have seen that actually reported receiving a JK form Docan. I have seen many Hankzor performance issues with little or no response including mine.
Before Hankzor started selling the 4s version and up till a week after I received my units with significant damage, I was able to contact @Nami anytime I had a question. Now that I have a dead unit, Hankzor has gone dark as far as answering my questions.
My bet is Hankzor probably sell 10 times more BMS's than Docan, I am still waiting on response from Jenny at Docan on my unit,
 
Connect the positive side of the 9 volt to the negative end of the cells, the B- lead of the BMS. Then connect the negative side of the 9 volt battery to the P- lead of the BMS.

Just touching it for a fraction of a second should get you the beep from the BMS and it will turn on. You might want to use a resistor in series (or a light bulb), especially when there are more packs in parallel.
 

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I'm not sure what you want - what your question is ?
I am NOT associated with JK or Hankzor, I only edited their manual so that it was more readable & translatable from English to other languages. I answer questions about them based on situations/conditions I've dealt with myself as I converted my fleet of batteries to JK-BMS [24S 2A 150A BT] Part Number: B2A24S15P.

In fact, I commissioned another Utility Pack (24V/105AH) and just finishing yet another 24V/280AH Pack.
I've renamed the 105 as "105-1" with No special Characters or Spaces in the name, then restarted the App as required, and voila.
Set the advanced settings to my desired profile etc, without issue. Now in this instance, I did not use the 9V Battery Start-up, I used an external power supply 24V/50A pushing 28V.

FYI, I used version 4.9.3 (build 69) APP to commission the 105 above and to manage the other packs in the bank.
- I have NOT changed Passwords though, so cannot speak to that. The default passwords are in use, the Main PW = 1234 and the administrative PW is 123456

I do not have any LCD Screens just a Power Switch which they provided.

Regarding Nami, I have tried to contact Nami myself via E-Mail which we used during the Manual Editing (Note that GMAIL a Google product is squelched in China) so I use Outlook Mail to communicate with them. I have not had any response from them either.

Pro-Tip for Startup:
1) The battery MUST be connected to a power supply or the Battery Bank.
if the New Battery is charged and too close to the Input Power that won't let it start, then you'll have to "kick it" with the 9V trick, with the 9V(+) to the B- (you can use the B- cell post on the battery) and the 9V(-) on the LFP battery on the (-) Post.
2) If using the 9V Solution I strongly suggest buying a connector and adding lengths of wire to facilitate it. They are CHEAP usually less that $1.00
1666187816638.png

3) Once the BMS is initialized, run the App: NB Give it permission's to use GPS etc.
a) Go to Settings & select LiFePo default config, then the number of cells
b) then if you want to rename it GoTo the main App screen and click on the pencil icon. No Spaces or Special Characters !!!
c) Restart the app and the new name should appear in the list after it scans.
d) Then go back to "Settings" and set the parameters for the battery, the defaults are NOT RIGHT for LFP. while doing so you may get errors "can't write to BMS" or similar, ignore and continue to finish the settings. CHECK THEM ALL including Temps (which are screwed up). Once done with that Restart the APP again, and go verify your settings and adjust if required in case any did not take the 1st time.

Here is my Settings Screen to correct their "defaults" and resolve issues BEFORE any pop up.
280-1-config-june-26-2022-all-bms-identical-png.100634























<- this seems optimal with various AH packs. I have 104AH, 174AH & 280AH packs & this is the sweet spot



<- Must be 0.5C of your battery pack





<- Set MAX of the BMS model. If you have a 200A BMS then set it to that









<- LFP Max Cell Temp is 60C SET THIS !

<- Release @ 55C


<- same as above

<- same as above

<- Stop Charge at 0C Temp (32F) !

<- Can start charging at 5C Temp (41F)





<- You CAN set info here for your pack.



Hope it helps good luck.
Steve
 
Pro-Tip for Startup:
1) The battery MUST be connected to a power supply or the Battery Bank.
if the New Battery is charged and too close to the Input Power that won't let it start, then you'll have to "kick it" with the 9V trick, with the 9V(+) to the B- (you can use the B- cell post on the battery) and the 9V(-) on the LFP battery on the (-) Post.
Hi Steve.
Could you please clear my doubts:
1. Are you saying that after connecting everything in the battery (cells, BMS, busbars, ...) , it will not startup if it's the only battery I have and I don't have a (24v) power supply?
How people do with it's first battery?
(Yes... Newbie here about to start it's first build - just bought a B2A8S20P and 8 LF280K)
2. Both (+) and (-) of the 9v battery connect to (-) (BMS and LFP battery), is that it?

Thanks in advance!

PS hope your health is doing as well as possible
 
Hi Steve.
Could you please clear my doubts:
1. Are you saying that after connecting everything in the battery (cells, BMS, busbars, ...) , it will not startup if it's the only battery I have and I don't have a (24v) power supply?
How people do with it's first battery?
(Yes... Newbie here about to start it's first build - just bought a B2A8S20P and 8 LF280K)
2. Both (+) and (-) of the 9v battery connect to (-) (BMS and LFP battery), is that it?

Thanks in advance!

PS hope your health is doing as well as possible
1.)Assemble battery pack.
Hook up battery, charger, inverter BIG 4 wires FIRST.
Hook up cell monitor small red wires second.
Hook up + red small and - black wires last to positive and negative of pack.
Push and hold start button for 3 seconds. If no start button as steve what to do.

Worked for me BUT I have screen and start button.
 
Is this “start button” just a momentary close switch ?

If so, are the pins accessible so a person could just short them for a second ??

Still waiting for my 16s JK to arrive from china and trying to be prepared.
 
Is this “start button” just a momentary close switch ?

If so, are the pins accessible so a person could just short them for a second ??

Still waiting for my 16s JK to arrive from china and trying to be prepared.
I dont know if you can short them. maybe ask someone else??
jkbms switch.jpg

bms wires2.jpg
 
Hi Steve.
Could you please clear my doubts:
1. Are you saying that after connecting everything in the battery (cells, BMS, busbars, ...) , it will not startup if it's the only battery I have and I don't have a (24v) power supply?
How people do with it's first battery?
(Yes... Newbie here about to start it's first build - just bought a B2A8S20P and 8 LF280K)
2. Both (+) and (-) of the 9v battery connect to (-) (BMS and LFP battery), is that it?

Thanks in advance!

PS hope your health is doing as well as possible
I am just finishing up building 2 more packs. 24V/105AH & 24V/280AH.
The 105 is done and I am using the JK with just the switch, no LCD. It's cells are at 3.540 so a tad over full IMO.
Using the switch only and nothing attached to the battery (+)(-) posts will not start it.
I attached a 24V/50A Powersupply (2x Meanwell S-600-12 paired) and then I can power up the Battery Pack. Take the powersupply off & the battery switch is dead and the App cannot see it anymore.

The "Simple Switch" click on Thumbnail to enlarge
1666294248078.png
 
I am just finishing up building 2 more packs. 24V/105AH & 24V/280AH.
The 105 is done and I am using the JK with just the switch, no LCD. It's cells are at 3.540 so a tad over full IMO.
Using the switch only and nothing attached to the battery (+)(-) posts will not start it.
I attached a 24V/50A Powersupply (2x Meanwell S-600-12 paired) and then I can power up the Battery Pack. Take the powersupply off & the battery switch is dead and the App cannot see it anymore.

The "Simple Switch" click on Thumbnail to enlarge
View attachment 117149
Hi Steve,
I've just assembled a pack with the same exact JK BMS
It did start up a couple of times initially, connected to phone app etc.
Then it would "partially" turn on - show 38V instead of 57V (this is with 17 fully charged cells)
The last thing it did was "turn on" to 38V blink for a few seconds and turn off.
After that - completely dead - does not react to the button press.

Have you had any progress with yours?
What's the final verdict?

[Edit]
At least once, while producing 38V, app showed "short" and 60s timer counting down. After that timer it switched on fully. It was connected to an inverter at that point - I thought it was just initial capacitor inrush current or something. But now - inverter is disconnected :(

[Edit2]
Fixed - the last positive lead blew the fuse. It wasn't really blown - wire inside seems intact but no continuity.
 
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