JK-B2A25S60P 500amp bms - how to connect to battery power leads?

[Prof Chill]

Folks, this is going to sound crazy, but I ordered a JK-B2A25S60P bms to run a motor on a sailboat. I went with such a big bms because I anticipate some moments when I might be pushing an awful lot of amps out of the battery, and I wanted to be oversized just in case.

But when it arrived, there doesn't seem to be any way to actually connect the BMS to the power leads from the battery. It came with a big shunt and the LCD display and the wiring, but there's nothing on the case that I can connect the battery to. No lugs. I can't find any documentation on JK's site, and what I am able to find lists the charge/discharge port as "separate." That's fine, but where can I get one, and how do I wire it in? Does anybody have any light they can shine on this for me?

Thanks in advance-

 

[Struc]

That is a solenoid BMS. You'll need to purchase the HD contactor that goes with it separate, and then that wires into the BMS

 

[Prof Chill]

That is a solenoid BMS. You'll need to purchase the HD contactor that goes with it separate, and then that wires into the BMS

Thanks - that makes sense. Do you have a wiring diagram for this setup that I can take a look at?

 

[Struc]

No... I don't own one, but I did look at it at one point.

Here is a link to the contactor on the Hankzor BMS store

500A Main Contactor

 

[Prof Chill]

No... I don't own one, but I did look at it at one point.

Here is a link to the contactor on the Hankzor BMS store

500A Main Contactor

Thanks again so much. I ordered it. Did you have any luck finding a wiring diagram for the system? I had assumed that one would come with the BMS unit, but there was no documentation at all. I'd like to make sure that I'm understanding the pinout correctly for all of the leads, and that I position the shunt where it's supposed to go.

 

[Struc]

I did not have any luck. I would reach out to the place you bought it from.

 

[perryg114]

This is why I don't want something that is gray market from China. You have to hack it to get it working since there are no instructions in English and very poor documentation. You also have to wait a long time for it to ship.

 

[Prof Chill]

JK was actually a lot better about this than I thought they would be. I sent them a message through the Aliexpress contact system, and they were back to me by the following morning with a website that has all the downloads on it. The instructions are in both Chinese and English, but they're pretty easy to work out. Here's the site, for anyone who finds themselves in a similar situation:

GitHub - NEEY-electronic/JK at JK-BMS

Contribute to NEEY-electronic/JK development by creating an account on GitHub.

github.com

 

[Burke]

I am thinking of getting one of these. How did the install go?

 

[Sonic3389]

I'm looking to get one of these as well, I'm a bit confused by the manuals diag though... is that showing 3 contactors??

I thought they'd be 1 contactor with the pos line going through it and 2 control wires from the BMS... this diag seems to show 3 contactors with different names for the control wires attached to each?

 

[Prof Chill]

Sonic - the lowest contactor with the resistor before it on O1 and O2 translates to "pre-charge contactor." Unfortunately the resistance value is unspecified. I'm trying to run it down now. The contactor above it translates to "discharge contactor."

 

[LukeL]

JK was actually a lot better about this than I thought they would be. I sent them a message through the Aliexpress contact system, and they were back to me by the following morning with a website that has all the downloads on it. The instructions are in both Chinese and English, but they're pretty easy to work out. Here's the site, for anyone who finds themselves in a similar situation:

GitHub - NEEY-electronic/JK at JK-BMS

Contribute to NEEY-electronic/JK development by creating an account on GitHub.

github.com

Thanks so much for sharing this link. I bought two of these BMS and they’ve been sitting on the shelf for a few months stressing me out. I also received this link to the manuals (well I used the QR code on the actual unit). Anyway I can’t find a thing in English. All I want is a wiring diagram. Have no idea where to start. Are you able to attach the English PDF to this?

I feel trapped into this. Had no idea I needed to be fluent in Mandarin and have an electrical engineering degree just to upgrade my battery bank from lead acid. So much buyers remorse it’s not even funny.

 

[rhino]

The English manual is one of the PDFs listed there... but here is the direct link: https://github.com/NEEY-electronic/JK/blob/JK-BMS/JKBMS INSTRUCTION.pdf

 

[rhino]

Also you can watch Andy wire one up here:

 

[LukeL]

The English manual is one of the PDFs listed there... but here is the direct link: https://github.com/NEEY-electronic/JK/blob/JK-BMS/JKBMS INSTRUCTION.pdf

Thank you! I ended up making a post with one specific to my unit but this also is really helpful thank you much. Making headway. Best!

 

[LukeL]

Also you can watch Andy wire one up here:

Thank you. Watched it. Very helpful but still need piles of answers as I have a different BMS. I’ll try contacting Andy. Thank you ?

 

[Prof Chill]

Thank you. Watched it. Very helpful but still need piles of answers as I have a different BMS. I’ll try contacting Andy. Thank you ?

I got mine up and running. How's it going for you?

 

[Burke]

Also posted this in the other thread for this BMS

I have the same BMS to upgrade an older failed unit.

I found this diagram which is in English.

The diagram below is from a Chinese manual I found for the JK-B2A25S-RP which has English labelled pin outs that actually match what the cables are labeled with. This is what I was guessing from the diagram posted just prior, but nice to have confirmation.

I am going to install likely today to replace my failed BMS - Balancing and power out to the display is not working. Using only one battery relay only as I have an integrated inverter/charge controller. If I had a separate charge controller I would use another relay for the charge function. I may add the charge relay in the future as I will occasionally charge the battery with a power supply as my setup is a whole house battery backup vs solar and I can run the external charger through the charge relay which will be more convenient. Using the Discharge relay outputs only, and I will wire K+/C to the load side of the Discharge relay. I am Wiring all the grounds to B-, not using the pre-Charge feature at this time so not wiring ACC+

 

[TorC]

Since I saw it asked about, but not answered: the precharge resistor can be anything you want within the following parameters:
1: Resistive only load. A motor could be damaged by the dwindling voltage. Incandescent light bulbs are a good choice, and provide a visual indicator of precharge progress. An old clothes iron with the switch bypassed (not designed to switch DC) could work, but left long enough on a 48V bank that actually was shorted might overheat. A toaster with switch bypassed would be fine - it reaches a more or less steady state on 120V in normal operation.
2: Capable of dissipating battery voltage into a dead short, or, if you prefer, capable of being placed as a load on your battery without exceeding appropriate draw on your batteries, and which presents a load your precharge relay/contactor can safely switch at battery voltage.

The lower the resistance of your precharge resistor, the faster it will charge, but the more power it must be able to safely dissipate.

 

[Burke]

Since I saw it asked about, but not answered: the precharge resistor can be anything you want within the following parameters:
1: Resistive only load. A motor could be damaged by the dwindling voltage. Incandescent light bulbs are a good choice, and provide a visual indicator of precharge progress. An old clothes iron with the switch bypassed (not designed to switch DC) could work, but left long enough on a 48V bank that actually was shorted might overheat. A toaster with switch bypassed would be fine - it reaches a more or less steady state on 120V in normal operation.
2: Capable of dissipating battery voltage into a dead short, or, if you prefer, capable of being placed as a load on your battery without exceeding appropriate draw on your batteries, and which presents a load your precharge relay/contactor can safely switch at battery voltage.

The lower the resistance of your precharge resistor, the faster it will charge, but the more power it must be able to safely dissipate.

The precharge circuit would be used to charge the capacitors in the inverter, it does need a resistive load to prevent a too fast inrush of current, or a resistor. Once the capacitors are charged, power is turned on to the inverter. After that the precharge circuit should be switched off. The Precharge relay would pass battery power (through a resistor) to the inverter for a short time then turn off.

 

[lichtimc]

Did anyone ever manage to get the precharge circuit working?
My precharge contactor is always on without a chance to change this, no matter if I switch on / off charging or discharging.