Connecting JK-BMS to Inverter - Any major advantage?

[kolek]

The newer version of the JK-BMS will talk to inverters, and there's a project to allow the JK-BMS to talk to the inverter.
It would mean my JK BMS could talk to my Deye inverter.
Sure it's cool, I get it. Maybe you can implement some cool charging strategies, etc., but beyond things like that, is there any real major advantage?
There's really only 2 advantages that I personally would be interested in:
- additional safety
- additional battery longevity
If it's not delivering either of the above, I probably won't bother.
Thoughts?

 

[hwy17]

If you are using your inverter for grid or generator input, SOC control is a lot more accurate than voltage control.

If the inverter does not use grid/gen input then it's less important.

 

[kolek]

If you are using your inverter for charging, SOC control is a lot more accurate than voltage control.

@hwy17 Thanks a lot for taking the time to respond.

Regarding "SOC control is a lot more accurate than voltage control," for the past day I've been reading about how the JK-BMS grasp on the SoC is less than trustworthy, and if you're using a JK-BMS, it's a better idea to use a Victron shunt to monitor SoC.

If that's true, maybe it's a better idea then to get the Victron shunt talking to the inverter than getting the JK-BMS talking to the inverter. No? If I'm spewing nonsense, please let me know. ;-)

 

[houseofancients]

The newer version of the JK-BMS will talk to inverters, and there's a project to allow the JK-BMS to talk to the inverter.
It would mean my JK BMS could talk to my Deye inverter.
Sure it's cool, I get it. Maybe you can implement some cool charging strategies, etc., but beyond things like that, is there any real major advantage?
There's really only 2 advantages that I personally would be interested in:
- additional safety
- additional battery longevity
If it's not delivering either of the above, I probably won't bother.
Thoughts?

It is a safety feature, will help the balancing of your cells, will prevent your mosfetts get hit by sudden shutoff under high amps ( both inverter and BMS)

 

[kolek]

@houseofancients Thank you for your response!
I recall you also have a Deye inverter, did you get your JK-BMS communicating with your Deye?
If so, are you using one of the new JK-BMS that have the feature built-in the latest firmware?
Also, what is your opinion of using the JK-BMS to monitor SoC? Is it reliable enough?
Thanks again!

 

[houseofancients]

@houseofancients Thank you for your response!
I recall you also have a Deye inverter, did you get your JK-BMS communicating with your Deye?
If so, are you using one of the new JK-BMS that have the feature built-in the latest firmware?
Also, what is your opinion of using the JK-BMS to monitor SoC? Is it reliable enough?
Thanks again!

I have sunsynk inverters ( deye's with some different software).
Do not use jk-bms at all..
Use seplos, but the jk may be interesting in a year or so for me..
Now there's simply to many issues with it, and not mature enough for me

 

[kolek]

Now there's simply to many issues with it, and not mature enough for me

Ah, so you strongly recommend it for me, but you personally wouldn't touch it with a 10' pole. Good to know.

 

[houseofancients]

Ah, so you strongly recommend it for me, but you personally wouldn't touch it with a 10' pole. Good to know.

Lol, never said I would strongly recommend the BMS itself for you, but if you decided to use it, I would highly recommend using communications

 

[kolek]

Well, as I understand it, the JK-BMS is relatively stable, it's the new firmware with the communications portion that is new and maybe less than 100% reliable.

I actually tend to agree with @houseofancients that the technology is too new to adopt yet, unless you are willing to take all the risks associated with being an early adopter.

 

[chaosnature]

I can only talk about my experience and set up.

i have Both the old and the new JKBMS's and even a JBD (not worked on this yet)

With my setup, i initially had a design to have the old JK x 2 in parallel to communicate to each other via RS485. but as the code for parralel has not been developed yet i used the concept of current flow like water and the extra feature provided by the old jk that balances the cells to contruct my design....so far it works well and the folks working of the sleeper85 projects are doing a great job improving the system .



...in my view it is now even better functiong that the manufacturers solution both on the Inverter side and the BMS side. it gives you full control and at the same time preserves the protection parameters set on either the BMS or the inverter.

it sits between the Inverter and the BMS so it's an added protection function, it does not take away rather it adds.

thats my observation so far....

 

[chaosnature]

As for the new JK .... the protocols are being developed and more and more protocols are being added, however, though i have not used it in production yet i do not see yet an extra benefit even though its an inverter designed BMS...i plan on testing it on my second string, and in the end i might also add the ESP tech developed by the guys between the BMS and the inverter as well even though it can work without the ESP developed integration.

 

[chaosnature]

The only flur for me is i am still calibrating after so many days....i believe i will get it right soon. been doing arithmetic and using data from the original battery datasheet

 

[kolek]

SOC control is a lot more accurate than voltage control.

Getting back to this comment, is the main point here sending the SoC from the JK to the inverter?

Edit: by that I mean, is the main point of the communications between the BMS and inverter so that the BMS can send the SoC to the inverter and the inverter can act on that information?

 

[hwy17]

Regarding "SOC control is a lot more accurate than voltage control," for the past day I've been reading about how the JK-BMS grasp on the SoC is less than trustworthy, and if you're using a JK-BMS, it's a better idea to use a Victron shunt to monitor SoC.

If that's true, maybe it's a better idea then to get the Victron shunt talking to the inverter than getting the JK-BMS talking to the inverter. No? If I'm spewing nonsense, please let me know. ;-)

Yeah I can agree with all that. In my BMS I have SOC drifts where if one cell drops below a certain voltage SOC gets dragged to 15% so my SOC trigger for charging at 20% will happen either of coulomb counting tells the BMS it's low OR if one cell is going low.

I don't know how the JK does it. And a downside to the victron shunt is it can't trigger on low cell, only coulomb counting or pack voltage.

 

[chaosnature]

Getting back to this comment, is the main point here sending the SoC from the JK to the inverter?

Edit: by that I mean, is the main point of the communications between the BMS and inverter so that the BMS can send the SoC to the inverter and the inverter can act on that information?

For me it was compatibility - before the integration, my inverter would not see my batteries - then I realized the protect that came with it after implementation

 

[chaosnature]

Yeah I can agree with all that. In my BMS I have SOC drifts where if one cell drops below a certain voltage SOC gets dragged to 15% so my SOC trigger for charging at 20% will happen either of coulomb counting tells the BMS it's low OR if one cell is going low.

I don't know how the JK does it. And a downside to the victron shunt is it can't trigger on low cell, only coulomb counting or pack voltage.

With my Solis setup it was'nt stopping at the 0% SoC until i decided to stop it way before the lower SoCof 3.32
So now i noticed it stops at 3.4 which around 47 volts



i set it to the lowest margin so in the event is has to Forcecharge it only does it to 5%...it been o.k so far

 

[kolek]

i do not see yet an extra benefit even though its an inverter designed BMS

@chaosnature just to be 100% clear, you're using the new JK BMS with the latest firmware and you're saying you don't yet see a clear benefit to having the communications between the BMS and the inverter. Is that correct?

 

[chaosnature]

@chaosnature just to be 100% clear, you're using the new JK BMS with the latest firmware and you're saying you don't yet see a clear benefit to having the communications between the BMS and the inverter. Is that correct?

I believe its the latest firmware - it's 2024 when I last checked.

# Edit

 

[100FUEGOS]

I believe its the latest firmware - it's 2024 when I last checked.

# Edit
View attachment 204280

Latest firmware for V15 is V15.11

 

[chaosnature]

Latest firmware for V15 is V15.11

you have the change logs? - its all in chinese