JK BMS CAN bus comms now possible for inverters that support Goodwe and Pylontech batteries

[Sleeper85]

I take this opportunity to confirm the proper functioning of the new TJA1051T chip which is backward compatible with the old TJA1050 chip.

TJA1051 High-Speed CAN Transceiver

NXP's TJA1051 is a high-speed transceiver for all types of High-speed CAN networks in nodes that do not require a standby mode with wake up capability

www.nxp.com

 

[Sleeper85]

Deye SUN-6K-SG03-LP1-EU
MAIN : 4384-1515
HMI : 0000-C362

First day with the JK-BMS-CAN module (1.13.3), I don't understand what's going on.

The battery remained below 50% all day.
The Time Of Use config is 40% SoC min from 8:00 to 12:00 and 50% SoC min from 12:00 to 16:00.

The inverter is configured to charge the battery first so all solar energy must recharge the battery up to the minimum SoC (40% SoC from 8:00 to 12:00 and 50% SoC from 12:00 to 16:00.)

The inverter never exports if the battery is not 100% charged, today the export started at 11:23 with a battery charged at 41% and a voltage of 53.2V far from the charging voltage of 55.2V.

I authorized a charge current of 100A and we stayed below 40A with 3320WV of PV which is normal.

This behavior is very strange and totally different from the behavior without the connection to the BMS.

In Deye I have enabled the 'Disable Float Charge' setting I will disable it and see how it goes tomorrow.

 

[uksa007]

The battery remained below 50% all day.
The Time Of Use config is 40% SoC min from 8:00 to 12:00 and 50% SoC min from 12:00 to 16:00.

The inverter is configured to charge the battery first so all solar energy must recharge the battery up to the minimum SoC (40% SoC from 8:00 to 12:00 and 50% SoC from 12:00 to 16:00.)

Deye Time of use is a bit confusing, It looks to me like it is doing what you have configured in the TOU setting.

It is only charging to ~40% before 12:00 and 50% to 16:00
Do you need to use TOU, maybe try turning it off and see what it does?

You should monitor the ESP32 logs or in Home Assistant the "Charging status", tells you what it is requesting from the inverter:
Bulk means it is requesting charge.
Wait means no charging as the battery is full.

Maybe the first part of the video helps, they have TOU not ticked or disabled?

Regards.

 

[Sleeper85]

Deye Time of use is a bit confusing, It looks to me like it is doing what you have configured in the TOU setting.

It is only charging to ~40% before 12:00 and 50% to 16:00
Do you need to use TOU, maybe try turning it off and see what it does?

I know Deye and TOU well and what is happening today is a completely different behavior from what is happening in 'Use Batt %' mode.

With the 'Use Batt %' mode it happens like this:

1. If at 12:00 Batt = 50% in TOU
2. If the battery is at 43% it will be charged as a priority by the PV up to 50% ('Batt First' checked)
3. Then the PV can power the load and the battery at the same time, the battery continues to charge.
4. When the battery reaches 100%, the surplus can be exported

You should monitor the ESP32 logs or in Home Assistant the "Charging status", tells you what it is requesting from the inverter:

Good idea, I'll see what's going on there.

Thanks.

Edit:

This morning it's on Bulk, we'll see how it goes the rest of the day.

 

[Sleeper85]

@uksa007

Yesterday I had no problems.

Today the problem started at 11:58 when the SoC was at 33%.

When the problem occurs the charging status is "Wait", the inverter stops charging the battery and exports energy to the grid.

 

[uksa007]

@uksa007

Yesterday I had no problems.

Today the problem started at 11:58 when the SoC was at 33%.

When the problem occurs the charging status is "Wait", the inverter stops charging the battery and exports energy to the grid.

It goes into Wait state when the battery voltage = absorption voltage, what was the battery voltage when it when into wait state?

The SOC is generated from the BMS, have you calibrated it for SOC and have you configured the battery chemistry and setting correctly in the BMS?

What is your battery setup, and what setting are you using?

These are the default setting, which should be good for 16s LiFePO4, LF280K cells:

• charge_a: "50" (Max charge current)
• absorption_v: "55.2" (Charge V, 3.45V/cell)
• absorption_time: "30" (Time to absorb)
• rebulk_offset: "2.5" (absorption_v - rebulk_offset = charge request)
• discharge_a: "100" (Max discharge current)
• min_dischange_v: "48" (Min discharge V, 3V/cell)

 

[Sleeper85]

The SOC is generated from the BMS, have you calibrated it for SOC and have you configured the battery chemistry and setting correctly in the BMS?

The voltage and amps have been perfectly calibrated, the SoC is realistic.

This morning at 06:00

SoC: 29%
Voltage: 51.7V
Current: -3.9A (no big voltage drop)

My settings

• charge_a: "100" (Max charge current)
• absorption_v: "55.2" (Charge V, 3.45V/cell)
• absorption_time: "30" (Time to absorb)
• rebulk_offset: "2.5" (absorption_v - rebulk_offset = charge request)
• discharge_a: "150" (Max discharge current)
• min_dischange_v: "48" (Min discharge V, 3V/cell)

It goes into Wait state when the battery voltage = absorption voltage, what was the battery voltage when it when into wait state?

53.7V

 

[uksa007]

53.7V

How much current was there at 53.7v?

53.7 /16 = 3.356 per cell with no load would be about 90% SOC

It should look like this:

 

[Sleeper85]

How much current was there at 53.7v?

53.7 /16 = 3.356 per cell with no load would be about 90% SOC

53.7V is the Deye charge voltage, this does not correspond to the BMS voltage.

Solar Assistant does not record the BMS voltage which is a little lower during charging.

12:18 = ESP32 reset, charging status remains on Wait

 

[uksa007]

53.7V is the Deye charge voltage, this does not correspond to the BMS voltage.

The charging voltage should be set by the ESP32 set absorption voltage when in bulk.

Have you configured the Deye inverter correctly:
Battery mode lithium
Lithium mode 00

After a reboot It will stay in Wait until the battery voltage is below: absorption_v - rebullk_offset = 52.7v (this stops micro cycling the battery)

 

[Sleeper85]

The charging voltage should be set by the ESP32 set absorption voltage when in bulk.

Have you configured the Deye inverter correctly:
Battery mode lithium
Lithium mode 00

After a reboot It will stay in Wait until the battery voltage is below: absorption_v - rebullk_offset = 52.7v (this stops micro cycling the battery)

Yes Lithium mode 00.

The 55.2V charging voltage is clearly displayed on the Li-BMS page.

 

[uksa007]

Yes Lithium mode 00.

The 55.2V charging voltage is clearly displayed on the Li-BMS page.

Battery mode lithium?
You can't use % or Voltage it has to be lithium!

 

[Sleeper85]

After a reboot It will stay in Wait until the battery voltage is below: absorption_v - rebullk_offset = 52.7v (this stops micro cycling the battery)

The BMS currently displays a voltage of 53.5V with a charging current of 30A. (I disconnected the ESP32 for the battery to charge).

This explains why after a reboot I stay on Wait.

But that doesn't explain why it stayed on Wait from 12:00 ?
Maybe a reboot of the ESP32 which will be unstable because of my DC 48V to DC 5V power supply?

I can set the offset to 0 to test again.

Battery mode lithium?
You can't use % or Voltage it has to be lithium!

Yes it's "Lithium" with mode "00".

 

[uksa007]

Maybe a reboot of the ESP32 which will be unstable because of my DC 48V to DC 5V power supply?

Yes that would explain it if it's rebooting.
The ESP32 logs will write a long entry for uptime every 1minute.
This will tell you if it is rebooting.

I'm currently testing a new interface board of mine that has a Built-in DC-DC power supply, and will run directly from the Jk-BMS as it supply V-BAT on the GPS/RS485 port.

 

[Sleeper85]

Ok I will check the ESP32 uptime.

I just reduced the offset to 0.8V (to test).

I also added messages in the logs to analyze the behavior.

Here we go again on Bulk.

Thanks for your help.

Wait and see.

 

[elusivesd]

I'm currently testing a new interface board of mine that has a Built-in DC-DC power supply, and will run directly from the Jk-BMS as it supply V-BAT on the GPS/RS485 port.

Would you happen to know how many amps the Jk-BMS V-BAT port is rated to support? I was considering using this at first, but since I did not have specs, decided to connect my DC-DC directly to the battery instead. I'm pretty sure it would have been fine to power from the port, but my main consideration was if there happened to be a short on the line, would my fuse blow first, or the BMS? Tapping into the 'main' V+ guarantees isolation of this specific failure mode, if it were to ever happen.

Side note - my isolated VRB4805S DC-DC has been running perfectly, no reboots or loss of communication yet!

 

[Sleeper85]

Would you happen to know how many amps the Jk-BMS V-BAT port is rated to support? I was considering using this at first, but since I did not have specs, decided to connect my DC-DC directly to the battery instead. I'm pretty sure it would have been fine to power from the port, but my main consideration was if there happened to be a short on the line, would my fuse blow first, or the BMS? Tapping into the 'main' V+ guarantees isolation of this specific failure mode, if it were to ever happen.

Side note - my isolated VRB4805S DC-DC has been running perfectly, no reboots or loss of communication yet!

The specification says that the JST 1.25 port can support 1A max.

It scares me too, especially in the case of a short circuit, and during assembly in my final box I will also connect after the BMS to + and - of the battery, behind my MCCB breaker.

Otherwise I measured 0.02A and 52.69V for consumption.

 

[Sleeper85]

@uksa007

absorption_v: "55.2"
rebulk_offset: "2.5"

Normally with the above parameters and a 53.5V battery, when starting I have to execute the procedure framed in pink but it does not work for several reasons.

It's late and it's a bit long to explain so I'll give more details tomorrow.

I modified this part of the script to correct this problem, we will see how it goes tomorrow.

 

[pongo]

I did some testing with the Voltronic inverter a while ago, I think the only issue we had was there no way to control the discharge current in the inverter, it simply didn't support max discharge current even though we were sending it. The inverter itself doesn't have any register or ability to set it even manually.
So you have to size the battery and BMS big enough to handle the max discharge current the inverter will pull from the battery.
Other than that it seemed to work well.

Hello,
this is not completly corret: Voltronic Max 7.2 inverter doesn't accept "Max Discharge Current" from BMS, but you can set it on inverter (on remote panel or via software)

 

[uksa007]

Hello,
this is not completly corret: Voltronic Max 7.2 inverter doesn't accept "Max Discharge Current" from BMS, but you can set it on inverter (on remote panel or via software)

Not on the model we were testing.
It didn’t exist.
No mention of it in the user manual.
No option on the front panel or via software.