rebulk offset, absorbtion time on Li-ion Nmc battery

[denveronly]

Have a question about configuring right the absobtion, rebulk offset voltage, and time for my type of battery chemistry. I just dont want to mess it up.
I have a Li-Ion NMC (LG CHEM) batteries from VW EV connected as 14s with total 58.8volts (at 4.2v per cell) with 12kWt total power
Ive set ESP Absorbtion voltage 58.7 (just dont really want it to be 4.2, its lithium)
Ive set the inverter to charge the battery to 97% SOC (a little improvement to battery life, it gets charged to 58.0 volts TOP seen on graphic)
rebulk offset is 2volts, time is 60 minutes.

Im seeing this graphic
Battery goes to 58v - highest spike, then a slight drop in an hour to 57.3, then i get a drop to 57.1 volts in 6 hours which contain every 15minutes charging spikes 1 minute duration of 0,3 volts higher (seen on graphic)

Ive googled and read many forums, and cant really tell if that is normal, and maybe i should edit the config to other settings.
Also im worried about that charging 1 minute spikes every 15 minutes

I made this as a new thread.
btw the window where i chose SOC97% is here.

[denveronly]

for now i will be making a test

  batt_modules: "2"
  absorption_v: "57.7"
  absorption_time: "30"
  rebulk_offset: "2"`

is esp32 code.
Inverter set to charge 100% SOC

BTW, Should i edit battery modules if i have a 14S battery? what it is affecting?

[denveronly]

ok, so far so good. I got absorbtion stage activated, after 30 wait stage started

Is this normal that i am experiencing a slight discharge that is appearing on the BMS discharge register 100w and then dropping to 30-40w. do you have just 0 charge and 0 discharge on your Deye?

[Uksa007]

OK so that's good news that you have finished Absorption and are now in wait, the charger should be off in the wait stage.

I don't use a Deye inverter I use a Goodwe inverter.
My Battery Discharge is 0 when in wait stage, and no load.

I think I remember reading in the Deye manual that suggest inverter does draw it's power from the battery, maybe this is what you are seeing?

[denveronly]

OK so that's good news that you have finished Absorption and are now in wait, the charger should be off in the wait stage.

I don't use a Deye inverter I use a Goodwe inverter. My Battery Discharge is 0 when in wait stage, and no load.

I think I remember reading in the Deye manual that suggest inverter does draw it's power from the battery, maybe this is what you are seeing?

i also thought about inverter drain just to power its brain because Deye cant work without battery

[Uksa007]

So that % charge "System work mode" menu seem to be the Time of use to charge from grid.
I thought you were charging from solar, why do you have Time of use charging from grid enabled?

Note it may also be selling power into grid?
"Note: when in selling first mode and click time of use, the battery power can be sold into grid."

Which mode are you running in?
Selling First
Zero Export To Load
Zero Export To CT

[denveronly]

So that % charge "System work mode" menu seem to be the Time of use to charge from grid. I thought you were charging from solar, why do you have Time of use charging from grid enabled?

Note it may also be selling power into grid? "Note: when in selling first mode and click time of use, the battery power can be sold into grid."

Which mode are you running in? Selling First Zero Export To Load Zero Export To CT

Yes it is time of use, and % charge to be done in that time. Ive set to 100% for now.

my Option set is Zero Export to Load ( i guess it is about Pv not battery) i dont have Pv right now, it is in process. And i dont experience any unwanted drain. Load w = Battery dischg W

This night showed exellent charging curve, no spikes, and drain was 0-10w in deep night (i think the inverter was making like a battery ping it is there and ready)

Im not sure that it is normal, but in the morning the LI-Bms screen shows 00 volts in the right side
When i was going to sleep, it showed 57.7 and all charging process went fine
JK status is in wait mode, discharge is in process with 1Kwt drained

[denveronly]

Upd. Have surely a little problem friend.
so i did a battery discharge of 1kWt, JK status showed Wait
Li Bms was as on screenshot on top, with the right side 0.0 volts.

i pushed battery charge, it charged to 57.7volts exactly as my config was

Li Bms is still showing 0.0v
JK Status is still in Wait but should be Absorbtion

I reinstalled ESP32 config once again with no changes made, just hit the install button so it gets rebooted and my Li Bms is showing volts, My JK status showing Absorbption

For some reason Li Bms info is working partially it gets charged to what config is, but doesnt show target V, and Changes the JK status (wait, bulk, absorbption) reinstalling (maybe ill try just usb reboot helps)

Ill check one more time if it gets wiped out

[Uksa007]

You may need to discharge a little more to trigger a charging cycle.

It will start charging at 57.7 - 2(rebulk_offset) = 55.7v

Try replacing this code segment to see if the voltage and SOC displays correctly.
#1 (reply in thread)

[denveronly]

You may need to discharge a little more to trigger a charging cycle.

It will start charging at 57.7 - 2(rebulk_offset) = 55.7v

Try replacing this code segment to see if the voltage and SOC displays correctly. #1 (reply in thread)

Well it did the trick for some time.
Indeed as it got lower my set 2 voltages offset it got in to bulk and then absobtion etc.
But again later, when it got fully absorbed i got this issue. with 0.0 voltage and charge spikes it somehow loses connection to CAN i guess or receives wrong info so it displays 0.0 voltage and behaves abnormal
Last time those spikes were my fault. Ive set voltage

57 without a dot .

Im trying the code you gave in the link, my jk status now is Startup (it is being discharged now because by charge spikes it hit higher voltage then the config is written)

BTW my JK Overcharge voltages are set lower on 4.15, JK got Overcharge error, inverter didnt show any errors.

[Uksa007]

Deye inverter behaves differently to my inverter when the charging is switched off.

The new code should fix the charging voltage going to 0 and the SOC changing when charging off (wait state)
Let me know how it goes.

[denveronly]

Deye inverter behaves differently to my inverter when the charging is switched off.

The new code should fix the charging voltage going to 0 and the SOC changing when charging off (wait state) Let me know how it goes.

So far the new code is working well, i usually got 0.0 volts in the morning.
I will keep testing and report tomorrow, if it will be ok, then it is fixed

[Eumobong]

I'm thinking during the wait stage, the voltage shouldn't be the charging voltage but float voltage to avoid the inverter keeping the battery at that voltage with no current flow.

[denveronly]

Confirmed working properly with the code here
#1 (reply in thread)

[Uksa007]

Here is how my charging curve looks like running this new code
It still turns off the charging voltage after absorption.
My Absorption voltage is 56V and rebulk is 2.5

[Eumobong]

@Uksa007 please can you introduce a float voltage parameter for deye and sunsynk users. I feel it's not a nice idea leaving the battery at absorption voltage after absorption timeout.

[Uksa007]

I feel it's not a nice idea leaving the battery at absorption voltage

Is your feeling backup by any facts that it operates like you suggest?
The charging is disabled by setting 0 current and setting the charging flag off, from what I see in my charging graph, the absorption voltage is turned off.

Can you show me a charging curve where it keeps the absorption voltage on after absorption?

[Eumobong]

Yes if you are using Deye / sunsynk.

It's based on this response by @denveronly

[Uksa007]

I believe he means the Battery Charge Voltage in the inverter display always shows the Absorption voltage (which is what it needs to operate correctly).

@denveronly Can you please show a Voltage charging curve and Charing status like mine above, so we can confirm it is correctly turning off the absorption voltage when in Wait status?

Thanks.

[denveronly]

I had a problem with not displaying Battery voltage charge on Deye screen and it is fixed now by the new code lines
My inverter is charging, and after absorption time 30min and some wait time 30min, there is no charging tickling.
Battery voltage make a very slight drop over time thus it is not showing any charging either. (my battery set absorption voltage is 57.2V)

[Uksa007]

@Eumobong This looks good to me you can see the charging is disabled as the voltage is slowly decreasing after absorption.
There is no floating of the battery at any voltage as per design of the charging logic.
All good?

[Eumobong]

Yes. It is all good.
Thanks.

[Uksa007]

@denveronly
Thanks, can you show the charging status on the same battery voltage graph(like mine at the top), you can add multiple things to graph in the HA history tab.

It seems the graph is pretty flat from 3 - 6 which is over 3 hours, I would expect it lose more voltage over 3hours, did the pack take a long time to reach the absorption voltage?

[denveronly]

Here is my graph. Absorbtion is 30 minutes, and there is like 30 minutes inverter makes charge for 30-50watts more on his own
but after i have a little more of charging times like 10w for a second, sometimes 10-30w discharge time over a second or two.
I think it is my inverter brain not the JKBMs code

[Uksa007]

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