*Edited, inserted instructions how to solve the SOC issue. All this here is based on WingNut's post here https://diysolarforum.com/threads/x...-remaining-capacity-display.22472/post-295322
Greetings to all JBD BMS owners!
Did you also notice that the SOC % value as well the remaining capacity value in your phone App is sometimes displayed inaccurately!?
How does this issue occur?
Whenever you change certain parameters in your BMS phone App, the app recalibrates the SOC in reference to following set % voltage values.
...and in particular to following more detailed ones which you can only access through the Chinese PC app (UART tool needed for that).
Inaccurate % voltage reference/calibration values will lead to inaccurate SOC and remaining capacity values.
How to solve the issue of inaccurate SOC?
There are two choices.
1. After every time you change parameters in the phone app you have to fully charge your battery to reset SOC and capacity again.
2. Or determine the precise 100 90 80 70 60 50 40 39 20 10% cell voltage values of your battery and replace the inaccurate values with the accurate ones.
How to determine precise % voltage values step by step:
(Btw the coulomb counter of the JBD BMS is highly accurate! I compared it with the TK15 coulomb counter and the EBC-A05+ battery meter. Once you start this test don't change any parameters in the phone or PC app. Doing so the readings of the internal coulomb counter will stay accurate.)
1.
1.1 In the BMS phone App set the right (actual capacity) nominal and cycle capacity value of your battery, set single full voltage to 3.65V or to whatever voltage you usually gonna top-balance up.
1.2 Charge and top-balance your battery to 100%
1.3 Let it rest for 30min (by this time the voltage is [almost] stable)
1.4 Write down the average (of all your cells) cell voltage (eg 3.500V)
2.
2.1 Calculate or time how much time it needs to discharge 10% of your battery capacity with your chosen test load and set an alarm when to pause discharging again.
2.2 Discharge to 90% and pause
2.3 Let it rest 30min
2.4 Write down the average cell voltage (like 3.333V)
3.
3.1 Discharge to 80% and follow through the same steps as before
3.2 Continue to follow those steps till 10%.
3.3 Connect BMS via UART tool to your PC (you can't adjust the 10 30 50 70 90% voltage calibration value points through the phone app) and correct all % voltage calibration value points.
I tested it and I can assure that now the totally inaccurate SOC issue doesn't occur anymore as well "reset capacity" in the phone app resets to almost (+-5%) actual SOC and true remaining capacity. If you want to have it spot on you have to go to one of the 100 90...10% points, let it rest 30min and then hit reset capacity.
Greetings to all JBD BMS owners!
Did you also notice that the SOC % value as well the remaining capacity value in your phone App is sometimes displayed inaccurately!?
How does this issue occur?
Whenever you change certain parameters in your BMS phone App, the app recalibrates the SOC in reference to following set % voltage values.
...and in particular to following more detailed ones which you can only access through the Chinese PC app (UART tool needed for that).
Inaccurate % voltage reference/calibration values will lead to inaccurate SOC and remaining capacity values.
How to solve the issue of inaccurate SOC?
There are two choices.
1. After every time you change parameters in the phone app you have to fully charge your battery to reset SOC and capacity again.
2. Or determine the precise 100 90 80 70 60 50 40 39 20 10% cell voltage values of your battery and replace the inaccurate values with the accurate ones.
How to determine precise % voltage values step by step:
(Btw the coulomb counter of the JBD BMS is highly accurate! I compared it with the TK15 coulomb counter and the EBC-A05+ battery meter. Once you start this test don't change any parameters in the phone or PC app. Doing so the readings of the internal coulomb counter will stay accurate.)
1.
1.1 In the BMS phone App set the right (actual capacity) nominal and cycle capacity value of your battery, set single full voltage to 3.65V or to whatever voltage you usually gonna top-balance up.
1.2 Charge and top-balance your battery to 100%
1.3 Let it rest for 30min (by this time the voltage is [almost] stable)
1.4 Write down the average (of all your cells) cell voltage (eg 3.500V)
2.
2.1 Calculate or time how much time it needs to discharge 10% of your battery capacity with your chosen test load and set an alarm when to pause discharging again.
2.2 Discharge to 90% and pause
2.3 Let it rest 30min
2.4 Write down the average cell voltage (like 3.333V)
3.
3.1 Discharge to 80% and follow through the same steps as before
3.2 Continue to follow those steps till 10%.
3.3 Connect BMS via UART tool to your PC (you can't adjust the 10 30 50 70 90% voltage calibration value points through the phone app) and correct all % voltage calibration value points.
I tested it and I can assure that now the totally inaccurate SOC issue doesn't occur anymore as well "reset capacity" in the phone app resets to almost (+-5%) actual SOC and true remaining capacity. If you want to have it spot on you have to go to one of the 100 90...10% points, let it rest 30min and then hit reset capacity.
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