Proper process for balancing two Dyness batteries

Mike Hoxbig said:
48V x 100A = 4.8kW. Or 50A at 0.5C. Still, 5A is enough to kill you, let alone these amounts. Those DC cables are thick for a reason...
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Again resistance, why do you think they put insulation and insulation is rated for a specific voltage? Insulation is non conductive up to a certain point at which it will start to degrade. Same principle with your skin. You need a high enough voltage for current to flow.
 
denmendez65 said:
Again resistance, why do you think they put insulation and insulation is rated for a specific voltage? Insulation is non conductive up to a certain point at which it will start to degrade. Same principle with your skin. You need a high enough voltage for current to flow.
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Just don't drop a spanner on the terminals.
 
wingnut771 said:
Just don't drop a spanner on the terminals.
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Yeah because the spanner is metal and it has low resistance. Take one hand and touch positive, another hand and touch negative on 48V. Wont do a damn thing. Hes only measuring with a high impedance meter. Not undoing the batteries from each other.
 
denmendez65 said:
Yeah because the spanner is metal and it has low resistance. Take one hand and touch positive, another hand and touch negative on 48V. Wont do a damn thing. Hes only measuring with a high impedance meter. Not undoing the batteries from each other.
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Exactly. :thumbsup:

and no undoing anything is required anyway.
 
Mike Hoxbig said:
48V x 100A = 4.8kW. Or 50A at 0.5C. Still, 5A is enough to kill you, let alone these amounts. Those DC cables are thick for a reason...
Click to expand...
Also If I am not mistaken its 30mA. That will kill you. Its enough to interrupt your heart rythm. 5A you will be cooking nicely.
 
Hanno Labuschagne said:
Got the multimeter, but struggling to find clear and safe steps for measuring the voltages on these batteries and I am not gonna lie — I am not playing around with electricity.

Would I need to disconnect the batteries when fully depleted to properly measure this?

Also read on Powerforum that Dyness recommends:
Discharging each battery as individual Master to shutdown, one after the other.
Reconnecting the BMS comms between the batteries and setting Master and slave as per the manual.
Charging the batteries in parallel to full.

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If you switch to AGM what are your settings? I wonder if based on what I said earlier about needing to set AGM first before switching to Lithium doesn't also affect the top end.

The manual has very specific values to enter in there and I wonder if those aren't mis-aligned.
 
SauRoNZA said:
If you switch to AGM what are your settings? I wonder if based on what I said earlier about needing to set AGM first before switching to Lithium doesn't also affect the top end.

The manual has very specific values to enter in there and I wonder if those aren't mis-aligned.
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I asked already but was given the wrong screen but still managed to find out it’s charging to 56.5V but yes, still curious about those settings.
 
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SauRoNZA said:
If you switch to AGM what are your settings? I wonder if based on what I said earlier about needing to set AGM first before switching to Lithium doesn't also affect the top end.

The manual has very specific values to enter in there and I wonder if those aren't mis-aligned.
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Sorry, 56.5V
1762851130283.png
 
When you run your system closed loop (in Lithium mode) the voltage setting in the inverter that regulate charging gets ignored and the BMS take precedence.

The maximum charge amps and discharge amps set in the inveter will remain and the inverter will not charge or discharge more than this setting even if the BMS allows for more. This is only true if the charge /discharge setting in the inverter is lower compared what the BMS allows, if the inverter setting is higher the BMS setting takes precedence.

There has been a few post that states that in lithium mode the BMS reports average SOC to the inverter. This is not always true. Pylon does average, PACE and a few others reports lowest SOC during discharge and highest SOC during charge. Most cheaper BMS just follow what Pylon does and reports average.

The BMS will have a low SOC warning setting, generally this is the SOC level, when using closed loop, at which point the BMS will force the inverter back to grid.

When using open loop (AGM mode) the low warning SOC level is just a warning. The SOC indicator lights, or one of then, generally starts flashing red at this point, but it does not stop battery discharging. The battery will only stop discharging once the cell or pack UVP is reached (so it is voltage based in AGM mode and SOC based in lithium mode).

In AGM mode, even when the batteries are connected to each other with the link cables, one battery shutting down due to reaching the UVP voltage level will not impact any others which can continue to discharge.

Tehcnically this cannot happen in Lithium mode due to the low SOC cut off unless there are large SOC differences between batteries.

@Hanno Labuschagne The 56.5v charge voltage in the picture is low. What is the maximum charge voltage per the battery manual?. Perhaps set this setting in the inverter and charge using AGM mode and see if this resets the SOC counter and if they are then closer to each other during discharge.
Quick google for the manual states work voltage up to 57.6v (or 3.6v per cell). Manufacturers often change this setting as they develop their product, it might be that your two batteries have different setting especially if one is version 1 and the other version 2.
 
Koosvanwyk said:
When you run your system closed loop (in Lithium mode) the voltage setting in the inverter that regulate charging gets ignored and the BMS take precedence.

The maximum charge amps and discharge amps set in the inveter will remain and the inverter will not charge or discharge more than this setting even if the BMS allows for more. This is only true if the charge /discharge setting in the inverter is lower compared what the BMS allows, if the inverter setting is higher the BMS setting takes precedence.

There has been a few post that states that in lithium mode the BMS reports average SOC to the inverter. This is not always true. Pylon does average, PACE and a few others reports lowest SOC during discharge and highest SOC during charge. Most cheaper BMS just follow what Pylon does and reports average.

The BMS will have a low SOC warning setting, generally this is the SOC level, when using closed loop, at which point the BMS will force the inverter back to grid.

When using open loop (AGM mode) the low warning SOC level is just a warning. The SOC indicator lights, or one of then, generally starts flashing red at this point, but it does not stop battery discharging. The battery will only stop discharging once the cell or pack UVP is reached (so it is voltage based in AGM mode and SOC based in lithium mode).

In AGM mode, even when the batteries are connected to each other with the link cables, one battery shutting down due to reaching the UVP voltage level will not impact any others which can continue to discharge.

Tehcnically this cannot happen in Lithium mode due to the low SOC cut off unless there are large SOC differences between batteries.

@Hanno Labuschagne The 56.5v charge voltage in the picture is low. What is the maximum charge voltage per the battery manual?. Perhaps set this setting in the inverter and charge using AGM mode and see if this resets the SOC counter and if they are then closer to each other during discharge.
Quick google for the manual states work voltage up to 57.6v (or 3.6v per cell). Manufacturers often change this setting as they develop their product, it might be that your two batteries have different setting especially if one is version 1 and the other version 2.
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You just said lithium mode uses BMS settings. We can't change BMS settings. Also, 56.5V is not low, its 3.53V per cell, that is way into the steep part of the curve, maybe 1Ah missing not going to 57.6V.
 
1762919817553.pngAI Overview



The SOC (State of Charge) counter on a Dyness battery is primarily managed by its internal Battery Management System (BMS) in communication with your inverter
. A formal "reset button" for the SOC counter itself is generally not a user-accessible feature. The most reliable method to recalibrate the SOC is by following a full calibration cycle and ensuring proper communication with the inverter.

Calibration Procedure
If the SOC reading is inaccurate (e.g., a sudden drop from 40% to 0%, or showing full charge when it's not), the recommended procedure to allow the BMS to recalibrate is to perform a full charge and discharge cycle:
  1. Full Charge: Charge the battery to 100% capacity and leave it connected to the charger (inverter/grid/solar) for an additional one to two hours without using it, allowing the charge current to drop to near 0A. This ensures all internal cells are balanced and the BMS accurately registers the maximum voltage and capacity.
  2. Full Discharge: Use the battery normally, allowing it to discharge completely until it reaches its low voltage cutoff point and the system shuts off automatically.
  3. Recharge: Charge the battery again, without interruption, to 100%.
This process allows the BMS to measure its maximum and minimum charge levels accurately, thereby recalibrating the SOC counter.
 
wingnut771 said:
You just said lithium mode uses BMS settings. We can't change BMS settings. Also, 56.5V is not low, its 3.53V per cell, that is way into the steep part of the curve, maybe 1Ah missing not going to 57.6V.
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You can change the bms settings, just need the software to do so. I change my settings frequently.

3.53v is low if you want to sort out and diagnose cell balance issues. You want to charge as high as possible and leave if there (float at the same voltage) for the BMS to balance the cells. If you charge to 56.5v and then float at a lower Voltage there is no time for the BMS to balance the cells since the delta dissapears as soon as the voltage drops. The higher the voltage, the larger the delta the more room for the balancing to work.

That is the theory, but this is how I sort out cell imbalances after winter. I cannot charge my bank full from early June to mid August using solar since my 8.2kWp is not enough to to charge 25kWh of batteries in the Cape winters meaning there are months without any balancing happening.
 
Koosvanwyk said:
You can change the bms settings, just need the software to do so. I change my settings frequently.

3.53v is low if you want to sort out and diagnose cell balance issues. You want to charge as high as possible and leave if there (float at the same voltage) for the BMS to balance the cells. If you charge to 56.5v and then float at a lower Voltage there is no time for the BMS to balance the cells since the delta dissapears as soon as the voltage drops. The higher the voltage, the larger the delta the more room for the balancing to work.

That is the theory, but this is how I sort out cell imbalances after winter. I cannot charge my bank full from early June to mid August using solar since my 8.2kWp is not enough to to charge 25kWh of batteries in the Cape winters meaning there are months without any balancing happening.
Click to expand...
Do we know what cell voltage the dyness bms starts balancing? It should start at 3.45V if I had my way.
 
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