Xiaoxiang BMS Settings

[loverofpeace]

Got my 4S 280ah LifePo4 (Xuba/Dongguan) 12.8V battery going. Do these settings look right?

Max load that gets pushed through is 40a.

 

[Walef]

Looks good to me.
On my JBD Smart BMS board the balance delta voltage is set to 50mV, triggered from 3400mV.

 

[thedodgersonline]

Got my 4S 280ah LifePo4 (Xuba/Dongguan) 12.8V battery going. Do these settings look right?

Max load that gets pushed through is 40a.


View attachment 16807View attachment 16808

Hi
Apparently you should set you cycle capacity to 80% of the designed capacity. Aleysa why are you using such a small portion of the battery range (3.4v to 3.0v) If you look at the data sheet from the battery supplier it stipulates the range on there.
Regards

 

[tictag]

Your Cell/Battery Over-Voltage and Cell/Battery Under-Voltage seem too low and too high, respectively, to me. I would recommend 3.85V/15.4V and 2.50V/10V respectively. Remember this is your BMS and these are your 'emergency shut-off' values. A typical LiFePO4 cell is optimally charged to 3.65V/14.6V per cell/battery so if you actually configure your SCC to charge to this, your battery will emergency disconnect before it is fully charged.

These are just 'typical' values, your battery manufacturer's specification should always be authoritative.

 

[jvbutter01]

@tictag why would you set the BMS to 3.85 cutoff if you state 3.65 is optimal charge? Wouldn't 3.65 be max cutoff?

 

[DJSmiley]

If you set it to 3.65 and you want to charge the cells up to 100%, they have to be precisely equally balanced.
When using a 14.6V power supply (=3.65V/cell), even the slightest inbalance will cause a single cell to (briefly) hit 3.65V+, thus causing the BMS to shutdown.

I personally did set it to 3.65, but I'm not going to charge my cells to 100% (I use 14.2V absorbtion)

 

[tictag]

@tictag why would you set the BMS to 3.85 cutoff if you state 3.65 is optimal charge? Wouldn't 3.65 be max cutoff?

As @DJSmiley says, your BMS is there for 'emergencies'; you should never, in theory, reach the parameters set by your BMS in normal operation but they are there as a 'back-stop' to prevent damage to the cells if something does go wrong. 3.85V would be a reasonable balance between avoiding damage and 'false positive' activation. LiFePO4 chemistry can handle a certain degree of over-charging, much more than NMC can, for example.

 

[ripcurldog]

Hi
Apparently you should set you cycle capacity to 80% of the designed capacity. Aleysa why are you using such a small portion of the battery range (3.4v to 3.0v) If you look at the data sheet from the battery supplier it stipulates the range on there.
Regard

Look at the data discharge graph for a lifepo4 cell and you will see the answer to your question...