diy solar

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Chargery issues

It is really important to update to version 4.04 of the firmware, it fixes some math issues and the sampling calculations plus more.
The External power board makes a difference but you can make one with a shottky diode as mentioned above. That connected to the battery terminals does indeed help settle readings. The ISO board between the BMS & DCC also does a little filtering and having the LED's indicators is certainly a handy thing to have on had as well.

The SOC issue. It is a bit wonky till it's worked through a couple of discharge/charge cycles (this is not that unusual, most BMS' have to cycle a bit) and you have to enter the PROPER kWh for the pack and too many flubb that up.

kWh is calculated as so: using 24V/280AH pack as example.
- always use 3.200V - it is the Nominal Voltage
- Always use 4x3.2 for 12V, 8x3.2 for 24V, 16x3.2 for 48V. Cells in parallel do not count.
8 cells X 3.2V nominal voltage = 25.6V nominal pack voltage.
25.6V nominal pack voltage X 280AH (cell AH rating) = 7168kWh

ALSO the BMS has a setting for Low SOC Cutoff which has a default of 20%, reset that to 0% because the moment a cell reaches 20% SOC it will trigger a discharge cutoff regardless of the other cells SOC. This can cause the BMS to kick off too quickly if under load or taking a surge start from a motor like a fridge kicking on.

My BMS8T settings are located in the spoiler on this page:
 
It is really important to update to version 4.04 of the firmware, it fixes some math issues and the sampling calculations plus more.
The External power board makes a difference but you can make one with a shottky diode as mentioned above. That connected to the battery terminals does indeed help settle readings. The ISO board between the BMS & DCC also does a little filtering and having the LED's indicators is certainly a handy thing to have on had as well.

The SOC issue. It is a bit wonky till it's worked through a couple of discharge/charge cycles (this is not that unusual, most BMS' have to cycle a bit) and you have to enter the PROPER kWh for the pack and too many flubb that up.

kWh is calculated as so: using 24V/280AH pack as example.
- always use 3.200V - it is the Nominal Voltage
- Always use 4x3.2 for 12V, 8x3.2 for 24V, 16x3.2 for 48V. Cells in parallel do not count.
8 cells X 3.2V nominal voltage = 25.6V nominal pack voltage.
25.6V nominal pack voltage X 280AH (cell AH rating) = 7168kWh

ALSO the BMS has a setting for Low SOC Cutoff which has a default of 20%, reset that to 0% because the moment a cell reaches 20% SOC it will trigger a discharge cutoff regardless of the other cells SOC. This can cause the BMS to kick off too quickly if under load or taking a surge start from a motor like a fridge kicking on.

My BMS8T settings are located in the spoiler on this page:
A x V = watts, not kWh -> 25.6V * 280Ah = 7168 watt hours. divide by 1000 to get kilo watt hours -> 7168 watt hours / 1000 watts per kilo watt hour = 7.168 kilo watt hour (kWh).
 
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