OnTheRoadAgain
Solar Enthusiast
- Joined
- Feb 22, 2021
- Messages
- 643
Let's say you are testing a LiFePO4 bank of cells that together make up a 12v 100Ah battery. Each cell is a standard 3.2v cell with max voltage of 3.65v
Fully charged you will be at 3.65v per cell so times 4 that is 14.6v fully charged. So let's say at the moment it reaches that full SOC you connect it to a dummy load discharge capacity tester. In my case I use a DL24P, 180 watt device.
What do you set the Cut-off voltage to? If you set it to 2.5 (or whatever the data sheet specifies), you will never reach that discharge voltage.
At least not on this discharge tester. Does your discharge tester go by battery terminal voltage or internal to tester voltage drop voltage?
You have your actual bank voltage at the battery terminals, and then you have your loaded voltage internally at the discharge device which will be significantly lower due to voltage drop and resistance Even if you use 0 gauge cables you will still have voltage drop.
So do you set the cut off voltage at the batteries specified cut off voltage and know that the battery will never actually reach that voltage because the discharge device will react to the loaded internal voltage and not the actual cell voltage....resulting in the appearance of reduced capacity.....
Or do you set the cut off voltage so that the voltage at the battery terminals reaches the data sheet minimum discharge voltage?
Fully charged you will be at 3.65v per cell so times 4 that is 14.6v fully charged. So let's say at the moment it reaches that full SOC you connect it to a dummy load discharge capacity tester. In my case I use a DL24P, 180 watt device.
What do you set the Cut-off voltage to? If you set it to 2.5 (or whatever the data sheet specifies), you will never reach that discharge voltage.
At least not on this discharge tester. Does your discharge tester go by battery terminal voltage or internal to tester voltage drop voltage?
You have your actual bank voltage at the battery terminals, and then you have your loaded voltage internally at the discharge device which will be significantly lower due to voltage drop and resistance Even if you use 0 gauge cables you will still have voltage drop.
So do you set the cut off voltage at the batteries specified cut off voltage and know that the battery will never actually reach that voltage because the discharge device will react to the loaded internal voltage and not the actual cell voltage....resulting in the appearance of reduced capacity.....
Or do you set the cut off voltage so that the voltage at the battery terminals reaches the data sheet minimum discharge voltage?