Causes and solutions of overdischarge of lithium iron phosphate batteries
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2020/12/18 18:41:34
Charging:
The charging process is the process of filling a bucket with water, and the process is a period of time.The bigger the tap, the faster it fills up.Similarly, charging the battery depends on the charging current, the higher the current, the shorter the charging time!
Discharge:
Discharge process is actually the reverse of the above, the water off a process, of course, here depends on the power of your power load end, the greater the power consumption, the discharge time will be relatively short!
Here you have to give the exact value before you can calculate.
For example, a set of LFP- 48V100AH communication base station power supply group.
The charging current is 20A, i.e. the charging time is 5 hours.The charge time is calculated by dividing the capacity of the battery pack by the current.
Discharge assumption: the power at the load end is 500W
Namely: 500W (power at the load end) / 48V (rated voltage) = 10.42a (current)
100AH (battery capacity) / 10.42a (current) =9.6 hours (working time)
Overcharge and overdischarge are all operations in excess of the original capacity.Overcharge and overdischarge can cause damage to lithium iron phosphate batteries, which is irreversible.Overcharge will lead to lithium dendrite, and overdischarge will lead to copper dendrite, which will cause short circuit and fault of lithium battery.Therefore, lithium batteries require shallow charging shallow release.At present, the use of lithium batteries should be as far as possible to protect the circuit, so as to ensure safety.At the same time, lithium iron phosphate battery is a relatively high safety of lithium batteries.
12 series of four 26650 power lithium iron phosphate battery pack, after a long time without charging, the voltage is very low.The charger is now connected and the light is green.Considering the large internal resistance of the long overdischarge, even if the current can be rushed in is very small, indicating green light is normal.A single lithium iron phosphate is out of power and you can use a charger to flush it directly and you can recover it.But does the battery pack, which has a balanced protection panel, fail to charge in?
The solution
Lithium iron discharge curve is very straight, it is impossible to judge the electric quantity only by the voltage, equilibrium can only rely on the monomer to fill the electricity to balance, after filling the discharge is not balanced, is the monomer internal resistance and capacity is not consistent, can only rely on the capacity replacement to solve, there is no other way.
A resistor is connected in series and charged directly from the battery for half an hour, and the guard is turned on.Then charge from the protection plate charging port, or find a way to charge from the discharge port for half an hour, you can normally charge.
Need to charge from the discharge port, pay attention not to reverse the polarity, if the red light, just do it.You can also use another battery pack to charge him, either 36/48 or 50, 100 or 200 euros. If you charge the battery to more than 30V, you can normally charge it. Your hand will be hot near the resistance, but not too hot.If it still doesn't work, you need to consider replacing it.
In fact, don't wait for the battery problems, and then to think of solutions, pay attention to the daily maintenance of the battery is important.
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