ebike lifepo4 battery troubleshooting

by:CTECHi     2020-04-12
This description is designed to help troubleshoot the lithium phosphate (
Lithium iron phosphate)eBike battery.
These batteries are usually sold online through a variety of sellers.
Although their size, voltage, capacity and battery type are generally different, they are similar in electrical terms, and the following trouble-shooting techniques should apply to any number
With internal BMS (
Battery Management System.
Lithium iron phosphate (AKA -LiFePO4)
More and more used in electric vehicles (
As a substitute for lead
General acid battery)
Because it has a long life (
> 1000 charge cycle)
Light weight, flat discharge curve, good chemical stability.
Lithium-ion batteries are now known for fire/short circuit, while lithium-ion batteries are less prone to fire/short circuit problems.
Similarly, lithium-ion batteries can be charged indefinitely.
They will not leak their charges or deaths over time.
Modern electric bicycle batteries use lithium iron phosphate chemicals to arrange multiple batteries in one grid to provide the right voltage, current and capacity.
The battery pack is described by the number of batteries in their series (S)
And in parallel (P).
As a result, the 16 S4 p battery has a total of 64 batteries (16x4).
The battery pack voltage is the sum of the single cell voltage (about 3. 33V-3. 35V charged)
Multiply by the number of cells in series.
Therefore, the voltage of our 16 s sample battery is about 53. 5VDC charged.
The battery pack amps are the sum of the individual battery amps and the number of parallel batteries.
So if our sample battery capacity is 2000 mAh then the capacity of the 16s4 p package will be 8000 mAh.
In addition to the community, there will be BMS (
Battery Management System
Board inside the battery.
The board monitors the battery voltage inside the battery and ensures that no single battery voltage is charged to more than 3.
Discharge below 65 V or 2.
Where they will be damaged.
It also balances the battery during charging (
Ensure that each cell receives the same power)
If the battery is short, disconnect the battery from the loadCircuit or past
The current condition is detected.
There are usually two types of battery problems
This is when the battery is not charged or not charged. (i. e.
It is still dead/empty after charging for one night)
Due to a discharge problem, the main symptom is that the bike is completely exhausted under load and does not restart until the battery is disconnected and then reconnected to the motor.
Another common discharge problem you may see is that the battery works but does not last for a long time.
This indicates that the battery is unbalanced or damaged, which may be caused by damage to the battery or damage to the balance circuit on the BMS, and will not charge all series batteries on average.
The video above shows the situation inside the electric bicycle battery and describes the basic process used to troubleshoot the battery that is cutting off or charging failure.
A schematic diagram of the BMS circuit is also included.
There is no need to troubleshoot, but it is there for anyone curious. . .
You will need: the basic trouble shooting step is-
These steps will help you determine if there is a problem with your BMS, battery, or electric bike motor, and hopefully help someone save their damaged battery without spending their arms and legs. . .
Give your lithium ion battery a long and enjoyable service life
The slower the charging speed, the more wear and tear the internal electrode of the battery, the faster the battery will fail.
Slow charging will reduce the pressure on the battery.
In any case, when the bike is going to sit overnight, the use of this \"quick charge\" reduces cell life over time.
Fast charging will also bring more wear and tear to BMS. (
My own electric bike BMS runs 20 degrees.
C. 5A \"fast\" charger is hotter than charger 2.
5A \'Standard\' charger. )
The battery is slow to charge and the balance is better.
If you store your bike for a long time, don\'t store it for full charge, run out of battery first.
A battery with no electricity can be stored to give it a hose.
But storing 100% of the battery can also cause internal battery wear. (
When the chemical activity is enhanced, the internal electrode of the battery is worn faster.
They are in the most active state when they are fully charged. )
So drive your bike to around 2/3 before you put it up for the winter.
Check regularly when storing, you should check the battery every few months.
While lithium-ion batteries do not leak or lose charge, BMS usually steal some.
Signalab V1 BMS only steals juice from the previous 4 units for logc/MOSFET buffers.
Therefore, in theory, the long-term storage of these cells will be unbalanced. . . (
You can see this in the included schematic.
Lines from the charging circuit 5 to R36 power the four-and non-gate IC on the back of the BMS. )
The updated version is stolen on average from all cells.
In any case, it is prudent to check every once in a while to ensure that BMS does not run out of battery.
Don\'t leave ChargerThis is probably the most important longevity secret and the reason why we didn\'t fully charge it.
Keep the lithium ion battery in ~ 3.
5VDC Top per battery
The Off \'voltage keeps the internal electrode in the most active state and causes unnecessary battery wear.
After the battery is fully charged, unplug the charger.
Conclusion This is a work in progress and I will continue to add information so feel free to post any questions and I will answer them if I can.
Thanks for watching!
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