Electronics > Projects, Designs, and Technical Stuff
TP4056 Li-ion charging and protection board
(1/2) > >>
santoshgurral:
Hi

I have a doubt regarding the TP4056 Li-ion charging and protection module. Attached the image of this board.
I see there are so many articles and videos on the internet regarding this board that it does not provide overcharge protection(never terminates charging) if a load of more than 100mA is connected to its OUT+ and OUT- terminals while charging. Why is this behavior? How to fix this issue?

As per the TP4056 CC-CV charging IC datasheet it states "The TP4056 automatically terminates the charge cycle when the charge current drops to 1/10th the programmed value after the final float voltage is reached" so if this IC can not terminate charging when the load is >100mA why does not the DW01A IC provide the over-charge protection? because as per DW01A IC datasheet it should. Please see the attached image.

Thanks
Santosh
SiliconWizard:
This circuit alone is only meant as a battery charger, not as a complete load sharing solution.

As you got correctly (and as is the case with any charger IC that doesn't handle a specific load path), if you connect a load in parallel with the battery, the charger IC has no means of knowing when the charge is over, as it relies on the current falling below 1/10 of the charging current when the charger is in constant voltage mode (last part of the charging cycle.)

Some charger ICs have an additional internal time-out counter, meaning that if the current has not fallen below 1/10 of nominal charging current after a given amount of time, the charging will just stop. I don't know whether the TP4056 has this feature. If it does, it would just shut down the load automatically after a while if said load exceeds the threshold current.

Another issue with this setup is that if your load is not a constant current load, the charging current to the battery will effectively vary over time, which is not optimal either.

Just putting the load in parallel with the battery is a bad idea overall in general and should be done only with extra care. You should preferably add some kind of switch-over circuitry to power a load while charging.
santoshgurral:
Ok
If TPS4056 IC does not terminate charging? How about DW01A IC why does not it protect from overcharging as it is present on this board?

Thanks
Santosh
magic:
Normal charging process it to charge the cell up to 4.2V and maintain it at that voltage for a short time, the usual rule being until charging current decreases 10x. After termination of charging, cell voltage quickly falls down some tens of mV even under no load.

I'm not entirely sure but I think that continuing charging at 4.2V for longer time causes slow degradation of the cell. If a TP4056 charger is used with 100mA load connected to the cell, it will keep the cell at 4.2V forever.

DW01A only disconnects the cell if voltage exceeds 4.3V. TP4056 never outputs that kind of voltage.
Peabody:
The DW01 protects against excessive charging voltage/current.  It does not limit the charging time so long as the charging voltage stays at 4.2V and current is greater than 100mA (or whatever value is determined by the charge current setting resistor).  But a LIPO supplied with 4.2V continuously will eventually swell up and possibly catch fire or explode.

What's needed is an added "load sharing" circuit which supplies the charger and the load separately so charging may properly proceed to shutdown.  The circuit consist of a P-channel mosfet, a diode, and a resistor.  Here's a datasheet that goes into it in detail.  Notice that the mosfet is oriented in an unusual way so the body diode protects the battery from the 5V supply.

http://ww1.microchip.com/downloads/en/AppNotes/01149c.pdf

And attached is a drawing showing such a circuit for a 5V Arduino powered by an 18650.

Navigation
Message Index
Next page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod