I was planning on making my own Li-ion battery charger using the TP4056. My setup for my charger is quite simple, I had my TP4056 hooked up to a 3.7V Li-ion battery (3100mAh), and I plugged the input of the TP4056 with my (5V, 2.5A) power supply. I had measured the battery voltage which was around 3.75V and was expected at least 600mA but found out that only around 160mA was pushed into the battery when I checked using my multimeter. Was there something that I missed in the setup?
Heres the link for the battery I am using:
Any idea on what may be going on here?
Been searching around for this on the net, but can't seem to find someone that faced this issue.
The current you measured is within the range of expected behavior for a trickle charge. I'm not familiar with the chip or module you're using, but it seems to be selectable on whether to go constant current or constant voltage. Pay attention to the time curve.
jremington:
Why were you expecting 600 mA? The battery is partially charged, and the regulator is probably doing its job correctly.
When i checked the capacity chart for the battery that i was using, i found that 3.75V is the voltage when the battery is nearly empty. Then according to the I-V characteristics of the TP4056, i believe that it should be drawing around current around 600mA - 700mA, or at least not something that is around 100+mA.
Who are you responding to? Obviously not me, because my point was pointing out that if the chip can be put into constant current trickle charge, then whatever your point is bringing up the battery, is irrelevant.
I think the issue i am having now is the confusion on the trickle charge. When i connected the battery to a li-ion charger which i purchased from the same manufacturer, it indicated that the capacity was somewhere between 30-70%, which should still be in the range where the charge current is high. I also believe that the trickle charging voltage range will only kick in when Vbat < Vtrick, where Vtrick = typically 2.9V, according to the datasheet for the TP4056.
Is it safe to say that battery may be the issue here?
Yes, you. Please study the link in reply #6 for how Li-ion batteries should be charged.
@OP: Whether the TP4056 works properly with that battery is another issue entirely. That is why you need to study the behavior over the entire charge/discharge cycle. Any conclusions you draw from 5 minutes of experimentation are useless.
ALSO: note that the TP4056 is PROGRAMMABLE. What are the settings on the module?
Should? I'm insinuating an improper use of the chip. Its current is programmable with an external resistor. OP does not mention using any resistor. It's just a matter of me lacking your level of faith in people to use things correctly.
jremington:
Yes, you. Please study the link in reply #6 for how Li-ion batteries should be charged.
@OP: Whether the TP4056 works properly with that battery is another issue entirely. That is why you need to study the behavior over the entire charge/discharge cycle. Any conclusions you draw from 5 minutes of experimentation are useless.
ALSO: note that the TP4056 is PROGRAMMABLE. What are the settings on the module?
Noted on that. Will continue to experiment and observe.
I did not adjust the Rprog for the Tp4056, so it is set at a default value of 1A for the charging current.
witheredfish:
I had measured the battery voltage which was around 3.75V and was expected at least 600mA but found out that only around 160mA was pushed into the battery when I checked using my multimeter. Was there something that I missed in the setup?
Why did you expect at least 600mA ?
The charge current, until the terminal voltage reaches 4.2V, is determined by a resistor, see the TP4056 datasheet.
If that resistor programs in a 160mA charge current, then that is what you will get.
Once the battery reaches 4.2V the charger will go into constant voltage mode, until the current reaches zero.
Trickle charge is initially applied until the battery reaches 3.0v or so, then it switches across to constant current charge, set by the resistor.
Data sheets are wonderful things, they tend to describe how devices work.
srnet:
Did you actually check the resistor value ?
Yup, the SMD resistor at Rprog reads 122 (1.2k), which i input into the Ibat formula given in the datasheet to give 1A. That is why i found it weird that the charging current was still so low, when it has not even reached constant voltage.
Guess I need clarification- are you using a bare chip or a premade module?
I read 'making my own Li-ion battery charger .... my TP4056 hooked up to a 3.7V Li-ion battery ....' as a bare chip situation.
