jremington:
Here is an excellent, independent study of the charging behavior of the TP4056.
I just finished reading the whole review, and it seems that i (correct me if im wrong) really should be getting a current value ranging from 750 - 850ma if i am using the default 1A charging current, with a battery voltage of 3.75.
Perhaps the issue really lies with the battery that i have been using. I will be purchasing other brands of 18650 Li-Ion batts to confirm this.
witheredfish:
Perhaps the issue really lies with the battery that i have been using. I will be purchasing other brands of 18650 Li-Ion batts to confirm this.
Or given that those TP4056 modules are so cheap, perhaps the TP4056 is one of the fakes ?
witheredfish:
Here is the link to the product that i purchased:goo.gl/WRX8Mw
When giving a link its a good idea to post it as a clickable link.
Saves lots of people the effort of cut and pasting, so they are more likley to offer you free help.
srnet:
Or given that those TP4056 modules are so cheap, perhaps the TP4056 is one of the fakes ?
Thing is that i have repeated this for other units of TP4056 that i purchased, and the readings seem to be identical. The one thing that remained constant was the NL188 battery, which could be it. Either that or i am really unlucky with the purchases.
srnet:
When giving a link its a good idea to post it as a clickable link.Saves lots of people the effort of cut and pasting, so they are more likley to offer you free help.
Will make sure of that from now on.
with a battery voltage of 3.75
Did you measure the voltage while charging? That is the relevant voltage, and your "schematic" doesn't show an arrangement for measuring it.
To investigate this properly, you need at least two multimeters.
jremington:
Did you measure the voltage while charging? That is the relevant voltage, and your "schematic" doesn't show an arrangement for measuring it.
Just checked that the relevant voltage for the 3.75V battery while it was charging is 3.91V. Didn't know that the voltage would jump while the battery is charging! But that still doesn't seem to add up, since the current was supposedly measured to be around 500+mA @ approx 3.91V with a 4.5V power supply, as referenced from the review you linked.
However, i did the measurements only with 1 multimeter since its all i got. I'll only get a chance to investigate with 2 of them on the coming weekday, when i get bck to school.
witheredfish:
Just checked that the relevant voltage for the 3.75V battery while it was charging is 3.91V. Didn't know that the voltage would jump while the battery is charging!
Did you measure that voltage on the battery (wrong) or on the terminals of the module.
Voltage on the module or on the battery could be tenths of a volt different if you use those long/thin wires and a breadboard between batt and module (post#0).
The chip could think that the battery is charged (4.2volt on the module), while it's not (~3.9volt on the batt).
Leo..
witheredfish:
Didn't know that the voltage would jump while the battery is charging!
Take a step back, take a short moment, and ponder this. Charging ONLY ever happens if incoming voltage is higher than what's in the battery.
And if you're poking at the battery while it is charging, you are NOT measuring the battery's voltage- you're measuring the incoming voltage.
Where you poke, whether it's the battery's terminals or the leads from the charger, are obviously electrically identical.
INTP:
Where you poke, whether it's the battery's terminals or the leads from the charger, are obviously electrically identical.
Uhhh, those thin dupond wires pictured in post#0 have a resistance of about 0.15ohm each.
That will give a significant drop if the battery is charging.
Battery voltage could easily be 0.2volt lower than the voltage on the charger.
Leo..
Uhhh, nah, jumper wires are much more like 0.05 ohm and that's only if they're about a meter long. And in that case, an amp of current would maybe at worst have 0.05 volt drop. At the 150mA OP is seeing, worst case 0.0075 volt.
INTP:
Uhhh, nah, jumper wires are much more like 0.05 ohm and that's only if they're about a meter long. And in that case, an amp of current would maybe at worst have 0.05 volt drop. At the 150mA OP is seeing, worst case 0.0075 volt.
Well, I must have special ones then.
The three randomly picked new/cheap ~20cm dupond wired I just measured ranged from 0.1ohm to 0.3ohm.
Measured with a 1Amp current from a lab supply (Kelvin measurement).
The variation must be the badly crimped (not soldered) pins.
Leo..
Wawa:
Did you measure that voltage on the battery (wrong) or on the terminals of the module.
The voltage that I measured was indeed just across the battery and not the Vbat terminal of the module while the battery was charging. I just repeated the setup, and I found that the voltage across the module was around 4.055V, while the battery was only 3.91V. From my assumption, I had thought that the battery was only taking 3.91V from the 4.055V output from Vbat terminal, and would eventually finish charging when it rises to the same value as the Vbat terminal.
However, is what you mean that the voltage across the Vbat terminal would increase and eventually reach 4.2V, before the battery is at full capacity? In the case when the Vbat is at 4.055V, it should still be drawing current that should still exceed 160mA, but the problem is that it doesn't want to.
INTP:
Charging ONLY ever happens if incoming voltage is higher than what's in the battery.
And if you're poking at the battery while it is charging, you are NOT measuring the battery's voltage- you're measuring the incoming voltage.
Got it. If I am linking correctly, is it safe to say that the Vbat stated in the TP4056 charging curve should be the incoming voltage, and not the battery itself?
I've not downloaded and viewed those pictures until just now.
I would be concerned with just sticking jumper cable pins into the pcb and they stay by virtue of gravity and friction. If the contact is maintained, I don't think it's the cause for low current, but that rickety arrangement of parts is something that should be remedied.
While it is possible the battery is faulty, I don't think it is likely. You could do a lot worse than a Nitecore battery.
I saw that you noted the input via usb being 2.5A. I find that claim suspect. If that USB is more like 500mA, I don't think your measured current is surprising.
INTP:
I would be concerned with just sticking jumper cable pins into the pcb and they stay by virtue of gravity and friction. If the contact is maintained, I don't think it's the cause for low current, but that rickety arrangement of parts is something that should be remedied.
The contact should be fine since the female side of the jumper cable is connected to the GPIO pin which I soldered for the terminals of the TP4056. I will fix up a more appropriate setup after I gather what the issue is.
INTP:
I saw that you noted the input via usb being 2.5A. I find that claim suspect. If that USB is more like 500mA, I don't think your measured current is surprising.
Sorry, I cant visualize how the input current would affect the charging side as I am still new to this area of electronics. Wouldn't the module be extracting the current based on the Rprog, as long as the input supply is sufficient?