"Doesn't the TP4056 module limit the current by itself? Owning this module I have never used a resistor in series... As far as I know the maximum current it can provide is 1A."
Yes it does and it turns that into heat. ! amp and 1V means you are dumping 1W into the IC. It can take that, but wouldn't you rather put that heat somewhere else. Check the spec sheet, they have the resistor there and it has a spot on the board that is just jumpered out. The boards are shipped 1A and then taper to 0.1A till they shut off at 4.2V. I grab a lot of recycled laptop power packs and they can be risky if left unattended. I prefer not to charge an old cell at the maximum. I use phone wall warts. Many are self limiting as far as current, others are rated at just about a half amp. The resistor easily limits maximum current, but not the end current which is fixed at 1/10 the max charge rate determined by that little snot of a resistor. I wish you luck changing that. The foil is so thin on these boards, think they just rubbed a penny on them, it is likely to lift off changing that resistor. If you are that experienced with surface mount I would hardly guess you need to come on a forum and ask questions. You can go to MUCH lower currents than the 130ma specified in the chart. Some use this board to charge coin cells (the rechargeable o4nes that is).
For current limiting, the TP4056 does not dump that much into heat. It lowers the charge voltage to keep the CC (constant current) selected by
Rprog.
So the waste heat does
not equal to
Vsupplied*(1A-Idesired), rather,
the waste heat is the
Idesired*Vdrop.
If the
Idesired is lowered, your waste heat is also lowered.
[ see EDIT below ]
You can see that for yourself and connect an Amp-meter before the TP4056 and after the TP4056. The current coming out of it is the same as the current going in.
Vdrop is the difference in voltage going into TP4056 and the voltage coming out of it.
Personally, I think letting TP4056 manage the current is just fine as long as your power supply is around 5V. I am however more concern about the (per-spec) 4.2V +/- 1.5% in charge voltage. On the real thing, 4.263V output is a bit more than I would like. If you get a fake-TP4056, it may be worst.
I have a cut-tape of 20xTP4056es. I actually paid more from what I thought would be a reputable dealer. I tested two of them and they were in the 4.4V to 4.5V range. Since it was to repair a board,
it could be other things on my board that caused the 4.5V out, but I now adopt the "
Trust but verify before use" mantra before I "deploy" the darn thing.
Once tested, they do work like a charm. Love it.
[EDIT: forgot to mention:]
If the
Idesired is lowered, it is done by increasing V
drop. So it may seem to be just a wash with
Idesired*Vdrop. Experience with charging shows you don't need to drop the voltage by 1/2 just to drop the current by 1/2. So, V
drop requires a small increase to cause a much bigger decrease in I
desired. End result is,
Idesired*Vdrop got smaller.