Need help with charging TP4056

Hi guys! I am new in microcontrollers and world of electronics and I need help. I'm making a project - a weather station and im stuck on charging the battery. I am using a 3.7V battery (4000 mAh) and i want to charge it using TP4056 and solar panels (curently using 2x 5.5V 1W - which should give me about 360 mA). That makes my battery barerly charge even though I put my esp8266 into deep sleep most of the time and use the panels on very bright days without clouds. I searched for help in this case on the internet but I can't find the exact answer and I don't really know what to do as the answers I found only made me confused. Should I probably change the R3 - RPROG Current setting resistor? Because its default setting is 1.2k Ohm - 1A. (Which works great when I use wall charger (5V 1A) and it charges my battery very fast). So is this resistor the part that makes my module not charge properly? Or will lowering the Amperage of charging to 400mA (3k Ohm resistor) help me? If yes, can someone explain me why? If not, maybe there is someone who can help me? Thanks in advance.

Instead of using word sallad, post schematics. That will make more helpers step in.
Posting a system block design would also be appreciated.


Yea sure.

When does the sensor go to sleep?

Is that a 5V panel unloaded? At the most you'll get 4.7ish volts out and into the TP4056. The TP can give you a max of 1AMP. The TP does a whole lot better at 6V, can take up to 8. The 5V panel is your charging issues.

Another thing, the TP will damage the battery in about 4 months. LiPo cannot operate at or below freezing.

The TP, when given sufficient volts will charge the LiPo, then cut off, the LiPo will provide power to the circuit, the TP detects a load on the battery so it starts charging the battery. When the battery is charged the LiPo is cut off from the circuit. This cycle occurs many times a second. Eventually destroying the battery. in about 4 months.

I did the LiPo/TP4056 thing for about 6 months. I switched over to LiPo4's and a PWM controller, and 12V (loaded) solar cells. Very low maintenance.

Temperature, humidity, AQI, PM2.5, pressure, volts, current, rainfall, wind speed, wind direction, and other things.

I get about 33 days of battery use before needing a recharge. I did an experiment this summer to see how long it will run. I have 2 ESP32's, lots of sensors, and it runs 24/7; no sleep modes used.

1 Like

hmm ok. Understood. So changing it to 3,5W/6V panel should solve my problem? Or can i use lower Wattage? Or maybe higher? I will try to do it using this TP and maybe in the future i will upgrade it as you did. By the way, very nice project :slight_smile:

and the panels are cnc95x95. I don't know if it's going to help somehow.

The important volts of a solar cells is the loaded output. You might consider a 10W 12V solar cell connected to a 6V regulator fed into the TP4056

1 Like

Changing R3 to a higher value would only reduce charging current, not increase it.

Do you know if your panels have blocking diodes built in? Panels configured in parallel should have diodes to prevent reverse current in case one panel is in partial shade, or they aren't mounted in the same plane.

What is the Vin pin on your Nodemcu? What voltage is supposed to be there? If it's the input to a 3.3V regulator, what is its dropout voltage?

The switching back and forth between charging and discharging doesn't happen rapidly. Once charging has terminated at 4.2V, it should restart only after battery voltage has dropped below 4.1V. At least that's what the datasheet says. However, over time, even that will take its toll on the battery. One solution to that would be adding what's called a "load sharing" or "power path" circuit, but such a circuit for solar panels is more complicated than for USB. I have a Github repo on that subject if you're interested. But it won't solve the slow charging problem.

If charging works ok on USB power, then the panels just aren't producing enough juice. Have you actually measured them? You should measure the open circuit voltage and the short circuit current in full sun, and post the results here.

One more thing. The TP4056 is a linear charger. So there's no point feeding it higher voltage than necessary to charge the battery - probably about 4.6V. Anything higher than that just results in more dissipation, which will trigger the TP's thermal protection, which will reduce charge current. So you want something like a 5V panel which produces lots of current, not a 6V panel of the same wattage but producing less current. Ideally, you want the most current at just barely enough voltage. Things would be different if the TP4056 were a switch-mode charger, but it isn't.