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I would like to match solar panel (6 V\1000 mA) to charge controller based TP4056 in order to charge 18650 battery around 3200 mAh.

In the TP4056 datasheet it says that the input voltage range is between 4 - 8 V, but I saw in several places that the input should not get over 5 V (for example- here, and the module description in Aliexpress says 4.5 - 5.5 V).

  1. Why is there different between the the two input voltage range?
  2. According to 5 V input, if the solar panel voltage will get to lets say 7v on sunny day, or 6 V on MPP, will the TP4056 module will tolerate it?
  3. According to 5 V input, if the solar panel voltage will get to 4 V on bit cloudy day, the TP4056 will stop charging?
  4. Maybe that TP4056 does not supposed to work with solar panels (so their voltage vary)?

I don't know if the seller on Aliexpress does not provide the right description, or the data sheet are not accurate, or that I am missing something.

If someone have experience with that ill be happy for guidance.

EDIT:

This is the schematics for the TP4056 module:

enter image description here

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  • \$\begingroup\$ Please post a manual or schematic for the charge controller otherwise this question is off topic \$\endgroup\$
    – Voltage Spike
    Commented May 9, 2022 at 13:50
  • \$\begingroup\$ There may well be a difference between what the chip itself can accept and what their module based around the chip has been designed to accept. \$\endgroup\$
    – Finbarr
    Commented May 9, 2022 at 14:23
  • \$\begingroup\$ Note that "Abs Max" ratings are not supposed to be used as normal operational ratings. \$\endgroup\$
    – user16324
    Commented May 9, 2022 at 14:33
  • \$\begingroup\$ @VoltageSpike I wish I had schematics, they dont provide it on Aliexpress... \$\endgroup\$ Commented May 9, 2022 at 17:33
  • \$\begingroup\$ Well, the only other option would be to reverse engineer the schematic, because that's what would have to happen to answer the question. \$\endgroup\$
    – Voltage Spike
    Commented May 9, 2022 at 17:57

1 Answer 1

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TP4056 is linear charging controller. That means it will dissipate power in order to regulate power that goes into battery. The higher input voltage and higher current the higher power is dissipated in TP4056 itself.
So, if the input voltage is 6V and charging current 1A, and battery is at say 4V, it would have to dissipate (6V-4V)*1A=2W. That is quite a lot for SO-8 package.
SO-8 has thermal resistance around 100 K/W, so I would not dissipate 2W in that. I would dissipate much less than 1W in that. Like 0.5 W, or so.

There is several options you could do:

  • Use 5V panel instead of 6V
  • Use 6V panel you have and add 1 or 2 silicon diodes in series. They will drop some voltage (and so offload TP4056) and they will act as reverse protection diodes as well
  • Set it for lower current, like 500mA

You can even combine those options.

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  • \$\begingroup\$ Thank you for the comment, it makes sense :) what about the input range of the TP4056 module? the solar panel voltage vary and can go lower than 4.5v or higher than 5.5v (without the diodes for example) \$\endgroup\$ Commented May 10, 2022 at 7:37
  • \$\begingroup\$ When the voltage of solar panel goes under ~4.5V, the battery charging will stop. \$\endgroup\$ Commented May 10, 2022 at 7:50
  • \$\begingroup\$ TP4056 is built in thermal limitation. Not ideal, but it won't fry itself due to overheating. \$\endgroup\$
    – winny
    Commented May 10, 2022 at 10:29
  • \$\begingroup\$ @winny Yes, it has built in thermal limitation. I know that. It doesn't change my answer, because I would not design to dissipate 2W in SO-8 package. \$\endgroup\$ Commented May 10, 2022 at 12:02
  • \$\begingroup\$ Indeed. 5 V would be much easier. \$\endgroup\$
    – winny
    Commented May 10, 2022 at 12:23

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