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As single TP4056 IC rated current is 1A,so I was thinking to connect multiple TP4056 ICs in parallel, such that enough current can be sourced to charge the li-ion battery(400mAh) connected.

Here is the schematic I was going through:

enter image description here

Will this circuit work well or does need any changes? And a schottky diode is being used at the input to maintain the supply voltage level at 5v, I'm guessing that it could be for that reason.

Is that 5.5v Schottky diode necessary? Can I avoid that instead?

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  • \$\begingroup\$ A 4Ah battery can be charged at 1A with no issue. \$\endgroup\$ – Ignacio Vazquez-Abrams Jun 23 '18 at 16:59
  • \$\begingroup\$ But when I connect a solar panel of 6v,9W,the TP4056 is badly heating. \$\endgroup\$ – Shiv Jun 23 '18 at 17:07
  • \$\begingroup\$ Did you connect the thermal pad to a large enough area of PCB? \$\endgroup\$ – Ignacio Vazquez-Abrams Jun 23 '18 at 17:16
  • \$\begingroup\$ I have used a ready made online bought module, which haa good thermal pad, bit still it is getting heated. \$\endgroup\$ – Shiv Jun 23 '18 at 17:28
  • \$\begingroup\$ Is the thermal pad at least 1in^2 on both sides of the board, with generous via stitching? \$\endgroup\$ – Ignacio Vazquez-Abrams Jun 23 '18 at 17:33
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The TP4056 is LINEAR charger. As such, at 1 A charge current and 6V power input, it will dissipate (6v-3v)*1A ~= 3 W. This is a lot for a small PCB to dissipate, and the chip will be HOT. If you use Schottky diodes, they will drop a bit of voltage difference, but not much.

If you want to fast charge your 4000 mAh battery (at up to 1C rate) without dealing with much of heat dissipation, you need to use switching-mode chargers, like Texas Instruments BQ24xxx- BQ25xxx series, or similar.

And if you are designing a solar-powered backup, you will be wasting a lot in linear chips and diodes, and it might need a more sophisticated engineering.

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Charging a single battery with paralleled TP4056 is okay as long as you are charging only one battery, without any load connected while charging.

Also, to get most out of it, heat sink attached with a thermal paste will help to sustain the charging current yet not over heat.

Since battery is 4000mAh charging at 1A is okay but yes reducing the current will relax thermal stress on the charger. TP4056 gets severely hot.

Schottky diode can be eliminated but then think of use cases..for example: when input power supply polarity is reversed, accidentally. Also, since drop across the Schottky will be very less, the lower dissipated by them will be lesser compared to ordinary diodes.

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  • \$\begingroup\$ I agree that, but one thing is can we not draw current simultaneously while charging. \$\endgroup\$ – Shiv Jun 23 '18 at 17:34
  • \$\begingroup\$ The load current will confuse the battery charger... Why can't one use the input voltage itself to the system when the input charging voltage is available? \$\endgroup\$ – Umar Jun 23 '18 at 17:35
  • \$\begingroup\$ May be i have to use a switching regulator, i think ,for switching between the two sources, whichever i available. \$\endgroup\$ – Shiv Jun 23 '18 at 18:53
  • \$\begingroup\$ No. Why not have a direct connection from input voltage to the load when input power supply is available? \$\endgroup\$ – Umar Jun 23 '18 at 19:10
  • \$\begingroup\$ Input voltage is higher than what the system runs on, iam using a regulator any way, but when the input voltage is not available then I have to take the supply voltage from the battery, but how can I short both input voltage and the battery supply. \$\endgroup\$ – Shiv Jun 23 '18 at 19:15

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