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Question

Is it ok to charge a battery with TP4056 while using it, if the current consumption of the load isn't higher than the charging current of TP4056? and if not why?

Trying:

  • To have a 200mah Li-ion Battery (502025)
  • Charging it at 130mah (TP4056 + Rprog[10kohm])
  • While using it with a load which consums about 30-60 mah

(Extra question: how much 130mah of charging would effect the battery in the long term)

Outro

if you have any other idea on how i could charge that li-ion with 30% of its current while being able to use it at the same time i would be really happy to know about it, just please have in mind that i am kinda noob with electronics [...]

Thanks in Advance for any Help

(PS. i think i've read somewhere that TP4056 is not meant to be used as a load driver for some reason..)

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1 Answer 1

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The TP4056 offers a constant current for the majority of what it senses as charging cycle. So, that won't work: I doubt your application will be very happy about a lower voltage the more current it draws.

Instead, since the voltage at the input of TP4056 always needs to be higher than the voltage of the battery that's being charged, it's very easy: While there is an external source, you'd want to use that, and as soon as that disappears, you'd want to use power from the battery (which then also can't be charging anymore!).

So, simple and easy: connect your power consumer directly to the same positive voltage input that you connect your TP4056 to. Add a Schottky diode between the positive terminal of your battery and that point, too. If there's an external voltage, it's going to be higher than that of the battery, so that the diode is in reverse bias and blocks. If there's none external voltage, the diode becomes forward biased and conducts current out of your battery into your consumer.

It's often a good idea to also have another Schottky diode at the very power input, so that you're not accidentally discharging your battery into whatever is usually attached there.

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  • \$\begingroup\$ Nice and simple, Thanks! \$\endgroup\$ Commented Sep 6, 2020 at 15:18

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