Author Topic: Charging current for 3.7V, 300mah lipo battery  (Read 1384 times)

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Offline Toby_CMTopic starter

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Charging current for 3.7V, 300mah lipo battery
« on: February 21, 2022, 01:23:24 pm »
I have a 3.7V, 300mAH lipo battery. I plan to charge it with TP4056 charging module. But the resistor is 1.2 kΩ which is 1A charging. For safe lipo charging is 1C (300mA in my case). So, I am wondering if I use a power source of 5V, 300mA for TP4056, will be it charging? Since the power source is 300mAH, the battery current draw will only be maximum at 300mAH. Am I right?
 

Offline wraper

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Re: Charging current for 3.7V, 300mah lipo battery
« Reply #1 on: February 21, 2022, 01:29:08 pm »
No, power source will either output more current than it's rated for, or the whole thing will malfunction. You need to replace the resistor for appropriate charging current.
 

Online Zero999

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Re: Charging current for 3.7V, 300mah lipo battery
« Reply #2 on: February 21, 2022, 01:48:55 pm »
This will end in magic smoke and fire.

If the power supply isn't current limited, it will be damaged.

If the power supply goes into current limiting it will become unstable and the battery still might overcharge.

Change PPROG for 12k, to reduce the current to 100mA.

Refer to page 2 of the datasheet.
https://dlnmh9ip6v2uc.cloudfront.net/datasheets/Prototyping/TP4056.pdf
 

Offline Toby_CMTopic starter

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Re: Charging current for 3.7V, 300mah lipo battery
« Reply #3 on: February 21, 2022, 02:57:44 pm »
So even I manage to find a 5v, 300mAH adaptor, it will cause unstable current which will damage the battery?
 

Online Zero999

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Re: Charging current for 3.7V, 300mah lipo battery
« Reply #4 on: February 21, 2022, 03:50:45 pm »
So even I manage to find a 5v, 300mAH adaptor, it will cause unstable current which will damage the battery?
There's no such thing as a 300mAH adaptor.  mAh, means milliamps per hour and is a unit of charge, not current.

Current refers to the number of electrons flowing per second.

Charge corresponds to the total number of electrons transferred, irrespective of the length of time.

Charge is analogous to the amount of water in a tank and current the amount of water flowing through a pipe, at a given instant.

A charge of 300mAh is: 100mA flowing for 3 hours, 150mA for 2 hours, 300mA for an hour, 600mA for half an hour etc.

What you have is a 5V power supply, rated to a maximum current of 300mA. This means no more than 300mA can be drawn from it, before there's a risk of it either overheating, or the output voltage dropping below. mA means milliamps, which is a unit of current, not charge.

The TP4056 module is a battery charger. It will deliver a fixed output current of 1A, into a battery, until the voltage reaches 4.2V, then it stops. As mentioned above, the current can be reduced to 100mA by changing PPROG to 12k.
« Last Edit: February 21, 2022, 10:01:24 pm by Zero999 »
 
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