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Topic: Merging TP4056 charging module (with protection circuit) with a 5V step up (Read 458 times) previous topic - next topic

qoobit

Problem (TLDR):
Unplugging and replugging the battery from the TP4056 doesn't always power on the 5V step up converter.

Description:
My current set up is exactly the same as this video:
https://www.youtube.com/watch?v=8rBnJ83STBA

Where I have the battery +/- connected to a 3.7V LiPo battery. The output from the TP4056 connected into the 5V step up converter. I run into two scenarios when I plug and unplug the battery from the circuit:

  • The circuit works as expected. 3.7V in, 5V out.
  • The 5V step up converter doesnt light up, but if I temporarily disconnect the connection from the TP4056 and connect it back to the 5V step converter it works again.

What I've Tried
Alternatively, I've tried wiring the 3.7V directly to the 5V step up converter and it works 100% of the time as expected.

I've also tried adding a capacitor to the output of the TP4056 and the 5V step up converter. It helps mitigate the issue with a higher percentage, but it still fails to push out enough to properly power on the step up converter unless I connect and disconnect the step up converter (not the battery).

What I think could be going wrong
I'm thinking if this has to do with the battery protection circuit inside the TP4056, or just not having enough initial currently to power up the step up converter.

Thanks in advance for any light you guys can shed on the situation. This is my first question post here :)

UKHeliBob

Has this question got anything to do with using an Arduino ?
Please do not send me PMs asking for help.  Post in the forum then everyone will benefit from seeing the questions and answers.

qoobit

The goal of this circuit is to have a recharagable battery solution specifically for power Arduino projects that run at 5V. If this is out of the scope of the forums I will remove the question. However I did see other questions on the forums regarding the TP4056 so that's why I posted here. Sorry for any inconveniences.

UKHeliBob

I will move the topic to the General Electronics section where it is probably more appropriate at this stage of your project
Please do not send me PMs asking for help.  Post in the forum then everyone will benefit from seeing the questions and answers.

ShermanP

I don't know why it wouldn't work.  What battery are you using?  Is it fully charged?  If you're using a fully-charged 18650, then it should work.  If you're using a tiny Lipo, it may not produce enough current and may be triggering the TP4056 protection.  When this happens, what is the input voltage of the boost converter?  If it's zero, and the battery voltage is still good, then protection must be kicking in.

This is not related to your problem, but I want to point out that this circuit is not really safe.  If you ever power the converter and the project while you are charging the battery, the load current on the charger may never fall to the level of 10% of the full charging current, and charging may never terminate.  That can lead to an explosion.  One solution is to always disconnect the converter while you are charging the battery.  The other solution is called a "load sharing" circuit, which lets USB power both the charger and the converter independently, so charging can proceed to termination while the project is running.  There should be charging modules which include this circuit, but I don't know of one.  More information can be found here:

http://ww1.microchip.com/downloads/en/AppNotes/01149c.pdf


srnet

The cut off voltage for those modules is also a bit low, as low as 2.4v, very questionable as to whether that is a safe voltage for a lithium.

In addition whilst the module will cut off the battery when it goes too low, when there is then no current load the battery voltage recovers and the power output is turned on again. Having a project power cycle in this way may not be desirable.
No PMs please, they dont get answered.

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