Developing DC UPS module

[anso-engineer]

Hello!

I am using some UPS modules, 15Wt power, but i found some things which is bad suitable for me.

1) In this layout it's hard to swith battery source
2) Actually I need something more powerful, around 25-30 Wt.

The basic idea for a new project is to concentrate on TP4056 layout and what is needed for there. If have a look at the already existed PCB,
I have found there some kind of MOSFET and protection elements,

but according general datasheet with TP4056 there is few resistors, capacitors and indication diodes.



I also plan to use ESP8266 or Arduino Nano for the managing state purposes.

Could you explain the general idea for it and what it need for it? For now I see that I definetly need 2items of TP4056 for share load between them.

 

[Nigel Goodwin]

What has the TP4056 got to do with a UPS?, it's just a Li-Ion charger IC - the extra FET's etc. are to add battery protection to it, to avoid over discharge of the battery.

Why would you need two?, can they even be paralleled?.

If you're using a micro-controller you could do the charging in software (with discrete hardware), rather than use a TP4056, and so make it do exactly what you want.

 

[anso-engineer]

In the most ready to use there is TP4056 IC, so I based on it because I plan to use 18650 also.
I decided to use 2x TP4056 becase the general reserving line probably will contain 4 batteries. Mainly in this workflow ESP8266 should be a simple switch and logger, so I am not sure what is the basic logic of charging should goes there. Probably it's more complicated than turn off charging when battery is 4,2 and turn it on when it's 3,5

 

[Nigel Goodwin]

Yes it's not as simple as that, charging Li_ion is fairly critical - assuming you can put TP4056's in parallel (and there's seems a lot of discussion on-line about it) all you're doing is doubling the charging current - using one will just take twice as long.

 

[danadak]

Warning : https://www.best-microcontroller-projects.com/tp4056.html

General charging considerations :

https://tayloredge.com/reference/Batteries/Li-Ion_Charging.pdf

https://www.ti.com/lit/an/slyt769/slyt769.pdf

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[anso-engineer]

Ok, do I need this extra staff as (2) and (3)? Or some of their functionality can be replaced with MCU?
Btw, what is the proper way to limiting current during the charge? Because I don't think that some variable resistors is good idea.

 

[Nigel Goodwin]

Ok, do I need this extra staff as (2) and (3)? Or some of their functionality can be replaced with MCU?

Those are basically to prevent over discharge of the battery, which ruins Li-Ion cells.

Here's one example of charging using a micro-controller, it's worth studying to see the various methods he uses, particularly for safety checking.

Btw, what is the proper way to limiting current during the charge? Because I don't think that some variable resistors is good idea.
View attachment 148379

On theTP4056 the charge current is set by the resistor on pin 2.