Have you built a Handmade small 5V UPS ?

[MoDu]

I've had more success recently with Powerbank pcb modules. It's been mostly luck to find a chip/board combination that's not one note. I absolutely detest the modern chargers (like my BT headphones) where if you plug it in, the device will turn off.

[jeffs555]

You are very close with the last diagram you posted. Would just need to add a couple diodes and a lipo protection board. The protection board keeps the lipo from discharging too low and ruining the cells. Also provides redundancy in case the charger breaks and tries to overcharge or short circuits. The diodes would supply power from the wall wart directly to the step-up and isolate the battery when the AC was on. When the AC went out, the battery would supply power through its diode. The diodes would waste a little power. Could use a low voltage Schottky or an ideal diode in the line from the battery to save power when operating from the battery. Not a problem when powered from the mains and a normal power diode would drop the 5V from the wall wart enough that you shouldn't need a step-up/step-down converter.

5v_ups__v2.jpg (208.73 KiB) Viewed 752 times

here is one of many protection boards available.
https://www.aliexpress.com/item/1s-3-7V ... 14272.html

Here is an ideal diode board(ie a mosfet with an ideal diode controller)
https://www.aliexpress.com/item/15A-Ide ... 96276.html

[jeffs555]

PS: Here are some Schottky power diodes. When drawing an amp or two from the battery they would waste less than 8% of your battery power so probably not worth trying to do an ideal diode board.
https://www.aliexpress.com/item/New-Ele ... 93279.html

[stevestrong]

The diodes do really make sense.
However, I think the step-up board implicitly has the low-voltage protection as it only works above 3.7 V.
And the charger modules have the high-voltage protection. So the battery cell is well protected.

[jeffs555]

When it comes to lithium batteries, especially unattended ones, you want a lot of protection. Electronics can and do fail so redundant protection is a very good thing especially when the results can be a lithium fire. The protection boards are very inexpensive.

[mrburnette]

cross post: ray posted this about LiFePO4 batteries
https://www.stm32duino.com/viewtopic.php?t=421
i think they'd cost more than the average common lipo batteries but may be interesting to look at
...

I ran the prototype for over 2 years! Never an issue. Test uC was an ESP8266 with OLED display .... UDP receiver for my remote based GPS UDP transmitter.

I used an old power-brick, an AliExpress buck module, an Amazon purchased LiFePO4.

Ray

[madias]

I use this for many projects and small series productions:
https://www.aliexpress.com/item/ESP32-E ... 96675.html
charger, step up, fuse.. everthing on board for lazy people.

[MoDu]

Thank you Mathias, I've already ordered a few to test. What about a version for LiPos (flat cells) ?

[Vassilis]

Madias, can this device be used as UPS ?
Can that module simultaneously charge the battery and provide 5V output ?

[madias]

Madias, can this device be used as UPS ?
Can that module simultaneously charge the battery and provide 5V output ?

Yes, should not be a problem, charging chip is (TP)4056e.