Few months back I had made my first UPS for Routers using lithium ion battery 18650, I had made two UPS, One for my router and one for my fibre converter. It was bit of mess with two power adaptor. It was in my to do list to make single UPS with dual output...
Making this my main challenge was that
- Single 5V charger, cannot provide enough power
- Single Li ion battery cannot supply enough current
- Solution was to use battery in 2S mode but TP4056 cannot be used
So in this instructable, I will share how I made my UPS with avaliable modules
Step 1: What Do We Need ?
- 2 Lithium Ion 18650 batteries ( extracted from old laptop)
- 2S battery protection board Aliexpress link
- CC CV Step down XL4015 Aliexpress link
- DC Step up volt MT3608 Aliexpress Link
- Step Down LM2596 Aliexpress link
- Male Power connector- 5.1x2.3mm, 5.1x2.1mm
- Female Power connector - 5.1 x 2.1mm
- Wires ( Using copper wire with multi strands)
- Case ( I made my own wooden case)
- 12V 1.5A DC adaptor
- Soldering Iron
Step 2: Circuit Design
We do not have any 2s lithium ion battery charging boards, like TP4056 that can supply constant voltage, current and provide battery protection on single module.
So have to break this into two
- WH 2S80A: 2 S 18650 battery protection, capable to divide voltage across two batteries, overcharge protection, short circuit protection etc. Battery once charged does not draw current and this module will prevent overcharging. This is key for this circuit to work as UPS
- XL4015 : To work as CC of 1.3A and CV of 8.4V
- Green light : When Battery is completely charged
- Blue light : Battery not charged or supplying constant current
Step 3: Setting Up XL4015
The XL4015 is a step down with adjustable CC and CV, using onboarded variable resisters .
To charge 2s lithium battery, we must set CV as 8.4 and ideal charging current upto 2A. Based on the your lithium ion batteries, these value may vary. please check datasheet before setting these value
My Charger could not supply 2A, so i set it to the max current it could supply without tripping
Anticlock : reduces voltage / current
Clockwise : increases voltage / current
If the variable resistors do not respond, disconnect power and turn clockwise till you hear "click" sound or the end. Note that now you have max current (5A), make sure your ammeter can take more than 5A . Turn anticlock to set the desired voltage with no load and then current
Step 4: 2s Battery
- Connect the battery protection board to 2 lithium ion batteries in 2S config
- Charge the batteries
- Note that while charging the Blue led on XL4015 should be on, this ensures the batteries are getting requires charging current
- When the batteries are completely charged the Green led will be on and Blue led will be off
- If the Green and blue leds are toggling that means the power adaptor is not able to supply enough current and we must either change to new adaptor or reduce constant current
Step 5: Circuit and Testing
Build the circuit as per the circuit diagram. I added a switch to disconnect battery when I want.
You need to charge the batteries before you connect any output. Set the MT3608 to 9V and LM2956 to 5V ( this is the voltage i need for my modem. You could adjust them )
Idf you want a 12V UPS,
- set the value MT3608 to 12V
- Replace power supply that can supply required current
- remove LM2956 from the circuit
Step 6: Finishing
I build my case using 4mm MDF sheet and added my logo to it.
I am adding a video to demo, UPS working
Please share your comments and suggestions