Hi, I'm currently working on a PCB design that uses an Arduino Nano, the general idea of the pcb is that it allows the Arduino to read various 24 volt signals via the use of optocouplers, but I also want to make the design able to be used without a constant power source in case that there is a power outage, currently my design provides 24 volt at an input, the input is reduced down to ~15.8 volts with a 17815 chip, but I also want to use a 2s or 3s battery to power the Arduino, my main plan was to adapt the circuit of a TP4056 and add it to my pcb design to provide power and charge a 3.7v battery, but the TP4056 as far as I know only works with a single cell, I also researched some BMS that I could use but I don’t know if they can provide energy to the Arduino while charging the 3s battery
TLDR: I require a 3s BMS to charge a 3s battery and power a Arduino Nano while there are 24 volts available, and should use the energy stored in the battery incase of a power outage to power the Arduino.
It sounds like you are not optimizing your design and have a lot of extra parts. Post your annotated schematic be sure to show all hardware. What are the loads and signals, I work with 24V all the time. Note whether we are talking AC or DC.
I was just thinking that I could use a single 3.7v battery along a boost converter to get a more appropriate voltage for my needs, everything is in DC, the signals that are going to be sent are mainly PWM. I added the mosfets due to the LEDs not lighting brightly enough.
What is the 24V power source? Why two wires for each input? Assuming it is DC you can switch the input low you can simply use a resistor divider and eliminate the optocouplers.
Most of the design comes from another PCB, on sale online, that is known to work with my system, that’s why my design has those optocouplers, they might come from encoders and other sensors, the 24v source is from a PLC power source.
I don’t have a buck converter in my design but for that reason I’m using the BA7820, to reduce the 24 volts down to 20 volts in the schematic, but the final design has a 7815 regulator, the purpose of the batteries is to have backup power in the case of a power outage so the Arduino can send a message or the status of the machine while there is no power, also can’t really use a buck or boost converter due to space limitations in the PCB design.
The TP5100 charger will do 2S, but with no balancing. But 2S should be more than enough for your Nano 33 IOT, even with diode OR-ing of the battery and the regulated supply.
I think the TP5100 will accept 15V, but not sure about 20V.
