this is my first question in the forum because i can't find a solution on my own... i hope you can help me. Also english is not my first language so excuse my writing errors.
i design an arduino system to be installed in a foresty truck, it has a series of sensors and microcontrollers and it has to be power on even if the truck is power off. For that reason i know that a need a sort of UPS (uninterruptible power supply) so i get one of this UPS for 18650 li-ion batteries.
Previously, i think that i can use a powerbank to work as ups, but i realise that i cant, the powerbanks can be charged or charge something, but not at the same time. For that reason i take the 4.2 lipo batteries from that powerbank and i connected to the 18650 ups like in this picture.
so, my system is the next one,
The idea is that when the 24V battery is connected, the buck converter converts 24V to 5V and powers the UPS,powers the arduino circuit and charges the lipo battery.
I test this system and it works, but the problem is that the arduino system consumes more current (around 350mA )that the given by the buck converter from the 24V truck battery (150mA), so the system works but the lipo battery is been discharged, so i need a way to take more current from the 24V battery...
I study the 18650 ups module and it uses a tp4056 as lipo charge IC and it should charge up to a current to 600mA... so i dont know why it charges with so low current.
For the buck converter i am using a L2596 module, it can get a maximum input voltage of 42V and deliver up to 3A, i test it with a 12V input and a 10 Ohm load and it gives a current of 500mA, so it can deliver more than 150mA...
I dont know what to do now, for now, i'm simulating the 24V battery with a 42V ebike charger with a buck converter but i dont think that is the problem...
I will be attentive to answer any questions. I hope you can help me, thanks in advance.