Hello! I'm starting a new project to add some flashing LED lights to a small RC car. Space is limited so I have to try to minimize the use of components.
The idea I originally had was to use an Arduino Nano 33 and about 20 or 25 3V SMD 402 LEDs. To power the circuit I had thought of using a LiPo battery but I have seen that the available options are 3.7V so I am not sure if it is a good idea...
I had thought of installing the battery with the option of disconnecting it once discharged and charging it with a specific external charger.
I ask for your advice on whether to use a battery of this type or look for another alternative. Thank you very much in advance!
The load adding all the LEDS will be about 400-500mA.
The battery (752035) is 400mAh, 3,7V.
Running time will not exceed 5-10 minutes, it is for short demonstrations
Hello! Yes, absolutely right, it is now corrected in my previous answer. My main concern is based on the different nominal voltages of the board, battery and LEDs as I mentioned in my initial post. The battery time can be more flexible. Thank you!
You may suffer brown outs if you supply LEDs and the Arduino board from the same battery ...and it is subjected to high current demand (relative to the battery).
Try it and see I guess.
That cell is rated 20C. This means it should be able to deliver 20 * 400 mA, or 8 amperes of current.
400 mAH goes away in three minutes. at 8 amps. With just 500 mA, the cell would deliver for 48 minutes, and would not be breaking a sweat. Lipos are an amazing source of power.
That's only theoretical. I would be happy taking 4 amps continuously with 8 amps briefly, and expect three or four minutes of joy.
You can get small boost/buck regulators to make a constant 3.3 volts as the cell voltage goes from 4.2 to as low as you plan to go, which I hope you realize is one good way to ruin the battery (discharge too far).
I use cells like that and don't usually discharge below 3.3 volts (under load) or so - I get less time with it, but they last much longer. Same with charging… any place you stop less than 4.2 volts will add to cell life as you would measure by the number of times you can charge it and use it.
You could use a linear low dropout voltage regulator and power your device with just the lipo cell and that regulator. You'd get quite a good fraction of the full capacity even with the waste that woukd be.
Okay, I understand. In that case, as the colleague says below, it may be better to look for a battery that has approximately 1C.
I planned to connect the LEDs to the digital pins of the Arduino Nano. As the LEDs will not all be on at the same time, they should not exceed the maximum amperage of the board.
Will it be possible to connect this way even if the LEDs are rated 3V? Or should I use a resistor between the pins and each LED?
The Faq's and reviews tab leads to no text, no entries. I'll try another browser when I can.
Meanwhile the first sentence of the Description reads
LiPo Battery 752035 (3.7V 400mAh) High Discharge Polymer Lithium Ion These Cells are Designed with 25C discharge.
This is why they are great for R.C. cars, planes, and drones...
So if something I can't see yet says different, I guess we get to take our pick. Since I have gotten all the life out of very many of this kind of cell, routinely pulling multiple amps during the brief joy which discharging them can afford, I'll go with the description that says that the cell is designed for that use case.