Wich battery is better to use?

Hi everyone, I have a line folllower robot already built. It has two motors and three infrared sensors(FC-51)

I am using an arduino UNO board stacked with a motor driver shield(L239D) to control the motors. I have two different power supllies: 11V to the motor driver shield(3X3.7V 18650 batteries) to power the shield and the motors, and I am powering the Arduino UNO through the USB port with a power bank.

With two different power supplies the car works fine. The 3X18650 batteries power the motors and the the power bank powers the three infrared sensors and the arduino UNO.

However I would like to power the arduino UNO and the sensors through a battery so I can get rid of the power bank, so I bought a 9V battery(6LR61) to power the arduino UNO and the sensors but when i connect the 9V battery to the arduino UNO DC jack, only the led on the UNO lights up and the sensors dont work. I am thinking of purchasing a 12V battery(a23) to connect to the DC jack on the arduino UNO, but I dont know if it is a good idea… I searched quite a bit and didn’t found anything that could help me.

Based on your experience do you think it would be a good idea to connect the 12V battery to the Arduino Uno DC jack? And will it have enough power to power my three infrared sensors?
Kindly answer.

Current Consumption of infrared sensor FC-51:

at 3.3V : ~23 mA
at 5.0V: ~43 mA

My scheme is also atached. In my scheme the arduino UNO is under the Shield conected to a usb cable.
Sorry for any errors, my main language isnt english.
Thank you.

Get a 5V DC-DC converter, connect it to the main battery and power the Arduino from that. You don't need two batteries.


Thanks for your answer. However my shield has a jumper(PWR) that when connected lets the motor driver shield and the arduino UNO be powered by the same power supply, and my main battery(3x18650) is not enough to power the shield and the arduino UNO. It can not provide enough power for the sensors and motors to work at the same time. That is one of the main reasons I am using two different power sources. There was a time in wich I could power the motors and the sensors only with my main battery(3x18650), but time passed and I cant do that anymore(I dont know why, and I would also like to know). Thanks for your answer but I can not power the whole car with the 11V, so I need more bateries.

The 5V regulator on L293 motor shields is usually feeble and not at all efficient. That is almost certainly where problem was NOT the battery. 18650s can provide plenty of power provided you are keeping them properly charged and a modern Dc-DC converter will be much more efficient. But if you don’t want to try it that’s your choice.


Sorry for misunderstanding you... I though you didnt have much knowlege about the motor shield I am using. Thank you for suggesting the DC DC converter , that might work. But i dont have much space left in my car... The chassis is quite small, so I cant put a breadboard on my car with the converter. I only have space left for a battery. That is why I was asking if i could use a 12v(a23) battery to power the Arduino Uno and the sensors and if the battery would have enough power to power the three sensors. But thank you for your suggestion I might look at the converter in the future. But i doubt i will use this shield ever again it has severe problems, like a high voltage drop and so on... This is for a school project, and my car works fine, I just want to get rid of the power bank so that my car looks better. Thank you

Why are you worrying about space for breadboards? They are for proof of concept only, not for a finished project. You should be using stripboard or similar.