Hello folks!
I am working on to plan a project to create a rc car. My problems starts att choosing a battery and I thought I would use lipo battrey to be able to recharge it. I know not so much about electronics, but at least I know I can't just buy a random lipo of the market. So Iv've got:
Arduino Uno
6V, 1.3 A, brushed Dc motor x2
micro Servo 9g SG90
l298 dual bridge
4 leds
piezo
I calculated that I would need aproximatly 12 volts to run the car at full speed with my two motors. Does that mean that i should get a battery with about 12 V? And also do I have any restrictions on the current to power the arduino through vin?
The 3 things that you need to know to choose a battery are voltage (you got that), current and run time between charges. Measure or calculate the average current the the project needs over some time. Multiply that current by how many hours that you want to run between charges. That gives the amp or milliamp hours required. Double that. Now look for a xV battery with a capacity of y milliamp hours.
The L298 is a very poor choice of motor driver, especially, for battery powered devices. Pololu has a good selection of modern motor drivers.
And also do I have any restrictions on the current to power the arduino through vin?
The recommended maximum power dissipation for the 5V regulator on an Uno is about 1 Watt. With 12V input to Vin the regulator must drop 7V. So the maximum current is 1W/7V or 143mA. The Uno, itself, uses around 50mA. Leaving, at best, 90mA. You must limit the current drawn from the regulator or the regulator will go into shutdown from the heat.
Alex_Joo:
I calculated that I would need approximately 12 volts to run the car at full speed with my two motors.
I'm puzzled as to how you calculated that; I see nothing in your list of components to suggest you need a 12V battery.
If I assume your battery voltage is correct. Use a SEPIC converter between the battery and the Arduino Vin. I set them for about 7.5 volts output, it helps keep things cool. They are cheep from China. You can use another one for the motors. That will allow the 12V battery to work for all. The ones I purchase are 3 amps output and they are in the low 90% efficiency range. This will allow you to keep your motors constant over the charge cycle of the battery. This response is to help you get started in solving your problem, not solve it for you.
Good Luck & Have Fun!
Gil
Alex_Joo:
My problems starts att choosing a battery ...........
6V, 1.3 A, brushed Dc motor x2
I calculated that I would need aproximatly 12 volts
Probably not true. It would appear that your problems start with learning the difference between volts and amps.