4x4 Car - Powering and DC Motor control question

Hi all,

First of all, as long as this is my first post I would like to say thank you for this awesome forum. I started "playing" Arduino one month ago and it was incredibly easy to start due to forums like this one.

I'm right now building a 4x4 RC controller car with a 16x2 LCD display, an ultrasound sensor to avoid front crashes (I'm waiting for another one to be installed in the rear and 2 servos to control the sensor's direction), an L298N and 4 motors, running with a Mega2560. Almost everything is fine, the controller with the Joystick works fine, the car move where I want but I have 2 main problems:

  • Power: I'm using 6x rechargable AA batteries and the battery lasts too fast. Any recommendation for this kind of deployment? I'm waiting for a 8x battery case but I don't know if this is the solution. LiPo maybe? Two 18650 batteries? Could you recommend one to me, please?
  • DC motor control: although the car moves where I want it's quite difficult control it. When I move the joystick the car moves on that direction for about 40cm even when I to a fast move. Is this normal with the L298N? Should I use a different motor driver? I haven't any delay configured in the program and in the display I can see that, while the car is still moving that 40cm, it's still receiving data from the controller when I move the joystick, but it ignores this data.

Thank you in advance!

Regards!

Hi,

As usually happens to me.. once I posted this thread I tested the car with 2 batteries, a 5V/1A power bank for the Arduino and the sensors/display and the 6x AA battery pack only for the l298N and the motor and it works much better (so this looks like a lack of power issue). Could someone please recommend a power solution for this car?

Thanks!

LiPo will be fine. Just make sure to get an appropriate charger.
A 2S 2200mah will last for a while-try hobbyking.com.

Thanks! 2S or 3S? Will I get any advantage with the 3S?

Could you recommend one and a charget, please? I'm completely lost about LiPos... One with a good quality/price ratio should be OK, I'm doing this for fun and my budget is not too vig xD

Is $15 USD OK for the charger?
If you are already using 6xAA, 2S would be better. 3S will give you more performance and put more load on everything, so use a meter to check the current draw.
The charger that I am thinking about is the Imax B6. IT is a 50 watt charger that can charge NiMH,NiCd,Pb,LiPo,LiIon batteries.
What capacity batteries are you using now? A lipo with the same mah rating is probably fine.
Be aware of the safety risks with lipos. Google "lipo house fire" to see what I mean.

I know that lipos are danger, I've read a lot about ways to poder arduino and these are always the danger ones.

The only other option (apart from buying more AA batteries? That I can imagine are the 18650, 2 should be enough to control this car I think, but I see more people using lipo than two 18650 so I suppose that's better.

I'll check how my car works with 8 AA batteries to calculte what battery I need (I'm waiting for the enclosure)

Thanks!

The main problem with 18650 is that many are about 2C rated. And they are Li-Ion so are 0.1 volts lower than lipo.