Hi, so im building a line foowing robot with 4 dc motors (one of these:https://images.app.goo.gl/UnXuppFzg2S4GtC56 but faster rpm). These are connected to 2 L298N motor drivers. These motor drivers are powered by 3 rechargable lithium ion batteries connected in series. They have a capacity of 6000 mah and can hold 3.7 volts. Im already suspicious of these batteres because of their ratings compared to their size (6000 mah is not believable). So the motor drivers are connected to the battery pack in parallel obviously. I used an arduino Mega at first and things seemed to be fine. But after a week, one of the motors would only move in one direction or would not move at all. I changed the motor,motor driver,batteries and the arduino (tested it with an UNO) several times. The motors still do not all work unless they are at 200+ pwm. However i want to run it at 100 pwm. When running at 100, it fails after a few minutes. I then increase the pwm and it works for a bit but it failes after a few minutes again. I really do not know what the problem is, could anyone help me, please?
Help I'm having the EXACT same issue. I have a similar model of motors and the same motor drivers and I run into the same problems. Can someone help?
@nightrider772 - Do not hijack another user's topic... watch this one proceed, but if it starts to move away from your issue, start your own topic.
Did you recharge your batteries (did the replacement batteries have a full charge)?
You showed a picture of a 6 to 12 vdc motor. Post a list of the components you are using, and how they are connected.
2 l298N motor drivers
Those motors im not sure about their rpm since i bought them locally at a shop.
An arduino mega 2560
3 Ultrafire 18650 6000mah 3.7v lithium ion batteries(fully charged)
As for the circuit its just the standard motor rmdriver connections where 2 motors are connected to the motor driver and 4 pins are connected from the arduino to the driver for motor control and 2 more from the arduino for pwm.
The L298 can handle only 1 Ampere continuously per channel, making it suitable for only very small motors.
I suggest to replace the ancient, extremely inefficient L298 with a modern motor driver. Pololu has the best selection. You need to know the start/stall current of your motors to make an informed decision.
I would start by by using drivers that have MOSFET outputs. you are burning the power of one of your batteries as heat. This heat causes the temperature of the driver to rise. As the temperature increases , Ibo or reverse saturated current through emitter junction increases and hence overall current through Je reducess, and hence Vbe also get reduces proportionally.
Could you recommend a few good budget models for this type of motor please?
Post the details of the motor. There are countless types.
Sorry, the picture could be of many things, including some things that are not motors.
Why did you buy that motor, if you don't know anything about it?
This web site has some useful basic information about motors and robot design.
Each motor is different. For your motors, don't let PWM be less than 200. You probably hear a sound from the DC motors as they struggle when you supply lower PWM.
Motors run on amperes. Compute the amperes being supplied at the various settings. The only way to get more amps at lower PWM is to increase the voltage being supplied. Kind of a rule that is mother nature and applies to your motor as well.
Well im supplying 11 volts to the driver and when i used a multimeter its around 10 in the output of thr drivers so do i still increase the voltage beacuse i dont think the motors are rated for 12+v
Thank you
They are not rated for pulsing current, either. Heat is caused by current and that, over time, will kill motors. You need to apply much more current for the short times you are sending the pulses. The short time limits the heat creation. The only time voltage rating enters the picture is when the internal wiring insulation is at risk. Motors are not "designed" for the service you have set up, so you need to experiment to see if the motor can be made to perform the way you require.
Found the specifications of the motor, it is a 200 rpm 12V dc motor.
Will try this out soon. Would it work on lower PWNs?
What you actually need to know is the start/stall current, the free running (no load) current and the rated current. Post a link to the specs.
200 RPM is very low, and I would guess it has a gear box. Does it?
Yes it does have a gearbox. There is no specifications about the current however.