Hello there, I am currently making a project of a smart car(Using Atmega2560 and L298 to control the motors).
One of the challenges is power consumption, so I was trying to find ways to reduce power consumption and make the car run for the longest time needed, I was thinking is it possible to use a dynamo(bike dynamo for example) to recharge the batteries that power the motors? if yes how can it be done or atleast where to start from.
if no, what's the optimum/efficient way power wise to run such a project, thank you.
Of course you can use a dynamo to charge batteries.
What will turn the dynamo?
Edit: I can't wait for the answer. If your plan is to run the dynamo using the power of your DC motors to charge the same batteries running the DC motors, then you are describing perpetual motion.
A battery to run a motor.
The motor turns a dynamo.
The dynamo charges the battery.
PROFIT!
Except that each step is very inefficient. You will remove MUCH more battery capacity to tun the motor than your dynamo will put back in.
vinceherman:
Of course you can use a dynamo to charge batteries.
What will turn the dynamo?
Edit: I can't wait for the answer. If your plan is to run the dynamo using the power of your DC motors to charge the same batteries running the DC motors, then you are describing perpetual motion.
A battery to run a motor.
The motor turns a dynamo.
The dynamo charges the battery.
PROFIT!
Except that each step is very inefficient. You will remove MUCH more battery capacity to tun the motor than your dynamo will put back in.
Instead, concentrate on efficiency of power use.
Yes that's what I mean, using the motors(which turns the wheels) to recharge the batteries.
Yes I am planning to use the L298, but I am pretty open to better suggestions, what do you suggest? thanks for your answer.
PS: The challenge is to make a line tracking system, the fastest longest lasting and most accurate car wins.
Yes that's what I mean, using the motors(which turns the wheels) to recharge the batteries.
Yup, the classic "free energy" idea, now called an "over unity" generator by the afflicted.
The earliest examples of this idea date back around two thousand years to the water screw, and despite the fact that the laws of physics absolutely forbid it to work, the idea will never die.
AliAmaim:
Yes that's what I mean, using the motors(which turns the wheels) to recharge the batteries.
Using motors as part of the braking system and using the energy generated to re-charge batteries is well established. Whether it would make a useful difference on a "toy" car is hard to know. My guess is that it would not because the car would not have enough momentum. Even if it did work well the amount of energy returned to the battery would probably be less than 10% of what was taken from the battery.
As @vinceherman has said the first requirement is to make the driving system as efficient as possible.
By the way, (in case of doubt) there is no need for a separate dynamo to do the charging. The driver motors will work perfectly well as generators when the vehicle is braking and forcing the motors to rotate.
How big and how heavy is the car?
Apart from the existing excellent suggestions of minimising the losses in the drive train, the only other area to look at is the battery type , and try to use the highest energy density battery you can find.
These are about the best you can get currently, but they arnt cheap.
mauried:
and try to use the highest energy density battery you can find.
Why would energy density matter?
I had not thought of this before, but it seems to me the important thing is to choose battery chemistry that minimizes the energy losses in the charge-discharge cycle. I have no idea which technology that might be and LiPos may well be the answer.
As the battery has to go in the car and will increase the weight of the car, you want the lightest possible battery with the highest AH rating if the aim of the exercise is to make the car go for as long as possible.
The 18650GA cell weighs 45 grams and is rated at 3.4 AH at 3.7 V.
mauried:
As the battery has to go in the car and will increase the weight of the car, you want the lightest possible battery with the highest AH rating if the aim of the exercise is to make the car go for as long as possible.
The 18650GA cell weighs 45 grams and is rated at 3.4 AH at 3.7 V.
Yes but energy per unit mass is not energy density, it is correctly known as specific energy. It's true that many, possibly most, people call energy per unit mass "energy density" but they're wrong.
It's possible that sometime soon the language will switch over and energy density will become the accepted term but at the moment....
mauried:
you want the lightest possible battery with the highest AH rating if the aim of the exercise is to make the car go for as long as possible.
I am not convinced that the mass of the battery will matter unless the vehicle is predominantly climbing hills without an equal amount of descents. The energy needed to accelerate a larger mass is not lost - it can be recovered in the free-wheeling phase and the energy in the momentum can be useful.
Braking is what wastes energy and it is true that braking a larger mass wastes more energy. But we have been given no information about the test conditions.
