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Topic: upgrade of RC Car (Read 357 times) previous topic - next topic

km1kze

Hello people,

I bought a RC Car (those off road types on aliexpress) and want to try to upgrade it with a bit more power and a FPV camera+transimtter.
I am no expert in this stuff, but I drew an example of what I would want to achieve.

Can someone please tell me if is possible to do it like is in the uploaded image? I skipped the connections from bluetooth, L298 module to Arduino because I'm more interested in the power distribution of this circuit. The car has 3 no name DC motors, don't know much about them... One in rear+one in front that are used simultaneously to go back/forward; and one for changing direction.

The car as it is, is using a 6 pack of AA Ni-Cd rechargable batteries rated 7.2V 2000mAh - I thought to use 3 18650 cells in series, of around 2000mAh for all components.

What do you guys think, it will work, or do you have any suggestions or improvements?
Thank you!


vinceherman


Robin2

#2
Jun 05, 2019, 03:20 pm Last Edit: Jun 05, 2019, 03:24 pm by Robin2
Am I correct to assume that the L298 is part of the original car system. If not, and you are thinking of buying one then DON'T. There are many motor drivers that are far more efficient. Also, even small DC motors can draw more current than an L298 is capable of. Have a look, for example, at the Pololu website.

It would be wise to measure the no-load current and the stall current for the drive motors. Only hold it in the stall condition for 2 or 3 seconds and expect a stall current of the order of 5, 10 or 20 amps.

You may find that the power draw of the motors interferes with the quality of the 12v power for other sensitive devices.

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

daysleeper

There are many motor drivers that are far more efficient.

expect a stall current of the order of 5, 10 or 20 amps.
True, but the price/performance is as good as the L298N? (it's not rethorical!)

The stall current will trigger the BMS's overcurrent protection.
3S 2A BMS is perfectly sized for a 25W L298N, except for loads with high current peaks.  :(
Se è stupido ma funziona allora non è stupido.

Robin2

True, but the price/performance is as good as the L298N?
It would be difficult not to be better.

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

daysleeper

I had more or less the same discussion this morning on another topic.
I didn't find (so far) a motor driver that doubles the efficiency and the rated amps without AT LEAST twice the price. Did you find something?
Se è stupido ma funziona allora non è stupido.

slipstick

I think the point is that if you need a 2A motor driver it doesn't matter how cheap a 1A motor driver is it is still completely useless i.e. it has NO value at all. It is simply a way of throwing a little money away before you give in and buy the right thing.

Steve

Robin2

I think the point is that if you need a 2A motor driver it doesn't matter how cheap a 1A motor driver is it is still completely useless i.e. it has NO value at all. It is simply a way of throwing a little money away before you give in and buy the right thing.
Nicely put.

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

daysleeper

#8
Jun 06, 2019, 12:50 pm Last Edit: Jun 06, 2019, 12:52 pm by daysleeper
if you need a 2A motor driver it doesn't matter how cheap a 1A motor driver is it is still completely useless
True, but  IF...
So far the bottleneck in the OP project is the BMS (or the 18650 cells, if poor quality) not the motor driver.
Not to mention that there are dozens projects of small rc car that use this driver, they actually move, mine moved, so "completely useless" doesn't seem to be true.

You could argue if, with this driver, the OP's request of "a bit more power" could be fulfilled or not, but so far we don't have numbers yet to say so.

@km1kze:
The L298N module has a 5V output, you don't need the second step down regulator.
I don't know the voltage input spec of the FPV camera, but the TS5828 can work in the [7-24]V range.
If it can work in the [7-12.5]V range you don't need any voltage regulator, only filtering caps, a proper BMS won't exceed this values.
Give us more info about the motors...

Se è stupido ma funziona allora non è stupido.

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