power loss with 2 dc motors

Other Hardware Motors, Mechanics, Power and CNC
1

Hi, i am trying to make a rc car/auto but i found a problem.

I use 2 dc motors: 1 for the back wheels, one for the steering, when i try to turn while the rear motor is going/active i have a huge loss of power, seems like the power is splitted between the two motors.

I use a h-bridge and i connected a 9v battery to power both motors.

My question is: is this a voltage battery problem, so i need a more powerful one? Or is it a code problem?

In the attachements you have my code and the sketch i followed to make the circuit (the only difference is that i have 2 motors)

Thank you in andvance for your answers

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ponteHv1-0.ino (1.52 KB)

2

xlr8:
so i need a more powerful one?

Yes, those 9V batteries belong in smoke detectors not robots.

Four, five or six AA NiMH batteries would probably be a good option.

I use LiPo packs in most of my robots.

3

9V batteries are good for 10mA, OK with 25mA, anything more and you overload them. Motors are typically in the amps range, not milliamps. R/C cars often have powerful motors capable of 10's of amps stall current -
LiPo batteries can provide this, perhaps 3 to 4 orders of magniture more current available than from a PP3
sized 9V battery...

4

Thank you for your answers.

I just need another help, looking for batteries i found a lot of models with different voltage, amperage etc etc and i really don't know how to chose.

Searching in an online shop i fuond two models of the same producer with almost the same price, the first is 3 cells 11,1v ; 1000mAh ; 45C , the second 2 cells 7,4v ; 1350mAh ; 45C.

At the same price wich do you think is the best?

5

Here's the photo attached to the top post.

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Here's a link to instructions on how to insert an uploaded image into your post (for next time).

What motors are you using?
What h-bridge are you using?

Why not add links to the batteries so we learn more about them?

45C is likely a much higher current rating than you need. It won't hurt to have a higher rating but a lower rated battery might not cost as much.

I usually purchase LiPo batteries from HobbyKing.

6

And make sure to add decoupling to your motor driver too BTW.

7

i use L293d (H-Brindge) and i found the motors inside a chinese RC auto toy, so i don't know the model.

Here are the link to the batteries:

8

xlr8:
i use L293d (H-Brindge) and i found the motors inside a chinese RC auto toy, so i don't know the model.

Which battery pack to use depends on the motors. What sort of battery (voltage and capacity) did the original toy have?

A picture of the motors might help make suggestions on how to control them.

The L293D is usually used with small low power motors.

Did the toy have an h-bridge you could use?