# Not enough power out of motor shield..?

I'm using the seeedstudios motor shield 2.1 with 11.1 v input running two dc motors the motors are plenty big enough to move my RC car but I'm not getting the power out of them it barely moves if at all...if anyone knows how to get more out of this shield or maybe suggest a better option for controlling a RC car motors ?

What is the power input? You've said 11.1V but is it capable of delivering the current required?

Most likely, the motors would draw more current than the motor shield can provide.

It says the shield can handle up to 15v

It is the current that matters here.

Specifications

Operating Voltage: 5V Motor Supply Voltage: 6 - 15V Output Current(For Each Channel ): 1.6 - 2A Output Duty Range: 0%~100%

You need to know the stall current and the typical running current of your motors.

The stall current can be estimated by measuring the resistance between the motor terminals, while moving the shaft very slowly (take the lowest reading). Divide that value into 11 volts to get the stall current. Brushed DC motors briefly draw the stall current every time they start up, and your motor driver + power supply has to supply it. Motors draw twice the stall current if they are rapidly reversed.

The typical running current has to be measured using an multimeter on the appropriate range and with a typical load on the motors.

Motor data missing from question. "plenty big enough" is almost zero information given we haven't seen your R/C car!

Please use numbers, not adjectives, since your idea of a big motor won't necessarily agree with other peoples'!!!

Well this is the motor I'm using Helion HLNA0029 Motor, 370 4300RPM

And the stall current at 11 volts is?

How do I measure the resistance?

The resistance of what? The motor? To do that, connect a meter set to ohms across it. Then, use Ohm’s law to determine the current.

I'm sorry I ment how do I measure the stall current

The same way. The stall current is how much power it will draw when completely stopped. You just need the voltage of your battery and the resistance of your motor when it is not connected to anything. Certainly do not power it when you measure the resistance.

There is virtually no information on the web about the Helion HLNA0029, but it is advertised as a 10 turn motor and is clearly intended for high performance race cars.

At a very rough guess, the stall current is somewhere in the range of 20-100 amperes.

That motor is completely and utterly inappropriate for the chosen motor driver, and needs instead to be driven by an RC-type ESC, with heavy wiring.

Absolutely, that thing probably doesn't get out of bed for less than 3A.

I have two outputs that go up to 2A so I could connect both to increase it to 4A .... Or would it not work this way?

Paralleling outputs is possible with some motor drivers. You must parallel the inputs too, so that both sides are driven identically.

However that only brings you a little closer to the suggested 20A minimum current for this motor.

Pololu high current MOSFET H-bridges are a possibility. Some do 15A or so, 30A peak.

can i modify my motor shield to go up to 20A?