Wiring Boost Regulator

I am interested in providing consistent power to the motors on my SV-328 so the motor speed can be profiled regardless of battery voltage. I’ve seen references to the Adjustable Boost Regulator (item #799) which I think will do what I need. I’m not clear on how this would be wired in to my configuration and am looking for some help and advice.
Q: do I just wire it between my battery source and the power inputs on the SV-328 ?
Q: to dial it in (set the output voltage using the pot) once in the beginning and then pretty much forget about it ?



Answer to Q1: Yes.

Answer to Q2: The boost regulator page has a section on setting the voltage. Please remember to set the input voltage to less than 2.5 V while you are first setting the output voltage.

Here is what I said about this boost regulator in another forum post:

So, if you power the SV-328 and your motors with this regulator, you want to make sure you only expect to draw power up to what your regulator can put out.

- Ryan

Thank you Ryan.
I think I don’t fully understand the boost regulator and have some follow on questions to help clarify.

I am running the SV-328 with motors that support 6-13.5V and have multiple Sharp Sensors.
I use 8 x 1.2-1.4V rechargable batteries and want to have constant voltage at 10V to the motors.

I thought by getting the boost regulator (item #799) which supports 4-25V output and providing my normal +10V input input that I could “condition” the voltage to keep at a steady 10V.

However, as I read the spec info it recommends that the input voltage be LESS than the output voltage. So in my case it looks like I would do the following:

  1. Get the 4-25V boost regulator
  2. Set it using a 2.0V input source to and adjust it to 10V output.
  3. Wire it into our system
  4. Reduce my # of batteries so that my new input voltage is ~5.0V and the output voltage will be 10V.

Q1: Is this accurate ?

Q2: if so, what can I expect for battery life now (in general) - e.g will they last half as long ?

Thanks again for your great support.
Obviously I am not a HW guy and I appreciate the help!


When VIN is greater than what you set VOUT to, it will pass the voltage through, so VOUT will be higher than what you set it to and it will probably damage the regulator chip. Even if it didn’t damage the regulator, you wouldn’t want it passing through greater than 10 V because that would be counter to your entire reason for having a boost regulator in the first place.

If you choose VIN to be 5 and VOUT to be 10 you can only expect 800 mA of current. I would recommend reducing the number of cells, but not as drastically as you suggest. 7 or 8 cells should work as long as you make sure that VIN is less than what you set VOUT to. Keep in mind that you don’t have to keep VOUT at 10 V.

The thing you need to be more concerned about, before you worry about battery life, is will the regulator support the current you need? What is the stall current on the motors you intend to use? Is the total current consumption of your system going to be over what the regulator can output at your desired boost level?

- Ryan

I am using the 130 size 6V motors (item #1117) and the stall current is 800mA.
I’m not sure of the SV-328 draw is … I think the (4) Sharp Sensors are 40mA each so 160mA.
Again - not sure how these get totaled up.

Thanks for and additional advise.


If you want your system to be very reliable, you sum the max current draws from all of the components and make sure your power system can deliver that kind of power. If both of the two motors get stalled, the current draw will be 1.6 A, which is already what the regulator can supply if it is not boosting the voltage at all. I would not recommend using this boost regulator for your application. If you avoid stalling the motors, you might be okay, but you run the risk of breaking the voltage regulator.

- Ryan

Another thing I forgot to mention is that 800 mA is the stall current at 6 V. The stall current at 10 V will be something like 1.3 A.

- Ryan