Running drive and weapon system with different voltages

[5upercrab]

Hi All

In the process of scoping out a build for a featherweight. I have come across a conundrum in the electronics.

I am running two 12v RS550 motors for my drivetrain (hacked from Argos drills).

I am planning to use the following monstrosity to power a spinning weapon (with great care!) https://hobbyking.com/en_us/9235-100...tor-motor.html

The issue I have is that it runs at 45v max.

I see two workarounds here.

- Use two power sources (which will presumably also require two removable links?)
- Regulate the voltage going into the drivetrain somehow.

The former leads to an obvious combat vulnerability, the latter I am less experienced with. My first guess is that this might be solvable using the ESC of the motors, but I am not sure how they regulate the power, is it via voltage or current? There is also the ever present chance of setting it up wrong on the day and burning the drive out.

What ways do roboteers use to get around this?

Cheers

5upercrab

[Ocracoke]

Hey there, welcome to the forum!

You could use a voltage regulator between the batteries and the drive ESCs but that is likely to get hot I should imagine. I don't see a problem with using 2 links though... yes, it is an extra link but it simplifies both wiring looms and if the battery to the weapon dies, the drive is unaffected.

[maddox10]

That outrunner will run on 4S , just as your drill motors.

We used that setup in Valkiri2 Just 1 BIG 4S pack.

[5upercrab]

Thanks guys

If I run at 4s will I be able to get the same wattage though? Taking P=VI at 14.8*57=843W and 1480 RPM.

Another option is dig around for even lower kV rating on the motor I guess?

@Ocracoke, am Wirral based too . Seems there are quite a few teams in the local-ish area!

[maddox10]

The motor will draw as much current as the load demands.
But you could look for a smaller motor, with a KV that suits your application, and as high as possible allowed Ampere rating.

[Ocracoke]

@Ocracoke, am Wirral based too . Seems there are quite a few teams in the local-ish area!

Nice, I am organising a meet up of the local(ish) roboteers for the 3rd of March if you fancy it (http://www.fightingrobots.co.uk/thre...l=1#post470829).

Personally, I am on the fence with having a smaller motor for driving the weapon. If the KV is a near enough match then I guess it would be OK.

[5upercrab]

Nice! Should be around for then.

Ahh so further research is required on the current front. Need to make sure the torque will be sufficient to accelerate the spinner.