Electrical question

[crusher]

Hi, I am scratch building a cat 330b, I have two track motors with two esc, do I use two channels for control or is there a better way. I am using an eight channel Futaba radio, it has several mixes available as well as several switches. I am slowly trying to absorb the manual for the radio. I have the boom, stick, bucket on the sticks using three channels to the valve body, the swing on a fourth channel. Also do I need to use a separate battery for the receiver, I have read somewhere that receiver power is received thru the esc connections?
Thanks for any help offered .
Terry

[Jack3M]

Well, if like most tracked vehicles, each side should be on different channel if using two different motors for a few reasons. Motors will need to run in opposite directions. Pirouette requires one going one way and the other going the other. Not sure what your setup is.

Using a separate power for Rx is possible, but these ESC's are pretty good about powering Rx. You can use separate smaller battery for Rx. In airplanes for competition that is required, but on the ground, not an issue if the breaker in the ESC cuts out like an airplane or worse a helicopter having a cut out.

On an excavator you use up several channels for the hydraulics, consider if you have sliders on either side of the radio as the means of running the tracks as most of your operation will be not driving around but digging.

[crusher]

Thanks for your reply, I was not sure about using esc for receiver power.
Appreciate your input.
Terry

[SteinHDan]

It varies a lot how much power an ESC can deliver to the RX. I would look up the spec on your ESC to see if it can power the RX plus three servos (for your valves). If you have the model number or product name, I can help you look it up.

If the ESC does not deliver enough power, then you can buy a separate SBEC/UBEC:
- Hobbywing 5V/6V 3A Switch-mode UBEC (http://amzn.to/2b8BmHm)
- Turnigy 5A (8-26v) SBEC (http://amzn.to/2blLxfd)
- Hobbyking YEP 20A HV (2~12S) SBEC (http://amzn.to/2blLKig)

Also you should not use both ESCs (or any two sources) to power the RX at the same time, as this could damage the ESC depending on how its BEC circuitry is build. Just use one ESC and remove the power line from the other, like this guy does:
- https://www.youtube.com/watch?v=clNvfjhMQ5w

If you end up using an external BEC, then remove the power lines from both ESCs.


Best regards,
Stein :-)

[crusher]

Thanks Stein, the ones I have are "Proboat" they list BEC output as 6vdc,1 amp max. forward current 50amps reverse 20amps, not expensive.
Terry

[SteinHDan]

1A is pushing it a bit, in my opinion. I usually assume 250mA per servo for no load and 1A per servo at stall. I guess in your application the chance of stalling the servo is very small as turning the valve probably isn't very heavy on the servo? But anyways, 3x250mA for the servos +50mA for the RX is around 800mA total which is quite close to the max 1000mA of your ESC.

You could get a 3A (or 5A) SBEC/UBEC to be on the safe side, and also it would be good to have that extra power if you're adding other things later, like lights, rotating beacon, rototilt, quick coupler, etc.


Best regards,
Stein :-)

[crusher]

Thanks for your help Stein, I think I am going to buy a separate bec and disable the red wires on the esc. That way I will be covered.
Terry

[TheBennyB]

It varies a lot how much power an ESC can deliver to the RX. I would look up the spec on your ESC to see if it can power the RX plus three servos (for your valves). If you have the model number or product name, I can help you look it up.

If the ESC does not deliver enough power, then you can buy a separate SBEC/UBEC:
- Hobbywing 5V/6V 3A Switch-mode UBEC (http://amzn.to/2b8BmHm)
- Turnigy 5A (8-26v) SBEC (http://amzn.to/2blLxfd)
- Hobbyking YEP 20A HV (2~12S) SBEC (http://amzn.to/2blLKig)

Also you should not use both ESCs (or any two sources) to power the RX at the same time, as this could damage the ESC depending on how its BEC circuitry is build. Just use one ESC and remove the power line from the other, like this guy does:
- https://www.youtube.com/watch?v=clNvfjhMQ5w

If you end up using an external BEC, then remove the power lines from both ESCs.


Best regards,
Stein :-)

Just wanted to say this post made my day. Just installed a sabertooth dual 25A ESC and was having a motor twitch problem in one track motor. I had left the positive from the pump and slew motor ESC's into the RX. Once I removed them and had just the sabertooth powering the RX all was fine. Gotta love forums such as this!

[Lil Giants]

These "ProBoat" esc's, did you get them from Robot Marketplace? If they're the ones I'm thinking of, then you might discover, as I did, that they are not that smooth, they're either full on or full off, no graduated acceleration/deceleration.

Sabertooths are the best for track motors & swing acceleration/deceleration ramping.

The E-Flite 30amp esc I used for pump has a 3amp BEC & has always been sufficient power for 3 servos & 4 other esc's. My quick coupler using a small gear motor, I had to use a separate BEC so I could preset the voltage to 8v output b/c 4s (16.8v) was too much for tiny motor (just pointing that out b/c not always one electrical system will work for entire model, you may need more than one external BEC for different current/voltage limits)

[crusher]

Thanks for the heads up on the esc, I didn't purchase from robot shop, but I will hook one up and see what it does.
Terry

[Jack3M]

Another option would be to purchase a Castle BEC Pro, a heavy duty voltage regulator and is programmable. Two power outputs. I don't think you need all that, but it is an option.