Questions about ESC's
 

Hi All,
I have a few questions about ESC's. While these are not strictly related to RC I hope some of you may be able to answer them.

I have an underwater scooter ( Cuda 550/650). It uses a large brushless motor with a ESC.
There are 3 sets of wires coming out of the ESC.
Battery +&- Battery is a 34s NiMh pack 14,000mah ( 50volt hot off the charger)
3 wires to Motor
3 wires to what I guess is a hall effect sensor. These sit next to a magnet that is connected to the trigger. To start motor you squeeze the trigger. To go faster you double click the trigger, to go slower single click the trigger. There are 7 or 8 speeds.
There is also a 35volt low battery cut out.
I can not ID the ESC although it does have the scooter manufactures logo stamped on it. But my guess it is made by a 3rd party.

The motor is a BFA42-2d-200 ( no link allowed) but I dont know its max voltage or current. But it has a 30 amp fuse and I have measured 16 amps current draw while in use loaded.

The scooter manufacture now offers a programmable ESC which I think is a Castle Creations ESC. But not sure what model. It cost $460us

So my questions.
Can I use any ESC with this motor and battery combo assuming it can handle 50 volts and up to 30 amps? anyone got any suggestions?
Are all ESC's programmable? Can I program the ESC I already have? I assume it must be programmable at some level, but by the user?
Do different manufactures require different programming interfaces and PC software or is it a standardized thing?


OK, now round 2 of questions.
I have a friend who has a different scooter. I have not seen it so am making some assumptions here. It uses 20 or 21 NiMh cells and a brushed motor. It does not have a ESC but it does have a low volt cut out circuit.

Can any brushed ESC be used on it assuming voltage and current requirements are met? Any ESC suggestions?
Will running the brushed motor ( no specs sorry) at a slower speed gain efficiency?
Ultimately this NiMh pack will be replaced with a Li Ion pack.
An option is to use a 6s Li Ion pack which will reduce voltage and therefor top speed. Top speed isnt so much of a concern by efficiency is. Its better to travel a long way as opposed to getting half way there fast.

Any feed back is appreciated.

Thanks

Greg

Any esc that meets the requirments should work. Easiest way to increase efficiency is to go up in voltage. You would have to go up significantly to really get any large effect though. Better to just get largeer capacity batteries, or wire a set or two in parallel.

Brushed VS. Brushless, brushless is more efficient.
Most hobby grade ESC's will run multi-pole motors little car motors are 2 or 4 pole & big airplane motors can be 12+ pole. "Pole" refers to the number or groups of electromagnets in the stator.

The thing that comes to mind is really how to make the conversion to have a simple switch to control an ESC that is looking for more than just on/off...

If you have a bunch of spare parts lying around & you are trying to make it work I'm sure something can be done. You can run old controllers off of modern LiPo's but you'll want some type of LVC or alarm so you don't go too far...

You may have better luck with some type of consumer grade tools & batteries like some Ryobi Lithium 18v drills with batteries & butcher parts off of them & series them to 36v to use the batteries? I think Dewalt has a 56V drill too.

have any pictures or what you have & are trying to accomplish?

Have you considered posting in a diving forum ?
https://encrypted-tbn3.gstatic.com/i...2R86m9nuC7qhFA

Thanks for the replies so far.


These questions are not about diving, they are about brushed and brushless motors and ESC's. I thought there would be more knowledgeable people on the subject in a RC forum than a diving forum. This pic you show is a Cuda 400. Same motor, just a shorter body and smaller capacity battery pack. (400 wh).


So how do the "throttles" on ESC work then? Do they simply have a variable resistor varying the input voltage on the 3 small wires? The higher the voltage seen the faster the ESC allows?
If this is the case a Arduino/PIC could be used to supply the input based on the actions of the hall effect trigger. It could also do the work of the LVC.

Indeed. This is what we are planning. For my scooter its not an issue. I can easily fit a larger battery pack. My friends one is a different story. While he can fit a very large battery, it may not be enough for what he needs. So increasing motor efficiency ( and over all efficiency) may be required as well.

I can not post pics of links yet. But image google "cuda dpv motor" and you will see the guts of the scooter.

The traditional control signal for a RC ESC (or servo) is a variable width 5V pulse. Repeating every 20ms (some newer high performance systems have a shorter frame/repeat rate).

http://www.electroons.com/electroons/images/pwm.jpg

This site may be of some usefulness: ServoCity,

This page in particular: Servo Controllers

Robotics sites might have Arduino info too.

Thanks Dave,

That is just the type of info I am after.

It may seem that this "protocol" for RC ESC has come from legacy systems. Perhaps a servo controlling the throttle on a gas engine???
But is the same protocol used on other ESC's? eg those used in robotics and production line machinery?

Correct, it is a hobby RC servo protocol to the best of my knowledge, later adapted for RC ESCs, so they could be used without modifications to the RC radio gear.

Best I can tell is is used for a lot of hobby type robotic stuff, as far as I know they tend to use RC components, including radio systems. Although probably aircraft type radios, as they can have a lot more control channels to work with.

I'm familiar with many servo controllers, both analog and digital, used in a industrial test lab, they do not use this type of protocol/control signal to the best of my knowledge. But an interesting question, I'll do a little 'scoping to confirm.

I'm not immediately familiar with industrial/plant floor servo and robotic systems, but I have some excellent contacts.

If I find out anything useful I'll respond.

I used to work in a manufacturing plant for vinyl windows and doors and some of their line equipment used 0-5V signals to control motor speeds. The more expensive motor controllers had multiple input protocols to select from including PWM, 0-5V, 0-10V, and multiple serial protocols.

I also have found some electric wheelchair ESCs at a "bargain basement" type store I frequent and they seem to primarily use PWM signals.