# Electric motor throttle?



## major (Apr 4, 2008)

Borgli said:


> I just got a small electric motor to put in my boat for fishing speed.
> It is 72v with a peak of 38hp.
> 
> What is the easiest way of controlling the speed?
> ...


What motor? You need a motor controller and that depends on the motor specifics. And yes, it matters about the batteries. What is your mission? How fast? How far? Load capacity (volume and mass)? Budget?


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## Borgli (Oct 20, 2013)

I am aiming for about 5-7 knots. The boat has a 6.0L V12 engine, but that scares of all the fish. I will also use the electric motor when leaving the harbor. 

It as called EMC-RT200. 
24-72 Volts
200 amp continuos, 400 amp for 1 minute.
11.5 - 22 kw

I found this for the throttle cable: 
http://www.evnetics.com/evnetics-products/throttle-assembly/

How would you recomend I setup the batteries? The gasoline engine has a 12v alternator so I guess it is best to stick to 12v batteries?


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## major (Apr 4, 2008)

Borgli said:


> I am aiming for about 5-7 knots. The boat has a 6.0L V12 engine, but that scares of all the fish. I will also use the electric motor when leaving the harbor.
> 
> It as called EMC-RT200.
> 24-72 Volts
> ...


That connects to this: http://www.evnetics.com/evnetics-products/soliton-1/

But for your motor http://www.electricmotorsport.com/store/ems_ev_parts_motors_me1003.php you could use one of these: http://www.electricmotorsport.com/store/ems_ev_parts_controllers_alltrax_4844.php or similar.



Borgli said:


> How would you recomend I setup the batteries? The gasoline engine has a 12v alternator so I guess it is best to stick to 12v batteries?


That motor won't put out much at 12V and will suck you battery dry real quickly. You need a separate battery bank at 36 or 48 volts. Maybe 24V would work. 

Did you consider just getting a large trolling motor made for the job?


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## Borgli (Oct 20, 2013)

I was thinking of connecting 6 12v batteries in series to get 72v, or 3 24v.

I found this controller, it has some throttle connections on the side of it so I guess I should be able to use the throttle I linked to earlier. 
http://www.electricmotorsport.com/store/ems_ev_parts_controllers_alltrax_SPM-72400.php

This is a project I'm doing with my dad. He really wants this kind of setup. It will connect to the same propshaft as the other engine. Supposed to make it all real seamless.


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## Borgli (Oct 20, 2013)

This throttle is a lot cheaper with forward and reverse
http://www.electricmotorsport.com/store/ems_ev_parts_throttles_parsun.php

One of those with the psm-72400 will probably be pretty good.


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## major (Apr 4, 2008)

Borgli said:


> I was thinking of connecting 6 12v batteries in series to get 72v, or 3 24v.
> 
> I found this controller, it has some throttle connections on the side of it so I guess I should be able to use the throttle I linked to earlier.
> http://www.electricmotorsport.com/store/ems_ev_parts_controllers_alltrax_SPM-72400.php
> ...


You'll have to gear the electric appropriately to use the same prop.


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## major (Apr 4, 2008)

Borgli said:


> This throttle is a lot cheaper with forward and reverse
> http://www.electricmotorsport.com/store/ems_ev_parts_throttles_parsun.php
> 
> One of those with the psm-72400 will probably be pretty good.


You'll need reversing contactors.


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## Borgli (Oct 20, 2013)

Yes, my dad is taking care if that bit

Any thought on my idea for the batteries?

The reversing contactor goes between the throttle and controller, right?
Something like this?
http://kellycontroller.com/reversing-contactor-zjwt-72vdc-coils-400amps-p-95.html


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## major (Apr 4, 2008)

Borgli said:


> Yes, my dad is taking care if that bit
> 
> Any thought on my idea for the batteries?





major said:


> And yes, it matters about the batteries. What is your mission? How fast? How far? Load capacity (volume and mass)? Budget?





Borgli said:


> The reversing contactor goes between the throttle and controller, right?
> Something like this?
> http://kellycontroller.com/reversing-contactor-zjwt-72vdc-coils-400amps-p-95.html


Yes, that is a reversing contactor. It goes between the controller and motor.


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## major (Apr 4, 2008)

By definition, a throttle is a device controlling the flow of fuel or power to an engine. For the electric motor, this device is the motor controller which is wired between the battery and motor. 

You have a DCPM motor. The appropriate motor controller for it will adjust the voltage to the motor such that the motor speed varies in response from an operator command and also in a way that keeps the motor in a safe operating zone (current limit). The command input to the controller is typically a small signal adjusted with a potentiometer, variable resistor or hall device. This method allows the control of hundreds of Amperes by adjusting milliamperes. In some industries, motor controllers are actually called amplifiers.

The device commonly used for the operator command input to the motor speed controller is a 5 kOhm pot (http://www.parts-express.com/pe/sho...source=google&utm_medium=cpc&utm_campaign=pla). The classic PB-6 potbox has been used on EVs for decades. The motor controller will define the exact type of input device required. Some now use hall devices or TPS (throttle position sensor) from automotive.

To reverse the PMDC motor you must reverse the polarity of the power to the motor. This is done with a robust DPDT switch or contactor(s) placed between the motor controller and the motor.


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