pwm controller for 11a dc fan motor etc

Discussion in 'General Electronics Chat' started by rodneygt, Feb 6, 2015.

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  1. rodneygt

    Thread Starter New Member

    Feb 6, 2015
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    I've a yamaha rhino to which I'm in the process of adding various electronic accessories. One of my concerns is having sufficient available and stored electricity for the various accessories. As to storage, the stock battery is rated at 35ah and I've now added a second 35ah battery parallel but through voltage sensing relay type of isolator, which should prevent items connected through it from draining the stock battery but allow it to charge when there is excess beyond my stock accessories' demands. All stock accessories will remain drawing from the stock battery. The new accessories will pull from the second battery. Ideally I would like enough amps to maintain both batteries. But, a slow drain of the second battery with all accessories on will be acceptable to me.

    To help a little, I've switched the headlight bulbs from 35w halogens to 20w leds (they've also roughly doubled my lighting) and will be changing the tail/brake light bulbs to leds. However, I will be adding an led light bar, as well as a fairly powerful stereo. Stereo and especially light bar choices remain dependent on available power.

    My rhino is an 06 model. Its stator produces about 320 watts at a typical driving speed. With stock lighting and accessories, it would typically be using about 60-100 watts running during daylight and 130 to 175 at night. I believe there are a couple of high output stators available in the 400-450 watt range but I'm not looking to upgrade the stator just yet.

    One of the items I have installed is a heater. It has a three speed dc fan motor. The motor is an 11a motor on high. I'm not sure how many watts it uses on low or medium. But Im assuming its 44w, 88w and 132w (but, then again, I don't understand how these things work other than that the 3 speed switch from the unit, if sold separately warns that it does not make a single speed motor have 3 speeds but requires a 3 speed motor to work). As it turns out, this fan is pretty powerful, even on low, and especially in the small confines of a rhino. In fact, about half of its air output on low would be about perfect.

    Anyway, I've noticed a number of pwm dc speed controllers on ebay and amazon. They seem reasonably priced. My question is whether, unlike a resistor, using a pwm controller to lower dc motor speed will reduce power consumption, and if so, how much?

    Rodney
     
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,771
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    I'm sure the "heating elements" require far more than the blower fan..
    I'd source a smaller heater vs messing with it.
     
  3. rodneygt

    Thread Starter New Member

    Feb 6, 2015
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    Sorry that I didn't specify. The heater itself, that is, the heat exchanger, is an automotive type heater wherein hot coolant from the engine flows during its trip to the radiator. The only electrical load is from the 12v dc fan motor.
     
  4. wayneh

    Expert

    Sep 9, 2010
    12,155
    3,061
    Slowing the fan will indeed save power more-or-less in proportion to the amount of air being moved. Make sure the device you get is generously rated. I mean, if you know you need 11A, I'd look for one rated to 20A or more and is meant for a motor. Two reasons: Motors have starting surges, and specifications tend to get exaggerated.
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,570
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    Many current 12v automotive fans use PWM control now, instead of the older series resistor control.
    They can be had for around $5.00 on ebay.
    Max.
     
  6. Wendy

    Moderator

    Mar 24, 2008
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    The owners of All About Circuits has elected not to host discussions of automotive electrical system modifications/enhancements due to safety concerns, the potential of legal ramifications and the possible circumvention of vehicle regulations at the state and federal level.

    This thread is against the AAC forum rules, Chapter 6, as seen here:

    This can be found in our Terms of Service (ToS)

    Automotive modifications of any kind are strictly forbidden. Therefore, this thread will be closed.

    Please try to understand the reasons behind this action, and feel free to browse and use the forums.

    You might find answers to your questions in one of these forums:

    http://forum.allaboutcircuits.com/showthread.php?t=54400

    Another good forum that shares many of the same membership is http://www.electro-tech-online.com/ . Good luck.
     
  7. Wendy

    Moderator

    Mar 24, 2008
    20,766
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    I was mistaken, this is an off road recreational vehicle, not a street legal car. It is a fine line, but as I understand it it passes muster.

    Sorry about that.
     
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