[NSRCA-discussion] Electric vs. Glow

[Bob Richards]

I agree, the more current flow the more of a load. I know about shorting the motor terminals, but if there is a perfect short between the motor terminals, where is the "load".  A perfect short will not have any voltage across it, so no power dissipated external to the motor.
   
  Bob R.
   

Jay Marshall <lightfoot at sc.rr.com> wrote:
        
            No, a load implies that there is current flowing, which produces heat. Unless the current is flowing back to the battery there is no load. Try this: take a small DC electric motor and spin the armature, then short out the power terminals and try to spin it. The latter is maximum load and the difference is dramatic.
   
  -----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Bob Richards
Sent: Sunday, February 19, 2006 9:29 AM
To: NSRCA Mailing List
Subject: Re: [NSRCA-discussion] Electric vs. Glow
   
    Maybe I'm not understanding what you are saying. Regenerative braking would cause less downline braking than a freewheeling motor?

     

    If you are comparing regenerative braking with non-regenerative braking, I would think the motor would heat less, since with non-regenerative braking the motor windings ARE the load, are they not?

     

    Bob R.

    

Ed Alt <ed_alt at hotmail.com> wrote:

      Also, though it's a great thing if it can be implemented well, regenerative braking will contribute to heating of the motor and it may actually reduce the downline braking effect somewhat.  If you don't dissipate the energy into a load, the motor will spin at a higher RPM while windmilling, effectively incr! easing the disc area and allowing it to cool a little bit on downlines.  Re heating, when a load is applied (the battery under charge in  this case), the voltage generated by the motor windings now results in a fairly significant current flow (no, or very little flow happens without the charge path closed).  This will result in electrical power being dissipated in the windings, therefore heating will occur on a downline, not cooling.  Also, since the battery is already running warm, it may not be very good for it to get these brief and relatively large charging currents.  Not sure how bad that effect may be, but it's got to get evaluated by a battey expert.  Sure would be
 good to solve the problem and keep everything within safe parameters though.

     

    Ed

     

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