[NSRCA-discussion] Electric vs. Glow

[Jay Marshall]

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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