Re: this regen thing again

["Joe Smalley" <joes@worldfront.com>]

The alternator on the driveline works because the cars are at 200 mph. I
doubt the handling of a Mighty Max to go that speed safely. To make it work
at street legal speeds would require a substantial RPM increase in the
mechanical coupling to that alternator or else an alternator that operates
at a much lower RPM.

To engineer this mechanism, You need to estimate the amount of power you
want to dissipate. Units are not really relevant. You could use something
like "4000 pounds at 25 MPH on a 5% grade." This specification can be
converted to an electrical specification like "XXXX watts at YYYYY RPM" for
the application at the driveline. If you are using a gearbox, a gear ratio
would need to be applied. Once you have this specification, you can start
looking for an alternator to do the task.

Engineering opinion hat on:
I doubt you will find anything to produce that much drag less than 100
pounds without raising the RPM thorough a gearbox. The gearbox will probably
be almost the size of the alternator.

The Kostov will generate as much drag is it will produce propulsion. It
already has a substantial gearbox attached. You could use the existing
components and not have to add anything mechanical.

As someone pointed out, you will need to watch the cooling on the motor.
Sizing of an external fan may need to be recalculated. Normally, the motor
cools while going down hill. With regen, it does not. Some may argue that
the highest heat load is going uphill. Going downhill, the PWM feeding the
field may generate more current that what is used going uphill, adding to
the heat load of the armature from the regen current. Extremely high field
currents are necessary to regen at very low RPM. This is where the internal
cooling fan circulates the least air and the motor generates the most heat.

Joe Smalley
joes@worldfront.com


-----Original Message-----
From: Mike Chancey <evtinker@hotmail.com>
To: ev@listproc.sjsu.edu <ev@listproc.sjsu.edu>
Date: Saturday, January 30, 1999 1:22 PM
Subject: Re: this regen thing again


>>Date: Fri, 29 Jan 1999 23:37:07 -0700
>>From: "steve.richardson" <steve.richardson@cwix.com>
>
>>I guess a lot of people missed part of my original post on regen.  I
>can't
>>add a alternator, dynamic brake and any other motor or drive shaft
>attached
>>device because I simply do not have the room.  I
>
>Hi Steve,
>
>Here is another idea.  Have you ever seen where NASCAR stockcars
>sometimes mount an alternator?  On the rear axle! They drive it off a
>pulley mounted on the input flange behind the rear driveshaft u-joint.
>I don't know if they still do this, but it is an idea.  Another
>possibility would be the same thing only on the output flange of the
>transmission, or perhaps on the center carrier bearing if your truck has
>one.  A bit funky perhaps, but with a proper splash guard it could work.
>AS I understand it, your more interested in reducing the load on the
>brakes than recovering energy.  Perhaps a setup such as this discharging
>into a resistor grid under the rear of the truck or perhaps behind the
>grill would work for you.
>
>Comments anyone?
>
>Thanks,
>
>
>Mike Chancey
>evtinker@hotmail.com
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>
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