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Re: [EVDL] Gizmo EV "gearing"

Hi David,

You know, the 3 to 1 ratio doesn't sound right to me.
Yes, counting teeth on the cogs should give you the
ratio. Double check with the pitch diameters. Is it
really 3 to 1? Were all Gizmos built with a 3 to 1?
Or is yours some type of experiment? Mark said his
was a 6 to 1. That sounds more reasonable. Can you
get the 6 to 1 cogs from Gizmo? Are they still in
business? And if you do, are you able to change the
settings in the Sevcon?

Jeff M

--- "David D. Nelson" <[email protected]> wrote:

> Thanks Cor,
>
> I wondered about that but after talking to D&D
> motors
> a few minutes ago I don't think I'll hit that hard
> max
> RPM. The guy I talked to said there shouldn't be a
> hard max rpm, but then he didn't think I had a 3:1
> gear ratio either. He didn't like my 30T drive gear
> to
> 90T wheel gear way of determining ratio. I told him
> it
> shouldn't matter since the same cogged belt had to
> match up on both gears so the tooth pitch had better
> be the same. Any way, he said that I should be
> getting
> to 4600rpm and 7ft-lbs of torque at the top end at
> 48V.
>
> Below is the response I received from Mark Murphy,
> after reading his reply I'm wondering if I should
> add
> one more 8V battery and see what happens. It looks
> like the controller can be set to accept a slightly
> higher voltage but I may be asking for trouble if I
> do. The maximum cutout _low_ voltage setting is 48V
> and the maximum cutoff _high_ voltage setting is
> 75V.
> Maybe if my DC-DC converter will handle 56V input it
> would be worth a try. Any ideas?
>
>
> --- Mark Murphy <[email protected]> wrote:
>
> > From: Mark Murphy <[email protected]>
> > Subject: Re: Gizmo EV "gearing"
> > Date: Mon, 27 Aug 2007 22:16:42 -0700
> > To: "David D. Nelson" <[email protected]>
> >
> > Hi David,
> > With the BugE we use a 5.5 ADC series wound motor
> > with a 6-1 gear ratio
> > ( on a 20" diameter wheel) My Gizmo is similarly
> > geared using a ADC
> > 6".6 series wound motor.
> > Both are 48 volt.
> >
> > My experience is that you need a 24 volt rated
> > series wound motor but
> > run it on 48 volts.
> > I don't think you need a larger motor,, you may
> need
> > lower gearing and
> > higher RPM.
> > if your motor is rated at 48 volts, run it at 72,
> > but don't increase
> > the weight of the battery pack.
> >
> > You can always install a fan for the motor.
> >
> > Belts are quiet, but usually require a lot of belt
> > tension and pressure
> > on the wheel and motor bearings. A chain is noisy
> > but is low drag.
> >
> <<<<<snip>>>>>
> ==========end of quote==========
>
> --- Cor van de Water <[email protected]> wrote:
>
> > Since the motor is SepEx, it will have a hard max
> > RPM limit
> > which depends on voltage.
> > You can easily use a larger gear ratio to reduce
> the
> > torque
> > (and thus amps) that the motor needs to sustain,
> but
> > the
> > drawback is that you have to increase the voltage
> to
> > reach
> > the same max speed, or accept that your max may
> drop
> > well below
> > 40, likely even below 35.
> > This can also be solved by rewinding the motor and
> > keeping
> > the same pack voltage - the choice is yours.
> >
> > Success,
> >
> > Cor van de Water
> > -----Original Message-----
> > David D. Nelson
> > Sent: Monday, August 27, 2007 3:08 PM
> > To: Electric Vehicle Discussion List
> > Subject: Re: [EVDL] Gizmo EV "gearing"
> >
> > Thank you for all the ideas coming in on this.
> >
> > I just sent Mark Murphy an email so I report back
> > what I hear from him. I have thought for a while
> > that I needed to figure out a way to do some
> forced
> > cooling.
> > I am pushing this motor to its max when I climb.
> The
> > brushes showed evidence of arcing from the brush
> > holder to the sides of the brush. I don't know if
> > this happens only when the motor is hot (higher
> > resistance) or at any time. The armature current
> > routinely goes over 300amps during my hill climb.
> >
> > David
> >
> > --- keith vansickle <[email protected]>
> > wrote:
> >
> > > david
> > > have you emailed Mark Murphy at Blue sky design
> he
> > is in creswell
> > > oregon and originally built these veh kEVs
> > >
> > > --- Jeff Major <[email protected]> wrote:
> > >
> > > >
> > > > Hi David,
> > > >
> > > > You might want to consider forced ventilation
> on
> > > the
> > > > motor. Sounds like your performance is O.K.
> > Just that your duty
> > > > cycle is too hard.
> > > >
> > > > Increasing the gear ratio will lower the load
> on
> > > the
> > > > motor and slow down the top speed of the
> > vehicle.
> > > > That would likely make the motor run cooler,
> but
> > take you longer to
> > > > get where you're going. I'd try keeping the
> > same ratio and blowing
> > > > a lot of clean air thru the motor.
> > > >
> > > > Regarding the larger motor, you'd probably
> have
> > to retune the
> > > > controller.
> > > >
> > > > Jeff M
> > > > > > --- "David D. Nelson" <[email protected]>
> wrote:
> > > >
> > > > > Hi all,
> > > > >
> > > > > I have a Gizmo EV (www.nevco-ev.com) which
> has
> > a
> > > > 48V
> > > > > pack and a 6.7" D&D Separately Excited
> Motor.
> > I
> > > > have
> > > > > run it for a year but the hill climbing I
> have
> > > to
> > > > do
> > > > > has started to burn up the motor. Jim H has
> it
> > > > right
> > > > > now to rebuild/repair. We had been
> considering
> > installing a 7.5"
> > > > > motor to see if it would
> > > handle
> > > > > the
> > > > > workout I give it a little better.
>
=== message truncated ===




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