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Discussion Starter #2
Re: [EVDL] ADC 9 air flow requirements, comments.

From: Bob Rice
> All this cooling bahoura, with the 9 inch motors! My 8 years of driving
> a ADV 9" rebuilt by Warfield Electric; Never an issue with cooling! ...

If you drive with the motor at high RPM most of the time, then its internal fan does a fine job. I don't have an external blower on my EV either.

However, many first-time EVers (and even some old timers) drive as if the electric motor were an ICE -- they try to shift to keep it at low RPM. This has the consequence of making the motor draw more current, so it makes more heat. It also gets less cooling air, so it runs too hot.

Another problem occurs with direct drive EVs, where there is no transmission. Here, you can't shift to make the motor's internal fan work at low driving speeds.

Finally, some people are using undersized motor to save money, or simply for the sake of expediency.

If any of these cases apply, an external blower helps a lot!

--
"Excellence does not require perfection." -- Henry James
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart-at-earthlink.net

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Discussion Starter #3
Re: [EVDL] ADC 9 air flow requirements, comments.

Lee,

You make some good points. I'd add a couple. Like a
lot of stop and go driving. The accelerations demand
high current, but then you come to a stop. With just
the motor fan, you get heat soak and no cooling
sitting there. The external blower will continue to
cool the motor even at rest. And, perhaps the real
killer, hilly terrain. Going up hills can really heat
the motor up. And after doing a couple of hills, if
you don't have a good section of level or downhill
travel, the motor fan isn't going to do a lot for you.

I think I mentioned before, I'm a big fan of forced
ventilation. Especially now that better batteries are
becoming available. I think in a lot of cases, with
Pb-acid, by the time the motor was too hot, the
battery would be dead. Now, if you have the same
system with a battery which can run 2, 3 or 4 times
longer, maybe the motor will not survive.

Jeff M



--- Lee Hart <[email protected]> wrote:

> From: Bob Rice
> > All this cooling bahoura, with the 9 inch motors!
> My 8 years of driving
> > a ADV 9" rebuilt by Warfield Electric; Never an
> issue with cooling! ...
>
> If you drive with the motor at high RPM most of the
> time, then its internal fan does a fine job. I don't
> have an external blower on my EV either.
>
> However, many first-time EVers (and even some old
> timers) drive as if the electric motor were an ICE
> -- they try to shift to keep it at low RPM. This has
> the consequence of making the motor draw more
> current, so it makes more heat. It also gets less
> cooling air, so it runs too hot.
>
> Another problem occurs with direct drive EVs, where
> there is no transmission. Here, you can't shift to
> make the motor's internal fan work at low driving
> speeds.
>
> Finally, some people are using undersized motor to
> save money, or simply for the sake of expediency.
>
> If any of these cases apply, an external blower
> helps a lot!
>
> --
> "Excellence does not require perfection." -- Henry
> James
> --
> Lee A. Hart, 814 8th Ave N, Sartell MN 56377,
> leeahart-at-earthlink.net



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Discussion Starter #4
Re: [EVDL] ADC 9 air flow requirements, comments.

Lee;

What is the Optimal RPM for efficiency and cooling on an ADC9" ?

Dennis


-----Original Message-----
From: Lee Hart [mailto:[email protected]]
Sent: Thursday, October 11, 2007 11:01 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] ADC 9 air flow requirements, comments.

From: Bob Rice
> All this cooling bahoura, with the 9 inch motors! My 8 years of
> driving a ADV 9" rebuilt by Warfield Electric; Never an issue with
cooling! ...

If you drive with the motor at high RPM most of the time, then its
internal fan does a fine job. I don't have an external blower on my EV
either.

However, many first-time EVers (and even some old timers) drive as if
the electric motor were an ICE -- they try to shift to keep it at low
RPM. This has the consequence of making the motor draw more current, so
it makes more heat. It also gets less cooling air, so it runs too hot.

Another problem occurs with direct drive EVs, where there is no
transmission. Here, you can't shift to make the motor's internal fan
work at low driving speeds.

Finally, some people are using undersized motor to save money, or simply
for the sake of expediency.

If any of these cases apply, an external blower helps a lot!

--
"Excellence does not require perfection." -- Henry James
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart-at-earthlink.net


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http://lists.sjsu.edu/mailman/listinfo/ev
 

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Discussion Starter #6
Re: [EVDL] ADC 9 air flow requirements, comments.

Hi Storm,

That would be in your Samurai, right? With the 5
speed. Appears to me a nice conversion. Some would
use a smaller motor in that size vehicle, or the 9
inch in larger vehicle. And, selecting a gear to keep
your motor at 3/4000 rpm is a smart move. Good air
flow thru it. It would appear that your duty cycle
and method of driving does not require a blower. I'm
not saying all do. Just that if you were taking the
hill at 50 mph, your motor might heat up. Or if you
had a direct drive, then motor rpm might be too low
for good air flow. These conversion applications are
all different.

As to stop and go traffic, you're right, no heat added
when stopped. But no air flow from the shaft mounted
fan. So a blower can cool the inside of the motor
during those idle periods. It may not be a problem
for you, but might be for others. Depending on all
sorts of things. But in general, traffic jam
conditions can be tough. Low speed acceleration,
creep, stop, repeat. Maybe up some grade. Could lead
to situation where heat is not purged from the inside
of the motor.

Say your motor is rated for 200 amps. That would be
at rated voltage and speed. It could well have heat
problems at 200 amps if speed is only a few 100 rpm.
A blower will help. And the other thing the blower
does is allow you to use clean air. This can be
valuable in areas where you get a lot of salt spray or
sand from the road. Neither are good inside the
motor.

Regards,

Jeff M



--- storm connors <[email protected]> wrote:

> I live at the top of a 3 mile hill that requires 200
> amps to maintain 30
> mph. The 9 inch doesn't heat up at all. I keep it
> between 3 and 4000 RPM.
> Can't speak for lots of stop and start. But it would
> seem to me that you're
> not adding any more heat when you're stopped.
>
> On 10/11/07, Jeff Major <[email protected]> wrote:
> >
> >
> > Lee,
> >
> > You make some good points. I'd add a couple.
> Like a
> > lot of stop and go driving. The accelerations
> demand
> > high current, but then you come to a stop. With
> just
> > the motor fan, you get heat soak and no cooling
> > sitting there. The external blower will continue
> to
> > cool the motor even at rest. And, perhaps the
> real
> > killer, hilly terrain. Going up hills can really
> heat
> > the motor up. And after doing a couple of hills,
> if
> > you don't have a good section of level or downhill
> > travel, the motor fan isn't going to do a lot for
> you.
> >
> > I think I mentioned before, I'm a big fan of
> forced
> > ventilation. Especially now that better batteries
> are
> > becoming available. I think in a lot of cases,
> with
> > Pb-acid, by the time the motor was too hot, the
> > battery would be dead. Now, if you have the same
> > system with a battery which can run 2, 3 or 4
> times
> > longer, maybe the motor will not survive.
> >
> > Jeff M
> >
> >
> >
> > --- Lee Hart <[email protected]> wrote:
> >
> > > From: Bob Rice
> > > > All this cooling bahoura, with the 9 inch
> motors!
> > > My 8 years of driving
> > > > a ADV 9" rebuilt by Warfield Electric; Never
> an
> > > issue with cooling! ...
> > >
> > > If you drive with the motor at high RPM most of
> the
> > > time, then its internal fan does a fine job. I
> don't
> > > have an external blower on my EV either.
> > >
> > > However, many first-time EVers (and even some
> old
> > > timers) drive as if the electric motor were an
> ICE
> > > -- they try to shift to keep it at low RPM. This
> has
> > > the consequence of making the motor draw more
> > > current, so it makes more heat. It also gets
> less
> > > cooling air, so it runs too hot.
> > >
> > > Another problem occurs with direct drive EVs,
> where
> > > there is no transmission. Here, you can't shift
> to
> > > make the motor's internal fan work at low
> driving
> > > speeds.
> > >
> > > Finally, some people are using undersized motor
> to
> > > save money, or simply for the sake of
> expediency.
> > >
> > > If any of these cases apply, an external blower
> > > helps a lot!
> > >
> > > --
> > > "Excellence does not require perfection." --
> Henry
> > > James
> > > --
> > > Lee A. Hart, 814 8th Ave N, Sartell MN 56377,
> > > leeahart-at-earthlink.net
> >



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