# [EVDL] motor heat and rpm



## EVDL List (Jul 27, 2007)

We have the motor rpm set for 5,000RPM on the 9" net gain in the car
I'm working on and to me this seem low. My customer and been through
the ringer with this conversion , He's paid good money , and I feel a
lot better about the car now than when I got here but still I'm not
happy with a lot of things . A lot of gear shifting when you drive .
In Florida it is so flat that the motor don't get the work out like
here . I see 15 to 25 kw being used to go a steady 55. And he drives
100 miles a day or more so this motor is getting a work out . I've
explained about how as RPM goes down UP goes motor amps and motor
heat. I'd like to set the RPM as high as possible so he can cruise
in a lower gear and not over heat the motor . Today I had a lunch
appointment with him in town 30 miles away . I had exactly 30 min to
get to the appointment so would have to drive like a race car driver
but as everyone out here drives that way.... I was going at it .
Pushing hard at 60 65 mph I probably was driving about the way he does
all the time . Ate up about 6kwh of power by the time I got back (
didn't make the lunch .. I forgot to put the fresh produce away ) . I
felt the motor and as Scotty would say on star trek " I don't know
how much she can take captain" . The motor was almost to hot to keep
your hand on ,,, we need a motor temp sensor . Maybe its just me,
but my motor pulling my lawn trailer never got that hot ... It didn't
feel like the rpm was that high . I'm almost feeling like we need a
blower on it . It is very hot out side . With a 40 kwh Li-ion pack ,
1k soliton controller we can put some power down and for some time ..
I would Iike to make this EV dependable but I see a potential problem
. The car may be heavier that I think as it rides nice but sure is not
a neck snapper. Got motor amps turned up all the way just to get safe
pick up , Pack voltage is low 160 approx . My 2nd ev with a 500 amp
zappi controller and 20 golf cart bats seemed pepper . Motor may have
been cooked ( don't really think so) or maybe I just reved my old guy
higher as I used 2 gear almost all the time cruising 65 mph ( foot
full to the floor) good old Bob Rice days .

Steve Clunn
-- 
Tomorrows Ride TODAY !
Visit our shop web page at: www.Greenshedconversions.com

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## EVDL List (Jul 27, 2007)

Hi steve,

That sounds similar to my situation. After driving my 9" DC (with 1000amp Warp Drive controller, limited at 700 amps) for 30-45 minutes, and going up a large hill, the motor will be too hot to touch for more than a brief moment. With an IR temp sensor, I think it was 80C or 90C on really hot days. That seems within the parameters of the motor's temperature limits. 

The only alternative is a blower to keep it cool. 

corbin
http://www.corbinstreehouse.com (for car info)



> Steve Clunn wrote:
> 
> > We have the motor rpm set for 5,000RPM on the 9" net gain in the car
> > I'm working on and to me this seem low. My customer and been through
> ...


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## EVDL List (Jul 27, 2007)

The typical ICE driver will shift to the highest gear possible for 
the road speed, resulting in the lowest motor RPM. It is tough to 
break that habit and do the exact opposite when you drive a 
conversion EV with a gear shift. However, that is what you need to do 
to get the lowest motor heating and the best efficiency.

What also makes it counterintuitive is that running at high RPM in a 
lower gear often requires that you depress the throttle pedal more. 
(Depends on the throttle programming of course, but that is typical.) 
The more depressed pedal makes it "feel" like you are using more 
energy, but the inverse is true.

Calculate the maximum speed you can go in each gear. Go very close to 
that speed in each gear. Then check the motor temp after the trip. 
You probably never want to go past 3rd gear. You may occasionally use 
4th, but just to pass.

Bill D.

At 10:25 AM 6/21/2011, you wrote:
>Hi steve,
>
>That sounds similar to my situation. After driving my 9" DC (with 
>1000amp Warp Drive controller, limited at 700 amps) for 30-45 
>minutes, and going up a large hill, the motor will be too hot to 
>touch for more than a brief moment. With an IR temp sensor, I think 
>it was 80C or 90C on really hot days. That seems within the 
>parameters of the motor's temperature limits.
>
>The only alternative is a blower to keep it cool.
>
>corbin
>http://www.corbinstreehouse.com (for car info)
>
>


> Steve Clunn wrote:
> >
> > > We have the motor rpm set for 5,000RPM on the 9" net gain in the car
> > > I'm working on and to me this seem low. My customer and been through
> ...


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## EVDL List (Jul 27, 2007)

Wow. I've been concerned about my motor ending a 45 minute trip around
120F or about 50C (with an IR temp sensor also). However, I haven't
measured it on a hot day yet. I'm looking into some ducting to force more
air into my motor before the hot weather shows up big time. My motor is
mounted behind the air shadow of the batteries. I'm going to run some
ducting from the front of the car next to the batteries to the motor intake.
I'm hoping that will keep me in the same range in the summer. 

Also a 9" DC motor, but an ADC and with a lower-power controller.

Mike

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of corbin dunn
> Sent: Tuesday, June 21, 2011 10:26 AM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] motor heat and rpm
> 
> Hi steve,
> 
> That sounds similar to my situation. After driving my 9" DC (with 1000amp
> Warp Drive controller, limited at 700 amps) for 30-45 minutes, and going
up a
> large hill, the motor will be too hot to touch for more than a brief
moment.
> With an IR temp sensor, I think it was 80C or 90C on really hot days. That
> seems within the parameters of the motor's temperature limits.
> 
> The only alternative is a blower to keep it cool.
> 
> corbin
> http://www.corbinstreehouse.com (for car info)
> 

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## EVDL List (Jul 27, 2007)

> Hi Steve,
>
> I don't follow you about the comment "seems low". 5000 RPM sounds like a
reasonable upper limit for RPM on a 9 inch diameter motor. Iam comparing it
with outer EV's.and this is only the 2nd one with a tack. the first

May be the tranny gearing . Most stuff I do will go 50 or 60 in 2nd gear and
maybe all these years I've been running on the hi side of the rpm. This car
needs to be shifted from 2 to 4th for over 60 .

> It should give you headroom up to 6kRPM for unintentional overspeed
without damage.

Makes sense .

>
> Too hot to touch on the motor frame is not an indication of motor
overheat.

I'm just comparing it to other cars I've done . This is a different world
i'M in (Taxes) With lots of hills and fast drivers ..


Of course, cooler is better. But a class H insulated motor can have a
frame temperature of 100 degrees C and still be well within temperature
limits (180 dC) inside.
>

very hot here
> I have had a suspicion that folks may run into motor heat problems with
the introduction of these higher energy Lithium batteries (compared to
PbAcid). With the old batteries, in normal driving, and maybe even hard
driving, by the time the motor heated up, the battery charge would be
depleted, and you'd have a lengthy charge period for the motor to cool off.
Now, with these new batteries, you can work the motor 2 or 3 times longer.
>

Very true and with a 41kwh pack it weighs almost as much a 20 golf cart bats
. And lots of hills


> I have always supported the use of an ammeter in the motor circuit.

I put on on Audrey's green bean and was VEARY supprized at how hi the motor
current was . The soliton Jr puts out 500 motor amp quite often ,I've seen
it with 40 battery amps Did you see your controller at the IRCC car show
Video pleas Audrey nice bling

> you can judge this with a tach for motor RPM. But motor current is best.

maybe I will get to put a motor amp meter ,,, If I have time

>
, so the heating stops, but so does the ventilation, so you get a heat soak.


ya we got heat soak here ,
>
> That's why I like forced ventilation.
>
> Jeff M
Thanks Jeff M
stEVe Clunn
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## EVDL List (Jul 27, 2007)

Has anyone tried a passive heatsink on the motor? (if so...do you have any pictures?) I used to use those on my old RC cars, and I'm wondering if it would work on the car's motor.

corbin



> Steve Clunn wrote:
> 
> >> Hi Steve,
> >>
> ...


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## EVDL List (Jul 27, 2007)

Hi Corbin,

Why would you do this on an EV?
For RC the size of the motor may be such
that it is hard to implement a blower, but
for EV size motors it is actually one of
the better ways to avoid a motor is heating up
by removing the heat from the *inside*, where 
the it is actually the brushes and windings that
are heating which get cooled by forcing air
through the inside of the motor, instead of
letting all heat accumulate and slowly seep out
through the case and only after the heat has
found a way out, remove it more efficiently.
Better to attack it at the root than at the
leaves and twigs...

Note that if your motor still has its internal fan,
then you best force air through the motor in the
same direction as the fan is blowing. This will
avoid a situation where they are cancelling and
it will improve cooling at low RPM.


Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water XoIP: +31877841130
Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203 

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of corbin dunn
Sent: Wednesday, June 22, 2011 3:13 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] motor heat and rpm

Has anyone tried a passive heatsink on the motor? (if so...do you have
any pictures?) I used to use those on my old RC cars, and I'm wondering
if it would work on the car's motor.

corbin



> Steve Clunn wrote:
> 
> >> Hi Steve,
> >>
> ...


----------



## EVDL List (Jul 27, 2007)

Hi Corbin,

My motor (the AC24) has passive cooling fins. And I *know* you've read 
my blog and my issues with overtemp. 

Only thing left to do is to add a water spritzer to the fan - 
fortunately, that sort of thing would work great down here in San Diego.

Cheers,
Peter

On 6/22/2011 3:13 PM, corbin dunn wrote:
> Has anyone tried a passive heatsink on the motor? (if so...do you have any pictures?) I used to use those on my old RC cars, and I'm wondering if it would work on the car's motor.
>
> corbin
>
>


> Steve Clunn wrote:
> >
> >>> Hi Steve,
> >>>
> ...


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## EVDL List (Jul 27, 2007)

Hi Cor,
Two reasons I thought it might be nice to make it passive:
1. A blower takes energy
2. It's noisy 

I think my temperature, while high, is within the limits, so I haven't done anything to make it cooler yet. If I end up buying a new motor in a year..then I'll change my tune 

corbin



> Cor van de Water wrote:
> 
> > Hi Corbin,
> >
> ...


----------



## EVDL List (Jul 27, 2007)

Hi Corbin,

*Good* fans/blowers can be very silent but it depends on
the designer going the extra mile of designing the shape
of the blades and the air path such as not to create the
usual annoying noise you hear of many fans.
I even disabled the fan in my EV because it was sized to
allow cooling a 100+kW waste heat blowing air through an
ICE-sized radiator (the original from the 4-banger that
the S10 was designed for) and even after disabling the
fan (cutting my EV noise by more than 10 dB!!!) I have
never seen the coolant temp rise more than 5 deg during
my commute. (This was a water-cooled AC system).

I would not expect the motor blower to consume more than
about 100 Watt (probably rated for 10 Amp at 12V) so even
if you drive your EV for an hour long, it would amount
to about 0.3 mi less range, but the lower temp and thus
lower resistance of the motor windings may actually 
improve the motor efficiency to the point that the 
addition of the blower has a net
positive effect on range!
It definitely will have a positive effect on motor life.

Regards,

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water XoIP: +31877841130
Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203 

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of corbin dunn
Sent: Wednesday, June 22, 2011 4:13 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] motor heat and rpm

Hi Cor,
Two reasons I thought it might be nice to make it passive:
1. A blower takes energy
2. It's noisy 

I think my temperature, while high, is within the limits, so I haven't
done anything to make it cooler yet. If I end up buying a new motor in a
year..then I'll change my tune 

corbin



> Cor van de Water wrote:
> 
> > Hi Corbin,
> >
> ...


----------



## EVDL List (Jul 27, 2007)

I would like to know a little more about proper design for a cooling 
blower on a 7 1/4 inch Prestolite motor. When it's 110 in Las Vegas the 
ambient air has very little cooling effect on anything and blowing air 
that hot thru a motor might cool it off but not by much!

Lloyd Wayne Reece
1981 Lectra Centauri
Las Vegas, Nevada

On 6/22/2011 4:02 PM, Peter C. Thompson wrote:
> Hi Corbin,
>
> My motor (the AC24) has passive cooling fins. And I *know* you've read
> my blog and my issues with overtemp. 
>
> Only thing left to do is to add a water spritzer to the fan -
> fortunately, that sort of thing would work great down here in San Diego.
>
> Cheers,
> Peter
>
> On 6/22/2011 3:13 PM, corbin dunn wrote:
>> Has anyone tried a passive heatsink on the motor? (if so...do you have any pictures?) I used to use those on my old RC cars, and I'm wondering if it would work on the car's motor.
>>
>> corbin
>>
>>


> Steve Clunn wrote:
> >>
> >>>> Hi Steve,
> >>>>
> ...


----------



## EVDL List (Jul 27, 2007)

Of course it will cool.
When ambient is 110 and your motor 200 then it is the same
90 degrees that you may be able to bring down to say only
30 deg difference, so the motor stays at a more healty 140,
as when it is 40 deg outside and your motor runs at 130, again
which can be brought down to say 30 deg difference for a cool
70 deg motor temp with the blower running at ambient 40.
The cooling effect will be the same, even though the absolute
numbers can shift up and down with the ambient temp....


Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water XoIP: +31877841130
Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203 

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Lloyd Wayne Reece
Sent: Wednesday, June 22, 2011 9:46 PM
To: [email protected]
Subject: Re: [EVDL] motor heat and rpm

I would like to know a little more about proper design for a cooling
blower on a 7 1/4 inch Prestolite motor. When it's 110 in Las Vegas the
ambient air has very little cooling effect on anything and blowing air
that hot thru a motor might cool it off but not by much!

Lloyd Wayne Reece
1981 Lectra Centauri
Las Vegas, Nevada

On 6/22/2011 4:02 PM, Peter C. Thompson wrote:
> Hi Corbin,
>
> My motor (the AC24) has passive cooling fins. And I *know* you've 
> read my blog and my issues with overtemp. 
>
> Only thing left to do is to add a water spritzer to the fan - 
> fortunately, that sort of thing would work great down here in San
Diego.
>
> Cheers,
> Peter
>
> On 6/22/2011 3:13 PM, corbin dunn wrote:
>> Has anyone tried a passive heatsink on the motor? (if so...do you
have any pictures?) I used to use those on my old RC cars, and I'm
wondering if it would work on the car's motor.
>>
>> corbin
>>
>>


> Steve Clunn wrote:
> >>
> >>>> Hi Steve,
> >>>>
> ...


----------



## EVDL List (Jul 27, 2007)

I remember being at a cafe in Palm Desert, CA when it was very hot.
I'm a Yankee and I notice the heat, dry or not. The common solution
was the use of those misters that would produce a gentle plume of mist
that settled on you and cool you off. It wasn't enough to get anything
wet, yet the evaporation was very affective. If you have a forced air
cooling system in your car, how about adding a mist feature. It
wouldn't be enough to cause problems, yet it might help lower the
motor temp in extreme conditions? And doesn't a little humidity help
give your commutator that nice brown patina? Just a thought.

DAC



> Cor van de Water <[email protected]> wrote:
> > Of course it will cool.
> > When ambient is 110 and your motor 200 then it is the same
> > 90 degrees that you may be able to bring down to say only
> ...


----------



## EVDL List (Jul 27, 2007)

Also important to note is that the hotter your motor, the more cooling forced
air will provide due to the larger temp difference.

I just added forced air to mine, and driving in 2nd would normally cause
temps up to 220 F and with cooling it was just under 200 F which was
disappointing, but driving in 3rd would normally cause temps up to 300 F and
with cooling is just over 200 F.

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