Motor Overheat (additional info)

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Motor Overheat (additional info)

Tom Keenan
For a few months, I have been troubleshooting an ongoing motor overheat problem in the Citicar. Since I had done a number of changes around the time it started to overheat while driving, I went back to version 1.0 to test how it compared.  The results were rather inconclusive.

for reference, about a year ago I tested the range remaining on my aging lead acid battery pack, and noted that the motor heated up at about 7 degrees F for every mile driven.  This is with a stock 48v traction pack.  The motor is modified slightly to advance the brushes about 5 degrees.  Since the motor is rated at Class F, it should be able to operate at up to 260F.  At 7 degrees rise per mile, I should be able to go about 27 miles without overheating - about the range of the Citicar.  Indeed, I have driven a couple of 20 mile drives in the past, and not overheated the motor.

Back to the present:  This afternoon, the motor heated to 204F after nine miles of driving - a rise of about 14F per mile.  This is with the same motor (5 degrees advance), but operating at 64v.  

Before we blame it on the slightly higher voltage, I tested the Citicar a week or so ago with a stock motor (zero advance) and 48v.  The stock motor was a bit cooler at 12.6 degrees rise per mile.  The difference is slight, and may have been simply driving style.  Both motors are GE series wound 6.8".

I've tested with various permutations of advance, pack voltage, brush styles (single-carbon stock, Helwig Carbon Red Top) different motors, different gear oils, different motor shaft seals, higher and lower brush spring tension - Just about everything I can think of.  Regardless of combination, the rise per mile is still from 12.5 to 14.1 - It has not even tried to run as cool as it used to.

Watt-hours per mile is still about what it always has been - roughly 240 wh/mi measured at the wall outlet, so it doesn't seem like anything mechanical is dragging.

The main source of heat seems to be at the brush end - on any of the motor configurations I've tested.

Could there be some esoteric problem with the controller (it is an Alltrax 7245)?  Could the brush holder be offset incorrectly compared to the commutator? (would .010" to .030" make a difference?)  Something obvious I am missing?  (Citicar jokes aside...)

Thanks in advance for any hints/suggestions...

Tom Keenan

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Re: Motor Overheat (additional info)

Cor van de Water
Is there air being blown through the motor?
Is the blower still working at the same capacity?
What is the terrain and speed you are driving,
did that change from the original tests you did?


Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [hidden email]    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: [hidden email] [mailto:[hidden email]] On
Behalf Of Tom Keenan
Sent: Tuesday, May 08, 2012 8:26 PM
To: EVDL
Subject: [EVDL] Motor Overheat (additional info)

For a few months, I have been troubleshooting an ongoing motor overheat
problem in the Citicar. Since I had done a number of changes around the
time it started to overheat while driving, I went back to version 1.0 to
test how it compared.  The results were rather inconclusive.

for reference, about a year ago I tested the range remaining on my aging
lead acid battery pack, and noted that the motor heated up at about 7
degrees F for every mile driven.  This is with a stock 48v traction
pack.  The motor is modified slightly to advance the brushes about 5
degrees.  Since the motor is rated at Class F, it should be able to
operate at up to 260F.  At 7 degrees rise per mile, I should be able to
go about 27 miles without overheating - about the range of the Citicar.
Indeed, I have driven a couple of 20 mile drives in the past, and not
overheated the motor.

Back to the present:  This afternoon, the motor heated to 204F after
nine miles of driving - a rise of about 14F per mile.  This is with the
same motor (5 degrees advance), but operating at 64v.  

Before we blame it on the slightly higher voltage, I tested the Citicar
a week or so ago with a stock motor (zero advance) and 48v.  The stock
motor was a bit cooler at 12.6 degrees rise per mile.  The difference is
slight, and may have been simply driving style.  Both motors are GE
series wound 6.8".

I've tested with various permutations of advance, pack voltage, brush
styles (single-carbon stock, Helwig Carbon Red Top) different motors,
different gear oils, different motor shaft seals, higher and lower brush
spring tension - Just about everything I can think of.  Regardless of
combination, the rise per mile is still from 12.5 to 14.1 - It has not
even tried to run as cool as it used to.

Watt-hours per mile is still about what it always has been - roughly 240
wh/mi measured at the wall outlet, so it doesn't seem like anything
mechanical is dragging.

The main source of heat seems to be at the brush end - on any of the
motor configurations I've tested.

Could there be some esoteric problem with the controller (it is an
Alltrax 7245)?  Could the brush holder be offset incorrectly compared to
the commutator? (would .010" to .030" make a difference?)  Something
obvious I am missing?  (Citicar jokes aside...)

Thanks in advance for any hints/suggestions...

Tom Keenan

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Re: Motor Overheat (additional info)

Mike Nickerson
Was there a significant difference in ambient temperature between the two
runs?  That can make quite a difference for an air-cooled motor.

Also, for a fixed resistance, power goes up as the square of the voltage.
However, I would expect you to see that difference in your Wh/mile.  Your
pack voltage is now 33% higher, so any resistive losses could be 77% higher.

Mike

> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On
> Behalf Of Cor van de Water
> Sent: Wednesday, May 09, 2012 12:33 AM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] Motor Overheat (additional info)
>
> Is there air being blown through the motor?
> Is the blower still working at the same capacity?
> What is the terrain and speed you are driving, did that change from the
> original tests you did?
>
>


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Re: Motor Overheat (additional info)

Cor van de Water
If the driving speed was the same then the motor voltage and current
should have been the same, independent from pack voltage....


Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [hidden email]    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: [hidden email] [mailto:[hidden email]] On
Behalf Of Mike Nickerson
Sent: Wednesday, May 09, 2012 12:35 AM
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] Motor Overheat (additional info)

Was there a significant difference in ambient temperature between the
two runs?  That can make quite a difference for an air-cooled motor.

Also, for a fixed resistance, power goes up as the square of the
voltage.
However, I would expect you to see that difference in your Wh/mile.
Your pack voltage is now 33% higher, so any resistive losses could be
77% higher.

Mike

> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On
> Behalf Of Cor van de Water
> Sent: Wednesday, May 09, 2012 12:33 AM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] Motor Overheat (additional info)
>
> Is there air being blown through the motor?
> Is the blower still working at the same capacity?
> What is the terrain and speed you are driving, did that change from
> the original tests you did?
>
>


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Re: Motor Overheat (additional info)

Voltswagon
In reply to this post by Tom Keenan
Tom Keenan wrote
For a few months, I have been troubleshooting an ongoing motor overheat problem
So...around since winter ended?  I've noticed mine getting toastier lately, may need to hook the forced air blower back on even though I'm only using 2nd.
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Re: Motor Overheat (additional info)

Tom Keenan
It doesn't appear to be voltage or ambient temp related.  For several years,
I drove it as a 48v car and did not have an issue with overheating, no
matter the ambient temp.  To check if it was a voltage problem, I went back
to the 48v setup, and still have an overheat problem - it does heat up a
little more slowly compared to 64v, but not much.

The motor is not ventilated (never has been...)  

Tom Keenan

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf
Of Voltswagon
Sent: Wednesday, May 09, 2012 3:36 AM
To: [hidden email]
Subject: Re: [EVDL] Motor Overheat (additional info)


Tom Keenan wrote
>
> For a few months, I have been troubleshooting an ongoing motor
> overheat problem

So...around since winter ended?  I've noticed mine getting toastier lately,
may need to hook the forced air blower back on even though I'm only using
2nd.

--

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Re: Motor Overheat (additional info)

Cor van de Water
If the setup is the same as before (no fan)
and you use approx the same amount of energy
(so it is not something dragging causing higher
current through the motor) and there are not
other obvious things like change of timing of
the brushes or some other change to the motor,
the only other thing I can think of is the
airflow - did you change the way air is flowing
over the motor or add a bellypan/splash shield
that may cause the air around the motor to stall
and remove cooling from the motor?

It sounds like you *need* to add a fan to that motor now!

Regards,

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [hidden email]    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: [hidden email] [mailto:[hidden email]] On
Behalf Of Tom Keenan
Sent: Wednesday, May 09, 2012 5:17 AM
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] Motor Overheat (additional info)

It doesn't appear to be voltage or ambient temp related.  For several
years, I drove it as a 48v car and did not have an issue with
overheating, no matter the ambient temp.  To check if it was a voltage
problem, I went back to the 48v setup, and still have an overheat
problem - it does heat up a little more slowly compared to 64v, but not
much.

The motor is not ventilated (never has been...)  

Tom Keenan

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On
Behalf Of Voltswagon
Sent: Wednesday, May 09, 2012 3:36 AM
To: [hidden email]
Subject: Re: [EVDL] Motor Overheat (additional info)


Tom Keenan wrote
>
> For a few months, I have been troubleshooting an ongoing motor
> overheat problem

So...around since winter ended?  I've noticed mine getting toastier
lately, may need to hook the forced air blower back on even though I'm
only using 2nd.

--

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Re: Motor Overheat (additional info)

Ken Fry
In reply to this post by Tom Keenan
By swapping motors, you've eliminated the motor from contention.  If the watthours/mile figure remains the same, then the only remaining variables seem to be ambient air temperature and airflow around the motor.  

Is the terrain identical?  The rate of heating goes up quickly with higher amperage, so you could (possibly) have a similar average Wh/mile figure but increased heating from hills, with the temperature not able to fall off between hills.  

I can't think of anything in the controller that would cause this in a series motor.

Hot to the touch after only 4 miles is way too hot.



 
Think Big.
Drive Small.  
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Re: Motor Overheat (additional info)

Mark Grasser
In reply to this post by Cor van de Water
Airflow could even be changed dramatically by raising or lowering the
suspension at one end of the car or both.


Sincerely,
Mark Grasser
 

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf
Of Cor van de Water
Sent: Wednesday, May 09, 2012 12:16 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Motor Overheat (additional info)

If the setup is the same as before (no fan) and you use approx the same
amount of energy (so it is not something dragging causing higher current
through the motor) and there are not other obvious things like change of
timing of the brushes or some other change to the motor, the only other
thing I can think of is the airflow - did you change the way air is flowing
over the motor or add a bellypan/splash shield that may cause the air around
the motor to stall and remove cooling from the motor?

It sounds like you *need* to add a fan to that motor now!

Regards,

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [hidden email]    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: [hidden email] [mailto:[hidden email]] On Behalf
Of Tom Keenan
Sent: Wednesday, May 09, 2012 5:17 AM
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] Motor Overheat (additional info)

It doesn't appear to be voltage or ambient temp related.  For several years,
I drove it as a 48v car and did not have an issue with overheating, no
matter the ambient temp.  To check if it was a voltage problem, I went back
to the 48v setup, and still have an overheat problem - it does heat up a
little more slowly compared to 64v, but not much.

The motor is not ventilated (never has been...)  

Tom Keenan

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf
Of Voltswagon
Sent: Wednesday, May 09, 2012 3:36 AM
To: [hidden email]
Subject: Re: [EVDL] Motor Overheat (additional info)


Tom Keenan wrote
>
> For a few months, I have been troubleshooting an ongoing motor
> overheat problem

So...around since winter ended?  I've noticed mine getting toastier lately,
may need to hook the forced air blower back on even though I'm only using
2nd.

--

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Re: Motor Overheat (additional info)

Roland Wiench
In reply to this post by Tom Keenan
I just got done yesterday testing out the different heights of the EV. Rear
vs. Front from even heights, lower front end height or lower rear end
heights.

Replace the existing air suspension that was install back in 1980 with Shock
Wave units for the front which replaces the springs.  Replace the rear air
shocks and install a air bag into the springs.

Instead of 100 psi air pressure it took to level a 7000 lb vehicle, it now
only takes 30 psi.

The old geezer at the auto shop, said if you raise the rear end higher than
the front, you will use less energy to move the vehicle, because you are
coasting down hill all the time.  Back in the old days, wagons had larger
wheels than the front.

I said, that will make the vehicle body at a angle which will cause more
front area which will included the top of the hood and roof area.  So we
tested out this theory to see what happens.

Drove the EV exactly for 2.5 miles at 35 mph on level grade with no wind and
the E-meter read 10 AH with the rear jack all the way up looking like a
dragster.  Lower the EV to exact level and this time it took 11.5 AH!

He said, see it takes less energy.  I said, the first leg was west and we
are going against the rotation of the earth.  The second leg was with the
rotation of the earth.

Actually, the motor ampere was more, because the battery voltage was less on
the return trip.  If I would let the EV set for about a hour and let the
batteries defuse for a while, it will be closer in the 10 AH range.

Roland






----- Original Message -----
From: "Mark Grasser" <[hidden email]>
To: "'Electric Vehicle Discussion List'" <[hidden email]>
Sent: Wednesday, May 09, 2012 11:57 AM
Subject: Re: [EVDL] Motor Overheat (additional info)


> Airflow could even be changed dramatically by raising or lowering the
> suspension at one end of the car or both.
>
>
> Sincerely,
> Mark Grasser
>
>
> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On
> Behalf
> Of Cor van de Water
> Sent: Wednesday, May 09, 2012 12:16 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] Motor Overheat (additional info)
>
> If the setup is the same as before (no fan) and you use approx the same
> amount of energy (so it is not something dragging causing higher current
> through the motor) and there are not other obvious things like change of
> timing of the brushes or some other change to the motor, the only other
> thing I can think of is the airflow - did you change the way air is
> flowing
> over the motor or add a bellypan/splash shield that may cause the air
> around
> the motor to stall and remove cooling from the motor?
>
> It sounds like you *need* to add a fan to that motor now!
>
> Regards,
>
> Cor van de Water
> Chief Scientist
> Proxim Wireless Corporation http://www.proxim.com
> Email: [hidden email]    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: [hidden email] [mailto:[hidden email]] On
> Behalf
> Of Tom Keenan
> Sent: Wednesday, May 09, 2012 5:17 AM
> To: 'Electric Vehicle Discussion List'
> Subject: Re: [EVDL] Motor Overheat (additional info)
>
> It doesn't appear to be voltage or ambient temp related.  For several
> years,
> I drove it as a 48v car and did not have an issue with overheating, no
> matter the ambient temp.  To check if it was a voltage problem, I went
> back
> to the 48v setup, and still have an overheat problem - it does heat up a
> little more slowly compared to 64v, but not much.
>
> The motor is not ventilated (never has been...)
>
> Tom Keenan
>
> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On
> Behalf
> Of Voltswagon
> Sent: Wednesday, May 09, 2012 3:36 AM
> To: [hidden email]
> Subject: Re: [EVDL] Motor Overheat (additional info)
>
>
> Tom Keenan wrote
> >
> > For a few months, I have been troubleshooting an ongoing motor
> > overheat problem
>
> So...around since winter ended?  I've noticed mine getting toastier
> lately,
> may need to hook the forced air blower back on even though I'm only using
> 2nd.
>
> --
>
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere.  Thanks.
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>
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>

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Re: Motor Overheat (additional info)

Lee Hart
On 5/9/2012 1:57 PM, Roland Wiench wrote:
> I just got done yesterday testing out the different heights of the EV...
> Rear vs. Front from even heights, lower front end height or lower rear
> end heights... 10 AH with the rear jacked all the way up looking like
> a dragster. Lower the EV to exact level and this time it took 11.5 AH!

A good story, Roland. It goes to show how difficult it is to accurately
measure these "feathers on the scale". When something makes a small
difference, it take a lot of time and effort to get enough data to prove
whether it helps or not!

Let's say it takes (on average) 200 wh/mile to drive your EV at 35 mph.
But the *spread* might be anything from 150-250 wh/mile, depending on
state of charge, how you drive, the wind, slope of the road, road
surface, tire pressure, weight of the vehicle (and whatever else is in
it at the moment), temperature, phase of the moon, etc.

Drive that same route a dozen times, and each trip gives you a dozen
different number within that range, no number repeating more than once.
Which one is "correct"? You can't tell!

But drive the same route a *hundred* times, and you have enough data to
begin to see the pattern. Most of the numbers cluster around (say) 220
wh/mile, with the rest scattered around it.

Jacking up the rear only changed the amphours by 10/11.5 = 13%. But I'll
bet the variation between runs could easily be more than this, even with
no changes between runs. So you'd have to make many runs to figure out
if the change is real, or just random luck.

However, it has been observed that the aerodynamics of cars are full of
odd paradoxes. Paul Macready observed that when you actually tested
cars, many were more streamlined in reverse, and things like riding
height and front/rear rake had a significant effect that was often
opposite of what "common sense" would imply.

--
Ring the bells that still can ring
Forget your perfect offering
There is a crack in everything
That's how the light gets in.
        -- Leonard Cohen, from "Anthem"
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart at earthlink.net

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Re: Motor Overheat (additional info)

Roland Wiench
In reply to this post by Tom Keenan
Hello Lee,

Here is another story about tire deflection that I got from my master
mechanic that use to work on the long haul big rigs.

The psi per load rating of the tire, may not be the best setting for that
tire at a certain load and road conditions.

First you find out what the load on each tire is by weighing each axle on a
scale.  In my case it was 4640 lbs. on the rear axle or 2320 lbs. per tire.
The front axle was 2560 lbs. or 1280 lbs. per tire.

The front spindles, rear axle and bearings must be rated a percentage more
than the load.  So we choose a 4000 lb. rating bearing, a 3500 lb. rating
wheel and a tire rating at 2350 lbs. at a 65 psi maximum rating.

The tire is a 2 ply polyester and a 2 ply steel ply face.  The side walls
are a 2 ply polyester.  The early model tires use to be a 6 ply nylon and a
2 ply steel ply face and a 4 ply nylon side walls.

In the colder climate it is best not to have a nylon tire, because if it
sets outside too long, it will set a flat spot on it which increases the
rolling resistance.

You want to set the deflection rate of your tire to about 3/8 to 1/2 inch
range.  To do this you first jack the tire off a smooth level surface.  Air
it up to the maximum psi rating that is listed on the side of the tire.
Lower the tire where it just touches the surface.

Measure the distance from the grade or floor surface to any point on rim of
the wheel.  Lets say it reads 5 inches.  Then lower the vehicles so the full
weight is on grade and measure it again.  Lets say it reads 4.5 inches.

Five (5) inches - 4.5 inches equal a 0.5 inch deflection rate.  If the
deflection rate is over this reading, then you do not have the correct type
of tires for your vehicle. If the deflection rate is under 3/8, then lower
the air pressure.

Today with a 2 ply poly and 2 ply steel face and only a 2 ply side, the side
wall takes up must of the defection keeping the face more rounded with less
resistance.

This is true is you are running on very smooth road surfaces.  Running on a
ripple road which they cut grooves into the surface, wash board surfaces and
the concrete gutters they place at every intersection in our town, high psi
rating tires tend to skip over the first ripple and hit the side of the next
ripple like a steel hammer at a certain speed which causes a high resistance
road surface.

So I lower the air pressure in the rear by 15 lbs. to 50 lbs. and the fronts
by 10 lbs. to 40 lbs.  Now driving over these rough residential streets at
25 mph becomes a softer ride with less thrust and energy.

Roland






----- Original Message -----
From: "Lee Hart" <[hidden email]>
To: "Electric Vehicle Discussion List" <[hidden email]>
Sent: Wednesday, May 09, 2012 1:32 PM
Subject: Re: [EVDL] Motor Overheat (additional info)


> On 5/9/2012 1:57 PM, Roland Wiench wrote:
> > I just got done yesterday testing out the different heights of the EV...
> > Rear vs. Front from even heights, lower front end height or lower rear
> > end heights... 10 AH with the rear jacked all the way up looking like
> > a dragster. Lower the EV to exact level and this time it took 11.5 AH!
>
> A good story, Roland. It goes to show how difficult it is to accurately
> measure these "feathers on the scale". When something makes a small
> difference, it take a lot of time and effort to get enough data to prove
> whether it helps or not!
>
> Let's say it takes (on average) 200 wh/mile to drive your EV at 35 mph.
> But the *spread* might be anything from 150-250 wh/mile, depending on
> state of charge, how you drive, the wind, slope of the road, road
> surface, tire pressure, weight of the vehicle (and whatever else is in
> it at the moment), temperature, phase of the moon, etc.
>
> Drive that same route a dozen times, and each trip gives you a dozen
> different number within that range, no number repeating more than once.
> Which one is "correct"? You can't tell!
>
> But drive the same route a *hundred* times, and you have enough data to
> begin to see the pattern. Most of the numbers cluster around (say) 220
> wh/mile, with the rest scattered around it.
>
> Jacking up the rear only changed the amphours by 10/11.5 = 13%. But I'll
> bet the variation between runs could easily be more than this, even with
> no changes between runs. So you'd have to make many runs to figure out
> if the change is real, or just random luck.
>
> However, it has been observed that the aerodynamics of cars are full of
> odd paradoxes. Paul Macready observed that when you actually tested
> cars, many were more streamlined in reverse, and things like riding
> height and front/rear rake had a significant effect that was often
> opposite of what "common sense" would imply.
>
> --
> Ring the bells that still can ring
> Forget your perfect offering
> There is a crack in everything
> That's how the light gets in.
> -- Leonard Cohen, from "Anthem"
> --
> Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart at earthlink.net
>
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere.  Thanks.
> |
> | REPLYING: address your message to [hidden email] only.
> | Multiple-address or CCed messages may be rejected.
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> | OTHER HELP: http://evdl.org/help/
> | CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
>

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Re: Motor Overheat (additional info)

Tom Keenan
In reply to this post by Ken Fry
One of those quandaries...  the ambient temp varies somewhat here, but it has not overheated during the past four years of (somewhat) variable temps.  Typically, it ranges from 50F to 80F.  

The terrain here is flat.  I basically drive the same route - 4.5 miles to work, and 4.5 miles home.  Most of the drive is in a 25 MPH zone, with about a mile in a 30 MPH zone, so speeds are relatively slow.

Adding a cooling blower would probably help, but it feels like it would be similar to adding an electric radiator fan to a car with a bad radiator - nothing but a band-aid...

Tom Keenan

--- On Wed, 5/9/12, Ken Fry <[hidden email]> wrote:

> From: Ken Fry <[hidden email]>
> Subject: Re: [EVDL] Motor Overheat (additional info)
> To: [hidden email]
> Date: Wednesday, May 9, 2012, 10:36 AM
> By swapping motors, you've eliminated
> the motor from contention.  If the
> watthours/mile figure remains the same, then the only
> remaining variables
> seem to be ambient air temperature and airflow around the
> motor. 
>
> Is the terrain identical?  The rate of heating goes up
> quickly with higher
> amperage, so you could (possibly) have a similar average
> Wh/mile figure but
> increased heating from hills, with the temperature not able
> to fall off
> between hills.   
>
> I can't think of anything in the controller that would cause
> this in a
> series motor.
>
> Hot to the touch after only 4 miles is way too hot.
>
>
>
>  
>
> -----
> Think Big.
> Drive Small.   
> --
> View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Motor-Overheat-additional-info-tp4619321p4621183.html
> Sent from the Electric Vehicle Discussion List mailing list
> archive at Nabble.com.
>
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere.  Thanks.
> |
> | REPLYING: address your message to [hidden email]
> only.
> | Multiple-address or CCed messages may be rejected.
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Re: Motor Overheat (additional info)

Dennis Miles
At only 25 mph what is your motor rpm? a 4.5mile trip at only 2,000 rpm
will overheat. the efficiency is increased at higher rpm and the internal
fan will be more effective. shift grars to low and raise the rpm to keep
the motor cooler.!.
Regards,
*Dennis Lee Miles*
+++++++++++++++++++++++++++++++++++++++++++++
On Wed, May 9, 2012 at 10:44 PM, Tom Keenan <[hidden email]> wrote:

> One of those quandaries...  the ambient temp varies somewhat here, but it
> has not overheated during the past four years of (somewhat) variable temps.
>  Typically, it ranges from 50F to 80F.
>
> The terrain here is flat.  I basically drive the same route - 4.5 miles to
> work, and 4.5 miles home.  Most of the drive is in a 25 MPH zone, with
> about a mile in a 30 MPH zone, so speeds are relatively slow.
>
> Adding a cooling blower would probably help, but it feels like it would be
> similar to adding an electric radiator fan to a car with a bad radiator -
> nothing but a band-aid...
>
> Tom Keenan
>
> --- On Wed, 5/9/12, Ken Fry <[hidden email]> wrote:
>
> > From: Ken Fry <[hidden email]>
> > Subject: Re: [EVDL] Motor Overheat (additional info)
> > To: [hidden email]
> > Date: Wednesday, May 9, 2012, 10:36 AM
>  > By swapping motors, you've eliminated
> > the motor from contention.  If the
> > watthours/mile figure remains the same, then the only
> > remaining variables
> > seem to be ambient air temperature and airflow around the
> > motor.
> >
> > Is the terrain identical?  The rate of heating goes up
> > quickly with higher
> > amperage, so you could (possibly) have a similar average
> > Wh/mile figure but
> > increased heating from hills, with the temperature not able
> > to fall off
> > between hills.
> >
> > I can't think of anything in the controller that would cause
> > this in a
> > series motor.
> >
> > Hot to the touch after only 4 miles is way too hot.
> >
> >
> >
> >
> >
> > -----
> > Think Big.
> > Drive Small.
> > --
> > View this message in context:
> http://electric-vehicle-discussion-list.413529.n4.nabble.com/Motor-Overheat-additional-info-tp4619321p4621183.html
> > Sent from the Electric Vehicle Discussion List mailing list
> > archive at Nabble.com.
> >
> > _______________________________________________
> > | Moratorium on drag racing discussion is in effect.
> > | Please take those discussions elsewhere.  Thanks.
> > |
> > | REPLYING: address your message to [hidden email]
> > only.
> > | Multiple-address or CCed messages may be rejected.
> > | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> > | OTHER HELP: http://evdl.org/help/
> > | CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
> >
>
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere.  Thanks.
> |
> | REPLYING: address your message to [hidden email] only.
> | Multiple-address or CCed messages may be rejected.
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--
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Electric car fire

David Dymaxion
In reply to this post by Tom Keenan
http://autos.yahoo.com/blogs/motoramic/fisker-karma-owner-blames-house-fire-car-offended-204708241.html
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Re: Motor Overheat (additional info)

Lee Hart
In reply to this post by Tom Keenan
Tom Keenan wrote:
> Adding a cooling blower would probably help, but it feels like it
> would be similar to adding an electric radiator fan to a car with a
> bad radiator - nothing but a band-aid...

Actually, I'm amazed that you have gotten by as long as you have without
a fan!

Temperature has an insidious effect on life. It's usually not the case
that below some temperature "X" it works forever, and above "X" it fails
immediately.

Instead, the higher the temperature, the shorter the life. Higher
temperatures speed up the deterioration of the various materials in the
motor (brushes, bearings, insulation, grease, oil). The motor fails when
one or more of these materials gets bad enough to stop further
operation. As a general rule, the motor deteriorates twice as fast for
every 10 deg.C rise in temperature.

So a cooling fan is not a "band aid". It is more like treatment for a
chronic illness, that prolongs the life of the "patient".
--
If we knew what we were doing, it wouldn't be called research, would it?
        -- Albert Einstein
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart at earthlink.net

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|
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Re: Motor Overheat (additional info)

Tom Keenan
I'd considered that the motor might be aging, and I have a recently
overhauled 'stock' motor that I swapped in for a test.  During a several day
test, the motor averaged about the same as the 'old' motor - from 12 to 14
degrees F per mile.

Yesterday's reading on the 'old' motor was 14.3 F per mile.  Today it was
12.3.  Today's ambient temp is a bit hotter than yesterday, but traffic
(such as it is) was a little slower today - perhaps an average of 23 mph
compared to 27 mph.  For reference, about two years ago the 'old' motor did
a 23 mile drive with about a 6 degree F per mile rise, averaging about 30
MPH.

I may end up putting in a cooling fan so I can drive it longer than a few
miles, but whatever the problem is probably won't go away on its own...

Tom Keenan

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf
Of Lee Hart
Sent: Thursday, May 10, 2012 9:56 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Motor Overheat (additional info)

Tom Keenan wrote:
> Adding a cooling blower would probably help, but it feels like it
> would be similar to adding an electric radiator fan to a car with a
> bad radiator - nothing but a band-aid...

Actually, I'm amazed that you have gotten by as long as you have without a
fan!

Temperature has an insidious effect on life. It's usually not the case that
below some temperature "X" it works forever, and above "X" it fails
immediately.

Instead, the higher the temperature, the shorter the life. Higher
temperatures speed up the deterioration of the various materials in the
motor (brushes, bearings, insulation, grease, oil). The motor fails when one
or more of these materials gets bad enough to stop further operation. As a
general rule, the motor deteriorates twice as fast for every 10 deg.C rise
in temperature.

So a cooling fan is not a "band aid". It is more like treatment for a
chronic illness, that prolongs the life of the "patient".
--
If we knew what we were doing, it wouldn't be called research, would it?
        -- Albert Einstein
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart at earthlink.net

_______________________________________________
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|
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Re: Motor Overheat (additional info)

Mike Nickerson
Hi Tom,

I was thinking about this today as I was watching my temperature gauge and
driving home.  If you are pulling the same power overall as before, but the
temperature is going up, it has to be something with the cooling airflow.  I
can only think of:  

  -  Internal Fan
  -  External ducting or cowling
  -  Ambient temperature

Since you mentioned this happens across a wide range of ambient
temperatures, I think we could rule that out.  

Have you changed the body, front grill or belly pan in the past so that the
motor is now in a "wind shadow?"  If not, the next thing that comes to mind
is the internal fan of the motor.  Is it working as well as it used to?
Since you've tried two different motors, it sounds like that isn't it,
though.

In my case, one of my battery boxes creates a wind shadow for the motor, so
I have ducting from the front grill to the motor air intake to try and
combat that.  Since much of my drive is at 55 mph, that works pretty well.

Other than that, I'm pretty well stumped!

Mike

> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On
> Behalf Of Tom Keenan
> Sent: Thursday, May 10, 2012 5:41 PM
> To: 'Electric Vehicle Discussion List'
> Subject: Re: [EVDL] Motor Overheat (additional info)
>
> I'd considered that the motor might be aging, and I have a recently
> overhauled 'stock' motor that I swapped in for a test.  During a several
day
> test, the motor averaged about the same as the 'old' motor - from 12 to 14
> degrees F per mile.
>
> Yesterday's reading on the 'old' motor was 14.3 F per mile.  Today it was
12.3.
> Today's ambient temp is a bit hotter than yesterday, but traffic (such as
it is)
> was a little slower today - perhaps an average of 23 mph compared to 27
> mph.  For reference, about two years ago the 'old' motor did a 23 mile
drive
> with about a 6 degree F per mile rise, averaging about 30 MPH.
>
> I may end up putting in a cooling fan so I can drive it longer than a few
miles,
> but whatever the problem is probably won't go away on its own...
>
> Tom Keenan
>

_______________________________________________
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|
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Re: Motor Overheat (additional info)

Tom Keenan
I'm stumped as well.  No changes to the body or airflow.  Same gearing.  Speeds are pretty much what they were before during my normal commute. Only change was an increase to 64v, but when I set it back to 48v (original voltage) the temperature remained at 12 to 14 degrees F per mile...

I've gone back to basically the oroginal configuration, with not much change.  This includes using a recently rebuilt 'stock' motor.

Again, quite the puzzle...

Tom Keenan

--- On Thu, 5/10/12, Mike Nickerson <[hidden email]> wrote:

> From: Mike Nickerson <[hidden email]>
> Subject: Re: [EVDL] Motor Overheat (additional info)
> To: "'Electric Vehicle Discussion List'" <[hidden email]>
> Date: Thursday, May 10, 2012, 6:39 PM
> Hi Tom,
>
> I was thinking about this today as I was watching my
> temperature gauge and
> driving home.  If you are pulling the same power
> overall as before, but the
> temperature is going up, it has to be something with the
> cooling airflow.  I
> can only think of: 
>
>   -  Internal Fan
>   -  External ducting or cowling
>   -  Ambient temperature
>
> Since you mentioned this happens across a wide range of
> ambient
> temperatures, I think we could rule that out. 
>
> Have you changed the body, front grill or belly pan in the
> past so that the
> motor is now in a "wind shadow?"  If not, the next
> thing that comes to mind
> is the internal fan of the motor.  Is it working as
> well as it used to?
> Since you've tried two different motors, it sounds like that
> isn't it,
> though.
>
> In my case, one of my battery boxes creates a wind shadow
> for the motor, so
> I have ducting from the front grill to the motor air intake
> to try and
> combat that.  Since much of my drive is at 55 mph, that
> works pretty well.
>
> Other than that, I'm pretty well stumped!
>
> Mike
>
> > -----Original Message-----
> > From: [hidden email]
> [mailto:[hidden email]]
> On
> > Behalf Of Tom Keenan
> > Sent: Thursday, May 10, 2012 5:41 PM
> > To: 'Electric Vehicle Discussion List'
> > Subject: Re: [EVDL] Motor Overheat (additional info)
> >
> > I'd considered that the motor might be aging, and I
> have a recently
> > overhauled 'stock' motor that I swapped in for a
> test.  During a several
> day
> > test, the motor averaged about the same as the 'old'
> motor - from 12 to 14
> > degrees F per mile.
> >
> > Yesterday's reading on the 'old' motor was 14.3 F per
> mile.  Today it was
> 12.3.
> > Today's ambient temp is a bit hotter than yesterday,
> but traffic (such as
> it is)
> > was a little slower today - perhaps an average of 23
> mph compared to 27
> > mph.  For reference, about two years ago the 'old'
> motor did a 23 mile
> drive
> > with about a 6 degree F per mile rise, averaging about
> 30 MPH.
> >
> > I may end up putting in a cooling fan so I can drive it
> longer than a few
> miles,
> > but whatever the problem is probably won't go away on
> its own...
> >
> > Tom Keenan

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| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
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Re: Motor Overheat (additional info)

Robert MacDowell-2
In reply to this post by Lee Hart
On Wed, May 9, 2012 at 12:32 PM, Lee Hart <[hidden email]> wrote:

> On 5/9/2012 1:57 PM, Roland Wiench wrote:
> > I just got done yesterday testing out the different heights of the EV...
> > Rear vs. Front from even heights, lower front end height or lower rear
> > end heights... 10 AH with the rear jacked all the way up looking like
> > a dragster. Lower the EV to exact level and this time it took 11.5 AH!
>
> A good story, Roland. It goes to show how difficult it is to accurately
> measure these "feathers on the scale". When something makes a small
> difference, it take a lot of time and effort to get enough data to prove
> whether it helps or not!
>


No kidding. http://www.tinaja.com/glib/bashpseu.pdf

For the overheating problem, I propose the right instrument: an ammeter.
Amperes are the dominant factor in motor overheating.  An ammeter should
lead you to the heart of the problem quickly.

You may find amps has increased because something has increased the car's
rolling resistance.



> Let's say it takes (on average) 200 wh/mile to drive your EV at 35 mph.
> But the *spread* might be anything from 150-250 wh/mile, depending on
> state of charge, how you drive, the wind, slope of the road, road
> surface, tire pressure, weight of the vehicle (and whatever else is in
> it at the moment), temperature, phase of the moon, etc.
>
> Drive that same route a dozen times, and each trip gives you a dozen
> different number within that range, no number repeating more than once.
> Which one is "correct"? You can't tell!
>


Yeah, that way lies madness.  The right instrument for that sort of thing
is a dynamometer.   It puts the vehicle in a controlled set of conditions
where performance can be measured absolutely.


However, it has been observed that the aerodynamics of cars are full of
> odd paradoxes. Paul Macready observed that when you actually tested
> cars, many were more streamlined in reverse, and things like riding
> height and front/rear rake had a significant effect that was often
> opposite of what "common sense" would imply.


Wind tunnel.
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