Re: [EVDL] question: hot motor (?) in a slow car

543 Views 2 Replies 1 Participant Last post by EVDL List, Oct 23, 2007

EVDL List

Discussion Starter · Oct 23, 2007

Re: [EVDL] question: hot motor (?) in a slow car

So you've got 10,000 watts of juice going through your
motor, and want to know how hot it's going to get.
(;-p

The temp ratings on motors get up there. 170F rings a
bell for my 8" series wound, IIRC. I live at the top
of a pretty good-sized hill (4% or better, 1.5 km
long). My casing _does_ get warm to the touch, but it
does not smell. I did go through a smell issue, and
it was the enamel of the motor windings. Changing my
RPMs lower (only going to about 3K now) apparently
changed my amp draw and now it doesn't smell.

My concern is that you're drawing that 200A for a
longer period than I am, b/c you've got less voltage.
I'm a bit concerned about the smell you mention.

No clue on temp. sense location...

Hope that helps,

--- "Darin at- forkenswift.com"

<[email protected]> wrote:

>
> I have a couple of questions about motor
> temperature:
>
> Occasionally, I'll wait patiently by a grown-up
> street for a gap in traffic
> big enough to accomodate the ForkenSwift and then
> accelerate for a long
> time, pulling 125-200A (@ 48v) during the gradual
> ascent to cruising speed.
>
> I've had occasion to open the hood not long after
> one of these scenarios
> (I'm in the habit of periodically checking cables &
> connections after a
> "big" amp draw - once I discovered a warm one
> because I had mistakenly left
> a washer between the lug and the terminal). I'm
> curious to know what I
> should be watching for in terms of motor heat:
>
> 1) Is it normal to be able to smell a warm motor? I
> have noticed this
> occasionally. It's not a burnt smell or anything,
> just a hot metal smell.
>
> 2) The only part of the motor that warms up (that I
> can easily feel) is the
> shaft, on the commutator end. Warm/hot,
> occasionally, but not
> burn-your-finger hot. The case itself is always
> cool all around Normal?
>
> 3) I know some motors have temp sensors installed -
> where are they usually
> located?
>
> FYI, this 8 inch pump motor has an internal fan at
> the drive end.
>
> thanks,
>
> Darin
> http://www.austinev.org/evalbum/1146
> --
> View this message in context:
>
http://www.nabble.com/question%3A-hot-motor-%28-%29-in-a-slow-car-tf4674923s25542.html#a13356676
> Sent from the Electric Vehicle Discussion List
> mailing list archive at Nabble.com.
>
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>

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Discussion Starter · #2 · Oct 23, 2007

Re: [EVDL] question: hot motor (?) in a slow car

--- "Darin at- forkenswift.com"

<[email protected]> wrote:

> 1) Is it normal to be able to smell a warm motor? I
> have noticed this
> occasionally. It's not a burnt smell or anything,
> just a hot metal smell.

Hey Darin

EVen though yours was a pretty clean lift motor, I'm
sure there was at least a little grime inside that
could be adding to the smell you're getting.

> 2) The only part of the motor that warms up (that I
> can easily feel) is the
> shaft, on the commutator end. Warm/hot,
> occasionally, but not
> burn-your-finger hot. The case itself is always
> cool all around Normal?

Yes, even bench testing without load at 12 volts will
get shafts pretty warm due to bearing friction, so
shaft warmth isn't something to be concerned about.

> 3) I know some motors have temp sensors installed -
> where are they usually
> located?

They're usually installed in the coils, which is a
poor area to place them as (on most motors) the coils
are the last thing to heat up. Once it did trip
you've probably begun to hurt the armature and or
brush rigging.

> FYI, this 8 inch pump motor has an internal fan at
> the drive end.

I believe that once you increase your voltage you'll
find that the motor temp will decrease (unless you're
an animal, lol) as you're probably bogging it down at
present. Keep an eye on the brush leads, if you begin
to purple them up (starts rose colored), then you have
an issue.

Sorry for the late responce to this, got a bout of the
crud going around here that my wife brought home from
the plague factory she works at!

Hope this helps

Cya
Jim Husted
Hi-Torque Electric

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Discussion Starter · #3 · Oct 23, 2007

Re: [EVDL] question: hot motor (?) in a slow car

Bob Bath wrote:
> The temp ratings on motors get up there. 170F rings a bell for my 8"
> series wound

170 is up there. I'm not in that territory yet. Thanks for that, Bob.

Jim Husted wrote:
> EVen though yours was a pretty clean lift motor, I'm sure there was at
> least a little grime inside that could be adding to the smell you're
> getting.

Well, it was definitely not clean when I first opened it up. Hadn't
considered that it might be stuff burning off. There was a film of
hydraulic oil over everything, so I took it all apart and washed it all with
citron cleaner. Maybe it's burning lemon I'm smelling. (No jokes about the
car.)

Jim Husted wrote:
> (unless you're an animal, lol) as you're probably bogging it down at
> present. Keep an eye on the brush leads, if you begin to purple them up
> (starts rose colored), then you have an issue.

You mean I should stop doing practice runs trying to improve my 0-30 mph
time?

That's just the kind of info I can use. I have a clear view of one brush
pair just by popping the hood, so that will be easy to monitor. Thanks!

Jim Husted wrote:
> my wife brought home from the plague factory she works at!

Oh, teacher, is she?

Thanks again.
Darin
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