Are you saying it could be worn brushes?
Not really. I don't really know what I'm talking
about, just dredging up bits and pieces from power
lab 25 years ago. Motors can be wound in a wide
variety of ways, and a starter motor is a candidate
for a series winding architecture. All the current
Philip asked:
Is it normal for a hot engine to require 5 times more current
through the starter?
Peter wrote:
The windings aquire high resistance with age, compounded by
further resistance increase when they are hot, with the result
that the starter will be pulling something like
You tried to make a 13ga shunt for something drawing hundreds of amps?
Seems too light to me.
Mitch.
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It seems than at Mon, 31 Mar 2008 22:31:23 -0400, Mitch wrote:
You tried to make a 13ga shunt for something drawing hundreds
of amps? Seems too light to me.
Mitch.
Well, my experience suggests you are right. *smile* At least
with a shorted starter...
6 inches of 13 AWG.
Heat is the death
On Mon, 31 Mar 2008 22:18:29 -0500 Fmiser [EMAIL PROTECTED] wrote:
But I would really like to have a baseline to figure from, so
maybe I'll find some time.
How about measuring the voltage drop on the wire from the battery to the
starter? Positive lead on the battery terminal, negative lead on
If the resistance goes up, the current draw will have to go
_down_! If we are to believe Ohm's law.
Compound-wound motors can act in some counterintuitive ways.
The two magnetic fields fight each other to produce torque
_and_ push down the field current. If the armature is weak
you won't get
The trick is getting it nicely
calibrated, 1 mV/A would be ideal.
Not ideal, really, in that you lose an entire
volt at 1000A, but that might be tolerable.
Your shunt needs to be physically larger so
it won't vaporize as it dissipates the
500*500*0.001=250W of a 500A load. There's
a reason a
It seems than at Mon, 31 Mar 2008 21:35:04 -0600, Craig wrote:
On Mon, 31 Mar 2008 22:18:29 -0500 Fmiser [EMAIL PROTECTED]
wrote:
But I would really like to have a baseline to figure from, so
maybe I'll find some time.
How about measuring the voltage drop on the wire from the
battery
It seems than at Mon, 31 Mar 2008 22:09:44 -0700, Jim wrote:
If the resistance goes up, the current draw will have to go
_down_! If we are to believe Ohm's law.
Compound-wound motors can act in some counterintuitive ways.
The two magnetic fields fight each other to produce torque
_and_
Normal starter draw is around 900A cold, less hot as the engine spins
easier. Higher draw hot indicates heat related resistance increase
in the starter windings.
Peter
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I had a very similar problem with my 126 when I first purchased it, I
was all set to replace the starter. I was able to start the car when
hot by rapping the solenoid, so I'm sure there were issues there,
however changing the battery resolved (overcame) the issue, at least,
a fully charged fresh
My 240D didn't start right yesterday.
I made half a dozen stops on a 300+ mile drive. A few of the
stops were short (30 minute), and two of them were more than 3
hours.
At the first short stop, when I turned the key to start the
engine, the solenoid made one click - but the starter didn't
turn.
You need a properly rebuilt or new starter, not one with new bushings
and a turned commutator.
The windings aquire high resistance with age, compounded by further
resistance increase when they are hot, with the result that the
starter will be pulling something like 2000A and not spinning
Is it normal for a hot engine to require 5 times more current
through the starter?
That is the beauty of using a clamp-on DC ammeter to
help diagnose. Gets rid of all the is-it-OK-or-not
wonderings because you only measure voltage. You measure
the current and compare to the baseline, and if
current is way out of line it _has_ to be the starter.
And by out of line, I mean high. If low, it could also
be the battery or cabling. Voltmeter time.
-- Jim
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It seems than at Fri, 28 Mar 2008 17:34:53 -0700, Jim wrote:
Is it normal for a hot engine to require 5 times more current
through the starter?
That is the beauty of using a clamp-on DC ammeter to
help diagnose.
I know... But I don't have one - yet. From your experience, is
it normal for
I know... But I don't have one - yet. From your experience, is
it normal for a hot engine to draw more current?
I have very little actual experience at this. It's something
I'm using now, now that I have the clamp.
What is normal current draw for a OM616/OM617 starter?
I've measured a
In a message dated 3/28/2008 6:25:53 P.M. US Mountain Standard Time,
[EMAIL PROTECTED] writes:
Maybe it's time to build a shunt or a coil. I have 12, 14, 18,
22, and 24 AWG wire. A few inches of one of them should get me a
shunt of suitable resistance.
Phillip,
You suffered the
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