Google Groups no longer supports new Usenet posts or subscriptions. Historical content remains viewable.
Dismiss

Starter solenoid current?

2,791 views
Skip to first unread message

Bernd Felsche

unread,
Nov 2, 2011, 3:45:59 AM11/2/11
to
Something I don't know ... and can't seem to find out all that
easily.

I'm trying to figure out the current draw by the starter solenoid,
(not the starter motor) at terminal 50.

It's powered through the ignition switch in the Golf GTI but the 4mm
wiring has me baffled. That's too much current to go through a
little ignition switch if the wire is sized for current capacity.

So I assume it's sized to avoid voltage drop, which leaves me none
the wiser regarding the current actually drawn by the starter
solenoid.
--
/"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia
\ / ASCII ribbon campaign | For every complex problem there is an
X against HTML mail | answer that is clear, simple, and wrong.
/ \ and postings | --HL Mencken

atec77

unread,
Nov 2, 2011, 4:10:03 AM11/2/11
to
On 2/11/2011 5:45 PM, Bernd Felsche wrote:
> Something I don't know ... and can't seem to find out all that
> easily.
>
> I'm trying to figure out the current draw by the starter solenoid,
> (not the starter motor) at terminal 50.
>
> It's powered through the ignition switch in the Golf GTI but the 4mm
> wiring has me baffled. That's too much current to go through a
> little ignition switch if the wire is sized for current capacity.
>
> So I assume it's sized to avoid voltage drop, which leaves me none
> the wiser regarding the current actually drawn by the starter
> solenoid.
Is it direct activation or relay switched ?
usually a solenoid like that draws upwards of 8 or 10 amps possibly
more in a foulcan , doesn't the solenoid have to drive the engagement
mechanism?

--
X-No-Archive: Yes

Scotty

unread,
Nov 2, 2011, 4:27:47 AM11/2/11
to


"Bernd Felsche" wrote in message
news:n297o8x...@innovative.iinet.net.au...

Something I don't know ... and can't seem to find out all that
easily.

I'm trying to figure out the current draw by the starter solenoid,
(not the starter motor) at terminal 50.

It's powered through the ignition switch in the Golf GTI but the 4mm
wiring has me baffled. That's too much current to go through a
little ignition switch if the wire is sized for current capacity.

So I assume it's sized to avoid voltage drop, which leaves me none
the wiser regarding the current actually drawn by the starter
solenoid.

Bernd Felsche - Innovative Reckoning, Perth, Western Australia
ASCII ribbon campaign | For every complex problem there is an
against HTML mail | answer that is clear, simple, and wrong.
and postings | HL Mencken
<><><><><><><><><><><><><><><><><><><><><><><><><><><><>

Use a multimeter if you have one. The size is usually for volt drop. The
actual solenoid Id imagine wouldn't draw much at all.
I'd take a wild guess at 7 or 8 amps for modern cars. the cables that size
as when cranking it needs the full voltage other wise it will do what you
call Motor Boating.
that is where the voltage drops too low to maintain the solenoid and it
drops out during cranking. As your still holding the key to the start
position it will re-engage as the voltage increases now the starter isn't
engaged, it keeps doing this until either a contact burns out or usually the
person trying to get to work takes the bus. (or its jump started of course)

Do you know that clicking sound when ya batteries very flat? that's it.


Clocky

unread,
Nov 2, 2011, 5:44:35 AM11/2/11
to

"Bernd Felsche" <ber...@innovative.iinet.net.au> wrote in message
news:n297o8x...@innovative.iinet.net.au...
> Something I don't know ... and can't seem to find out all that
> easily.
>
> I'm trying to figure out the current draw by the starter solenoid,
> (not the starter motor) at terminal 50.
>
> It's powered through the ignition switch in the Golf GTI but the 4mm
> wiring has me baffled. That's too much current to go through a
> little ignition switch if the wire is sized for current capacity.
>
> So I assume it's sized to avoid voltage drop, which leaves me none
> the wiser regarding the current actually drawn by the starter
> solenoid.

Why not put an ammeter in series?






PeterD

unread,
Nov 2, 2011, 8:27:44 AM11/2/11
to
On 11/2/2011 3:45 AM, Bernd Felsche wrote:
> Something I don't know ... and can't seem to find out all that
> easily.
>
> I'm trying to figure out the current draw by the starter solenoid,
> (not the starter motor) at terminal 50.
>
> It's powered through the ignition switch in the Golf GTI but the 4mm
> wiring has me baffled. That's too much current to go through a
> little ignition switch if the wire is sized for current capacity.
>
> So I assume it's sized to avoid voltage drop, which leaves me none
> the wiser regarding the current actually drawn by the starter
> solenoid.

I believe you will find there is a relay in the circuit. What year Golf
is it? BTW, yes, it is a lot of current--more than one might expect.

--
I'm never going to grow up.

Scotty

unread,
Nov 2, 2011, 8:36:26 AM11/2/11
to


"PeterD" wrote in message news:j8rcvu$huq$3...@speranza.aioe.org...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I think that you are thinking of the starter motor current which can easily
reach 300amps. He is asking about the current draw of the actual solenoid.

theres two ways of easily testing the actual draw. Use an ammeter in series
(or clamp style) and test it, or use an ohmmeter to see what the resistive
load is and work it out that way @ 12v.


Clocky

unread,
Nov 2, 2011, 10:23:56 AM11/2/11
to

"Scotty" <sco...@warmmail.com> wrote in message
news:4eb13946$0$13391$afc3...@news.optusnet.com.au...
Yep, pretty simple really.


Bernd Felsche

unread,
Nov 2, 2011, 10:29:14 AM11/2/11
to
atec77 <ate...@hotmail.com> wrote:
>On 2/11/2011 5:45 PM, Bernd Felsche wrote:
>> Something I don't know ... and can't seem to find out all that
>> easily.
>>
>> I'm trying to figure out the current draw by the starter solenoid,
>> (not the starter motor) at terminal 50.
>>
>> It's powered through the ignition switch in the Golf GTI but the 4mm
>> wiring has me baffled. That's too much current to go through a
>> little ignition switch if the wire is sized for current capacity.
>>
>> So I assume it's sized to avoid voltage drop, which leaves me none
>> the wiser regarding the current actually drawn by the starter
>> solenoid.
>Is it direct activation or relay switched ?

Direct. 4mm wire from the battery to the switch and all the way back
to the strater - via a couple of connections through the central
electrics backplane. Madness.

> usually a solenoid like that draws upwards of 8 or 10 amps possibly
>more in a foulcan , doesn't the solenoid have to drive the engagement
>mechanism?

It has to start. Once it gets going, the contacts of the solenoid
close and the tarter current runs a holding coil in parallel with
the one powered through the key switch.

Bernd Felsche

unread,
Nov 2, 2011, 10:31:59 AM11/2/11
to
"Clocky" <not...@happen.com> wrote:
>"Bernd Felsche" wrote

>> I'm trying to figure out the current draw by the starter solenoid,
>> (not the starter motor) at terminal 50.
>>
>> It's powered through the ignition switch in the Golf GTI but the 4mm
>> wiring has me baffled. That's too much current to go through a
>> little ignition switch if the wire is sized for current capacity.
>>
>> So I assume it's sized to avoid voltage drop, which leaves me none
>> the wiser regarding the current actually drawn by the starter
>> solenoid.

>Why not put an ammeter in series?

Because it could fry the poor thing ...
Most multimeters maxo ut at 10 Amps.
I suspect that it could be 30A, if not more.
Bosch book says 30 to 70A, depending on the size of the starter.

Bernd Felsche

unread,
Nov 2, 2011, 10:35:56 AM11/2/11
to
1990. There's 4mm wiring into and out of the ignition switch when I
last had that part of the sah and steering column uncovered.

Current flow diagrams (two sources) draw it as direct-wired.
No relay.

PeterD

unread,
Nov 2, 2011, 11:26:58 AM11/2/11
to
On 11/2/2011 8:36 AM, Scotty wrote:

> I think that you are thinking of the starter motor current which can
> easily reach 300amps. He is asking about the current draw of the actual
> solenoid.

No, I'm thinking the solenoid, which does draw more current that most
people realize.

>
> theres two ways of easily testing the actual draw. Use an ammeter in
> series (or clamp style) and test it, or use an ohmmeter to see what the
> resistive load is and work it out that way @ 12v.
>

An ohmmeter would be less accurate due to the lower resistance, and
would not provide a good indication of shorted turns (assuming that is
his problem...) The best testing tool is a DC clampon meter, a tool that
I find invaluable when diagnosing starter problems.

Clocky

unread,
Nov 2, 2011, 12:33:03 PM11/2/11
to

"Bernd Felsche" <ber...@innovative.iinet.net.au> wrote in message
news:c318o8...@innovative.iinet.net.au...
> PeterD <pet...@hipson.net> wrote:
>
>>On 11/2/2011 3:45 AM, Bernd Felsche wrote:
>>> Something I don't know ... and can't seem to find out all that
>>> easily.
>>>
>>> I'm trying to figure out the current draw by the starter solenoid,
>>> (not the starter motor) at terminal 50.
>>>
>>> It's powered through the ignition switch in the Golf GTI but the 4mm
>>> wiring has me baffled. That's too much current to go through a
>>> little ignition switch if the wire is sized for current capacity.
>>>
>>> So I assume it's sized to avoid voltage drop, which leaves me none
>>> the wiser regarding the current actually drawn by the starter
>>> solenoid.
>
>>I believe you will find there is a relay in the circuit. What year
>>Golf is it? BTW, yes, it is a lot of current--more than one might
>>expect.
>
> 1990. There's 4mm wiring into and out of the ignition switch when I
> last had that part of the sah and steering column uncovered.
>
> Current flow diagrams (two sources) draw it as direct-wired.
> No relay.

That would explain the 4mm.


D Walford

unread,
Nov 2, 2011, 7:19:17 PM11/2/11
to
On 03/11/2011 1:31 AM, Bernd Felsche wrote:
> "Clocky"<not...@happen.com> wrote:
>> "Bernd Felsche" wrote
>
>>> I'm trying to figure out the current draw by the starter solenoid,
>>> (not the starter motor) at terminal 50.
>>>
>>> It's powered through the ignition switch in the Golf GTI but the 4mm
>>> wiring has me baffled. That's too much current to go through a
>>> little ignition switch if the wire is sized for current capacity.
>>>
>>> So I assume it's sized to avoid voltage drop, which leaves me none
>>> the wiser regarding the current actually drawn by the starter
>>> solenoid.
>
>> Why not put an ammeter in series?
>
> Because it could fry the poor thing ...
> Most multimeters maxo ut at 10 Amps.
> I suspect that it could be 30A, if not more.
> Bosch book says 30 to 70A, depending on the size of the starter.

That's a hell of a current to be going through the switch, it would be
very unusual for there not to be a relay?


Daryl

D Walford

unread,
Nov 2, 2011, 7:24:30 PM11/2/11
to
On 03/11/2011 1:35 AM, Bernd Felsche wrote:
> PeterD<pet...@hipson.net> wrote:
>
>> On 11/2/2011 3:45 AM, Bernd Felsche wrote:
>>> Something I don't know ... and can't seem to find out all that
>>> easily.
>>>
>>> I'm trying to figure out the current draw by the starter solenoid,
>>> (not the starter motor) at terminal 50.
>>>
>>> It's powered through the ignition switch in the Golf GTI but the 4mm
>>> wiring has me baffled. That's too much current to go through a
>>> little ignition switch if the wire is sized for current capacity.
>>>
>>> So I assume it's sized to avoid voltage drop, which leaves me none
>>> the wiser regarding the current actually drawn by the starter
>>> solenoid.
>
>> I believe you will find there is a relay in the circuit. What year
>> Golf is it? BTW, yes, it is a lot of current--more than one might
>> expect.
>
> 1990. There's 4mm wiring into and out of the ignition switch when I
> last had that part of the sah and steering column uncovered.
>
> Current flow diagrams (two sources) draw it as direct-wired.
> No relay.

Most starter relays are no more 30amps so that suggests the current is
less than 30amps on most cars.
Not having a relay is most unusual but it is a VW.
Are you trying to fix a fault, why do you need to know how much current
its drawing?


Daryl

Bernd Felsche

unread,
Nov 2, 2011, 9:46:00 PM11/2/11
to
Since you ask; not unusual. They're probably counting on the current
being intermittent.

As the at least 8 million vehicles of that type have exactly that
same starter wiring, from 1983 to 1992. And probably another few
million Jetta clones produced in China over the past 20 years with
the same.

Bernd Felsche

unread,
Nov 2, 2011, 9:49:10 PM11/2/11
to

Clocky

unread,
Nov 3, 2011, 5:27:42 AM11/3/11
to
I don't think the current draw is as high as you think. I remember a common
fix for starting problems due to volt drop was to fit a standard relay.

The heavier guage wiring would be to reduce volt drop, not for high current
draw.



D Walford

unread,
Nov 3, 2011, 7:45:39 AM11/3/11
to
That was a common fix on many older Toyota's, I've even fitted a couple
myself for the same reason.

> The heavier guage wiring would be to reduce volt drop, not for high current
> draw.
>

Most likely spot on.


Daryl

Scotty

unread,
Nov 4, 2011, 5:47:45 AM11/4/11
to


"Bernd Felsche" wrote in message
news:vr08o8...@innovative.iinet.net.au...

"Clocky" <not...@happen.com> wrote:
>"Bernd Felsche" wrote

>> I'm trying to figure out the current draw by the starter solenoid,
>> (not the starter motor) at terminal 50.
>>
>> It's powered through the ignition switch in the Golf GTI but the 4mm
>> wiring has me baffled. That's too much current to go through a
>> little ignition switch if the wire is sized for current capacity.
>>
>> So I assume it's sized to avoid voltage drop, which leaves me none
>> the wiser regarding the current actually drawn by the starter
>> solenoid.

>Why not put an ammeter in series?

Because it could fry the poor thing ...
Most multimeters maxo ut at 10 Amps.
I suspect that it could be 30A, if not more.
Bosch book says 30 to 70A, depending on the size of the starter.


/"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia
\ / ASCII ribbon campaign | For every complex problem there is an
X against HTML mail | answer that is clear, simple, and wrong.
/ \ and postings |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I'd be VERY surprised if it was over 10 Amps to be honest. a 4 mm2 cable.
Seeing as a 4mm cable is really only capable of 30 Amps for a reasonably
short time.

Id be testing with an ammeter. 90% of ammeters have internal fuses
protecting the device anyway.

Scotty


Scotty

unread,
Nov 4, 2011, 6:02:21 AM11/4/11
to


"PeterD" wrote in message news:j8rng0$g1f$1...@speranza.aioe.org...
I'm sure that a DC Clamp meter is definitely the best option to start with,
if its under 10 amps then utilise an in series meter as they are more
accurate than most DC clamp meters.

Then again, DC clamp meters are not something that most people have lying
around in their garage.

Message has been deleted
Message has been deleted
Message has been deleted

Bernd Felsche

unread,
Nov 5, 2011, 2:51:29 AM11/5/11
to
Paul Saccani <sac...@omen.net.au> wrote:
>Bernd Felsche wrote:

>>Something I don't know ... and can't seem to find out all that
>>easily.
>>
>>I'm trying to figure out the current draw by the starter solenoid,
>>(not the starter motor) at terminal 50.
>>
>>It's powered through the ignition switch in the Golf GTI but the 4mm
>>wiring has me baffled. That's too much current to go through a
>>little ignition switch if the wire is sized for current capacity.
>>
>>So I assume it's sized to avoid voltage drop, which leaves me none
>>the wiser regarding the current actually drawn by the starter
>>solenoid.

>Easiest way to find out is to stick a clamp meter on it. If you don't
>have one, as usual, I can offer to loan you one and you can decline
>the offer. ;)

I've got one. Actually, a couple.

>It also depends on what timescale you want to look at. As an
>inductive rather than resistive load, the current can have quite wild
>transients, but for average current, 3 to 10 A would be typical for a
>pre-engaged starter, and a clamp meter would be able to provide the
>average current no worries.

>If you do want to know in more detail, and inductive probe and a
>storage oscilloscope and a good deal of calculation would be needed.
>A short loan of the equipment is possible.... ;)

Please stop trying to lend me stuff. Everything that I've ever
borrowed uses up space in my shed. ;-)

I also have a hand-held, digital 'scope. One of the clamp meters has
peak-hold -- I'd forgotten about that. It might do the trick.

Well, it'd tell me the current through the circuit. Which isn't
necessarily the same current that'll be drawn when the long wire is
replaced with a short one and a transistor switch.

Scotty

unread,
Nov 5, 2011, 7:53:11 AM11/5/11
to


"Paul Saccani" wrote in message
news:5n79b75bq5d67su5c...@4ax.com...

On Fri, 4 Nov 2011 19:47:45 +1000, "Scotty" <sco...@warmmail.com>
wrote:

>
>I'd be VERY surprised if it was over 10 Amps to be honest. a 4 mm2 cable.
>Seeing as a 4mm cable is really only capable of 30 Amps for a reasonably
>short time.
>
>Id be testing with an ammeter. 90% of ammeters have internal fuses
>protecting the device anyway.

That's a rather optimistic view of the effectiveness of the fuse. The
fuse is intended for personnel protection - they rarely protect the
meter from *high* currents - errant students demonstrate the art of
meter destruction to me at regular intervals.

They often blow the tracks away before the fuse blows, sometimes even
the internal shunt goes before the fuse does.

Cheers,
Paul Saccani
Perth, Western Australia.
><><><><><><>><<><><><><><><><><><><><><><><><><><><><><><><><><><><><

There should be HRC fuses in meters. They should blow well before the
tracks, should that is,

PeterD

unread,
Nov 5, 2011, 8:16:49 AM11/5/11
to
Face it, when you pay $5 for a DVOM today (WalMart, Harbor Freight,
etc.) any fuse is a luxury.

PeterD

unread,
Nov 5, 2011, 8:19:27 AM11/5/11
to
On 11/4/2011 10:21 PM, Paul Saccani wrote:

>
> Easiest way to find out is to stick a clamp meter on it. If you don't
> have one, as usual, I can offer to loan you one and you can decline
> the offer. ;)

<BSEG> Careful someone may take you up on that!

>
> It also depends on what timescale you want to look at. As an
> inductive rather than resistive load, the current can have quite wild
> transients, but for average current, 3 to 10 A would be typical for a
> pre-engaged starter, and a clamp meter would be able to provide the
> average current no worries.
> ]

Many (better) clamp-on meters have a peak read feature that will save
the highest reading as well display the current value. Very useful for
seeing start-up surges.

> If you do want to know in more detail, and inductive probe and a
> storage oscilloscope and a good deal of calculation would be needed.
> A short loan of the equipment is possible.... ;)

Again, some DVOMs have RS-232 or other computer output that may allow
similar features.

Ah, but we're over testing, I think, the OP's problem!

Noddy

unread,
Nov 5, 2011, 9:06:53 AM11/5/11
to
On 5/11/2011 11:16 PM, PeterD wrote:

> Face it, when you pay $5 for a DVOM today (WalMart, Harbor Freight,
> etc.) any fuse is a luxury.

Walmart? Harbor Freight?

Surely you mean Bunnings or Repco :)



--
Regards,
Noddy.
Message has been deleted

PeterD

unread,
Nov 5, 2011, 4:28:04 PM11/5/11
to
Uh, sure... <bg>

Jeßus

unread,
Nov 5, 2011, 4:54:07 PM11/5/11
to
On Sat, 05 Nov 2011 16:28:04 -0400, PeterD <pet...@hipson.net> wrote:

>On 11/5/2011 9:06 AM, Noddy wrote:
>> On 5/11/2011 11:16 PM, PeterD wrote:
>>
>>> Face it, when you pay $5 for a DVOM today (WalMart, Harbor Freight,
>>> etc.) any fuse is a luxury.
>>
>> Walmart? Harbor Freight?
>>
>> Surely you mean Bunnings or Repco :)
>>
>
>Uh, sure... <bg>

Shouldn't you be waiting for some sucker to post in
alt.marketing.online.ebay? I wonder how Lumpy is going...

Bernd Felsche

unread,
Nov 5, 2011, 11:27:45 PM11/5/11
to
Paul Saccani <sac...@omen.net.au> wrote:
>Bernd Felsche wrote:

>>I also have a hand-held, digital 'scope. One of the clamp meters has
>>peak-hold -- I'd forgotten about that. It might do the trick.
>>
>>Well, it'd tell me the current through the circuit. Which isn't
>>necessarily the same current that'll be drawn when the long wire is
>>replaced with a short one and a transistor switch.

>...and now we get to what you are really up to. No doubt with a
>MOSFET in mind. Don't neglect the back EMF, and the transient inrush
>current could be significant.

That's my main concern. The inrush and other transients.

>You could always buy a COTS solid state relay - for you to engineer as
>good a solution from parts for the hostile environment it can expect
>to live in, is something that will cost you a good deal more than the
>$23 for a COTS 80 A 0-100VDC solid state relay.

BTS50055-1TMB is designed for the environment, provides useful
feedback and therefore diagnostics (at about $6). I need to
determine the solenoid current to allow for an adequate "overkill".

Bernd Felsche

unread,
Nov 5, 2011, 11:49:20 PM11/5/11
to
Bernd Felsche <ber...@innovative.iinet.net.au> wrote:
>Paul Saccani <sac...@omen.net.au> wrote:
>>Bernd Felsche wrote:

>>>Well, it'd tell me the current through the circuit. Which isn't
>>>necessarily the same current that'll be drawn when the long wire is
>>>replaced with a short one and a transistor switch.

>>...and now we get to what you are really up to. No doubt with a
>>MOSFET in mind. Don't neglect the back EMF, and the transient inrush
>>current could be significant.

>That's my main concern. The inrush and other transients.

>>You could always buy a COTS solid state relay - for you to engineer as
>>good a solution from parts for the hostile environment it can expect
>>to live in, is something that will cost you a good deal more than the
>>$23 for a COTS 80 A 0-100VDC solid state relay.

>BTS50055-1TMB is designed for the environment, provides useful
>feedback and therefore diagnostics (at about $6). I need to
>determine the solenoid current to allow for an adequate "overkill".

In retrospect (?), I can prototype just the power circuit to make
sure that it doesn't release the magic smoke. Although testing would
only be for the conditions under which I'm testing ... so need to
make them as bad as possible.
Message has been deleted
Message has been deleted
Message has been deleted
Message has been deleted

Scotty

unread,
Nov 6, 2011, 5:46:01 AM11/6/11
to


"Paul Saccani" wrote in message
news:iblcb7d3dvp4jn5rp...@4ax.com...

On Sat, 5 Nov 2011 21:53:11 +1000, "Scotty" <sco...@warmmail.com>
wrote:

>><><><><><><>><<><><><><><><><><><><><><><><><><><><><><><><><><><><><
>
>There should be HRC fuses in meters. They should blow well before the
>tracks, should that is,

A lot of DMM don't come with HRC fuses. I always replace those with
HRC before letting the unwashed use them. Nonetheless, it still
happens with depressing regularity. I also use a cheap $1.50 6A fuse
instead of the $60 13A fluke DMM fuse. The cheap will never blow
later than the expensive one for an overload, but of course, is not
rated for 13A continuous. As none of the training program requires
more than 6A continuous, it is OK.

I did a test program before doing that, and it was quite interesting.
At 4.5 A constant, the Fluke blows after a while, even though it is
rated at 13A constant, whilst the 6A is happy, and always blows sooner
than the fluke fuse with a genuine overload.

Cheers,
Paul Saccani
Perth, Western Australia.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Have you tried RS Components for HRC Fuses. My fluke takes them and they are
$28 for a pack of 5 last time I bought one. The downside for me is that they
only sell them in packs of five, for you that is a bonus ;o)

PeterD

unread,
Nov 6, 2011, 8:41:08 AM11/6/11
to
I see a bunch of posts there, so I suspect he's going balls to the wall!

As for cheap DVOMs, I was in Harbor Freight the other day. The deal was
spend a relatively nominal amount, and they gave you a free DVOM. So I
got two!

I tested their accuracy, it was OK (not great, but usable) so for the
price a winner.
Message has been deleted

Scotty

unread,
Nov 9, 2011, 3:18:46 AM11/9/11
to


"Paul Saccani" wrote in message
news:54dib71a87vcv26r8...@4ax.com...

>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>Have you tried RS Components for HRC Fuses. My fluke takes them and they
>are
>$28 for a pack of 5 last time I bought one. The downside for me is that
>they
>only sell them in packs of five, for you that is a bonus ;o)

I know the ones you mean.

A fluke fuse is a HRC fuse, but it is a very special one. You won't
get an equivalent from RS for less than $50 each. You will get ones
that are HRC and the same size, but they are not equivalents.

Inside a fluke fuse, you have the usual sand, but the fuse itself is a
perforated strip, folded concertina style on the perforations. That's
what lets it react so quickly to overload to protect not just you, but
the meter too (though fluke meters usually have VDRs as well).

The ones that you are getting, if rated to 1000 V and 5kA will provide
personnel protection, but will diminish the meter protection
significantly.


Cheers,
Paul Saccani
Perth, Western Australia.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Interesting, thanks for that.

Scotty

PeterD

unread,
Nov 9, 2011, 8:22:32 AM11/9/11
to
Agreed, this has been an interesting thread with a lot of good
information. BTW, a common failure on (I'm going to say earlier, but
we're talking 80's and later) VWs is the inline spade connector to the
solenoid. Corrosion builds in that connector resulting in a high
resistance joint. This got me on my Cabriolet (an 88) a few years ago.
Someone here pointed out what the likely problem was and he was correct.
Because the solenoid does draw a lot more current than one realizes any
resistance is a big problem.

Bernd Felsche

unread,
Nov 20, 2011, 6:21:18 AM11/20/11
to
Bernd Felsche <ber...@innovative.iinet.net.au> wrote:
>Paul Saccani <sac...@omen.net.au> wrote:
>>Bernd Felsche wrote:

>>>I also have a hand-held, digital 'scope. One of the clamp meters has
>>>peak-hold -- I'd forgotten about that. It might do the trick.

>>>Well, it'd tell me the current through the circuit. Which isn't
>>>necessarily the same current that'll be drawn when the long wire is
>>>replaced with a short one and a transistor switch.

>>...and now we get to what you are really up to. No doubt with a
>>MOSFET in mind. Don't neglect the back EMF, and the transient inrush
>>current could be significant.

>That's my main concern. The inrush and other transients.

>>You could always buy a COTS solid state relay - for you to engineer as
>>good a solution from parts for the hostile environment it can expect
>>to live in, is something that will cost you a good deal more than the
>>$23 for a COTS 80 A 0-100VDC solid state relay.

>BTS50055-1TMB is designed for the environment, provides useful
>feedback and therefore diagnostics (at about $6). I need to
>determine the solenoid current to allow for an adequate "overkill".

The clamp meter shows just 5A peak in the solenoid. I suspect that's
the average over about 0.1 seconds; which is about how long it takes
to close the contacts that pull in the starter fully.

The 5A is the highest peak out of about 20 (*) successive starts. I
suspect that that's an average over the sampling period. Figures
are scattered all over the place; from 0.3A up to 5A. Most in the 3
to 5A range.

I'll have to put the digital scope with linear Hall-effect sensor on
the wire to find the peak inrush current.

(*) Don't want to cook the starter motor with too many successive starts
without a reasonable cooling off period.

Paul Saccani

unread,
Nov 23, 2011, 6:33:28 AM11/23/11
to
On Sun, 20 Nov 2011 19:21:18 +0800, Bernd Felsche
<ber...@innovative.iinet.net.au> wrote:

>The clamp meter shows just 5A peak in the solenoid. I suspect that's
>the average over about 0.1 seconds; which is about how long it takes
>to close the contacts that pull in the starter fully.
>
>The 5A is the highest peak out of about 20 (*) successive starts. I
>suspect that that's an average over the sampling period. Figures
>are scattered all over the place; from 0.3A up to 5A. Most in the 3
>to 5A range.

You would be real lucky if the clampl meter had a sample rate as high
as 10 Hz - many seem to have a sample rate of less than one per
second!
Cheers,

Paul Saccani,
Perth,
Western Australia

cl...@snyder.on.ca

unread,
Apr 8, 2012, 6:50:07 PM4/8/12
to
On Fri, 4 Nov 2011 19:47:45 +1000, "Scotty" <sco...@warmmail.com>
wrote:

>
>
>"Bernd Felsche" wrote in message
>news:vr08o8...@innovative.iinet.net.au...
>
>"Clocky" <not...@happen.com> wrote:
>>"Bernd Felsche" wrote
>
>>> I'm trying to figure out the current draw by the starter solenoid,
>>> (not the starter motor) at terminal 50.
>>>
>>> It's powered through the ignition switch in the Golf GTI but the 4mm
>>> wiring has me baffled. That's too much current to go through a
>>> little ignition switch if the wire is sized for current capacity.
>>>
>>> So I assume it's sized to avoid voltage drop, which leaves me none
>>> the wiser regarding the current actually drawn by the starter
>>> solenoid.
>
>>Why not put an ammeter in series?
>
>Because it could fry the poor thing ...
>Most multimeters maxo ut at 10 Amps.
>I suspect that it could be 30A, if not more.
>Bosch book says 30 to 70A, depending on the size of the starter.
>
>
>/"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia
>\ / ASCII ribbon campaign | For every complex problem there is an
>X against HTML mail | answer that is clear, simple, and wrong.
>/ \ and postings |
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>I'd be VERY surprised if it was over 10 Amps to be honest. a 4 mm2 cable.
>Seeing as a 4mm cable is really only capable of 30 Amps for a reasonably
>short time.
>
>Id be testing with an ammeter. 90% of ammeters have internal fuses
>protecting the device anyway.
>
>Scotty
>
Put a 7 amp fuse in line and crank the engine. If it doesn't blow you
pretty well know it;s less than 12 amps (fuse can take about 60%
overcurrent for several seconds)

cl...@snyder.on.ca

unread,
Apr 8, 2012, 6:51:51 PM4/8/12
to
On Sat, 05 Nov 2011 10:41:58 +0800, Paul Saccani <sac...@omen.net.au>
wrote:

>On Fri, 4 Nov 2011 19:47:45 +1000, "Scotty" <sco...@warmmail.com>
>wrote:
>
>>
>>I'd be VERY surprised if it was over 10 Amps to be honest. a 4 mm2 cable.
>>Seeing as a 4mm cable is really only capable of 30 Amps for a reasonably
>>short time.
>>
>>Id be testing with an ammeter. 90% of ammeters have internal fuses
>>protecting the device anyway.
>
>That's a rather optimistic view of the effectiveness of the fuse. The
>fuse is intended for personnel protection - they rarely protect the
>meter from *high* currents - errant students demonstrate the art of
>meter destruction to me at regular intervals.
>
>They often blow the tracks away before the fuse blows, sometimes even
>the internal shunt goes before the fuse does.
The PROPER fast blow instrument fuse IS there to protect the meter -
and IS generally effective. Using a standard or slow blow fuse WILL
fry the meter. NEVER replace the meter fuse with other than the
proper quick-blow meter fuse.

cl...@snyder.on.ca

unread,
Apr 8, 2012, 6:53:47 PM4/8/12
to
On Sun, 06 Nov 2011 17:47:51 +0800, Paul Saccani <sac...@omen.net.au>
wrote:

>On Sat, 05 Nov 2011 08:16:49 -0400, PeterD <pet...@hipson.net> wrote:
>
>>>
>>> There should be HRC fuses in meters. They should blow well before the
>>> tracks, should that is,
>>
>>Face it, when you pay $5 for a DVOM today (WalMart, Harbor Freight,
>>etc.) any fuse is a luxury.
>
>Besides us not being merkins, the fuse is there to protect you more
>than the meter.
Nope. Unless they work different when they are upside-down, and I
didn't notice that effect in Livingstone.
Message has been deleted
Message has been deleted

PeterD

unread,
Apr 11, 2012, 2:23:15 PM4/11/12
to
On 4/8/2012 11:18 PM, Paul Saccani wrote:
> I'm sorry, but with the greatest of respect, you do not know what you
> are talking about.

Someone thinks the fuse in the meter protects the user, which is not the
case. Whether the fuse is there, blown, or not in existence, the hazards
are the same. The fuse is intended to protect the meter from excessive
currents, and nothing else.
Message has been deleted

Trevor Wilson

unread,
Apr 12, 2012, 3:04:47 AM4/12/12
to
On 11/3/2011 1:31 AM, Bernd Felsche wrote:
> "Clocky"<not...@happen.com> wrote:
>> "Bernd Felsche" wrote
>
>>> I'm trying to figure out the current draw by the starter solenoid,
>>> (not the starter motor) at terminal 50.
>>>
>>> It's powered through the ignition switch in the Golf GTI but the 4mm
>>> wiring has me baffled. That's too much current to go through a
>>> little ignition switch if the wire is sized for current capacity.
>>>
>>> So I assume it's sized to avoid voltage drop, which leaves me none
>>> the wiser regarding the current actually drawn by the starter
>>> solenoid.
>
>> Why not put an ammeter in series?
>
> Because it could fry the poor thing ...
> Most multimeters maxo ut at 10 Amps.
> I suspect that it could be 30A, if not more.
> Bosch book says 30 to 70A, depending on the size of the starter.

**This'll do the trick:

http://www.jaycar.com.au/productView.asp?ID=QM1563&keywords=clamp+meter&form=KEYWORD

You should be able to borrow one from your local sparky. Most have them
now, though DC rated ones are a little rarer. Auto electricians have
them. Or should.

--
Trevor Wilson www.rageaudio.com.au

Krypsis

unread,
Apr 12, 2012, 4:57:17 AM4/12/12
to
Have one similar out in the garage. Much easier to use.

--

Krypsis
Message has been deleted

Krypsis

unread,
Apr 12, 2012, 7:56:52 AM4/12/12
to
On 12/04/2012 9:01 PM, Paul Saccani wrote:
> I already offered him a loaner. He prefers not to borrow equipment.
>
> You can't fault that.

A group of us used to share equipment. Had all manner of things. If we
needed something, we'd pool our resources and just buy it. Trouble is,
most members of the old group have shuffled off their mortal coils now.
I was one of the youngsters in the group. Actually, come to think of it,
I am the youngest that's left out of the few who "were" young'uns.
Ah well, I'm a tad too knackered to be crawling around and under cars
now. Best leave it to the next generation I guess!

--

Krypsis

itsu...@protectorfire.com.au

unread,
Jun 9, 2016, 5:00:53 AM6/9/16
to
It is a little more complex.

The initial current required to move the solenoid is far higher than that required to hold it in place. Thus, many cars have duel coils, one to move, and the other to hold. Thus, you may get say a 15 amp 1/2 second pulse, followed by a steady 2 amps.

Mal
http://protectorfire.com.au

shane...@gmail.com

unread,
Nov 7, 2016, 10:11:23 PM11/7/16
to
With a starter on the bench from a VT ecotec v6 the solenoid pulls over 20a from my 30a powersupply.

aziz...@gmail.com

unread,
Oct 28, 2017, 10:10:46 AM10/28/17
to
I want to modify the circuit to add another relay to power the solenoid thus lessen the load, to energize relay it takes around 150mA.
Supply taken directly from battery.

Bernd Felsche

unread,
Oct 28, 2017, 10:39:10 PM10/28/17
to
Solenoid current draw is around 30A. The starter solenoid performs
two tasks; to switch the very much larger starter motor current
(300+ amps) AND to engage the starter motor's drive pinion.

A solid state relay (SSR) will switch faster than a mechanical relay
but is more expensive, especially when allowing for engine
compartment temperatures. When shopping for one, make sure it's a DC
SSR and rated for at least 105 degrees C operating temperature. You
can tuck it in near the battery so that it's not exposed to the
hottest parts of the engine.

If you're good with electronics, you have the option of making your
own solid-state relay around a high-side MOSFET with "logic level"
control. There are lots of them made by e.g. Infineon designed for
engine-compartment (automotive 125 degrees C) temperatures. They can
switch up to hundreds of amps, depending on type.
--
/"\ Bernd Felsche - Somewhere in Western Australia
\ / ASCII ribbon campaign | For every complex problem there is an
X against HTML mail | answer that is clear, simple, and wrong.
/ \ and postings | --HL Mencken
0 new messages