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Startus interruptus fix caused other problems. Advice needed please!


Jim in NZ
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Is this the only starter solenoid you have found to have this setup . This setup is seen a lot on fuel  {shutoff} control solenoids on diesel systems , and I forgot ,gasoline fuel injectors . 

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Should we add an electrical theory forum to this site or is a part of the Moto Guzzi ownership included ?

p.s. I thought I was the only one curious {stupid} enough to take off down the driveway with a coil in my hand seeing how much wire IS in a winding . 

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3 hours ago, gstallons said:

Should we add an electrical theory forum to this site or is a part of the Moto Guzzi ownership included ?

p.s. I thought I was the only one curious {stupid} enough to take off down the driveway with a coil in my hand seeing how much wire IS in a winding . 

Ever since a kid I have been pulling stuff apart to see how it works, and why it don't of course.  I carried on through my career as an electrician and instrument technician why should I change now LOL

https://ibb.co/JdRY2x0

 

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That's a Bosch solenoid but they are all similar, all have two coils from 70s to today.

The coils on my VII Sport measured 1.25 Ohms and 0.25 Ohms

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I hate to think and get this wrong , but which "coil" leads when this this action takes place and what does the other coil do during this event ? 

 Then when does the other coil "take over" ?

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Both coils work together, they both turn on the instant the start relay closes.

The "holding coil" is wired between the spade connector and chassis so as long as the spade connector is powered up (Start Relay closed) it's drawing current ~10 Amps. On its own the holding coil will never be able to pull the solenoid in.

The "grunt coil" is wired between the spade connector and the motor armature, it will draw up to 50 Amps through the armature to chassis so its potentially 4-5 times as strong as the "holding coil" but only while the solenoid is stroking. As soon as the solenoid reaches the end of travel the main contact closes, now you have +12 Volts on both ends of the "grunt coil" so it's effectively switched out of the circuit. The "holding coil" is strong enough to hold the solenoid in place.

While the starter is stationary the armature is effectively a short circuit, the current from the "grunt coil" will tend to start it spinning which generates back EMF but it happens so fast <50 milliseconds it doesn't have time to accelerate.

If you get the 50 Amps the solenoid is designed to work with it will stroke in 15 milliseconds. (I have measured this with an Oscilloscope).

Of course the solenoid operation depends on the bike wiring being able to feed enough current to the coils, the stock wiring will deliver about 30 Amps on a good day, so working at about 60% of starter design. 

Another thing that chokes the solenoid down is the tiny wire from the Start Relay to the Solenoid spade connector, it needs to be at least one size larger.

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I will NEVER understand why things are underdesigned (if that is a real word) when something a little larger does the job ! Smaller gauge wire , mini-relays , etc... Yuck . I hope underwater craft & aircraft are not built with this spartan design .

 

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31 minutes ago, gstallons said:

I will NEVER understand why things are underdesigned (if that is a real word) when something a little larger does the job ! Smaller gauge wire , mini-relays , etc... Yuck . I hope underwater craft & aircraft are not built with this spartan design .

 

Let me help;

Profit margin.

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Hey Kiwi Roy,

I jumped batt + to the starter solenoid male spade terminal on my '03 V11 Lemans with a D'arsonval movement ammeter.  On my first attempt the meter bounced to 7amps and then came down to 4a during cranking, my 2nd attempt the needle went to 4amps and remained during cranking until I disconnected power.  So, I guess if some folks are getting substantially higher current draws in the starter primary circuit, they have a problem...shorted solenoid pull in or hold in coils, dirty contact in solenoid not allowing hold-in to energize.

On the other hand, I wonder how many are encountering cranking problems as a result of excessive voltage drop in the starter circuit...poor switch/relay contacts, etc.

Yeah, it sucks as these bikes get older and oddball things begin to manifest. 

  

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2 hours ago, guzziart said:

 . . .  get older and oddball things begin to manifest. 

  

When you say "get older" and "oddball things" in the same sentence, I get a creepy feeling  and have to take a leak and swap my relays around . . .  :unsure:

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12 hours ago, docc said:

When you say "get older" and "oddball things" in the same sentence, I get a creepy feeling  and have to take a leak and swap my relays around . . .  :unsure:

Yeah, I definitely leak more than my bikes.  One nice thing is that I replaced all the relays last week on the Lemans so, one less thing to worry about and the price was right!

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11 hours ago, guzziart said:

Yeah, I definitely leak more than my bikes.  One nice thing is that I replaced all the relays last week on the Lemans so, one less thing to worry about and the price was right!

"The Price Is Right " relays are why I carry spare OMRON G8HE or high current rated CIT onboard.

Not for mySport, but for my V11 buddies that didn't get the memo . . .  :luigi:

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On 5/23/2022 at 2:51 PM, guzziart said:

Hey Kiwi Roy,

I jumped batt + to the starter solenoid male spade terminal on my '03 V11 Lemans with a D'arsonval movement ammeter.  On my first attempt the meter bounced to 7amps and then came down to 4a during cranking, my 2nd attempt the needle went to 4amps and remained during cranking until I disconnected power.  So, I guess if some folks are getting substantially higher current draws in the starter primary circuit, they have a problem...shorted solenoid pull in or hold in coils, dirty contact in solenoid not allowing hold-in to energize.

On the other hand, I wonder how many are encountering cranking problems as a result of excessive voltage drop in the starter circuit...poor switch/relay contacts, etc.

Yeah, it sucks as these bikes get older and oddball things begin to manifest. 

  

I have no explanation as to your low current but your meter is not fast enough to measure the initial inrush, its all over in a few milliseconds.

Ohms law doesn't lie, try measuring the coil resistance from spade connector to chassis and then calculate  12 / Ohms.

Actually you will have trouble measuring Ohms with a multimeter because its less than 1/4 Ohm, I use a method called a "Drop Test", its where you pass a known current through a resistance then measure the Voltage across it, using this method you can measure very low resistances accurately.

I have used an instrument that would measure busbar joints down to 1 millionth of an Ohm (yes 0.000,001 Ohms) but it passed 100 Amps through the joint.

You could use a headlight bulb e.g 60 Watts in series with the solenoid measure the current through the coil say 5 Amps, the drop would be ~ 1.25 Volt, easily readable with your average multimeter. Remember the heavy coil is in series with the starter armature, its very close to zero resistance.

Of course your current may be low because you have too much resistance in series

There is something else you could try with your Ammeter, disconnect the main positive lead to the solenoid, now your inrush current will last as long as the spade connector is powered up, because the starter armature will never see +12 Volts it effectively keeps the heavy current (Grunt Coil) in circuit. The 15 Amp fuse will blow in < 1 second so be prepared to replace that with a 20.

Now you have a nice stable current into the solenoid then you can measure the Voltage across the coils and calculate the resistance accurately. One thing that will disrupt your reading is if the motor starts to spin, if that happens the motor will develop what is known as Back EMF (the motor generating Voltage), you should hear the motor if that happens.

 

I had to look this up "D'arsonval movement ammeter", I would just call that a moving coil meter, of course the main current must be passing through a shunt.

It's very easy to measure current by passing the current through a copper wire and measuring the Millivolt drop with any $10 multimeter., I'm sure I posted something a while back on that.

https://ibb.co/3kkcX7P

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On 5/23/2022 at 9:13 AM, Kiwi_Roy said:

Both coils work together, they both turn on the instant the start relay closes.

The "holding coil" is wired between the spade connector and chassis so as long as the spade connector is powered up (Start Relay closed) it's drawing current ~10 Amps. On its own the holding coil will never be able to pull the solenoid in.

The "grunt coil" is wired between the spade connector and the motor armature, it will draw up to 50 Amps through the armature to chassis so its potentially 4-5 times as strong as the "holding coil" but only while the solenoid is stroking. As soon as the solenoid reaches the end of travel the main contact closes, now you have +12 Volts on both ends of the "grunt coil" so it's effectively switched out of the circuit. The "holding coil" is strong enough to hold the solenoid in place.

While the starter is stationary the armature is effectively a short circuit, the current from the "grunt coil" will tend to start it spinning which generates back EMF but it happens so fast <50 milliseconds it doesn't have time to accelerate.

If you get the 50 Amps the solenoid is designed to work with it will stroke in 15 milliseconds. (I have measured this with an Oscilloscope).

Of course the solenoid operation depends on the bike wiring being able to feed enough current to the coils, the stock wiring will deliver about 30 Amps on a good day, so working at about 60% of starter design. 

Another thing that chokes the solenoid down is the tiny wire from the Start Relay to the Solenoid spade connector, it needs to be at least one size larger.

Ahhhh , I now understand how the pull winding is "turned off" . Damn , that is a smart way to control the on/off of the pull winding on the solenoid .

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