starter solenoid pull in voltage

I don't think so. Once the solenoid passes enough current to begin moving, it accelerates rapidly to full stroke, since the force that current produces increases as the stroke takes place.

The inrush capability has more to do with the physical size of the contacts.

Thanks for your reply John,

The reason I asked is I did a study with 2000pcs of 12V starter solenoid. 1000pcs has pull in voltage of 4.5V and the other 1000pcs has 6V. Both batch went through 420A in rush for 1ms.

A few of the 4.5V got stuck while none of the 6V got stuck.

I was thinking may be increasing the pull in voltage will increase the in rush current that that starter solenoid can withstand.

Games I am currently play> snipped-for-privacy@advanceagent.com wrote:

A few out of 2000 is a pretty small sample. I can't imagine the mechanism that would couple pull in voltage and sticking, unless it is the return spring force (lower for the lower pull in voltage units, if everything else is similar). That spring force is what breaks the contacts apart after they spot weld.

The 4.5V and 6V lots are identical starter solenoid with the exception of the stated pull in voltage. I think the manufacturer adjusted the weight of the plunger to get the different pull in voltage. This has the same effect as changing the spring force, correct?

So what you're saying is that the reason the 6V lot did not have any sticks was because it has a higher spring force(due to lower plunger weight, everything else being equal) thus a higher force to break the contacts?

Thanks again for your inputs.

The 4.5V and 6V lots are identical starter solenoid with the exception of the stated pull in voltage. I think the manufacturer adjusted the weight of the plunger to get the different pull in voltage. This has the same effect as changing the spring force, correct?

So what you're saying is that the reason the 6V lot did not have any sticks was because it has a higher spring force(due to lower plunger weight, everything else being equal) thus a higher force to break the contacts?

Thanks again for your inputs.

Games I am currently playing:

If you increase the coil voltage you will increase the current in proportion.

-- _____ _ _ |_ _| | | | | | | __ _ _ __ ___ | |__| | ___ _ __ ___ ___ _ __ | | / _` | '_ ` _ \\ | __ |/ _ \\| '_ ` _ \\ / _ \\ '__| _| |_ | (_| | | | | | | | | | | (_) | | | | | | __/ | |_____| \\__,_|_| |_| |_| |_| |_|\\___/|_| |_| |_|\\___|_| __ ____ / _| | _ \\ ___ | |_ | |_) | ___ _ __ __ _ / _ \\| _| | _ < / _ \\| '__/ _` | | (_) | | | |_) | (_) | | | (_| |_ \\___/|_| |____/ \\___/|_| \\__, (_) __/ | |___/

...

...

I don't know why one pules in with less voltage than the other. You say they are otherwise identical, so I assume they draw the same coil current for the same drive voltage (same coil resistance).

They could have altered the pull in voltage by changing the travel distance, changing the spring stiffness, altering the shape of the moving core and stationary pole piece, and probably some other things, too.

But, if they altered the spring stiffness (used a stiffer spring) it would have raised the pull in voltage and increased the force separating the contacts, lessening the chance of a stick.

That hundreds of amps inrush goes through the motor windings in the starter, not the solenoid. So I think the conditions of the solenoid will have very little effect on it.

Maybe, but good programmers know how to set the clock on their computers.

the reason the 4.5 are getting stuck is because there is insufficient impact created from the velocity generated from the coil to clamp the the contacts together soon enough before the induction of the motor (starter) can cause damage to the contacts and thus weld them.

a Peak and Hold driver circuit most likely could work here, the same theory as used in fuel injectors for the same reason to prevent sticking of the mechanism in response. because you also have to worry about the initial force required to get the core moving.

we have some special motor started relays at work that have dual coils in them that use a low level AUX contact mounted on the body. the idea is when the relay is in the OFF state, both coils are connected., when the core reaches almost to the close point the AUX contacts open one coil. this gives us a low but effective holding current. when making contactors to be compact, its important to think about these things. they also make electronic Peak and Hold types.

really, my clock seems to be working fine! :)) l'll look into that.

Thank you for the suggestion of using Peak & Hold driver, but that will not be an option in this case. I can change the starter solenoid only and not other electricals.

So in your opinion, increasing the pull in voltage to 6V(either by a stiffer spring or change the core, or other means) will lessen the chance for sticking?

Games I am currently play> snipped-for-privacy@advanceagent.com wrote:

Evidently (based on your test data) whatever they did to raise the pull in voltage gave at least a slight improvement in the sticking problem. But you give up something. You give up any possibility of pulling in the solenoid below 6 volts. Is that worth anything to you?

By the way, are you at all sure a 420 amp inrush in the first millisecond represents what your actual contact load does? If the load is inductive, it may not allow the current to rise that fast. If the current rises after the contacts stop bouncing, they are less likely to weld.

Juz' unbelievable...