Ignition coil testing

[boscoe99]

Would offering a procedure to test an ignition coil that uses AC wall outlet voltage to charge a capacitor be less than desirable for a wannabee trainee marine mechanic?

110 volts AC is converted to ~ 170 volts DC to charge a capacitor.

A fool could quickly kill or injure himself and I have no way of differentiating fools from non fools.

[ausnoelm]

In my experience....anything to do with mains supply can be a death sentence to home handymen who don't/won't/can't follow instructions. Once the capacitor is charged, it would be safe enough, might give you a fright and a shock, but chances of death would be slim (unless it's a very big capacitor)

[99yam40]

Since I was an electrician for many years, I know better than touching stuff I should not be touching when testing.
But I did touch something once that sent me to the Hospital for observation overnight just incase my heart stopped hours after the shock. (it was a long shutdown and many hours being worked, knew I had cleared the transformer and other equipment and had an ESWP (electrical safe work permit) on it.
Just forgot where we hooked into the system it was back feeding into that transformer and stepping up the voltage)

So I am not sure what non trained people would do when told not to touch certain things during testing.

but then discharging a cap at 170VDC into a coil that creates real high voltage could get their attention real quick and learn them not to touch it again.

maybe the resistance testing & peak voltage in service manual is good enough.
but as rodbolt mentioned long ago having the proper test equipment to test the KV output of a coil would be a good idea

[ausnoelm]

I wonder where Rodbolt is and if he's well?

[99yam40]

Would offering a procedure to test an ignition coil that uses AC wall outlet voltage to charge a capacitor be less than desirable for a wannabee trainee marine mechanic?

110 volts AC is converted to ~ 170 volts DC to charge a capacitor.

A fool could quickly kill or injure himself and I have no way of differentiating fools from non fools.

Would a lower voltage work like a 24V transformer feeding lower voltage into it?
what about a walwart feeding Lower voltage DC.

I would like to see this procedure to fully understand the process and how you would measure the output of the coil

[99yam40]

I wonder where Rodbolt is and if he's well?

Not sure if he is still turning wrenches in NC or went south to be around his wife's family

[ausnoelm]

Last I heard, he was somewhere in Sth America and there was some political "turmoil" but that was ages ago. I used to enjoy his posts, from way back on Iboats, THT and here, he got around, but was very knowledgeable, didn't take too well to idiots......

[boscoe99]

Would a lower voltage work like a 24V transformer feeding lower voltage into it?
what about a walwart feeding Lower voltage DC.

I would like to see this procedure to fully understand the process and how you would measure the output of the coil

I was not measuring the output of the coil. A spark plug is connected to the coil and when the capacitor is connected to the coil a spark jumps the spark plug gap.

Photos to follow.

[99yam40]

does it stay hooked up to the 120volt and just keep sparking the plug as the field collapses and builds back up as the AC goes thru zero in the sine wave?

back when I was an auto tech we had plug testers that you could adjust the gap that it had to jump along with the plug gap and add air pressure from shop air system to see if the pressure stopped the sparking(bad plug)
I never looked to see what operated that thing.

[boscoe99]

No to the capacitor staying connected to AC. Just takes a nano second to charge the capacitor. The capacitor then is moved to the coil to discharge its power into the primary of the ignition coil.

[boscoe99]

I well remember those spark plug testers.

After cleaning and gapping a plug into the tester it would go. Pressurize it to X psi and see then press the spark button. Watch to verify a good spark.

No one cleans or re-gaps plugs anymore. At least for automobiles. Throwing perfectly good plugs away.

[boscoe99]

[zenoahphobic]

Of course the only sure way to test anything is to put it into service and “then some”. We have all sorts of standards that expect more out of products to ensure they can hold up to service for sometime before deterioration becomes a problem.
Thus electrical devices tend to have higher voltage resistance expected of them. The only sure way I would be satisfied that an ignition coil is OK would to have it up to working temp (200degrees?) and that a spark plug attached is screwed into a high pressure chamber (maybe add some fuel as well). It is the high air pressure that resists arching, so voltage rises within the coil testing insulation, because insulation breakdown is the number one cause of ignition coil failures

[99yam40]

that plug tester is way too expensive

Full wave bridge rectifier and covered connectors should be safe to work around.
may need a dark room to see a single spark

[99yam40]

I would have thought the compressed air would move the molecules closer together, so letting the spark jump easier.
but that is not the way it works.
I do not fully understand.