Shocked by an alternator coil

DanMan2k06

DanMan2k06

NAXJA Forum User
Location
Damascus, MD
In class a couple days ago we were bench testing alternators, dismantling, reassembling, messing around with the voltage regulators etc etc. Well one cool thing to do was induce some voltage into the rotor (with it sitting on the table) and listen to it magnetize. We did this with a 12v test battery, those little gel cell guys. Then when you pull the leads off the coil, there is a SERIOUS arc as the field collapses and the voltage spikes. Well, I had a different experience. Instead of arcing and creating light, my fingers were on the metal. The voltage went straight into me. Holy HELL that was the worst shock I've had to date. Anyone know just how much power that would generate?
 
thats one shocking experience
 
DanMan2k06 said:
Holy HELL that was the worst shock I've had to date.
Click to expand...

Here's some advice...... Quit shocking yourself. Most humans don't shock themselves on purpose, much less more than once, then compare it to the last one....... Sounds like it may be affecting your smart parts........ But hey, if you're interested - I have a Taser and you could "ride the lightening" and compare it to your alternator zap......:D
 
Even better than an alt grab a bad plug wire while the engines running, it's a real eye opener.
 
DanMan2k06 said:
In class a couple days ago we were bench testing alternators, dismantling, reassembling, messing around with the voltage regulators etc etc. Well one cool thing to do was induce some voltage into the rotor (with it sitting on the table) and listen to it magnetize. We did this with a 12v test battery, those little gel cell guys. Then when you pull the leads off the coil, there is a SERIOUS arc as the field collapses and the voltage spikes. Well, I had a different experience. Instead of arcing and creating light, my fingers were on the metal. The voltage went straight into me. Holy HELL that was the worst shock I've had to date. Anyone know just how much power that would generate?
Click to expand...
No idea how much power, but as for voltage, a couple thousand volts easily. What's happening is the current flowing through the coil is creating a magnetic field around the coil, and when you disconnect the power source, the magnetic field collapses and creates a voltage across the coil. The coil is essentially an inductor when you don't combine it with the rest of the alternator, and inductors oppose change in the amount of current flowing through them. The equation (if you like math) is V = L*di/dt where L is the inductance, i is current, and t is time. Really what this means is that the current builds up slowly flowing through the coil and when you disconnect the battery, the inductor attempts to keep the current flowing at the same rate and ramps the voltage across its terminals up quite quickly.

dave92cherokee said:
Even better than an alt grab a bad plug wire while the engines running, it's a real eye opener.
Click to expand...
Yeah :shocked:

I actually managed to shock myself on a 12 volt battery yesterday, probably because I accidentally put my forearm across it while completely saturated with sweat. Glad it was only one arm! It felt only slightly worse than licking a 9V battery.
 
The worst shock that I have ever endured is one from and OLD mercury outboard, those suckers have high voltage stickers and can jump a 2" gap with a bright blue spark. OUCH! Automotive spark has nothing on that.
 
YELLAHEEP said:
Here's some advice...... Quit shocking yourself. Most humans don't shock themselves on purpose, much less more than once, then compare it to the last one....... Sounds like it may be affecting your smart parts........ But hey, if you're interested - I have a Taser and you could "ride the lightening" and compare it to your alternator zap......:D
Click to expand...

Don't they make you take a taser hit as part of your training?

.
 
Buddy of mine was trying to get a 1972 Chevy C60 straight truck to start. There's enough room under the hood with a 366 small block that he was just sitting on the fenderwell. He pulled a sparkplug wire off, and held the end close to the plug and had his co-worker turn it over.

It was then that he found out the hard way that his jeans were worn a little thin in the seat, he grounded out through 2 vital portions of his anatomy.
 
I can think of like ten answers to that and none of them belong anywhere except the Den :shocked::eyes:
 
I've tried plugging a plug wire back into the distributor with the engine running :laugh: It got me about 4 times, didn't hurt but was very surprising.
 
DrinkBeer said:
I've tried plugging a plug wire back into the distributor with the engine running :laugh: It got me about 4 times, didn't hurt but was very surprising.
Click to expand...

Slow learner huh?
 
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