[TomS]

Glad I could help Tom. Unfortunately, a good 50% of the fried amps we replaced were damaged by AAA or various other roadside assistance companies, or general tow truck drivers. I can only assume these guys are 'old school' enough that they're thinking of cars made 'back in the old days'. These guys need to be educated with modern automotive systems and their weaknesses.

Bob

Yep, one of those clowns did something to our Pontiac Vibe electrical system that I don't think it ever recovered from.  It's someone else's problem now though.

[jneutron]

The keys should be turned off and removed from the ignition when installing the jumper cables (of modern cars).
With the key on (or even IN the ignition) three dozen solid state control modules are powered up and unprotected from the voltage spike created by jump starting.
Where I work, the common smoked component is the cars audio amplifier. A $1,300 punishment for the vehicles owner that (obviously) already having a bad day. It's best to call roadside assistance and let them be responsible. If you're lucky, the guy that comes to help might be slightly more knowledgable about cars than you, but if nothing else THEY'LL be responsible for any damage not you. 
We replace about 2 amps per month due to improper jump starting techniques. cha ching 

Bob

Hmmm..I'm not buying that explanation at tall at tall..

I believe the amplifiers you are talking about were faulty design.  That, coupled with bad technique (as you said).

The auto enviro is one of the toughest to design within.  Temp of course, being one big hurdle...

Two transients are of concern here.

1.  Sparking during connection.  Yes, there will be transients, and yes, it's easy enough to protect against..a reverse bias diode snubber set is a good example.  This is consistent with reversed polarity, but the energy available is not too bad, transient absorbtion is typically used.

2.  Load dump.  THIS is the beech...accept no substitutes!!!..

Load dump occurs when the engine is revving, the alternator is charging the battery heavily..then the battery is disconnected. 

Typical 3 phase alternators adjust their output power via a regulator which alters a small dc current that flows in the rotor.  Need more juice, push more current into the rotor.  Problem is, the rotor is an inductor, so it's current does not change as fast as it should.  So when the alternator is pushing lots of charging current, it is because the rotor current is high.  If you disconnect the battery while this heavy charging is occuring, there will be a massive overvoltage spike until the regulator can get the rotor current under control again.

This is called load dump.  Typical tests for car electronics (used to be) an exponential waveform of 70 volts peak, with a 200 millisecond time constant (to 36.8%).

Now, jump start...the tips given are excellent..but one important thing needs to be added.

Once the target car has been started, DO NOT rev the target engine while the cables are being disconnected.  The dead battery is high impedance at that time, and removing the cables will simulate removing the battery.  Worst possible case.

Turn the headlights of the target car on, do NOT rev either engine at this time, and remove the cables.

Once the cables are disconnected you may do what you wish to the target engine.  The regulator is more than capable of protecting the target car system against engine rpm changes, it is much faster at reacting than the engine.

Cheers, John

[Bob in St. Louis]

Turn the headlights of the target car on, do NOT rev either engine at this time, and remove the cables.

YES! I forgot to mention this, very good John, thank you. 

Everything you said (albeit a bit over my head) sounds good. I would like to add one more piece to the puzzle:
Jumper cables in the hands of the general public gives them instant "I know how to do this, and I want to be the hero" syndrome, when in reality you've put the potential of several hundred amps in their ignorant hands. A bad combination with a modern car.

I've never seen so many amps fried in my career. These amps I deal with may be a weak link, poor design, unprotected or what ever you want to call it, but the fact of the matter is: The first step in the short process of letting the smoke out starts with jumper cables.
Sorry if I sound bitter, I'm being cynical. But I really do hate cars and the people that drive 'em.

We've gotten way OT, and I appologize. 
Jim, have you found a workable solution?

Bob

[jneutron]

We've gotten way OT, and I appologize.
Bob

ribbonspeakers directed the thread this way...so you are absolutely NOT off topic...he IS the OP...

Cheers, John

[James Romeyn]

Steak dinner for anyone who could remember the correct jump start procedure first read!  (kidding)  Have to admit it actually made quite a bit of sense.  To say modern cars are overly complicated is the biggest understatement of the day.  Just for the fun of it I visited an MB dealer once.  The slick sales guy gave me about a 15 minute overview of the insanely long list of features while we sat in the cab.  He said the delivery lesson to buyers lasted hours.  Designers & manufacturer's seem completely deaf to professional journalist complaints concerning control complexity, esp ze Germans.   

The safety & electronic gizmos (& ever larger humanity) are most responsible for car's chronic weight gain, always bad for fuel economy (i.e. terrorism financing) & every other performance parameter (well maybe except for windy road holding). 

No fixes employed yet; I'm just getting used to being zapped & keeping the AED nearby, but thanks for the concern.  And yes, I don't care about the OT thing.  This was a casual thread to begin with....no high-end company, personnel or product to taunt or mock or scorn!  HOW BORING!!!!!!!!!!!!!!   

[electricbear]

At an audio dealer I used to work for a few years ago we got in an integrated amplifier on trade in. It was made by a company who's name sounds a little like "swell".
On cold days the static generated by walking across the carpet was enough to make the integrated jump inputs when it was touched. I found this to be quite alarming for a company who is supposed to be high end.

[James Romeyn]

One of you engineer types please chime in.  My position is it's asking too much to expect even high-end manufacturers to design w/ total immunity to hundreds or thousands of static electricity volts in proximity to the component. 

Some of these blue-yellow-white zaps crossing from my finger tip to the wall light switch are miniature lightning flashes!  I really wish this could be harnessed. 

[electricbear]

Here's the solution. Just keep one of these in your pocket
www.stopshox.com/buy.htm

[James Romeyn]

Here's the solution. Just keep one of these in your pocket
www.stopshox.com/buy.htm

THAT'S WUT IM TAWKIN 'BOUT!!!!!!!!!!!!!!!!!!!!! aa aa aa  I knew there had to be something like this out there; and HOPED one of you gear heads would be able to refer me to it.

I'm not worthy!  It's going on a chain around my neck: get up in the morning, put on my watch, slide my StopShox over my neck.    

[randytsuch]

Here's the solution. Just keep one of these in your pocket
www.stopshox.com/buy.htm

THAT'S WUT IM TAWKIN 'BOUT!!!!!!!!!!!!!!!!!!!!! aa aa aa  I knew there had to be something like this out there; and HOPED one of you gear heads would be able to refer me to it.

I'm not worthy!  It's going on a chain around my neck: get up in the morning, put on my watch, slide my StopShox over my neck.    

I would not expect too much from this.  I saw a test on a device similiar to this, where they measured the static charge on someone wearing the device, and not wearing it.  The device basically had no effect on the static charge.

Randy

[James Romeyn]

You are probably right.

Please be wrong.

[*Scotty*]

You could try holding a key firmly in your hand and touching things with the end of the key before using your bare hand. By wrapping the end of the key in self fusing silcone tape you can raise the voltage rating above that of the stopshox device.  http://www.buyhardwaresupplies.com/?t=5&m=g1&itemNumber=3073533 This type of tape should be available at your local ACE or TruValue hardware store.
This trick will work as well as an eight dollars and change substitute for a key. The specs rate the stopshox for 15kV and you are easily exceeding that without even scuffing your feet on the carpet.
Scotty

[Russell Dawkins]

I went to remove the plug from the charger to my digital personal organizer the other day (HP pocket PC) and felt a tiny spark jump from my thumb to the plug. When I went to power it up by pushing the illuminated on/off switch the light would not come on and the device was completely dead. Resetting and hard re-setting had no effect.

The thing was completely toast. When I plugged the charger plug back in, the light indicating charge did not even light up, although I checked and found out the charger was putting out the correct voltage.

There was a lot of valuable info in there. I'm going to resurrect the paper appointment book now!

When I lived in a high static environment (the Canadian prairies in winter) I always had a metal barreled pen or key at the ready for when I got out of a car or had to open a door. Some of the sparks would be a couple of inches long and had enough amperage to leave a slight ache in your forearm. I got in the habit of keeping my hand on some grounded part of the car while I slid across the seat.

[jneutron]

You are probably right.

Please be wrong.

The unit does not auto-discharge a person by dangling it around the neck.  It is designed to be used instead of your fingers, to flash the potential.  It is a resistor.

Using a key, as Scotty said, is what I do.  The caveat is...DO NOT USE A WIRELESS KEY!!!!!  They cost waaaay too much.

Discharge via metal can work in one of two ways.  First, if you use a simple metal object, make sure you have lots of surface contact to the metal, then touch the knob or whatever, with the object.  You will see the large spark, but the current concentration is no longer a pinpoint.

Second, resistive discharge, like that thingy linked to.  The lifetime of that thingy is related to the discharge spike speed and intensity...Spark discharge currents rise in unbelievable timeframes, less than a nanosecond. At that rate of rise, the current flows over the surface of any resistor, and probably is close to degradation levels, hence their lifetime limit.

Static discharge is typically 10 kilovolts per quarter inch.

Cheers, John

[James Romeyn]

My work outs & temperature changes in north Utah often result in several changes of clothes throughout the day.  The key goes around my neck just for convenience so it's always available.  But thanks for mentioning proper useage anyway in case someone else misundertood me to be even dumber than I otherwise appear     

Whooda thunk four pages already?

[jneutron]

My work outs & temperature changes in north Utah often result in several changes of clothes throughout the day.  The key goes around my neck just for convenience so it's always available.  But thanks for mentioning proper useage anyway in case someone else misundertood me to be even dumber than I otherwise appear   

 

Whew...had me thinkin for a minute there...

Actually, if you made a necklace ornament using needles, hundreds of them, all pointing out, you could use it to bleed off excess charge.  Just like with a van de graff..if you put a thumbtack on the top, pointed up, it will prevent the sphere on top from collecting a significant charge.  You'll see this type of structure at large power company substations, tall poles with this ball of spikes..they help bleed off ground charge to reduce strikes.

Course, it wouldn't be very comfortable...

Whooda thunk four pages already?

It's a Seinfeld thread...

Cheers, John

[James Romeyn]

Someone PM'd & informed me the zaps are part of the "vast" (somekinda) "wing conspiracy" & the opposing candidate promises universal access to static electricity barriers for all Americuns.

[Bob in St. Louis]

 

[2wo]

Sorry, lost this thread for awhile. If you are still looking, the resistor is probably 1 meg or better. The idea is to let your charge bleed down rather than zap. Go to Rat Shack and buy a four pack. If you still get zapped with one twist another in series.

Or you could buy a ESD wrist strap. Digikey SCP141-ND Connect the clippy end to ground. Now the problem with that is you can’t move more than 6’ for the rest of the winter.  Although I suppose you could unsnap the wristband and touch the snap end of the cord when needed …John     

[James Romeyn]

Minimum wattage?  Or should I just try it & if it burns up I know to go higher?