Fire Danger Warning

[Mike Jones]

Yesterday I was looking over a mechanic's shoulder as he was troubleshooting a charging system problem on my '57. All of a sudden smoke began coming from the generator and I noticed my ammeter pegged at -40 amps. An apparent short! We hurriedly disconnected the battery.

I was surprised to learn that there is no fuse or any type of failure prevention on several elements in the electrical system (generator, ammeter, cigarette lighter, etc.) and that many cars have gone up in flames as a result. Since I store my Vette in a remote garage, I had nightmares all night about it going up in flames. After looking through my NCRS encyclopedia of back articles, I found several on the subject of battery disconnects and fuse links. I'm going to RUN not walk to my auto parts store this morning and buy some cheap protection!

Mike

[Terry M.]

Re: Fire Danger Warning

Mike,

I hope one of those articles you found was mine. Some additional information:

The style of cut off with the screw down knob does not have a large contact area. If there is a high current draw to the starter (high compression motor or six volt system) there is a chance that cut off will fail. Several instances of intermittant failure have been reported in different chapter newsletters.

If you anticipate a high current draw you might want to consder the knife blade syle cut off switch, especially if your battery installition has sufficient room for it, My story had an illustration of the knife blade style switch. It is available from an Illinois advertiser in The Driveline or from JC Whitney.

Terry

[Terry M.]

Re: Fire Danger Warning

Mike,

I hope one of those articles you found was mine. Some additional information:

The style of cut off with the screw down knob does not have a large contact area. If there is a high current draw to the starter (high compression motor or six volt system) there is a chance that cut off will fail. Several instances of intermittant failure have been reported in different chapter newsletters.

If you anticipate a high current draw you might want to consder the knife blade syle cut off switch, especially if your battery installition has sufficient room for it, My story had an illustration of the knife blade style switch. It is available from an Illinois advertiser in The Driveline or from JC Whitney.

Terry

[Richard E.]

Re: Fire Danger Warning

Hi Mike-Something else to consider. John Pirkle Jr gave us a lecture at one of our chapter meetings, on the criticality of polarizing a generator. He contends that one should polarize EVERY time the battery is disconnected, even if by a cutoff switch, in addition to the usual times of generator/regulator replacement. He sez, you'll getaway with it most of the time, but there is always a chance that it'll mess something up big time. I've disconnected my battery off and on for years with never a problem, but John knows his stuff and it seems like it is a pretty simple, quick precaution. If you have any further questions, I'm sure either one of the Pirkles would answer any questions. He advertises in the Driveline and Hemmings. Welcome to the sleepless nights club!

[Richard E.]

Re: Fire Danger Warning

Hi Mike-Something else to consider. John Pirkle Jr gave us a lecture at one of our chapter meetings, on the criticality of polarizing a generator. He contends that one should polarize EVERY time the battery is disconnected, even if by a cutoff switch, in addition to the usual times of generator/regulator replacement. He sez, you'll getaway with it most of the time, but there is always a chance that it'll mess something up big time. I've disconnected my battery off and on for years with never a problem, but John knows his stuff and it seems like it is a pretty simple, quick precaution. If you have any further questions, I'm sure either one of the Pirkles would answer any questions. He advertises in the Driveline and Hemmings. Welcome to the sleepless nights club!

[Jack H.]

Re: Fire Danger Warning

Amen, to Terry's advice about cut-off switch style/design. I'm one of those who have had problems personally with the screw type AND had the pleasure of making jury rig repair to another member's screw type switch that failed DEAD-SOLID-PERFECT on him in a Chapter road caravan at 75 mph. He almost lost the car....

Pay the extra money and get the heavy duty knife switch that's made in the US and designed with adequate safety margin for the application!

As far as finding out a car is NOT electrically foolproof, welcome to the Real World guys! Nothing designed my man is perfect. There are limits to how far designers go in anticipating each/every possible failure mode of their products. There are a number of circuits that are always 'hot' (including the battery itself, on a standalone basis). So, there is always a point at which designers of any/all products draw the line and leave it alone....

The lecture of John Pirkle referenced in an earlier thread piece is on the money. The standard practice was an is to re-polarize a generator when it's been disconnected from the battery. But, in reality it takes quite a while for the internal laminations to 'forget' their magnetic polarization. That's the reason most who apply a cut off switch to a generator based charging system 'get away' with not having to re-polarize the system during short (overnight, maybe a week, sometimes even an entire winter) disconnect period.

Without some external force to randomize the lamination's magnetic alignment from prior polarization (heat, mechanical work, stray E/F field of reasonable magnitude), they'll stay aligned as they were. But, if you're doing electrical work for a living, you take no chances and follow the book. If the generator just happens to come up in reverse polarity, it'll 'run backwards' and try to suck the battery dry. Think you saw smoke in the shop????

[Jack H.]

Re: Fire Danger Warning

Amen, to Terry's advice about cut-off switch style/design. I'm one of those who have had problems personally with the screw type AND had the pleasure of making jury rig repair to another member's screw type switch that failed DEAD-SOLID-PERFECT on him in a Chapter road caravan at 75 mph. He almost lost the car....

Pay the extra money and get the heavy duty knife switch that's made in the US and designed with adequate safety margin for the application!

As far as finding out a car is NOT electrically foolproof, welcome to the Real World guys! Nothing designed my man is perfect. There are limits to how far designers go in anticipating each/every possible failure mode of their products. There are a number of circuits that are always 'hot' (including the battery itself, on a standalone basis). So, there is always a point at which designers of any/all products draw the line and leave it alone....

The lecture of John Pirkle referenced in an earlier thread piece is on the money. The standard practice was an is to re-polarize a generator when it's been disconnected from the battery. But, in reality it takes quite a while for the internal laminations to 'forget' their magnetic polarization. That's the reason most who apply a cut off switch to a generator based charging system 'get away' with not having to re-polarize the system during short (overnight, maybe a week, sometimes even an entire winter) disconnect period.

Without some external force to randomize the lamination's magnetic alignment from prior polarization (heat, mechanical work, stray E/F field of reasonable magnitude), they'll stay aligned as they were. But, if you're doing electrical work for a living, you take no chances and follow the book. If the generator just happens to come up in reverse polarity, it'll 'run backwards' and try to suck the battery dry. Think you saw smoke in the shop????

[Joe Peplinski]

Re: Fire Danger Warning

Since this is the second time in a few months that someone has mentioned "polarizing" a generator, can someone please give a brief description of the process. I've never heard of polarizing a generator anywhere else, but do disconnect my car's batteriy in the winter. Is polarization only required for the older C1, C2, and/or C3 generators, or the newer C4 and C5 genrator's as well? Thanks for explaining this to a first time old Vette owner.

Joe '69 L68

[Joe Peplinski]

Re: Fire Danger Warning

Since this is the second time in a few months that someone has mentioned "polarizing" a generator, can someone please give a brief description of the process. I've never heard of polarizing a generator anywhere else, but do disconnect my car's batteriy in the winter. Is polarization only required for the older C1, C2, and/or C3 generators, or the newer C4 and C5 genrator's as well? Thanks for explaining this to a first time old Vette owner.

Joe '69 L68

[Joe L.]

Re: Fire Danger Warning

Joe----

In your case, "polarizing" is not an issue. This technique/service operation is applicable only to DC GENERATORS used in Corvettes from 1953 until 1962. Starting in 1963, Corvettes changed to ALTERNATORS which continue in use in Corvettes to this day. Alternators do not require "polarizing".

[Joe L.]

Re: Fire Danger Warning

Joe----

In your case, "polarizing" is not an issue. This technique/service operation is applicable only to DC GENERATORS used in Corvettes from 1953 until 1962. Starting in 1963, Corvettes changed to ALTERNATORS which continue in use in Corvettes to this day. Alternators do not require "polarizing".

[Mike Jones]

Re: Fire Danger Warning

Thanks for all the help! I've installed a battery knife switch.

Would someone please tell me how to polarize the generator or where I can find an article describing the process.

Mike

[Mike Jones]

Re: Fire Danger Warning

Thanks for all the help! I've installed a battery knife switch.

Would someone please tell me how to polarize the generator or where I can find an article describing the process.

Mike

[Chuck G.]

Re: Polarizing Generator

Hi Mike; It's simple to polarize your generator. Ground the FIELD(F) terminal on your generator to the frame, engine, etc. Take a wire from the positive battery terminal, or any other hot terminal (horn relay), and touch and "spark" the ARMATURE(A) terminal on your generator. Don't connect the wire to the armature terminal....just "spark" it. That's it....you're done. This gives the proper electrical "orientation" to your generator so that it charges your battery when it is turned by the fan/generator belt. If your generator isn't polarized correctly, it will not charge, and can damage the generator itself. Hope this helps. By the way, I've used a "wheel type" cut off switch on my 54 for many years, and have never had to re-spark my generator. I know that this has been discussed on this BB before, and I have tremendous respect for John Pirkle, but I have not experienced any problems, and my 54 will sit for months upon months between starts, with the battery shut off. Chuck Gongloff

[Chuck G.]

Re: Polarizing Generator

Hi Mike; It's simple to polarize your generator. Ground the FIELD(F) terminal on your generator to the frame, engine, etc. Take a wire from the positive battery terminal, or any other hot terminal (horn relay), and touch and "spark" the ARMATURE(A) terminal on your generator. Don't connect the wire to the armature terminal....just "spark" it. That's it....you're done. This gives the proper electrical "orientation" to your generator so that it charges your battery when it is turned by the fan/generator belt. If your generator isn't polarized correctly, it will not charge, and can damage the generator itself. Hope this helps. By the way, I've used a "wheel type" cut off switch on my 54 for many years, and have never had to re-spark my generator. I know that this has been discussed on this BB before, and I have tremendous respect for John Pirkle, but I have not experienced any problems, and my 54 will sit for months upon months between starts, with the battery shut off. Chuck Gongloff