1 (edited by firebert 2020-11-11 11:24 PM)

Topic: Pyrotech Kill Switch & 2 dead alternators

We just killed our second alternator. The car is a 2001 Infiniti G20 (fancy Nissan Sentra) and the kill switch is a Pyrotech purchased from the Lemons store. This is how we have it rigged up. I install auto and marine audio and lighting systems for the last 20yrs so I'm pretty certain I have it wired correctly. I had another guy on our team (automotive master tech for 20+ yrs) check my work and he says everything looks correct. Can someone tell us why we're idiots? Wiring diagram below:

https://i.postimg.cc/FHb5Yf4p/kill-sw.jpg
Kill switch works and shut off car but once we flip it the alternator dies

Re: Pyrotech Kill Switch & 2 dead alternators

I go simple. Put the battery and alternator output on one pole and everything else on the other.  When you throw the switch the alternator just dumps into the battery.  No nuked alternators in last 10 years. I'm guessing your alternator is getting nuked as its output is not being properly dealt with after the switch is thrown.

1990 RX7 "Mazdarita"  1964 Sunbeam Imp (IOE 2013 Sears Pointless) 2002 Jaguar x-type (Winner C-Class 2021 Sears Pointless)
Gone bye-bye
1994 Jaguar XJ12 (Winner C-Class 2013 Sears Pointless)  1980 Rover SD1 (I Got Screwed 2014 Return of Lemonites)

Re: Pyrotech Kill Switch & 2 dead alternators

Yes, that's my guess too but I thought the purpose of the resistor is to give the voltage spike a path to ground and that was supposed to solve that issue.

4 (edited by Lemon_Newton-Metre 2020-11-08 11:36 PM)

Re: Pyrotech Kill Switch & 2 dead alternators

1. Did you test the functions of the switch before installing it, to make sure it was manufactured properly?

2. Pyrotect is looking for a 3 ohm, 11 watt resistor, not a 33 kOhm resistor. You might be off by a factor of 10,000, though I'm not sure about the watts. I think it's supposed to be just a little something while the alt is spinning down.

5 (edited by firebert 2020-11-08 11:54 PM)

Re: Pyrotech Kill Switch & 2 dead alternators

1. Not before I installed it but did test while trouble shooting

2. My mistake. It is a 3Ohm 11W resistor that was included with the kit. The diagram was edited off a existing image from google

Re: Pyrotech Kill Switch & 2 dead alternators

cheseroo wrote:

I go simple. Put the battery and alternator output on one pole and everything else on the other.  When you throw the switch the alternator just dumps into the battery.


Like this?
https://i.postimg.cc/vHMhHKBC/kill-sw-2.jpg

Re: Pyrotech Kill Switch & 2 dead alternators

I see one other - albeit remote - possibility: did you get "the main power wire from the ignition switch to the ignition coil" ?
Everything else seems to be specifically accounted for in your first diagram.
I'm at a loss also.

Re: Pyrotech Kill Switch & 2 dead alternators

Lemon_Newton-Metre wrote:

I see one other - albeit remote - possibility: did you get "the main power wire from the ignition switch to the ignition coil" ?
Everything else seems to be specifically accounted for in your first diagram.
I'm at a loss also.

We basically found the main wire going to the (+) terminal of the battery, cut it in half, and install the kill switch in between. (extended the leads to the cabin of course)

Re: Pyrotech Kill Switch & 2 dead alternators

Did you verify that when the switch is in the Off position you have full conductivity from the alternator to Ground + 3,000 Ohms? I've seen these sometimes put on something that LOOKS like a good ground, but isn't.

Mistake By The Lake Racing (MBTL)
88 Thunderbird "THUNDERBIRDS ARE GO!", Ex Astris, Rubigo / Semper Fracti
A&D: 2014 Sebrings at Sebring (NSF), 2014 NJMP2 Jurassic Park (SpeedyCop), 2012 Summit Point J30 (PiNuts)
2018 Route Sucky-Suck Rally Miata, 2019 World Tour Of Texas 64 Newport

10 (edited by Lemon_Newton-Metre 2020-11-09 05:20 AM)

Re: Pyrotech Kill Switch & 2 dead alternators

What I put in quotes in my last post was the wording of paragraph 5 of Pyrotect's directions, which is photo 3 in the switch ad in the Lemons store.

I don't know if your car's wiring comports with the directions, and I don't know if it makes an electrical difference, but I interpret the Pyrotect wording to mean:

interrupt the main power wire from the key cylinder to the ignition coil

and I interpret your description to mean:

you cut a different wire.

But I'm not sure that should make a difference, right?!?

Does the switch - as you wired it - cut the power to the ignition coil?
[edit] And by that, I mean power from the alternator to the ignition coil.

Re: Pyrotech Kill Switch & 2 dead alternators

firebert wrote:
cheseroo wrote:

I go simple. Put the battery and alternator output on one pole and everything else on the other.  When you throw the switch the alternator just dumps into the battery.


Like this?
https://i.postimg.cc/vHMhHKBC/kill-sw-2.jpg

I'm not sure what the blue and yellow trace lines on are doing.  The left pole with the alternator output and battery on one side and everything else on the right side (red trace) is the way I do it.  Nothing on connector #2

1990 RX7 "Mazdarita"  1964 Sunbeam Imp (IOE 2013 Sears Pointless) 2002 Jaguar x-type (Winner C-Class 2021 Sears Pointless)
Gone bye-bye
1994 Jaguar XJ12 (Winner C-Class 2013 Sears Pointless)  1980 Rover SD1 (I Got Screwed 2014 Return of Lemonites)

Re: Pyrotech Kill Switch & 2 dead alternators

cheseroo wrote:

I go simple. Put the battery and alternator output on one pole and everything else on the other.

I know people get away with this, but it doesn't satisfy Lemons' rules which state:

All electricity, including the battery, charging, and ignition circuits, must be interrupted by the kill switch.

If you wire the alternator directly to the battery then the charging circuit isn't interrupted by the kill switch.

@firebert
A resistor isn't good enough. You need a TVS diode to prevent the voltage spike.  Like this one: https://www.littelfuse.com/~/media/elec … et.pdf.pdf


See the discussion here for details:
https://www.electro-tech-online.com/thr … ed.159915/

Re: Pyrotech Kill Switch & 2 dead alternators

DefectiveLemon wrote:

If you wire the alternator directly to the battery then the charging circuit isn't interrupted by the kill switch.

I should clarify that this statement assumes you have a "1 wire" alternator that doesn't have an external wire that powers the field coil.

The Pyrotect switches are designed for an alternator that has an externally supplied field coil.  The second circuit on the switch is to interrupt the field circuit, which then stops the alternator from generating voltage.  However, many modern alternators are "1 wire" type that don't need a field circuit to generate power.

14

Re: Pyrotech Kill Switch & 2 dead alternators

https://en.wikipedia.org/wiki/Load_dump


Load dump can affect any system in the car that is sensitive to high voltage transients.

https://forums.24hoursoflemons.com/sear … =646576993


Varistors are another option with trying to suppress load dump transients. The resistor will help, but it can't completely eliminate the transient. Different alternators will react to the transient voltage in different ways.

https://m.littelfuse.com/~/media/electr … de.pdf.pdf


Keeping the alternator connected to the battery will eliminate the load dump, but that means there is no way to disconnect the 12V battery voltage from the alternator. In a heavy front-end crash, you may create a short circuit at the alternator with no way to turn it off. That in itself can cause a fire in an area where there very well may be fuel leaking. Not a good combination.

DefectiveLemon has a good point - what type of alternator do you have? If you have a 2-wire device, then maybe you are damaging the diodes in the excitation input, and maybe not the diodes in the output. Here is the wiring for our car (1986 Audi Coupe GT), note that switch "Z" disconnects the field wire (D+) from the alternator output (B+), so any transients generated at B+ will not make it to D+.

Check your wiring diagram - you may still have the field wire connected to the same bus as the alternator output even when the kill switch is "off".

https://i.postimg.cc/1tQHpQr5/Kill-Switch-Iff.jpg-

We Audi Be Faster
'85 Audi Coupe G(in &) T(onic)

Re: Pyrotech Kill Switch & 2 dead alternators

DefectiveLemon wrote:
cheseroo wrote:

I go simple. Put the battery and alternator output on one pole and everything else on the other.

I know people get away with this, but it doesn't satisfy Lemons' rules which state:

All electricity, including the battery, charging, and ignition circuits, must be interrupted by the kill switch.

The car I bought from Pagel was wired this way.  I think he knows the rules.

Team whatever_racecar #745 Volvo wagon

Re: Pyrotech Kill Switch & 2 dead alternators

rb92673 wrote:
DefectiveLemon wrote:
cheseroo wrote:

I go simple. Put the battery and alternator output on one pole and everything else on the other.

I know people get away with this, but it doesn't satisfy Lemons' rules which state:

All electricity, including the battery, charging, and ignition circuits, must be interrupted by the kill switch.

The car I bought from Pagel was wired this way.  I think he knows the rules.

If your car was equipped with an old two-wire alternator, then it wouldn't violate the rules.
Also, like I said, the charging circuit isolation requirement isn't strictly enforced.

Re: Pyrotech Kill Switch & 2 dead alternators

RSB wrote:

DefectiveLemon has a good point - what type of alternator do you have? If you have a 2-wire device, then maybe you are damaging the diodes in the excitation input, and maybe not the diodes in the output. Here is the wiring for our car (1986 Audi Coupe GT), note that switch "Z" disconnects the field wire (D+) from the alternator output (B+), so any transients generated at B+ will not make it to D+.

From your diagram, it doesn't look like D+ is the field input. It looks like it's just a charge-fail warning light.  Are you sure the alternator output stops if you disconnect D+?

Re: Pyrotech Kill Switch & 2 dead alternators

DefectiveLemon wrote:
cheseroo wrote:

I go simple. Put the battery and alternator output on one pole and everything else on the other.

I know people get away with this, but it doesn't satisfy Lemons' rules which state:

All electricity, including the battery, charging, and ignition circuits, must be interrupted by the kill switch.

If you wire the alternator directly to the battery then the charging circuit isn't interrupted by the kill switch.

It isn't "getting away" with anything.  It's exactly how Mr Pagel does his own cars and says is the acceptable way to wire the switch.  I suggest you ask the man yourself directly.

1990 RX7 "Mazdarita"  1964 Sunbeam Imp (IOE 2013 Sears Pointless) 2002 Jaguar x-type (Winner C-Class 2021 Sears Pointless)
Gone bye-bye
1994 Jaguar XJ12 (Winner C-Class 2013 Sears Pointless)  1980 Rover SD1 (I Got Screwed 2014 Return of Lemonites)

Re: Pyrotech Kill Switch & 2 dead alternators

RSB wrote:

Varistors are another option with trying to suppress load dump transients. The resistor will help, but it can't completely eliminate the transient. Different alternators will react to the transient voltage in different ways.

https://m.littelfuse.com/~/media/electr … de.pdf.pdf

Varistors are great for suppressing small spikes, but the largest varistor I saw on that sheet is only rated to take 35J, which equates to only 35W over a second.  Alternators can put out over 1,000W, so I don't think that's enough.
The TVS diodes are rated for over 200 Amps.

Re: Pyrotech Kill Switch & 2 dead alternators

cheseroo wrote:

It's exactly how Mr Pagel does his own cars and says is the acceptable way to wire the switch.

If so, he should update the rules to eliminate the requirement for the kill switch to interrupt the charging circuit.

Meanwhile, I'd rather be safe and just follow the rules as written, and add a $3 TVS diode to protect the alternator from the spikes.

Re: Pyrotech Kill Switch & 2 dead alternators

DefectiveLemon wrote:
rb92673 wrote:
DefectiveLemon wrote:

I know people get away with this, but it doesn't satisfy Lemons' rules which state:

The car I bought from Pagel was wired this way.  I think he knows the rules.

If your car was equipped with an old two-wire alternator, then it wouldn't violate the rules.
Also, like I said, the charging circuit isolation requirement isn't strictly enforced.

3 Wire.

Team whatever_racecar #745 Volvo wagon

22

Re: Pyrotech Kill Switch & 2 dead alternators

DefectiveLemon wrote:
RSB wrote:

DefectiveLemon has a good point - what type of alternator do you have? If you have a 2-wire device, then maybe you are damaging the diodes in the excitation input, and maybe not the diodes in the output. Here is the wiring for our car (1986 Audi Coupe GT), note that switch "Z" disconnects the field wire (D+) from the alternator output (B+), so any transients generated at B+ will not make it to D+.

From your diagram, it doesn't look like D+ is the field input. It looks like it's just a charge-fail warning light.  Are you sure the alternator output stops if you disconnect D+?


Absolutely. The circuit going to D+ serves 2 functions: 1) excitation of the alternator and 2) charge-fail indication. If the 12V going to the D+ terminal is removed the alternator will not 'start'. Proven this to ourselves many times.

Here is what the inside of a 2 wire alternator looks like: https://electronics.stackexchange.com/q … -generator

When the car is not running, the battery provides 12V (12.0 to 12.6, depending on its condition) to the D+ terminal. This is connected inside the alternator to the voltage regulator. When the car is not running, the regulator provides essentially a ground reference. This results in a voltage drop across the warning light, causing it to illuminate.

The D+ voltage also provides excitation to the regulator when the motor begins to spin. After the revs reach a high enough value, the alternator will output its normal voltage (13.8 - 14.2V range) out of both the B+ and the D+ terminals. Now that the voltage is the same across the alternator warning light, there is no current flow and the light goes out.

The diodes for the B+ output are heavy duty and sized to source the high currents demanded by the car's systems. There are 6 diodes, so the AC voltage coming out of the alternator is subject to 'full wave rectification' and will be a pretty good (but not perfect) DC. https://www.electronics-tutorials.ws/diode/diode_6.html

The diodes for the D+ output are kinda wimpy since they only have to handle the current for a small light bulb. There are only 3 diodes here, so that output is half-wave rectified. The DC is a bit lumpy but it doesn't matter.

We Audi Be Faster
'85 Audi Coupe G(in &) T(onic)

23 (edited by TheEngineer 2020-11-09 01:10 PM)

Re: Pyrotech Kill Switch & 2 dead alternators

Silly question, did you make sure the resistor is on the right circuit on the switch?

of the two extra circuits, one of them will mimic the master switch state, meaning it is on when the switch is on, and off when off. The other is a mirror image, meaning it is on when the switch is off and off when the switch is on. You want the alternator circuit on the one that is opposite the switch position. If you have it backwards it won't work.

You have it drawn the same as the picture on the Lemons store. But I think i've seen other brands that want the alternator dump on the second circuit. I've always tested with a multimeter before connecting wires to make sure I put them in the right place.

20+ Time Loser FutilityMotorsport
Turbo Dodge Powered E36 Build
2008 Saab 9-5Aero Wagon
Retired - 1989 Dodge Daytona Shelby 2011-2015 "Lifetime Award for Lack of Achievement" IOE, 3X I got screwed, Organizer's Choice

24

Re: Pyrotech Kill Switch & 2 dead alternators

DefectiveLemon wrote:
RSB wrote:

Varistors are another option with trying to suppress load dump transients. The resistor will help, but it can't completely eliminate the transient. Different alternators will react to the transient voltage in different ways.

https://m.littelfuse.com/~/media/electr … de.pdf.pdf

Varistors are great for suppressing small spikes, but the largest varistor I saw on that sheet is only rated to take 35J, which equates to only 35W over a second.  Alternators can put out over 1,000W, so I don't think that's enough.
The TVS diodes are rated for over 200 Amps.

The transient protection device does not have to tolerate the steady state output of the alternator. It only has to handle the transient that goes above some specified value (16V or 20V usually). Below the breakdown voltage, they are high impedance and no current flows through them. The load dump transient is only 120V for 400ms. The varistor is more than capable. As indicated in the Littlefuse datasheet, it is widely used in the automotive industry.

TVS diodes can typically handle more power, but again, they are not designed to operate under a steady state load of 1000W. Below the rated breakdown voltage they are high impedance and do not do anything. They are designed to handle transients, usually from lightning strikes or other high-power events. But they certainly would work in this application.

We Audi Be Faster
'85 Audi Coupe G(in &) T(onic)

25

Re: Pyrotech Kill Switch & 2 dead alternators

firebert - you said 3 wire. The 3rd wire is usually a voltage sense wire for the regulator that gets connected to the battery.

For a 1 or 2 wire alternator, the voltage regulator causes the alternator to produce 14V at the output terminals of the alternator. There is always a little bit of voltage drop between the alternator and the battery, due to the resistance of the wire, so somewhat less voltage gets to the battery (maybe 13.8 or 13.9).

A 3 wire alternator allows the voltage regulator to 'sense' what the voltage is at the battery. Since there is no current flow in this wire, there there is no voltage drop and the regulator can adjust the output a little higher so the 14V is present at the BATTERY (thereby accommodating any voltage drop in the main battery wire).

Have you done any post-mortems on the failed alternator? What actually failed? The diodes in the main output? The excitation diodes? The voltage sense? The voltage regulator? Knowing that and a more detailed review of your wiring should give you the answer. You need to trace out where all the alternator wires go, and what is switched and what is not.

We Audi Be Faster
'85 Audi Coupe G(in &) T(onic)