installing an alternator

[A68DART360]

My 68 Dart with a 440 has no alternator on it (race car). And I want to put an alternator on it. Where do I have to run wires too to make it work correctly. Batteries are in the trunk and it has aftermarket dash and no stock wiring. Do I wire from Alt to battery, ign. etc. Can someone point me in the right direction so I can get me car to charge correctly.

I also have to add that I do have a one wire alternator. Would I just go from the positive on the alternator to the positive on the battery. No need to to to any relays. I f I do this will it charge the batteries while the car is running. That is my whole purpose of doing this.

 

[the67fish]

For a racing application only I would get a one wire alternator and run the one wire straight to the +post on battery.

 

[ntsqd]

If you have a battery kill switch (commonly required by most racing rules) be sure that your charge wire is attached on the battery side of the switch and NOT on the car side of the switch. If you can't turn off the engine by turning off the kill switch it's not correct.

AND don't test this unless absolutely necessary, it can be hard on the alt.

 

[67Dart273]

If you have a battery kill switch (commonly required by most racing rules) be sure that your charge wire is attached on the battery side of the switch and NOT on the car side of the switch. If you can't turn off the engine by turning off the kill switch it's not correct.

AND don't test this unless absolutely necessary, it can be hard on the alt.

This is where I disagree with several

The NHRA rules has wording to the effect as "kill all power." Hooking the alternator to the battery directly does not do this, and in order to run a "one wire" you need a large charging wire, at least no6. This is a fairly good sized welding wire in case of an accident / short

There's a couple of ways to wire these, Crackedback had one using an additional solenoid. IF you use a 4 terminal disconnect (DPST) and wire the two small terminals to a relay controlling the ignition, you can then come up with "everything cold" with the disconnect pulled.

 

[ntsqd]

With a one wire alt if that one wire is on the vehicle side of the switch then turning off the switch only separates the battery. If the alt is working then it will keep working (I'm going to ignore how hard that is on the alt, and it is) and the engine will continue to run and all electrical in the car will continue to be live. So turning off the kill switch won't kill the engine or anything else so long as the alternator is producing.

If not a one wire alt, then using one of the multi-contact kill switches can be used to kill the alt's exciter circuit and it won't matter where the charge wire is connected.

I just ran into this. I had been planning on putting the kill switch on a drag car that I'm wiring for a friend in the ground cable. Thinking it thru that won't work because it doesn't also separate the alt's ground from the rest of the car, so if the alt were producing turning off the kill switch wouldn't stop the engine and everything else would still be live due to the alt's putting out power.

 

[BillGrissom]

No need to run the alternator output all the way the trunk. You already have a thick wire from BATT+ running forward so simpler, cheaper, and lighter to connect to the end of that.

 

[67Dart273]

Thinking it thru that won't work r.

Of course "it works"

Get a 4 terminal disconnect, and run two no 14's up front

Break the series from the ig switch feed to the ignition system.

Run the switched ignition output from the ig switch to one of the no 14 wires going to the disconnect

The return no14 coming back from the disconnect keys a relay, and the relay then fires the ignition system.

You don't even need a relay if you use MSD, just use the small red MSD energizer wire.

 

[ntsqd]

No need to run the alternator output all the way the trunk. You already have a thick wire from BATT+ running forward so simpler, cheaper, and lighter to connect to the end of that.

That is exactly what I thought too, until I realized that it won't meet the rules requirement of turning everything off when you turn off the kill switch. Say that you connect the alt's power output to the starter relay (I did) and that the kill switch is next to or near the battery. Turning the kill switch off removes the battery from the circuit. Good so far (except for the trauma that the alt may have just endured). If the engine was running then the alternator should have been producing power. Once it is doing that it becomes "self-exciting" in that it can feed it's own exciter circuit and not need the battery. So turning off the kill switch has only removed the battery from the system, it hasn't turned off the engine or the alternator.

With one of the kill switches that has the second set of low current contacts in it you can run the exciter circuit thru those contacts. Now when you turn off the kill switch you remove the battery and you turn off the alt's exciter circuit, which will kill everything, no relays required.

If it is a one-wire alternator that won't work because there is no exciter circuit (not external to the alt anyway). In this case the charge wire has to go to the battery side of the kill switch. That is the only place that I can think of that will turn off everything when the kill switch is turned off.

 

[ntsqd]

Of course "it works"

Get a 4 terminal disconnect, and run two no 14's up front

Break the series from the ig switch feed to the ignition system.

Run the switched ignition output from the ig switch to one of the no 14 wires going to the disconnect

The return no14 coming back from the disconnect keys a relay, and the relay then fires the ignition system.

You don't even need a relay if you use MSD, just use the small red MSD energizer wire.

By 4 terminal disconnect you're talking about something like this?
http://www.rallylights.com/all/elec...y-master/tt061-battery-master-switch-fia.html

As it happens this one has two sets of low current contacts, so both the ignition and the alternator's exciters could also be switched.

In the case of the car that I'm about to wire the guy has one of the old school type battery kill switches with the gray pot-metal lever so when I said "it won't work" I was thinking specifically of that car and not of the bigger picture. My bad.

 

[A68DART360]

They type of battery disconnect switch I currently have on the car is a 2 Stud on/off switch that has been used by everyone for years.

 

[67Dart273]

They type of battery disconnect switch I currently have on the car is a 2 Stud on/off switch that has been used by everyone for years.

Here's the thing.........it's difficult if not impossible to completely isolate the alternator, which gets back to my original post. If the alternator wire is still hot, then you have the makings of a welding display in case of a crash.

There's many guys who do this, and I believe get by because the tech guys just ain't payin' attention.

It's your car. Do what you want.

 

[ntsqd]

67Dart and I are in violent agreement on this, unless the alt's charge wire goes to the battery side of that switch then the alt will stay live and keep everything running even after the switch is turned off.

I agree on the tech guys as well. If not doing what I mentioned above is passing tech then they're not really doing their job. I'm sure that it's not an intentional thing. My guess would be that they haven't thought it thru as I had not until very recently.

 

[A68DART360]

By 4 terminal disconnect you're talking about something like this?
http://www.rallylights.com/all/elec...y-master/tt061-battery-master-switch-fia.html

As it happens this one has two sets of low current contacts, so both the ignition and the alternator's exciters could also be switched.

In the case of the car that I'm about to wire the guy has one of the old school type battery kill switches with the gray pot-metal lever so when I said "it won't work" I was thinking specifically of that car and not of the bigger picture. My bad.

So lets say I get this style switch how would I hook up the alternator to the car and make it work correctly and also make the disconnect switch work too.

 

[67Dart273]

Just hook the alternator up to whatever battery cable you have coming up front from the cold side of the switch.

Again, I know nothing about the quality of that switch. I think I saw a Moroso switch recently advertised of alleged high quality, but it is likely "really" a Cole Hearse or some other known brand in "Moroso" wool.

One of the members here came up with this, and it works. I wish I could remember, I'd credit him

 

[ntsqd]

So lets say I get this style switch how would I hook up the alternator to the car and make it work correctly and also make the disconnect switch work too.

Connect the charge wire to a Battery + cable anywhere convenient.

If an internally regulated alternator, run the exciter/ign feed wire through the small contacts on that switch.

If an externally regulated alt run either wire from the VR through the small contacts on that switch.

Then as far as the alternator is concerned turning off the battery kill switch is the same as turning off the ignition. Plus turning off that switch also separates the battery from the rest of the vehicle.

And, since that particular switch has two pair of low current contacts you could also run the ignition "exciter" wire for any sort of MSD etc. ign box through the switch as well. Then turning off the switch would turnoff the ignition system, turn off the charging system, and separate the battery from the vehicle with one action and no relays.

I like the no relays part, as reliable as the quality relays are, they are still a potential failure point. No matter their quality, additional components are additional failure modes. Buying a quality relay gives more confidence in the circuit, but not using a relay at all gives much more confidence in a circuit that is "Mission Critical".

If you're the "belt and suspenders" type then using a constant duty solenoid in the charge wire could make doubly sure. Wire it's control side in parallel with the IGN box exciter wire. That way when the battery switch is turned off all of the above happens plus the charge wire will also be separated from the rest of the vehicle.

 

[nm9stheham]

I like the no relays part, as reliable as the quality relays are, they are still a potential failure point. No matter their quality, additional components are additional failure modes. Buying a quality relay gives more confidence in the circuit, but not using a relay at all gives much more confidence in a circuit that is "Mission Critical".

Depends on the racing application but in physically rough racing environments, (off-road and some circle track), the relay can drop out for a moment in some of the harder hits on the suspension. You can orient the relay a certain way but it won't fix this. You sure would not want your ignition or fuel pump tied to 12v in this way. Drag racing tends to not see this very much, so I susepct it would be fine there. I tend to favor the no-relay approach for racing for this reason. If off-road in the desert or on a long rally, 50 miles from your crew and in the middle of nowhere, KISS reliability wins the day.
And, having been a racing tech for many years, yeah, stuff gets by 'cuz you just can't check it all, every time. Everyone is very conscientious, but really, the fact that there are very few bad wrecks overall tends to be the most important factor!

 

[A68DART360]

well I finally got the alternator and the brackets for it. Here is what I end up with. It is a Powermaster ultra mini 75 amp alternator and a DMI billet alternator bracket kit and billet crank pulley. It went on easy and fits perfect. I would recommend it to anyone. The car also shuts off when I turn off my battery disconnect swtch. All I did was run the wire from alternator to battery. I will post a couple more better pictures that I took with my digital camera tomorrow. These were taken with my crappy camera on my phone.

 

[A68DART360]

Here are a couple of pics.

 

[Les Gibson]

Just hook the alternator up to whatever battery cable you have coming up front from the cold side of the switch.

Again, I know nothing about the quality of that switch. I think I saw a Moroso switch recently advertised of alleged high quality, but it is likely "really" a Cole Hearse or some other known brand in "Moroso" wool.

One of the members here came up with this, and it works. I wish I could remember, I'd credit him

If using a one-wire alternator with this set up, where there is no AF/VR"I"/ ballast wire, where does the alternator output wire come into play? I'm running a MSD 7AL-2, would the +12V 'exciter' wire, from the IGN toggle switch on my Painless Wiring switch panel, take the place of the AF/VR"I"/Ballast wire? Just trying to get this straight before I start rewiring my drag race only 72 Dart.

 

[oldkimmer]

Ur best bet is to get a NHRA rule book. It spells out how to wire ur car for the kill switch. The only wires to and from the kill switch is the pos and neg cables. Kim

 

[67Dart273]

If using a one-wire alternator with this set up, where there is no AF/VR"I"/ ballast wire, where does the alternator output wire come into play? I'm running a MSD 7AL-2, would the +12V 'exciter' wire, from the IGN toggle switch on my Painless Wiring switch panel, take the place of the AF/VR"I"/Ballast wire? Just trying to get this straight before I start rewiring my drag race only 72 Dart.

Use the secondary contacts on the disconnect to open the MSD "small red" power trigger wire. Run the alternator to whatever main cable leads up front to the starter, just like you would if the battery is up front

 

[famous bob]

So lets say I get this style switch how would I hook up the alternator to the car and make it work correctly and also make the disconnect switch work too.

Last I saw , that switch was not nhra legal to start with ------------

 

[oldkimmer]

Last I saw , that switch was not nhra legal to start with ------------

That’s right Bob. Kim