ERA 289FIA alternator replacement

[Dangerous Doug]

I have installed a set of PIAA lights on my 289 FIA. I've wired them correctly by PIAA instructions (pull power from a battery source, switch by relay, wire the lights to come on only with brights, et cetera).

Now, when I turn on my headlights the ammeter goes below zero, showing that the addition of the lights is drawing much more current, and my alternator cannot keep up. This is true with my driving lights off.

Now, the question: Checked Summit Racing and it seems that all of the 140 Amp alternators are "internally regulated". Is this as opposed to having a regulator box like I have in my ERA? Is an internally regulated alternator compatible with the ERA wiring? Can it be made compatible.

I am not sure what my current alternator output is, but I think it is a stock Mustang unit.

DD

[patrickt]

Doug, where exactly did you wire the feed for the lights -- which side of the ammeter?

[Dangerous Doug]

I pick up the feed for the lights at the battery cable attach to the solenoid on the firewall. The control signal (that switches the relay) goes to fuse #7, which is for the brights. For the PIAA's to light up, the piaa switch has to be on, and the brights need to be on.

DD

[patrickt]

Originally Posted by Dangerous Doug

I pick up the feed for the lights at the battery cable attach to the solenoid on the firewall. The control signal (that switches the relay) goes to fuse #7, which is for the brights. For the PIAA's to light up, the piaa switch has to be on, and the brights need to be on.

DD

OK, let's say those new lights draw 20 amps. With that load being fed from the battery side of the ammeter, when you turn the lights on, and everything is perfectly normal and the battery is not charging nor discharging, you will immediately show a charge of 20 amps on your ammeter (because your alternator will be feeding that load through your ammeter). Some guys don't like this (some don't care). You just have to remember that if you're showing a typical "slight charge" on the ammeter, and those lights are on and are drawing 20 amps, then you are really discharging your battery and your ammeter is fooling you.

[xb-60]

Originally Posted by patrickt

....your ammeter is fooling you.

An ammeter is authentic, but a voltmeter ("battery condition gauge") is more use.
Cheers,
Glen

[ceslaw]

Yes, a single wire alternator could be easily installed. The existing external regulator would essentially be left for appearance only and effectively bypassed.

Look up the specific alternator you have in mind on line and see if they have an on line installation manual. I suspect you may find a detailed wiring diagram for what you are seeking to do.

[Dangerous Doug]

Patrickt: I'm showing a discharge---the ammeter is going negative. You'd expect your regulator to compensate for the load and the ammeter to return to zero---you're not drawing excess current from your battery. This drained by battery down in 20 minutes such that I didn't have sufficient current to crank the starter...

I don't think the ammeter is lying to me. It's never lied before...

DD

[patrickt]

Originally Posted by Dangerous Doug

Patrickt: I'm showing a discharge---the ammeter is going negative. You'd expect your regulator to compensate for the load and the ammeter to return to zero---you're not drawing excess current from your battery. This drained by battery down in 20 minutes such that I didn't have sufficient current to crank the starter...

I don't think the ammeter is lying to me. It's never lied before...

DD

My previous post was for when you have an alternator that is strong enough to carry the entire load. When that happens, by having your new lights load on one side of your ammeter, and the rest of the load on the other side of the ammeter, you could show a partial "charge" but actually be discharging (if the amount of indicated "charge" is less than the amperage draw of the lights that are now on the battery side of the ammeter). The fact that you are showing a discharge now is an indication that your alternator is not carrying the load at all.

[patrickt]

If your new lights drain off 20 amps, and the ammeter only shows 5 amps of current going through the ammeter to those lights from the alternator, then the battery is supplementing the needed 15 amps (discharging it), but your ammeter still shows a nice healthy charge of 5 amps! That's why you generally don't put a load on the battery side of the ammeter.

[Dangerous Doug]

Ah, I see your point: put the main power line for the lights on the - side of the ammeter to get a correct current reading of the consumption.

I'll have to look at my lights wattage to see how much power they use.

So, back to the original question: After I change my power wire to the other side of the ammeter....

...I'm looking at alternators on Summit and everything I find in the 140 amp range is internally regulated. Is there a source of high output alternators that are externally regulated? Or can a internally regulated alternator be used redundantly?

Also, any way to know the amps output from markings on a alternator?

DD

[RICK LAKE]

Dangerous doug This company sell a kit for cobras that looks OEM. Plug and play with 1 wire need ing to be connected. Alt output is 95 amps. YOur amp gauge insolutors will not last in the amp gauge. need to convert to voltage gauge. Rick L.

[strictlypersonl]

Originally Posted by Dangerous Doug

I have installed a set of PIAA lights on my 289 FIA. I've wired them correctly by PIAA instructions (pull power from a battery source, switch by relay, wire the lights to come on only with brights, et cetera).

Now, when I turn on my headlights the ammeter goes below zero, showing that the addition of the lights is drawing much more current, and my alternator cannot keep up. This is true with my driving lights off.

But this didn't happen before you installed the new lights? Does the ammeter go positive when the engine is at 1500 rpm and just the headlights are on?

[Dangerous Doug]

Correct, Bob, the ammeter was pegged at zero with or without the headlights on before I installed the lights (which actually LOOK pretty cool). However, now if I merely turn on my headlights the ammeter goes slightly negative (to an obvious degree). I have yet to disconnect the PIAA harness to see if the problem persists.

Ah, I just recalled! I forgot about this: the turn signals had stopped working just prior to the PIAA installation. Hhmmm...

Any advice on the wiring? My relay control line I've wired to the brights side of fuse #7; the power source line I've wired to the +battery cable, at the solenoid. The power line has it's own inline fuse. I am wondering if the PIAA relay has gone bad and is drawing more current in either it's on or off state?

The dims, brights and the driving lights all work correctly, but the driving lights are not as bright as I anticipated. And, of course, there is that little battery discharge problem...

DD

[strictlypersonl]

Fuse 4 (bottom, passenger's side) feeds power to both the signal lights and the voltage regulator...

[Dangerous Doug]

Bob, I take it that fuse#4 is the recommended placement fit the driving lights power draw line? DD

[patrickt]

I think Bob thinks you blew that fuse and that's wire you're showing a heavy discharge all the time....

[RICK LAKE]

Dangerous Doug. Doug first off what pulleys are you running on the motor?
Is the crank shaft pulley small? This is an underdriven setup. The Alt will not spin fast enought to charge the battery and handle the load on the electrical system. Should run a 65 -75 amp alt in the car to start with extra electrical draws on the system like lights, radio., ac system, etc. Get a cheap volt meter. Hook it up to the car, turn on what you normally run and check the voltage reading at idle. Any thing less than 12.5 volts means the battery is nto being recharged and is slowly draining the battery at idle. Run the motor up to 1,500 rpm and repeat the test. Alt should be running 13.7-14.2 volts with the same curcfuits on. If it is less your alt will not FULLY charge the battery. Cobras had basic charging systems. Some came with a 38 amp output Alt others got in the 60-70's in ampage output. Here's the other thing. If you run a charging system in the 70 amps or higher it will over time burnt out the insolators on the terminals for the amp meter. All the power goes through here. This is the reason to convert to a volt meter for the dash and hook the (2) white 10 gauge wires to each other and tape Hook 1 wire there for the volt meter, use the light from the volt meter and you just need a ground. My system runs a 95 amp setup. 5 fans, MSD ignition, ECU, fuel injector, heater blower motor, lights, wipers and 2 fuel pumps. I also ran under size pulleys and would kill the battery if the car idled for 10-15 minutes before. With 95 amp setup I have 40 amps at idle and 13.8 volts at idle and 78 amps with 14.2 volts at 2,000 rpms with all power ideas on and running. Alt is still charging the battery. Most cars today have from 100 amp to 220amps on highbreds. I think you will find that if you turn on your, head lights, wipers, electric fuel pump, and coolant fans running you will see a draw larger than the charging system can supply at idle. It doesn't matter where you power those lights from, they still drain the system with anywhere from 8-20 amps. Again tyoo much at idle for your charging system. Rick L. you have p-m.

[xb-60]

Doug, IMO, you need to go back to what you know works. So that means first up, disconnect the wiring and the relay for the new lights, then fix the turn signal problem and then make sure everything is then working the way it should be.
Only then should you wire in the lights and relay, remembering that if you take power for the relay directly from the battery, it won’t show up correctly on the ammeter. If you wire it this way, then just accept that your ammeter won’t read correctly ONLY when the big lights are on, but that’s OK. So consider changing to, or adding, a voltmeter.
If you take power from the ‘non-battery’ side of the ammeter, it will show correctly, but you will be putting an extra 16amps (if the lights are 100W each) through your ammeter wiring, and I wouldn’t do that.
Taking power for the relay direct from the battery is the most efficient way to do it.
Incidentally, I have run two 100W Super Oscars on a car with a Lucas generator (22 amp rated output). That worked OK (just) but I eventually replaced the gen. with a 35 amp alternator which was more than adequate. That car didn’t however have significant other electrical loads other than ignition, normal lights and radio.
Fix the turn signals first.
Cheers,
Glen

[strictlypersonl]

First, take Pat's advice and check the fuse to make sure you've got an actual working charging system.

For the amount you're going to use the lights, I wouldn't run their current through the ammeter at all. Take the power directly from the battery, use a relay to switch the power from the dash switch.

Unless you're going to run night races, I wouldn't bother to put in a larger alternator. You're not going to need the big lights under 50 mph, at which point you won't be using the radiator fan at the same time. Keep things simple.

[patrickt]

Maybe he doesn't have any problems at all. Maybe he just bumped the voltage regulator fuse and it blew and he didn't notice it. Then, if that happened, he effectively has no charging at all. And maybe those new lights only draw 15 amps and his existing alternator is plenty good enough and he could move the source over to the hot side of the #1 fuse holder and everything will work perfectly and he won't have to do much of anything....