Civic alternator shut off, the easy way

[brucepick]

Originally Posted by steffen707

Well I never thought about doing that, but great idea.

That way when the deep cycles are depleated you flip it over to regular starting battery and the alternator doesn't see the huge load of the depleated deep cycles. I got it!

Did you ever find the female side of the alternator plug? I guess I don't know which one is considered the male end and which the female. I was hoping i could find the other end somewhere, but without tearing apart an alternator housing i don't know if this path is possible.

Thanks!

I never did find the other side of the alt connector. I asked a few people and in parts stores and even an auto electric shop. No go. I tried using 1/8" wide male blade crimp connectors. You need to narrow them some otherwise they don't want to go into the metric-dimensioned slots in the cables' side of the connector. I used a Dremel for that, with a (fiber-reinforced) cutoff wheel. One of my absolute favorite tools, sorry I didn't get one years earlier.

Anyway, the narrowed blade connectors do the job but access is horrible until you remove the alt + cable. I gave up on the idea and did my thing with a new alt cable and the green knob switch. With that, I didn't need to build switched wiring between the separated 4 pin connectors.

Even with the positive cable out of the way, it's kinda cramped there, but you might be able to make your connections. Just be sure you pull the battery ground cable before you go near the alt + cable.

[steffen707]

I actually don't have that hard of a time getting at it. I might have a smaller brake master cylinder or something. I've got smaller hands as well. Also when I had to completely modify the engine harness I seperated the alternator wiring from most of the engine harness and re-loomed it back over by the starter to the rest of the wires, so my main alternator charging wire isn't in the way of the green plug.

I de-pined the green alternator plug last night to see what kind of connections they are. Kinda look like ECU pins.

I think what i'm going to do is buy two 4pin plugs, cut off the old plug and solder/heat shrink the wires to the new 4 pin male plug, then make a female plug that goes to the switch, then back from the switch to another 4 pin male plug that plugs into another female plug that's soldered and heat shrink tubed to my new alternator plug.

Kinda confusing, but if you follow, I can unplug the switch alltogether and just plug the male end of the wires to the female end connector and go right back into the alternator for a back to stock configuration.

[steffen707]

Disapointing update guys:

I went out and performed a bunch of tests with the alternator on, with it in low mode, and then I shut the car off, pulled the 4 pin plug from the alternator, started up the car to do an alternator off test and my volt meter was reading 14volts..WTF!? HOW IS THIS POSSIBLE.

So I remembered a thread where people said you need to soft ground the yellow/black wire from the alternator because the field has residual charge in it, even if you shut the car off.

I noticed when you first start the car it isn't at 14 volts, but as soon as you rev it past 2000rpm it starts charging. Also it goes up to 14 volts and then stays there until you shut the car off.

I tested the voltage from the alternator yellow/black wire to ground, it read .01volts. I disconnect the main charging wire at the fuse box, the alternator yellow/black wire now reads 0, put the charging cable back on it reads .01 again.

Keep in mind I don't have the 4 pin plug connected to the car, its completely severed, I cut all 4 wires and am just testing voltage coming from the alternator to the yellow/black wire.

I fire up the car, test the voltage and its somewhere around .05-.3 volts, it likes to skip around, as soon as you rev past 2000rpm it goes to 3-5 volts and stays there.

So now i'm thinking, okay the main charging wire is supplying this voltage to the alternator somehow, so just disconnect the main charging wire, right?!! WRONG.

I disconnect the main charging wire at the fuse box, tape the wire off and isolate it from touching anything. Car is off, check the yellow/black wire, 0 volts, start the car, it reads .05-.3 volts again. Rev it up past 2000rpm and it reads 3-5 volts.

So now i'm clueless. Even if you disconnect the 4 pin plug and disconnect the main charging wire from the alternator to battery, that stupid yellow/black wire still gets electricity and i'm guessing that its still forcing the alternator to charge, even though the electricity isn't going anywhere because you disconnected the main charging wire.

The only way i can think of testing this is to do some MPG tests with the alternator belt off, and then with the belt on but disconnect the wires to the alternator. Compare those 2 results and see if it is in fact charging.

Back to that soft grounding of the field wire to discharge any electricity that's being generated. I tried the light bulb trick, but it didn't stop the alternator from charging, it did lower the volt output from say 14.2volts to 13.6, and when you would take the bulb off ground, it would shoot back up to 14.2 volts at the battery.

Do I need a bigger bulb or instead a resister to drain all this power? I'm afraid to play around with it, for fear of burning up some components in the alternator, and then i'm SOL. I used a test probe bulb, and also a light bulb from one of my craftsman work lights.

So frustrated........

[brucepick]

Steffen707,

Good testing. Thanks for doing all that and writing it up.

Re. your note below - -

Originally Posted by steffen707

... Even if you disconnect the 4 pin plug and disconnect the main charging wire from the alternator to battery, that stupid yellow/black wire still gets electricity and I'm guessing that its still forcing the alternator to charge, even though the electricity isn't going anywhere because you disconnected the main charging wire ....

Please google "Single wire alternator" or take a look at this Summit Racing results page. Only one wire is needed for an alternator. One.

You have to remember that the mechanical load of an alternator (or generator) is basically proportional to the amount of power being use at the alternator's output. If there's zero output, the alt's mechanical load on the engine will be very low indeed, just bearings and belt flex resistance etc. Now, for two examples of the same alternator, running at the same (say) 3000 rpm. One running a little cluster illumination bulb, the other running headlights plus a bank of off-road illumination bulbs plus a monster stereo. The fuel needed to run the first alt will be a lot less than the fuel needed to run the second one.

What allows the alt to get going?? I'm still convinced it's just a property of spinning magnets and stationary wire coils. Spinning fast enough and long enough, the system will set up a magnetic field and eventually will start outputting some voltage. The yellow-black wire is just an "exciter" wire, to get that going immediately. That's all.

[steffen707]

Originally Posted by brucepick

You have to remember that the mechanical load of an alternator (or generator) is basically proportional to the amount of power being use at the alternator's output. If there's zero output, the alt's mechanical load on the engine will be very low indeed, just bearings and belt flex resistance etc.

So are you saying that if you disconnect the alternator output from the battery, the alternator will see no electircal load, and therefor exert little to no mechanical load on the engine?

Is it safe (for the alternator) to have the alternator output wire disconnected as long as it doesn't touch anything to cause a fire or short circuit?

[brucepick]

Originally Posted by steffen707

So are you saying that if you disconnect the alternator output from the battery, the alternator will see no electrical load, and therefor exert little to no mechanical load on the engine?

Is it safe (for the alternator) to have the alternator output wire disconnected as long as it doesn't touch anything to cause a fire or short circuit?

I'm sure of it, on both points. I'd do a pretty thorough job of taping protecting the disconnected end of the alt's original + output wire, as the other end is connected directly to the battery + wire, at the starter motor.

I also keep the alt's 4-pin connector detached from the alt. I do that because

1. We're pretty sure it delivers some signals from the computer to the alt. With the alt disabled, that current now comes from our deep cycle battery, which we want to discharge as slowly as possible. (and)
   
2. We haven't completely figured out how that circuit works but its certainly possible that at least SOME of those wires deliver current from alt to computer. So that power will have to be generated by the alt, or possibly by the deep cycle battery, and we don't want either to be happening; it's a waste of the energy we're trying to conserve.

[wagonef8]

All that work just disable the alternator why not just put a toggle switch on the fuse #15 witch is ALT fuse when blown alternator wont charge at all

[California98Civic]

Originally Posted by wagonef8

All that work just disable the alternator why not just put a toggle switch on the fuse #15 witch is ALT fuse when blown alternator wont charge at all

Because cutting Fuse 15 kills several functions, not just the alternator.

[wagonef8]

What functions are they I thought that was just for alternator

[brucepick]

Originally Posted by wagonef8

What functions are they I thought that was just for alternator

Speed sensor is one; that's visibly fed by the same fuse when you view the circuit diagram.

When I tested pulling that fuse I got a check engine light while the fuse was pulled. Stayed lit while I idled the engine for several minutes. CEL went away after I shut down engine, replaced the fuse and then restarted engine.

"All that work" is relatively little work when doing it.