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chilimac02 05-29-2009 02:28 AM

Alternator Delete, How?
How would I go about deleting my alternator?

More specifically, I want to install a button to turn off the stinking alternator so that I can get the mpg that my car is capable of. I know the strain it will put on the battery - so be it.

dcb 05-29-2009 07:19 AM

If you have an external regulator than you switch off the field lead.

If you have an internal regulator then you may have to dissect it a bit and bring out a field lead to a switch.

But it will be completely unloaded if you make sure the field is de-energized (the field is the rotor in this case, connected via the slip ring brushes). The regulator *shouldnt* self destruct if it loses field continuity, but can't guarantee it (could be some dumb voltage regulators out there I recon).

You can also put a hefty switch in line with the alternator output lead (the thick one) but the alternator will stay self-excited and take a little extra power until the engine comes to a stop.

theunchosen 05-29-2009 11:08 AM

I would go with the second option. BIG switch between the output and the battery itself. If you have lawn solar panels. . .rip those out and slap them on your dash and hook them to the battery.

If you are running fans, the radio, your clock, or any other device that uses electricity your battery won't last. It also will not last for night driving and I predict its only got about 50-60 cycles of being driven for 20-30 minutes just powering the engine ECU and ignition.

You'll need solar panels or extra deep cell batteries or you're going to get stranded next week with a dead battery that can't maintain voltage enough to make the engine run, let alone turn over.

JacobAziza 05-29-2009 11:07 PM

I have read several places that you should not disconnect the alternator from the battery (the thick cable) without also disconnecting the field circuit (thin wire to the regulator) because the alternator will continue producing charge and with no where for the charge to go, it will overheat and eventually self-destruct.

Charging System Checks (Alternator Testing) (in bright red) (very bottom of the page)
Self build adjustable alternator controler (about 9/10ths of the way down, begins "important")

I think "If you have an internal regulator then you may have to dissect it a bit and bring out a field lead to a switch." is what you have to do if you have a one wire alternator (internally regulated).

You need to put the lead on a switch, not a button.
I have done this, and mainly charged the battery at home, but you need to watch it very closely. I forgot 2 or 3 times to recharge after a few hours driving (including some night driving) and the thats all it took. Wouldn't hold a full charge anymore. Car batteries aren't really meant to be used for more than a few seconds at a time.
I just put in some RV batteries today. Hopefully I should be able to remove the alternator belt altogether, and avoid even the power loss from the freewheeling alt pulley.

chilimac02 05-30-2009 09:54 AM

I understand the battery issues. I'm planning to mount a few deep cycles in the trunk and connect them into the electrical circuit. I'm looking to put in a switch (should have been more accurate) which will disengage the alternator when I want it to be disengaged. Then I'll watch a battery voltage display to know when I need to flip the switch and re-engage the alternator. Of course in order to keep from trying to charge the extra deep cycles, I'm going to have a switch to turn them off too.

JacobAziza 05-30-2009 12:56 PM

I could be totally underestimating the draw of a cars electric system or how much you drive, but a "few" deep cycles plus the starting battery seems excessive.

However much power you draw, its sure to be less than the max output of the alternator, which usually aren't more than 70 or 80 stock. Even a small group 24 deepcycle is 70-85amp hours, so absolute worse case scenario a single battery should get you an hour of driving with no alternator - thats assuming headlights, stereo, heater fan, everything on at once. If you replace all running lights with LEDs you remove 5-10 amps, and if your can has separate DLRs or can be retrofilled with them, LEDs will shave another 5-15 amps off of power needs.

On my system (and its a diesel, so no coil to power - but I do have a 200watt stereo, electric cooling fan and brake pump, and use the starter alot due to EOC in the city) the couple times I drove several hours at night, forgot to recharge at home and then drove again the next day the most I ever drained the batteries to was about 65% which is too low for a starting battery but a deep cycle can go as low as 20% w/o hurting it.
The only disadvantage to deepcycles is that they don't have as high of maximum amps (CCA) so might possibly not be strong enough to start the engine on a cold day - but if you had 2 in parallel the maximum CCA would be both added together.

In other words, if you have 2 of them, I can't imagine you needing the starting battery at all, never mind a 3rd deep battery.

If the alternator is switched and you monitor with a volt meter, as long as it has the CCA to start the car, I can't see why you would need more than one. Just keep it above 50% charge, (which you may never go below depending on the size of the battery and length of the drive), and top it off at home.

They are after all rather expensive and very heavy. All that extra weight will take back some of the mpg gains of the alternator delete, so you don't want to get anymore than you need.

If you do go all out though, you can get a switch to choose between 2 battery banks (bank 1, bank 2, both, or off) at any marine or RV store.

I found this site helpful when I was shopping for batteries just yesterday: Deep Cycle Battery FAQ

theunchosen 05-30-2009 05:07 PM

Pretty much Jacob,

The alt doesn't provide that much power so its not neccessary to use a ton of batteries, but if you use more you get alot more life out of them.

So 2-3 batteries you might be able to avoid dropping into or below the 20% discharge and have a very long battery life. I think thats the only reason to use multiples, especially if the alts on a switch.

Some users on here have deleted it and removed the alt and the belts, so I understand that they wanted extra power because. . .well if the battery dies the car is stuck.

Other than that I would have the switch connect the deep cell when the alt is off(one switch or two switches side-by-side) to make sure you don't leave the deep cell on. I'd route it so that the deep cell being on means the starter battery is disengaged and the alt doesn't need alot of places to dump charge at that point the resistance in the battery is enough to fight it as well as recharging the battery(its probably not at 100% charge). This also keeps you from draining your cranker which won't survive cycle loading at all(I predict about 20 times but you might get 50 cycles out of it).

Daox 06-13-2009 05:36 PM

Alright, I'm looking into how I want to go about disconnecting the alternator in the Paseo. So, I opened up my service manual and took a look at the wires going to the alternator. There is the main wire going to the battery and three more on a separate connector.

The pictures are huge, so I linked to them.

alternator diagram

So, in an effort to figure out what one of the three wires controls the field strength, I started pulling fuses. As it ends up, the '10A gauge' fuse is the one that disables the field. Unfortunately, it also disables my gauges cluster.

Here are the other diagrams for the whole system and gauge cluster where the 10A gauge comes in.

system diagram
cluster diagram

Any ideas on how to get around this? I'd rather not disconnect the high amperage line to the battery if possible.

stevet47 06-13-2009 05:57 PM

There have been a lot of thread about getting rid of the alternator, and it seems like the natural answer to me, and I know it has been brought up before, but I don't think anyone has done it. Why not put a clutch on the alternator pulley, like an AC clutch? Yes it would require a little fabrication/creativity, but you would have no worry about field coils, and damaging anything. Plus you could just flip a switch, activate the clutch and have you alternator back. Or you could trip a relay off a volt gauge so that it automatically turned the alternator on and off at set voltages.

JacobAziza 06-13-2009 06:13 PM


Originally Posted by Daox (Post 109796)
So, in an effort to figure out what one of the three wires controls the field strength, I started pulling fuses. As it ends up, the '10A gauge' fuse is the one that disables the field. Unfortunately, it also disables my gauges cluster.

Just disassemble the 3 wires on the separate connector.
Chances are they separate out on their own on one end or the other (either at the alternator or voltage regulator).

If they are all in one connector on both ends, you can usually get the crimp ends out of the plastic connector with a tiny screwdriver. The crimp ends are held in place by having a little bit of the metal bend and catch the plastic. If you slip a tiny screw driver in, you can pull the wires out w/o breaking them.
Once they are separate, disconnect one at a time and see what happens. Which ever one makes the battery voltage (or ammeter) fall, you found your field circuit.
Put the other two back in the connector and reattach them.

The other one can either be left off altogether; what I did is cut that wire in the middle, splice in a much longer wire, and put it on a switch on the dash so I can engage the alt from the cab if I have to.

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