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oil pan 4 08-29-2015 01:26 AM

Alternator delete switch
2 Attachment(s)
Just turning power off to the alternator isn't good enough for me.
No I want to stop the alternator from turning and sever its electrical connection, with the push of a switch, because I am lazy.

Just removing the electrical load is only removing half the over all load at best. Since vehicle alternators are around 50% efficient at their peak efficiency (max amp draw for that RPM).
So most of the time the vast majority of the engine power sent to the alternator is used to beating on the air around the alternator.
This is why you want to stop it.
Then you must cut power to the voltage regulator, With the alternator stopped and the voltage regulator powered up it will still draw 2 to 3 amps. I found this out the hard way when I rewired my charging system to use the high amp output post on the alternator and put one of the wires in the wrong spot. It slowly drained my batteries.

I have seen people put A/C clutches on an alternator. Only problem with that is you put a bigger pulley on, reducing amp out put. For some applications that larger alt pulley is great. Not mine.
When I need power, really I need power.

How then?
I believe I should take the alternator, make it pivot. Install a spring to bring the alternator belt under tension. Then counter the spring tension with a pneumatic linier actuator when alt power is not required.
But that would allow the belt to fall off the pulleys.
Not unless I install a guard around the belt holding it in place. Just like on a riding lawn mower. The guard holds the belt just off the alternator drive pulley when tension is relaxed.
Since its riding lawn mower technology I think it could work.

All it then needs is a source of compressed air.
I have that at least.

How to control the air? The smartest way to do it would be non electronic. Something like this.

Frank Lee 08-29-2015 01:54 AM

I like the train of thought. But being opposed to Rube Goldberg complexities, I think I'd want an all-mechanical solution, like a cable or lever.

Then what happens to the other stuff on the belt drive? (water pump, pwr str + a/c if you have 'em)

oil pan 4 08-29-2015 02:59 AM

Its a lever, spring and pneumatic actuator. The simplest Rube Goldberg device in the history of Rube Goldberg devices.
The alternator is the only thing being driven by this v belt.
The coolant pump is electric.

Frank Lee 08-29-2015 03:32 AM

OK Carry on.

Baltothewolf 08-29-2015 03:44 AM

Just have an electric motor turn alternator, creating it's own energy, therefore cresting an infinite power source. Great Scott!! Why didn't I think of this sooner!! Infinite renewable energy!!

OK seriously though, why not just use an A/C clutch, but upgrade your alternator to compensate for the bigger pulley size?

GhostWolfGT 08-29-2015 09:36 AM

I can't see it making all that much of a difference. I've seen a homemade wind generator spin out of control because there was no load on the alternator being used. Almost no resistance. Put 1 light on it and it comes down to a safe speed. You could probably test it before rigging it all up by observing engine load at idle with and without the belt.

I do like Frank's idea if it was worth splitting hairs, though. A parking brake lever and cable from a car would be perfect. A trampoline spring holds it loose and you pull up on the parking brake to tighten it up and activate the alternator. Locking it in place. Less weight. Less room for a failure later on. And you could find an even better use for the actuator.

You could even wire the switch in the parking brake to a relay that turns the alt back on when pulled up.
Alternatively, a spring loaded idler pulley would probably work best so not to wear out the pivot point on the alt. But use the cable to release tension when pulled up instead of create tension.

oil pan 4 08-29-2015 02:32 PM


Originally Posted by Baltothewolf (Post 491522)
OK seriously though, why not just use an A/C clutch, but upgrade your alternator to compensate for the bigger pulley size?

A typical A/C clutch is so much bigger than a regular alternator pulley that the alternator over drive ratio would go from a 1:3 over drive down to a 1:2 or 1:1.5 over drive.
Then at idle being over driven at 1:2 the alternator would only spin 1200 to 1400 RPMs and make almost no power. Getting a bigger alternator would not fix this.

This is on a 6.5L mechanically injected diesel. I cant hook a computer up to it and look at the difference in load. The only way to see how much the load changes with out the alternator hooked up is to watch for the RPM increase at no load with the injector pump metering lever set in a fixed positions. Such as idle and fast idle.

All the air compressors I have built and rebuilt use a idler tensioner. This is my preferred method but I don't think loosening an idler can prevent the belt from rubbing on the crank pulley.

I would use spring to tension the alternator so that if the cable broke, the actuator or its air supply failed or what ever mechanism I used failed, the alternator's belt would go to tension and start supplying power.
This is a fail safe mode.

oil pan 4 08-29-2015 02:44 PM


Originally Posted by GhostWolfGT (Post 491533)
I can't see it making all that much of a difference. I've seen a homemade wind generator spin out of control because there was no load on the alternator being used. .

Most vehicle alternators red line at 15,000, they can exceed this speed, but not for extended time.
Those small turbine alternators only have to turn a few hundred RPM to make power because of permanent rare earth element magnets. They spin "out of control" at under 2000RPMs because of the huge relatively unbalanced blades attached to them.
You are correct, it does take almost no power to turn an alternator 2,000RPM, but in a vehicle the only time the alternator in a vehicle spins less than 2,000RPM is at idle.
At cruise speed the alternator is typically spinning between 6,000 and 10,000 RPM.
Every time you double the speed, aero dynamic drag on the alt increases by 4 times.
This is why vehicle alternators are not very efficient.

Frank Lee 08-29-2015 03:33 PM

I slowed mine down and it does the job.

markweatherill 08-29-2015 04:13 PM

If you want to mechanically disengage and re-engage the alternator at will, I feel a more reliable solution would be to adapt things so it is driven by the outside of the belt, and just needs to pivot towards or away from the belt surface.

oil pan 4 08-29-2015 06:09 PM

Whats more reliable then a pneumatic actuator countered by spring in a manor so that if the actuator or the air supply were to fail alternator belt would engage the crank pulley by default?

oldtamiyaphile 08-29-2015 10:21 PM

I've never seen a ride on mower tensioning system, but it seems like a disengaged belt would have quite a lot of friction rubbing against it's guides? As a guess a ride on mower is designed to only be moved short distances with the blade disengaged, it's primarily designed for mowing with the belts tensioned. I wonder if extended use of the alternator disconnect would lead to quickly worn belts.

How much energy does a mechanical diesel need anyway? With so much roof space on a suburban it seems like a perfect candidate for some flexible solar panels. Before you say 'glow plugs', they're only needed on a cold start when the panels would have had time to fully top up the batteries. Of course if you do a lot of night driving it might be less attractive.

oil pan 4 08-29-2015 11:10 PM

Only the injector pump is mechanical now.
The fuel pump, coolant pump are electric now. Other electric loads I have that will only run occasionally is that little ARB air compressor it only draws like 10 amps a shut off pressure, some more lights. Other goodies I have in my possession, but not installed yet are a Gast air compressor that takes 50 amps just to free spin it (it is a starter motor with 2 air compressors on it) and a Xantrex 1000 watt pure sine wave inverter.
Then also 98 inch by 18 foot deck tandem axle trailer with 4 electric brake hubs plus its light (my trailers lights are full LED already)
Other devices I need to acquire are a vacuum pump to operate the hvac controls and an LED light bar.
When I need the alternator, I really need the alternator to produce.

I already have solar panels, a left over from when I had lead acid batteries. Only about 20 watts worth. But it could bring the lead acid batteries up to 13.4 volts on a freezing cold day as long as the sun was out.
I want to go from 15 to 20 watts to more like at least 70. There are a lot of really cool flat flexible panels out there now compared to even just 2 or 3 years ago.
But that's a whole nother post.

The glow plugs are needed pretty much any time the engine coolant temperature is below 120'F or it just wont start, or I will have to crank it several seconds longer to get it to fire.
If I know it will fire with out using the glow plugs I don't use them, saves the battery, relay and glow plugs.

If I can get the belt holding guards just right when the alternator belt goes loose it should only be touching the guard, the alt pulley and be sitting just above the crank pulley not touching it at all.

oil pan 4 12-21-2015 03:49 AM

I think I figured out how to do it.
Billet Specialties drivers side alternator bracket and windy nation linier actuator.

oil pan 4 12-27-2015 12:22 AM

I got the windynation linier actuator. It looks like it will work for what I need.
The Billet Specialties drivers side alt bracket should be here any day (Monday?).

yellow2000sr 01-09-2016 02:41 PM

Couldn't you possibly come up with a new bracket/mount to offset the alternator back from the belt. Do an AC clutch style pulley on the alternator then have a machine shop fab up a cupped plate to weld onto the AC pulley. Then fasten the factory pulley to that plate.

Seems easier then messing with a bunch of actuators/air lines, and extra wiring.

Just have a single switch to turn clutch on/off.

oil pan 4 01-09-2016 08:38 PM

The AC clutch pulley won't over drive the alternator to the desired speed at idle. It would only overdrive the alt by between 1:1 and 1:2, I need the full 1:3 overdrive. I have the billet specialties drivers side low alt mount and I am going to replace the tensioning bolt with a liner actuator
I need the alt for winter driving so the alt on off will be manual with easy belt removal, then fully automatic later.

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