Alternator Kill Switch, Worse MPG?

[JohnNeiferd]

At busypaws and Daox, I understand what you mean by using a switch in the field wire. I did this on my 1987 Civic. However, when I unplug the green connector on the Metro's alternator, the battery still reads the same voltage as when it is plugged in. Even with the engine running and lots of accessories on.

I'm not sure, but my theory is that the Metro's alternator is similar to GM's 1-wire alternator which has only an output wire and no other connectors. The Metro's alternator may detect battery voltage and power the field through the output wire. The green connector may just be for the battery light on the dash to let the driver know when voltage output is too low. Like I said, I'm not sure on this. I'm still trying to figure out how it works for sure.

At idle, when I turn my toggle switch off, the engine does slightly idle a bit higher. When you turn the toggle switch back on, you the idle drops a little lower and you can hear it in the engine. So the engine is obviously under more load with the toggle switch on. However, even with the toggle switch off (so the alternator is not connected to the battery), if I check the voltage at the alternator (not the battery), my digital multimeter says around 26.8V, and it remains the same whether I have no accessories on, or all of them on.

[Christ]

Here's the bad part of that whole thing: The alternator is charging... nothing.

It's building a charge, which it then has to shed somehow. Probably as heat. That will probably eventually kill your alternator.

Gm's 1 wire alternator isnt' really an alternator, IIRC. I'm pretty certain it's a permanent magnet generator, which later routes power through a voltage regulator. That being the case, it's always charging something, which is why lots of those older cars always have some electrical load running, so they don't overcharge the battery.

My $0.02, FWIW.

[JohnNeiferd]

Hmm... that sounds discouraging.

An A/C electric clutch on the alternator would solve the problem. There are several at the Century Trading Company salvage yard in my town. Basically a junk yard, for anything metallic. They charge around $0.30 a pound for anything in there, so I could get one incredibly cheap. I assume they just run on 12V to engage them. If I could find a way to mount it to the alternator, it'd be very similar to MetroMPG's unbelted alternator experiment, except I'd still have my belt on. I could use my toggle switch to engage/disengage the clutch then.

I'll probably play around with the alternator a little more first and see if I can figure out some electrical solutions before I go with an A/C clutch.

[silverinsight2]

Originally Posted by RobertSmalls

I drive around with the IMA disabled with a clutch switch mod, and when the brakelights come on, it energizes a relay that reenables the IMA. Since, in the winter, I don't have enough high-voltage juice for assist, it's more like a really fast alternator than regenerative brakes.

http://ecomodder.com/forum/showthrea...tml#post150133

Btw, I have an Optima yellow top in there, so I'm cooking up a DC-DC converter disable.

Another great idea Robert, a few questions;

1.When cruising at night, does this tend to drain the HV battery?
2. Any effects on the auto-stop?
3. Will the car restart automatically if the voltage drops below the IMA preset level?
4. Any luck with the idle air circuit?
Thanks

[JohnNeiferd]

The only problem I see with a brake light enabled recharging system is that it wouldn't work for dedicated hypermilers. I don't consider myself a hypermiler, but I hardly ever use my brakes. I always engine brake as it puts my car into DFCO. Others without DFCO sometimes just cost in neutral to avoid using their brakes or engine off coast.

For those who do use their bakes regularly, I think it'd be a great system.

[JohnNeiferd]

Just an update and warning for everyone who wants to try this.

I believe Christ was correct. My voltmeter showed the alternator putting out around 23volts when it wasn't connected to the battery. So it was still charging. I hardly used my cut-out switch, maybe a combined total of 35 minutes and my alternator decided to die. Voltage regulator would only put out around 12.5 volts at idle (with it hooked to the battery) and around 11.6 volts with a lot of accessories on.

Luckily, I have a wrecked Metro for spare parts and took the alternator off of there. So I am back up to around 14.2 volts. I removed the cut-out switch. Running a vehicle without a alternator is possible for MPG gains. However a good deep cycle battery with a lot of reserve capacity should be used, a solar panel (even a small one) would help extend the life of the battery, and the battery should be charged whenever not driving the vehicle to keep it from getting to low. A smart battery charger that turns off automatically and has a desulfate mode would help as well.

If someone could adapt an A/C clutch to work on an alternator it could be used for a regenerative breaking system as well.

I may attempt all this eventually, right now I am working on aerodynamics for my Metro right now so this will be on the back burner for now.