Alternator relaxer

[DieselJan]

Originally Posted by cajunfj40

BTW, great circuit DieselJan. If I understand it right, this circuit does enable "regular" charging if the battery gets below a voltage you set with the correct diodes, as well as the "charge when brake circuit is active"? IE, it's "foolproof" barring a sudden overnight drop in temperature on a barely-above-set-charge-threshold battery.

Does it continue to charge when you sit at idle at a stoplight with your foot on the brake?

Thanks,
-cajunfj40

Hi Cajunfj40
Thanks. Yes the circuit is fool proof if you set it up correctly. Not foolproof if you set it up to put it on overnight charging.

I always try to do modifications that don't need special attention, etc. I feel modifications should be able to go into production vehicles.

Yes it does continue to charge when idling while breaking. My thoughts was that if you drive around town, you will switch off vehicle more to do shopping, etc. So you will need to start it more and use more battery power. So it can just as well charge wile idling, use the engine turning for something useful.

Out on the highway and longer distances driving around town there will be less load on the engine and you save fuel there. My diesel has a hand adjustable idle screw, so if idle is slow enough the alternator doesn't charge.

I have also lowered my pressure in power steering pump, so it barely work for assisting with parking in town and highway cornering. The power steering still works but I have to put in a bit more arm steering. I will discuss it somewhere in a power steering delete thread. Anyway with that added I have another problem now that the engine is barely loaded in town and now raw diesel is coming from exhaust. Freeway driving is fine with exhaust burning nice and "clean."

[oil pan 4]

Lowering the power steering pump pressure actually doesn't do anything for you while driving down the road, or any time not using power assistance.
When you are not trying to turn the wheel the steering system is in full bypass only making 100psi or so.

[DieselJan]

Originally Posted by oil pan 4

Lowering the power steering pump pressure actually doesn't do anything for you while driving down the road, or any time not using power assistance.
When you are not trying to turn the wheel the steering system is in full bypass only making 100psi or so.

Hi Oil Pan
Shortening the "flow control spring" in the power steering lowers the back pressure the pump has to force against. So in effect the 100psi the pump has to pump against is lowered to maybe 20psi guest-amating. This reduces the torque the engine has to put on the pump, so it turns the pump easier.

I agree that the bypass valve/ flow control valve will open up enough that all the oil that is pumped can go back to the input of the pump while not turning. So it is in effect in full bypass.

I have shortened the spring progressively and every time I could feel it takes a bit more effort to steer. Now it is at a level where I am comfortable with it. The engine can also now idle much slower without roughly shaking than the day I bought it. It must be the alternator mod and power steering pressure.

We had a same make pickup at work which was just the opposite, it was extremely sensitive to steering. When hitting potholes it would jump left or right and was difficult to keep straight.

[freebeard]

Not to discount what you say, but that could just be wheel alignment. I've seen some [potential] deathtrap trucks owned by business.

OTOH, I once drifted 5 tons of dairy feed on gravel.

[stovie]

You could put the power steering pump to the driveline or use a reducer pulley for a car, and have a diaphragm accumulator tank to store some fluid for when you need to steer!! That way you have full power for awhile.

[Stubby79]

I will be looking in to relaxing one of my alternators soon on an older car...it's not smart enough to drop the voltage down from at least 14.4v. A bit too much for my tastes.

[teoman]

Modern cars use 14.4 V, why do you consider it too much?

[Stubby79]

Originally Posted by teoman

Modern cars use 14.4 V, why do you consider it too much?

Modern cars, afaik, come down to 13.8v after a couple of minutes. Maybe this one does too, but if so, it's taking it's sweet time.

I was seeing over 14.4v on start up with no load...anyway, if it doesn't come down, I'll make it come down.

[oil pan 4]

Most of the load the alternator produces even at no load is fan windage and just powering up the armature to energize the stator to even just 12v puts a surprising amount of load on the engine. You have to kill power to the armature to completely electricity unload the alt. Then you still have the windage, it spins 3x crank speed.

[oldtamiyaphile]

New cars generally run at up to 14.8v. They out grew the ancient 12v systems a while ago.

My Jeep has a battery temp sensor. I took it out after replacing the original 12 year old battery, I bench tested it drew up a table of resistance vs temp.

It seems like that would be a very simple way to stop the alt charging at high loads? Simply to ground (or switch in a resistor) the sensor in line with a switch on the throttle and or brake?

I'm not sure there's much point to actually doing it on a Wrangler, but it could be useful on more typical eco cars fitted with such a sensor.