Battery and charging

[Jackson1320]

The alternator is computer controlled and will change more or less depending on the state of the battery does not matter rpm. You can adjust the alternator in the tune if you want.
on the premium cars the alternator is 200amps

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[Rapid Red]

The charging system needs current to the alternator rotor windings to energize. The initial current comes off the battery and then after it powers up the alternator provides its own excitation current. It has nothing to do with engine rpm. You can size the alternator pulley as fast as you need at engine idle to meet maximum demand. Obviously you don't want it spinning at warp speed when the engine is at red line rpm, so there are some limitations. Some alternators are the permanent magnet design. I think, but not certain, that they don't require any current to the rotor. They self energize as soon as they rotate.

In the old days generators were a problem. The have a much lower output at low rpm as compared to an alternator. Sizing the pulley to provide enough current at engine idle while not moving so fast at red line that that it would over speed and self destruct was challenging.

Think of this. If your scenario is true, a 6MT Mustang would need to be moving at better than 73 mph in 6th gear (2000 rpm) to energize the alternator. 72 mph for the A10.

Don't confuse engine rpm with alternator rpm.

The CD did not specify pulley or engine RPM, 2k can easily be reached, upshifting. I like your thinking and may or may not be true.

The point intended for the post was to inform.
A. There is much more to be known about the charging and battery of the car.

B. One cannot charge a battery sitting in the garage with one's favorite hot cocoa. Car idling, and change the state of the battery. It has the opposite effect.

It is not the windings that are excited it is the field, and that takes a regulator to make that happen.

"They self energize as soon as they rotate."

That's just not so, I could go into the one wire alternator that hotrodders love to think is the same. That does work as you have posted, and is not the same.

Cheers

 

[WD Pro]

I have noticed that the decay in battery voltage / SOC is much faster following a 20 mile run than it is following a stint on the battery maintainer :

WD

 

[djpayne2]

Was reading thru some topics, on a Ford CD. Not looking for any particulars, just board. Spot a large amount of information with regards to the battery & charging system.

To say the least there is a lot going on there, quite a sophisticated design & its operation. That is one point, the second I want to point out. Starting the car letting it idle, and thinking one is charging the battery.

Is killing the battery, the car is running totally on the battery. The charging does NOT happen before 30 mph.

Interesting I'd say, for anyone having battery problems, and figuring out what's going on. Doing their own troubleshooting, for repair. I highly recommend spending 250 for a Ford CD, pages of information on the system, defined steps to isolate problems.

my .02

OP, I have been debating getting the CD.

Does it detail essentially how to take the entire car apart and put it back together?

Thank you.

 

[ZeroTX]

Baloney. If your battery reads at 12-13v and when idling you read 14.5, then you're charging. I don't care what the book says. That's physics. I've idled my F150 for *hours* during 17 degree weather with no heat in the house. If it were just running on battery, it would've died. It didn't die.

 

[Buldawg76]

Baloney. If your battery reads at 12-13v and when idling you read 14.5, then you're charging. I don't care what the book says. That's physics. I've idled my F150 for *hours* during 17 degree weather with no heat in the house. If it were just running on battery, it would've died. It didn't die.

You are exactly correct. If the alternator is working correctly and charging the battery can be completely dead and incapable of holding a charge, but as long as the engine is running, and the alternator is charging it will continue to run until you are out of fuel or shut the engine off.

BD

 

[Rapid Red]

OP, I have been debating getting the CD.

Does it detail essentially how to take the entire car apart and put it back together?

Thank you.

Sort of has enough to allow a DIY guy to work thru & make repairs. You want every nut & bolt that is a 1500 a year subscription.

 

[Buldawg76]

I got thick skin, and no one is tearing me down for any reason. Been working on vehicles of one kind or another since I was 5 years old both as a hobby and a career so do know how things work and don't work.

Been ASE master certified since 1976 till 2015 and was also a Cadillac/Olds master tech and Harley Master of Technology so know a thing or two about vehicles. Got 50 years of tools in my garage to work with as well. Worked on cars as old as a 1938 Bentley and up. I have yet to find a job I am incapable of diagnosing and repairing correctly the first time.

He can blow smoke all he wants but I don't inhale.

BD

 

[Vlad Soare]

Here's what the service manual says about the alternator:

Strange that it's called "175A" when in fact it will max out at 155. Kind of like Mercedes 6.3-branded cars which are actually equipped with 6.2 liter engines.
But anyway, it seems to charge at idle, too. I think 70 amps should be enough to charge a depleted battery, given enough time with no massive consumers turned on. Of course it will be slow, but at least it will charge, eventually.

 

[DougS550]

yep its charging at idle at that voltage, more of a trickle without amps behind it.

It charges at idle and delivers amperage accordingly. Put meter on battery and measure static voltage usually 12.4 vdc or so, start engine let idle. Voltage is around 14.5 vdc, turn AC on, Fan Blower max, turn headlights on for max amp draw. If your voltage is above static voltage, it's charging and delivering appropriate Current.

 

[Rapid Red]

Nope, not so it's just keeping up the load being required.

The Voltage is the delivery of the electrical load (AMP). Low voltage, fewer amps (power).

If the car actually had an amp meter to monitor. You will be eating your words. Turn all that shit on it will go negative.

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