Low Alternator Output In the Desert Heat

Huh? Sounds like something more serious. My ignition system designs run down to ~4V! Maybe it's a fuel injection failure? I had some funny business with the previous Q45... turned out to be a clogged filter at the electric fuel pump. ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

I thought that was the problem too for awhile but replacing the filter [cheap fast and easy] had no effect.

What works is (a) cool weather and (b) low load on the alternator.

The "module" in the distributor may be compromised too but that doesn't change the fact that the system works with low load.

Bret Cahill

They make a teater for fuel pump pressure for that.

The filter you changed is only part of the story, there is a screen in the tank that also can get clogged.

Monitor the battery voltage. Most cars, if the battery boltage goes too low will not go onto closed loop operation. This is not because it cannot do it, usually it can. It is a protection thing.

Also, some of these engines now pull more current to run than to start.

The key indicator here is the battery voltage. Check that.

Also, car alternators are set up to put out slightly less in high heat.

Is that to save the battery?

If so then it works. I get 6 years out of a cheap battery.

Bret Cahill

Really? I didn't know you were expert in alternator design. ...Jim Thompson

-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

| 1962 | I love to cook with wine. Sometimes I even put it in the food.

I might have put that rong. They are made to put out more in the cold becau se of the change in the battery's characteristics.

Alot went into figuring all that out and quite frankly I do not know all of it. But lead acid batteries have different characteristics at different te mperatures. And they had to thing about cold cranking amps as well, especia lly bacvk in the 1970s when assholes like me had 455 engine with 12:1 compr ession rtios nd wanted to go now when it ws zero degrees outside and I hadn 't changed the oil in two years.

I thought you had me killfiled !

Anyway, not really an expert on the design, but somewhat on the operation o f the device. Though I DO know the design.

What's more, the design has changed. Back in the 1970s they would work into a dmanear short circuit and be fine. Now when you buy a new one it says to make sure the battery is charged. That means charge the battery before sta rting the car, DO NOT just jump start it and let the alternator charge the battery. It will fry it out because you know, less is more. We had 60 amp a lternators that worked way back and now we got supposedly 200 amp alternato rs that will burn right up if the battery is dead. You know math, and you k now how it has changed. Less is more. You get less, and it is more money. A nd cars use more power running than starting these days. I think that is ri diculous.

So you didn't like my little political rant eh ? Why ?

I had a problem like that with my old Toyota Land Cruiser. The problem turned out to be rusted diodes in the alternator. They were pressed in place and managed to rust between the aluminum and zinc coated steel of the diodes. Temperature had everything to do with how well they made contact with the alternator casting.

I got a used salvaged alternator with some good diodes in it.

your battery is most likely getting old.., can't handle the short duration of current loading and the alternator is seeing too many dips in the AC cycle coming out and screwing up the regulator control.

It's a common problem, maybe not be yours but something to think about. Regulators on alternators in most systems these days react early into the cycle to deduce the chance of peak voltage exceeding a device handling. This also drops the average charge abilities too.

If you have a scope you can see this on the screen as a small ripple at the battery, if that is the case.

Then again, one diode not working properly can also cause some issues, but that you can also see on the scope.

Jamie

Hah, I had a similar issue with the battery/ electrical system in my "farm" truck. In one of the electrical connections to the battery someone had put the steel lock washer between the two contacts rather than on top to them. Several years later the corrosion made the resistance enough to cause issues.

I still remember trouble shooting it a wondering why the "f" there was a ~0.5 V drop across the connection.

George H.