Christmas Dash Lights, but no Electrical Problem

[Lockleaf]

I've run the normal set of dc tests with the christmas tree lights on and off both. The results were close enough to be considered the same. It does seem a little high, but not seriously high on my DC. The voltage showing is between 14.7 and 15.0 with loads on and off both.

Trevor, when I run an AC test, I am simply looking for any AC reading correct? I'm not incredibly electrical savvy so please correct me if I should be looking for something else.

I do have frayed lines on my pigtail, so I ought to replace it anyways. After I do the AC test I will report my findings. I also intend to go ahead and bench test the thing to see what I get from that. Thanks for the help guys even if half of it is in greek.

[kwren]

I would replace the alternator before I start the car again! If this thing can blow the fuselink it could also blow a bunch of stuff! There is no way that the alternator is functioning right and doing what it is doing.
Since it is established that the alternator is sending way too much voltage to the system, just change it!

If there happens to be another problem, then go after it.

I would bet that with a new alternator, which you will have to do before you go places in your car, everything will be fine... unless you keep screwing around with it and blow up more things than you can ever replace!

fuses blow much faster than circuit breakers trip. How long would you like to shoot umpteen volts into your system???????

Keith

[kwren]

an alternator can work and be spasmodic and again not work at all.

You certainly didn't blow the fuse link with your 14.7 - 15 but it could damage something in your system.

like tom said... " I had dealt with the same problem. Regulator gave up the ghost and within 5 mins of driving fried over half a dozen modules."
he kept running his
No short will fry over half a dozen modules... no short!!!

Not the way it works.

Change the danged alternator.

[Trevor]

Originally Posted by Lockleaf

I've run the normal set of dc tests with the christmas tree lights on and off both. The results were close enough to be considered the same. It does seem a little high, but not seriously high on my DC. The voltage showing is between 14.7 and 15.0 with loads on and off both.

Trevor, when I run an AC test, I am simply looking for any AC reading correct? I'm not incredibly electrical savvy so please correct me if I should be looking for something else.

I do have frayed lines on my pigtail, so I ought to replace it anyways. After I do the AC test I will report my findings. I also intend to go ahead and bench test the thing to see what I get from that. Thanks for the help guys even if half of it is in greek.

From my earlier thread:-
If you wish to check for AC. Switch your meter accordingly and look for any level of AC. The meter should not record DC as this is blocked by the internal rectifier. Please report your findings on the basis of considerable interest.

Start with your meter on an AC range of around 20 volts full scale and step scales down from there. You are looking for any level of AC which may register.

It could be a half wave component with only a single diode shorted through, but you will have no way of reliably confirming this. If the meter flicks up and down over a couple of digits, this could provide a clue, depending on whether the meter is or is not, input smoothed.

There is several possibilities in all this. Some other factor could have caused the fuse link to open. Because of the rather poor way the alternator control/sensing circuit is arranged by the factory, a rebounding spike from an inductive load,at the opening of the link, could have upset the voltage regulation, so that the output went very high for an instant.

By rights the voltage sensing conductor should connect directly to the positive bus, hence the battery, via a low rated fuse. Whereas this wiring has been combined with other circuits and is not independent and separately protected at a low level, as it should be.

N.B. A further possibility is that the sensing circuit became intermittently faulty, leaving the regulator to fly free. Check the plug connection and light wiring for any sign of a problem.

[TexasSwift]

Trevor,
I recharged the battery and found the following:
1) Under static non-running conditions the rear defroster was pulling 9.25A. Thanks Tom.
2) With the engine running I found 25.4 VAC at the alternator. This was from the top (output?) terminal to ground. There was no DC output that I could find. It read only battery voltage. At the battery it read 25.7 VAC. Both reading were steady with no flicker.
As a check of technique, I thought I would duplicate my efforts on my wife's Outback. Her alternator shows 14.3 VDC and 31 VAC.
I guess I need two alternators at a minimum.
Keith

[kwren]

Originally Posted by kwren

Change the danged alternator.

Keith

[benebob]

Originally Posted by TexasSwift

Trevor,
I recharged the battery and found the following:
1) Under static non-running conditions the rear defroster was pulling 9.25A. Thanks Tom.
2) With the engine running I found 25.4 VAC at the alternator. This was from the top (output?) terminal to ground. There was no DC output that I could find. It read only battery voltage. At the battery it read 25.7 VAC. Both reading were steady with no flicker.
As a check of technique, I thought I would duplicate my efforts on my wife's Outback. Her alternator shows 14.3 VDC and 31 VAC.
I guess I need two alternators at a minimum.
Keith

Keith,
Take your alternator to a local starter/alt. shop. For $100-150 you'll be good to go with a local warranty where you can always stop in and give 'em a piece of your mind if it fails on a cold dark rainy night. Plus it'll be a better rebuild then your average rebuild factory does. More than likely you won't get a "lifetime" warranty but I've replaced more lifetime warranty alt or starters then I have one build at the shop 2 miles away (have yet to have an issue with anything they've done).

[kwren]

Thanks.. already played their game and got a lifetime guarantee about 40,000 miles back.

Our alternators should have a higher amperage rating than the factory ones do. My next move is to go for the high amp rebuilt exchange.

Also our HID lights will help us a bunch with the amperage draw on the regular factory type alternators.

Things are looking up!

Glad this worked out well!

Quote-KWren (change the danged alternator)

Take care
Keith

[benebob]

Originally Posted by kwren

Thanks.. already played their game and got a lifetime guarantee about 40,000 miles back.

Our alternators should have a higher amperage rating than the factory ones do. My next move is to go for the high amp rebuilt exchange.

Also our HID lights will help us a bunch with the amperage draw on the regular factory type alternators.

Things are looking up!

Glad this worked out well!

Quote-KWren (change the danged alternator)

Take care
Keith

Why? The stock alt is more than ample for what the car has on it provided you're not loosing amps with a poorly maintained electrical system. Every single alt builder I know says the stock rating is about all the mitsu can handle over the long haul anyways. Higher output will lead to a dead alt quicker plus your wiring system isn't up to the stuff of it as wiring is used based on the specified alternator.

[Trevor]

Originally Posted by benebob

Why? The stock alt is more than ample for what the car has on it provided you're not loosing amps with a poorly maintained electrical system. Every single alt builder I know says the stock rating is about all the mitsu can handle over the long haul anyways. Higher output will lead to a dead alt quicker plus your wiring system isn't up to the stuff of it as wiring is used based on the specified alternator.

Increasing the output of a standard alternator will most certainly increase the heat developed. This will place the machine outside the designers criteria and under abnormal stress. It is a matter of experience to establish the designers latitudes and that there is still sufficient headroom to provide reliability.

The short length of wire involved in passing high current, should not become overloaded to any practical extent. The main concern will be a possible increased voltage drop, due to increased current.

The so called "up grade" often appears to have been fitted, when the requirement is simply a restoration to factory specs. The reported joy being due to out of whack measurements having been taken from an originally faulty system, by way of comparison when establishing performance.

[Trevor]

Originally Posted by TexasSwift

Trevor,
I recharged the battery and found the following:
1) Under static non-running conditions the rear defroster was pulling 9.25A. Thanks Tom.
2) With the engine running I found 25.4 VAC at the alternator. This was from the top (output?) terminal to ground. There was no DC output that I could find. It read only battery voltage. At the battery it read 25.7 VAC. Both reading were steady with no flicker.
As a check of technique, I thought I would duplicate my efforts on my wife's Outback. Her alternator shows 14.3 VDC and 31 VAC.
I guess I need two alternators at a minimum.
Keith

Keith, thanks for your efforts.

Very interesting, but rather confusing in one respect. You report measuring an output of 25.4 volts AC from the SVX alternator output terminal, but no DC that you could find. You say that you read only battery voltage.

Was the DC measurement taken at only the battery end of the charging circuit? If there was no DC at the alternator, this would indicate no connection between battery and alternator, i.e. no back feed from the battery. Please advise accordingly.

In respect of your wife's car, I would say that one diode in the rectifier network is shot, but even so there is an adequate DC output to keep the battery charged. If the AC is causing no concern, (The SVX is probably rather novel with its fault lamp arrangement.) leave as is and save money. However should charging trouble become apparent later on, you will know what to do.

Your experiment with your mother's car, is very useful, as many times members have reported a shop testing an alternator and reporting it OK, but afterwards the flashing fault light problem has continued. I have commented that the shop would have done no more than a simple voltage test and your findings confirm this theory. ≈

In order to confirm theory with practice, I have checked my SVX, which I know to be spot on, and can read only a wisp of AC, i.e. 0.025 VAC flickering +-. This amounts to no more than noise and is understandable in a set up which is not smoothed in any way.

We now have a very cost effective and simple test confirmed. Hoooooray.

Thanks! Trevor.

[Lockleaf]

I measured the AC volts in my vehicle. The dashboard lights come on when there is more than 33 volts AC passing through the harness. When it drops to 30 volts AC my dashlights go off. Either way, now that curiosity is satisfied, I'm ripping the dumb thing out and putting in a new one. I only replaced it a few months ago, so warranty time it is. Thanks for your help guys.

[Trevor]

Originally Posted by Lockleaf

I measured the AC volts in my vehicle. The dashboard lights come on when there is more than 33 volts AC passing through the harness. When it drops to 30 volts AC my dashlights go off. Either way, now that curiosity is satisfied, I'm ripping the dumb thing out and putting in a new one. I only replaced it a few months ago, so warranty time it is. Thanks for your help guys.

Special thanks for this precise information, which expands the record of experience regarding the method of testing. The cut off point you describe is interesting and not easily explained. I will try to fathom a reason for same.

[kwren]

Originally Posted by benebob

Why? The stock alt is more than ample for what the car has on it provided you're not loosing amps with a poorly maintained electrical system. Every single alt builder I know says the stock rating is about all the mitsu can handle over the long haul anyways. Higher output will lead to a dead alt quicker plus your wiring system isn't up to the stuff of it as wiring is used based on the specified alternator.

The stock alternator is not more than ample for what the car has on it. Why do you think we have so much trouble with our alternators??

No one is talking about losing amps with a "poorly maintained electrical system" ... whatever that means, or higher voltage output. Higher rated alternators allows the same voltage output but uses higher rated components in the alternators system.

The wires and accessorys relate to voltage, not the current carrying capacity of the components within the alternator. The voltage output remains the same.

We all know, at least I think we all know, that heat is a killer... especially in electrical components. The higher rated electrical components in the heavy duty alternator withstand more heat without damage.

There you go... some Whys!

Keith

[Trevor]

Originally Posted by kwren

The stock alternator is not more than ample for what the car has on it. Why do you think we have so much trouble with our alternators??

No one is talking about losing amps with a "poorly maintained electrical system" ... whatever that means, or higher voltage output. Higher rated alternators allows the same voltage output but uses higher rated components in the alternators system.

The wires and accessorys relate to voltage, not the current carrying capacity of the components within the alternator. The voltage output remains the same.

We all know, at least I think we all know, that heat is a killer... especially in electrical components. The higher rated electrical components in the heavy duty alternator withstand more heat without damage.

There you go... some Whys!

Keith

If the alternator involved is the factory machine modified for increased output, the end result will be an increase in internal heat.

Components are unlikely to be more highly rated and in this respect voltage is the main issue, aside from heat the real enemy as stated. It is the windings which will have been altered. Correctly, more turns of a heavier wire are required, not more of the same gauge. In order to do this without reducing insulation space, more space is required, which should require a larger carcass.

When on open circuit the modified machine could produce an increased voltage. This will be offset in service by the voltage regulator but the potential exists.

I am not saying that a carefully modified alternator should not be used, but only that there should be no intrinsic increase in reliability expected over the original, other than a factor of possibly better quality assembly. This of course could also apply and more so without any increase in heat, in respect of a machine rebuilt for standard output.