Consequences of Too Small an Alternator?

[idiot 10+ year member]

I apologize for the stupid question, but I don’t know enough about car electrical systems to answer myself…

What are the consequences of trying to pull too high an amperage from too small an alternator? I have a (hopefully unfounded) fear of driving along the interstate, and watching my quickly die in the fast lane due to the alternator and battery both being drained. And then there are cars hitting me at 85MPH, and spinal columns snapping, and blood on the hood, and severed arms through the windows…

Anyway, I don’t want to upgrade my stock (100A) alternator, at this point, and I’m curious what the worst situation involving an overtaxed alternator could be.

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[saywhat? 5,000+ posts]

100 amp can hold a bit of power, im gunna put close to 1400 of my stock 60 amp with just the BIG 3

 

[idiot 10+ year member]

Your alternator overheats from trying to produce more current than it can muster, seizes up, and your car dies ...

So the freeway scene I described above is a definite possibility?

Would there be any warning signs, either one month or one minute in advance?

 

[JimJ 5,000+ posts]

i think that comment was made with tongue a little in cheek, although you can definitely kill your alternator if you really push it...

 

[idiot 10+ year member]

100 amp can hold a bit of power, im gunna put close to 1400 of my stock 60 amp with just the BIG 3

I’m going to be installing a ~1500W system as well. I’m sure that the alternator will be able to supply the necessary current… for a time, at least. I’m just worried whether or not it might suddenly give out and leave me in an unfortunate situation.

 

[idiot 10+ year member]

i think that comment was made with tongue a little in cheek, although you can definitely kill your alternator if you really push it...

Meh. I **** at the internet, I guess. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

But if I don’t constantly have severe dimming issues or other problems indicative of a stressed electrical system, this shouldn’t really be a worry, correct?

 

[diminishedpower 10+ year member]

even if your car dies on the highway it doesnt mean you stop instantly you have time to pull to the side and stuff, so your fear is unfounded

 

[JimJ 5,000+ posts]

even if your car dies on the highway it doesnt mean you stop instantly you have time to pull to the side and stuff, so your fear is unfounded

^^^

happened to me, actually. ended up being a bad batch of fuel - every time i'd step on the gas it would make it's displeasure known...i was able to get off the highway and coast into a truck stop, fortunately. AAA 100 mi. free towing rocks //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[idiot 10+ year member]

even if your car dies on the highway it doesnt mean you stop instantly you have time to pull to the side and stuff, so your fear is unfounded

[hypothetical]

Not if there is no shoulder, or if construction has taken away all but one lane, or if one is driving in the center of one of the 10-lane Atlanta highways…

[/hypothetical]

Anyway, I’ve never been in that situation. Is there any way to estimate about how much time I might have to pull off (considering that I drive a little 4-cylinder Toyota)?

 

[diminishedpower 10+ year member]

all depends on what speed your going, but as long as you watch for excessive dimming, don't worry about it

 

[tRiGgEr 5,000+ posts]

If it ever does happen just be a smart driver. When the car dies put those hazards on thats what they are for. Slowly and safelly pull to your right if you cant, then go left in to the center divide of the freeway. People will see what is happening and slow down. If your lucky people will stop and help get it off the freeway or let you use there cell phone. How old are you??? You should know this.

100a alt. should be of with the 1500. As long as you do not drive the amp that long. And are you sure the toyota has a 100a alt. I have a 90a and I thought that was big for stock???

 

[idiot 10+ year member]

I’m 17. I’ve only been driving for ~8 months, and my on-road experience can hardly be described as comprehensive. So yea, I bet that my inexperience is shining through. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

And I’m fairly certain that the car has a 100A alternator. In fact, when I was contacting Rick of Raamaudio for information regarding the purchase of his sound deadener, I asked him about the amperage of a stock Toyota Matrix alternator (assuming that he would know, since he had essentially stripped his Matrix down and rebuilt it into the baddest stationwagon in existence, about a year ago), and he confirmed that it was rated at 100A. For an economy car built off the Corolla frame, I was rather impressed.

Out of curiosity, how much power are you pulling from your 90A alt?

 

[JimJ 5,000+ posts]

i have a 135a stock alt...

system is in sig.

 

[ShakinSupra 10+ year member]

I've found that when the alternator is about to go (I've gone through a couple..), I start getting bad dimming problems. My car has a stock voltmeter guage, and I noticed the voltage drop much more than usual right before the alternator dies.

After the alternator goes, the voltage drops to 12v (running off the battery), and the car will run for a little while until the battery drains. Once I almost didn't make it, I watched the voltage drop as I was trying to make it home, it started cutting out while rolling into the driveway at about 6v.