Could an alternator be used to power a PC?

vetali · October 9, 2017

1 hour ago, tbake0155 said:

I'm 99% sure that it's not false. Unfortunately I can't seem to find a resource to describe this (searching google for car alternators is a huge hit). The spikes will be fractions of a second and will not show up on a voltmeter, but they will destroy sensitive electronics. If I had more time I'd search for it, but we can agree to disagree since it's not really a major issue.

1 hour ago, tbake0155 said:

Sorry for the double post, but searching for transient over-voltage pretty much clears this up. If you still disagree, I consider you take your argument to an electrical engineer and not debate with me, since all I can do is regurgitate what I've seen on this topic.

So you're pretty much saying you aren't informed enough to support what you're saying, and to defer to someone else if I still disagree. That really bolsters your opinion. Even skimming over the PDF you provided it states overvoltage from an alternator occurs when a battery is disconnected while the car is running. Which is not a normal condition.

40-400ms for a voltage spike is a long time, and would be viewable on an oscilloscope. This event is something I've never seen in my professional career.

Arika · October 9, 2017

/r/iamverysmart

tbake0155 · October 9, 2017

6 hours ago, vetali said:

So you're pretty much saying you aren't informed enough to support what you're saying, and to defer to someone else if I still disagree. That really bolsters your opinion. Even skimming over the PDF you provided it states overvoltage from an alternator occurs when a battery is disconnected while the car is running. Which is not a normal condition.

40-400ms for a voltage spike is a long time, and would be viewable on an oscilloscope. This event is something I've never seen in my professional career.

I'm truly not informed enough to support what I'm saying, but I would not intentionally spread false information. I am certain that I previously saw evidence of what I'm referring to, and thus did not create the idea from my imagination. Also, when I say not visible on a voltmeter, I mean a multi-meter tool and not an oscilloscope. You would certainly be able to see these types of spikes on an oscilloscope.

Although I cannot argue with your stance, I have found more evidence that what I'm referring to does in fact exist. It's my (limited) understanding that even the discharge of each spark plug will cause transient voltage spikes in the system (because it's a load that appears and disappears). Here's an article that I found: http://www.electronicdesign.com/power/eliminate-those-automotive-load-dump-circuit-protection-headaches. It appears that automotive power supplies are inherently noisy and transient.

I will concede to your expertise, and it's possible that I'm mistaken and not interpreting the materials I'm presenting to you correctly.

PETRGangKing · October 9, 2017

Alternator can and do spike up to 100v or higher. This occurs when the connection to the battery is disturbed, could be caused by incorrect installation of battery, or high levels of corrosion on terminals.

klh2000 · October 9, 2017

Unless you bypass the rectifier and regulator on an automotive alternator, it's going to put out 13.8 or 14.4 VDC. Most alternators on cars are rated at 70amp output, some are more. So a smaller alternator can produce about 980 watts. That should be plenty for running most computers, assuming that you don't have anything else connected to the alternator. The safest option would be to use a pure sine wave inverter to convert the 12v to 120/240v for the computer's power supply. This is inefficient because you would essentially be converting 12v -> 120/240 -> 12v/5v/3.3. there are some micro atx motherboards which allow a single 12v input, but the electrical noise from the alternator would probably cause issues with the computer.