Could my car inverter fried my laptop?

snipped-for-privacy@yahoo.com (Dru) wrote in news: snipped-for-privacy@posting.google.com:

What are the chances? Zip. It wasn't your doing, at least the doing of the converter. Not one week after you used it.

Likely your laptop is running on battery even when attached to the wall, then the charging circuit acts like a voltage regulator into to the computer circuitry.

It is more likely the shock of traveling broke a component on the motherboard.

But who knows? Laptops break. They get banged around, on planes, in cars, in cases. That's why I always buy the extended warranty with on site or fast replacement with them. It has *always* been worth the money.

Don't worry about your job.

You need to tell us the 120 v side of your IBM power supply. 75 watts is not a lot of power, I would imagine that the laptop draws well over 2 amps at 120 v not counting the inefficiency of the converter.

I had 2 IBMs and they both lasted more than 2 years, I did 100 flights a year. A friend had one last 2 months. I would look for a bigger inverter and check the IBM web page for specs on the power supply. Cheapy inverters are either a square wave or modified square wave. If I remember does not IBM make a 12 volt charger for their machines?

Put a 17 volt avelanche diode (some times called a zener diode) across the line from the power supply to the computer. and between the zener and the power suply put a 5 amp fuse. If the fuse blows, your power supply is putting out to much voltage.

Make sure you get at least a 10 watt device.

You may want a little bigger fuse.

Most ThinkPads these days have a 72W power adapter which is used to run the ThinkPad and charge the battery at the same time. No way is a laptop going to dissipate 250W. Ouch!

Yes, it's called the Auto/Airline Adapter. P/N 10K3820, $99. See:

A square wave will not hurt PC power supplies. They actually run more efficient on a square wave.

Buying IBM's adaptor is the safest way to go (from a warranty perspective) but the inverter described should not have hurt the computer. BTW, saying it is bad and "power related" is the normal way of explaining any computer failure; regardless of whether or not the supplied power had any cause.

Charles Perry P.E.

The inverter provides no specs. That by itself is suspicious. Any after market product that will not provide specs (so that the less than 1% who understand those specs cannot praise or condemn the product) is suspect. Specs must be provides so that the few who understand them can review the product's merits. Don't provide specs when the product is missing essential functions.

Rare but all so destructive problem in auto power is called load dump as cited by SAE J1455 and ISO 7637-1. What happens if a 60 volt spike is impressed on that inverter? Amplified and passed through into the computer? Any after market inverter must claim some sort of load dump protection. Exampled is this computer power supply

It is quite unlikely that your computer was damaged by load dump. But if seeking all reasons for failure, then ask if that inverter has load dump protection. Specs says that 12 volts can even spike above 100 volts - although that would only be a worst of the worst case conditions.

Low power does not damage electronics. If voltage falls too low on any electronic device, then the device simply shuts down. After all, what is a power down? First voltage drops too low, then computer does a shutdown, then voltage drops to zero. Even power off creates a 'too low voltage' condition - without damage.

Problem was on motherboard? If not on power board, then why blame power? If problem was due to power, then repair man could have identified reason. More likely reasons for failure are vibration or manufacturing defects. Just had same on a disk drive of eight+ years. After eight years of reliable operation, then one transistor that drives motor failed. Not from surges. System is not moved - not from vibration. Just the more typical reason for failure - manufacturing defect in that transistor. Replaced transistor and drive now works normally (except for one mangled file).

Right to worry about the power - especially when the manufacturer refuses to provide l> My work laptop froze up last week (IBM T30, only about 6 months old).

and if charles says so, you can lay money on it.

If your minus 12 goes out first, I believe you can damage a computer.

Umm, Charles, I did not say a square wave would hurt anything. I simply voiced a disbelief (in fact awe) at the 250W number for a laptop. ...and gave the PN, cost and a web page for the "authorized" power adapter.

Inverters never produce sinusoidial voltages, but square ones (digital like?).That´s one reason why wind generators and photovoltaic cells never can replace alternators.(And that´s something the company producing the inverter 'failed' to mention.Never forget, power supplies and transformers (for almost everything-from cell phones to laptops to videocameras)are meant to operate on mains ac with a sinusoidial wave.

-- Dimitris Tzortzakakis,Greece

Actually PC power supplies work perfectly well on square and modified square waves. There are inverters with filtering that produce sine waves.

Charles Perry P.E.

Computers monitor all critical voltages so that if one voltage goes 'out of spec', then all voltages are removed. No damage. In the meantime, I have run computers with a missing

-12 volts - which typically is only used for RS-232 drivers.

As l> If your minus 12 goes out first, I believe you can damage a computer.

There are many inverters which produce nearly perfect sinewave (granted, they are not cheap) - in particular, the "grid-tie" type inverters powered by wind generators which produce DC first. Local power companies will "buy back" power from these generators only if the sinewave is nearly perfect.