24v power supply in a 19v laptop

[oldexpat]

If you put a 24volt power supply into a 19v laptop would anything bad happen to the laptop at all? Or what if the power supply was 12v?

[ChuckFickens]

24v, probably fizzle, smell, laptop no longer working...

12v, probably just not turn on, no damage.

[jomifl]

a 19 volt power supply is cheaper than a new laptop,

[oldexpat]

jomifl I know it is. I was only asking because my current adapter can be switched from 12v - 24v. Somebody at work must have worked night time and used my desk leaving crumbs all over the place and using my laptop charger. I couldn't bring myself to do it but I was just wondering what would happen if I accidentally slipped the switch from 19v to 24v.

[Hymie]

ChuckFickens is correct in that the laptop will not switch on with an input of 12V. But at 24V, I reckon all will be OK – it is only 5V above the rating, and many of the laptop’s circuits (if not all) will be powered via regulators, reducing the input voltage to the required level. But at some elevated input voltage – the laptop will be destroyed. The actual voltage at which this happens will vary between models. Something else to bear in mind that many nominal adapter output voltages (eg 24V) are based on full load. The no load output of a 24V adapter could easily be above 28V. My claims of no damage is based on a 24V input, not 28V or more.

[beso]

Hymie is way off the mark. This is over twenty percent above specification in a precision electronic device.

Laptop power supplies are virtually always regulated supplies and will not rise to higher voltages at no load. Even if they did a circuit that can survive extra voltage at no load might not be able to cope with a substantial load at the elevated level.

Even if regulators do protect other components the extra voltage may damage them. Some types of regulators will overheat due to the extra power they must dissipate while other may simply have their input voltage rating exceeded.