A question of Amperage

Ruckus

Laptop Power Requirement:
19V 3.42A 65W

Replacement Power Adapter outputs:
19V 3.16A 60W

Would this cause a heat buildup in the notebook (in the power input/voltage regulation area of the mainboard) or only in the brick itself?

Feral

Depending on the notebook, it might:

A) not run
run but not charge the battery
C) run but speedstep the CPU down to the lowest level
D) run but bitch at you for having an "unknown" or "incompatible" power adapter
E) any combination of the above.

It doubt it would cause a heat buildup in the notebook. The brick outputs less power than the laptop needs.

Ruckus

Actually the laptop runs fine as far as I know, I'm just trying to eliminate the user's incorrect replacement power supply as the source of a heat buildup.

Sarcastro

I'd say its possible. I beleive devices draw what they need to operate when the specs are close, and in this case because of the mismatch the adapater may be being asked to provide a touch more than it can handle. That scenario would put the heat build on the adapter or the batterey pack though, I dont think in the laptop itself.... (?)

nexuscrawler

DO NOT USE ANYTHING OTHER THAN YOUR STANDARD ADAPTER FOR A NOTEBOOK.

Most things will heat up or simply not work but notebook computers are extremely sensitive to voltage differences. It's entirely possible ot do serious damage to your comp by using it.

Edit: I guess if it works you should be ok. I'd still be wary though.

darkgrue

The replacement adapter is about 5W short (Wattage is Volts * Amps, so the Wattage rating's actually redundant when both the voltage and amperage is provided).

Sarcastro wrote: »

I'd say its possible. I beleive devices draw what they need to operate when the specs are close, and in this case because of the mismatch the adapater may be being asked to provide a touch more than it can handle. That scenario would put the heat build on the adapter or the batterey pack though, I dont think in the laptop itself.... (?)

This is not necessarily the case. Inside the laptop, the 19V from the adapter is probably not being used directly - it's getting regulated down to different voltages, probably in many different places, to supply whatever the hard drive, processor, LCD backlight, etc. need. If you're undersupplying those regulators, they could be overheating as well. Which one goes first could be quite the complicated interaction.

Now, that being said 5W isn't a whole lot. Frequently, power packs are actually rated for far higher loads than they actually see, since they would rather use off-the-shelf components in standard values rather than build exactly to need. So it's possible that a 60W adapter still has more than enough headroom to run the laptop without bumping up against it's limits. On the other hand, if the original adapter only had a 10% margin, you're running the 60W adapter on it's redline margins (58.5W), and if the replacement adapter's on the low end of it's acceptable tolerance variation, it could very well be causing problems.

What the story's not clear on is if the replacement adapter was OEM or aftermarket? If the manufacturer's sourcing it, then it's probably just a spec change that isn't relevant, if they just bought something that was "close" and the plug fits... they could be pushing both the adapter and the internal voltage regulating components of the laptop too hard. It's also possible that the replacement adapter is bad, or very far out of specification.

It's also not clear if the laptop is actually running hot. Many laptops run very hot normally, and depending on where you hold your hand, can be quite surprisingly hot. If you never noticed until after you replaced the adapter, you might very well think your laptop was "feverish", when it fact it's operating quite normally.

Ruckus

The full story on this is that one of our overpaid suits in Toronto's power adapter died, so he went and bought a replacement at a local computer shop. This computer shop happened to be an HP dealer and sold him an HP power adapter, I can only assume that they looked at the voltage and amperage rating on the old one and found the nearest HP equivalent. This is an Asus notebook, by the by.

This was months ago. I found out about it earlier today when he called to complain about excessive heat and hot electronics smell coming from his notebook.