Using a 20V power block on a 19V notebook
Is that dangerous :
- for the computer (without the battery)
- for the cells
If possible, explain why.
Edit : Here are some more assumptions : Without the battery included, there is no risk of overheating the cell, or over charging them. But there is still some dc to dc conversion taking place on the motherboard. I assume this dc to dc stage to be quite tolerant. What kind of trouble can I run into when using 20V instead of 19V ? Overheating ?
It's always inadvisable to use the wrong voltage power supply. However, most power supplies are so cheap that they may vary a couple volts from design spec. Most electronics have some tolerance built in. Batteries themselves are even more tolerant (but special charging circuits, if they exist, may not be).
I can't recommend doing it since the risk of damage is high enough to make it a bad idea. However, the other posts that seem to suggest that using the wrong power supply will immediately cause the LHC to overpower and create an earth destroying black hole, are a bit extreme. :-) You might get away with it. You might cause a fire. You might not notice any problems at first, but have one of those early unexpected failures shortly down the road...
ATX specification (which describes power supply units for desktop computers) says that:
Generally, supply voltages must be within ±5% of their nominal values at all times. The little-used negative supply voltages, however, have a ±10% tolerance.
It applies to power delivered directly to sensitive microelectronics: mainboard and CPU, memory, graphics card, drives.
But in case of laptops, I belive, microelectronics are not fed directly from AC/DC adapter, because still various components need different voltages - it's not a desktop, but it still has CPU, memory and drives.
20V is 5,26% more than 19V. I wouldn't worry about damaging laptop or batteries. I'd just measure if it really produces 20V (or at least it's within 10% from 19V).
I have the definitive answer: IT DEPENDS.
It depends, not on the text "19V" or "20V" written on the power supply, but on the actual voltage and current profile as provided by that power supply... which can vary wildly from the writing on the outside.
Comparing the proposed replacement supply voltage and idle, medium current and full current versus the original (requires still having the original) is the only way to find out for sure. Another caveat is what happens in a short situation. If one power supply has OCP (over current protection) and the other happily provides more current, that can be an issue too.
Technicians and Engineers regularly replace power supplies on equipment, it is one of the most common mods that gets old equipment working again, especially where strange old proprietary battery packs were involved. Often performance can be improved by providing more consistant voltage over a broader range of current draw. These mods are well within the hobbyist's capability, provided they are able to spend the time, do the tests, and set up a test load (12V automotive light bulbs work well) and use a multimeter.
yes, it IS dangerous and may very well destroy the notebook.
higher voltage can cause serious damage to your mainboard, damage that is not covered by any warranty.
also the batteries can overheat, potentially causing burns, an explosion or a fire.