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Notebook Battery vs Notebook Power Adapter

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haemse

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Hi,

I am new here and I hope I've found the right spot to place my questions.

There's something I'd like to understand.

Very often notebooks use internal batterys with 11,1V (wich porpably corresponds to 3S 3,7 LiIon).

However, the power adapter comes in at ~19,5V.

Is the 11,1V converted internally up to a 19,5V or do the components run on 19,5V?

Since converting looses quite some power, why dont they just use f.i. 5S LiIon = 18,5V. Most notebook ma also be supplied with that Voltage so they could spare the conversion.

For sure, there is a reason.

Thanks for providing your knowledge and experience.
 

Hi,

I don't know. Maybe something to do with a compliance voltage.
 

The adapter needs to be several volts higher than the battery pack, just to push 2 or 3 charging Amperes.
Additionally is often provides power to the computer. So if 19.5V reaches the computer, I'm pretty sure there is a step-down converter (or voltage regulator) in the path.
 

Yeah, but to which Voltage. Also the LiIon Cells are usually charged with about 0.5V over the avg 3.7 cell voltage so thats not where to 19,5 are needed.
 

I suspect manufacturers try to cater to user demands. It's common for people to want a fast charge for their battery pack. Suppose a fast charge makes it rise to 13 or 14 or 15V? Then the adapter needs to be greater by several volts.

As you noticed, extreme situations are likely. Recently manufacturers have pushed things to the point where fires and explosions occur so often, that HP and Samsung executed worldwide recalls of their Li-on batteries. Two airlines have refused to transport equipment containing rechargeables, in their cargo area.
 

As far as I see, many notebooks are prepared to use either 3-cell (9.8 V nominal) or 4-cell (14.4V nominal) lithium batteries. The latter need 17V + charger circuit voltage drop power supply. That's the reason why 19V or 19.5 V has been established as a standard, I think.

And yes, the notebook provides buck converters for charging and internal power supply. Higher input voltage also reduces input current. "Mobile desktops" have still > 10 A supply current.
 

Since my NB Battery is 11.1V (printed on) I guess its 3S (3 x 3.7V) LiIon. Charging a LiIon Cell over 4.3V might be dangerous ... that x 3 would still be 12.9V.

However, whats the voltage the components run on?
 

haemse said:
Since my NB Battery is 11.1V (printed on) I guess its 3S (3 x 3.7V) LiIon. Charging a LiIon Cell over 4.3V might be dangerous ... that x 3 would still be 12.9V.

However, whats the voltage the components run on?
Click to expand...
Components like the processor and such? Probably a mix of 3.3V, 2.5V, 1.8V, 1.5V, and 1.0V (maybe even 0.9V) depends on the part. I'm sure if you opened your laptop up (not suggesting you do this), you will find quite a few DC-DC converters on the motherboard or a power board.
 

sure, but I mean the voltage for provided to the motherboaed itself and SSD etc.
 

should be 5V

- - - Updated - - -

Oh, yeah the screen probably runs off something higher, not exactly sure what that would be though.
 

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