laptop power adapter/charger and battery volts differ...In t

February 4, 2018 at 13:46:24
Specs: win-10, .../lots...
As an example... An Acer Aspire has a power adapter/charger which outputs 19volts (very common), and the laptop will work fine on that adapter, with the 10,8 volt battery removed.

Remove the 19volt adapter and install the correct 10,8volt battery, and laptop of course works fine.

Why the need for a 19volt adapter when the battery of 10.8volts runs it fine?

Is the 19volts simply split into two legs - and one leg voltage limited (dropped down) to 10.8volts to power the system when no battery present; and equally even when the battery is present. But the other 19volt leg is used to provide the battery charging volts/amps?

I know adapter/chargers vary in the DC volts they provide, depending on make and model of laptop involved. Likewise some laptop batteries are 10.8 volts and some a whisker over 11 volts.

The specs. I’ve given re’ OS are token, as my question relates to just about any laptop, and so on. Although the initial reason for the question is focused on a replacement Acer battery.

message edited by trvlr


See More: laptop power adapter/charger and battery volts differ...In t

Report •

#1
February 4, 2018 at 17:10:26
19 volts is the output of the power adapter. There will be voltage regulation between the "adapter" and the "battery and computer". The higher voltage is necessary to achieve that control, particularly when the battery discharges and/or the computer is under load.

I've not physically checked but I would expect the adapter voltage to go straight to the regulator with the regulator output split into two legs, the computer and the battery. The voltage would be slightly more than 10.8V to ensure a small trickle charge is maintained when the load is light and the battery is fully charged.

Always pop back and let us know the outcome - thanks

message edited by Derek


Report •

#2
February 4, 2018 at 20:27:03
The battery needs more than the nominal voltage in order to charge. Because of this I assume that there is a regulating both before the battery and again between the battery and the main board. A 10.5 Volt battery would achieve a peak voltage of about 13.5 volts at full charge (used as an example, may be slightly different in actual) and be considered empty at some point just below the nominal listed voltage. A battery meter on your desktop is based on this voltage change to the battery. For the laptop to get a consistent voltage the primary regulation needs to be between the battery and the main board because it needs to be the same whether the AC cord is plugged in or not.

You have to be a little bit crazy to keep you from going insane.


Report •

#3
February 5, 2018 at 06:25:02
Thanks chaps: you effectively confirmed my own thoughts and experience in general. Was more seeking re-assurance that I wasn't too far out of the loop these days with such items as adapters and charger ccts etc.

I recall designing and building a switchable (various voltages) psu - stabilised with a zener diode way back in the '60s. The input dc from the rectifier cct. was approx double the max volts out required at any time.

Goldstars and an extra piece off cake to you both...

trvlr


Report •

Related Solutions

#4
February 5, 2018 at 06:58:35
These days you're more likely to see a buck converter and inductor in a laptop, for efficiency's sake.

How To Ask Questions The Smart Way


Report •

#5
February 5, 2018 at 08:52:30
Buck Converter - is that anything to do with Bitcoins?

Always pop back and let us know the outcome - thanks


Report •

#6
February 5, 2018 at 14:09:42
It's used in the venison industry. You see--

Actually, as I understand it, it's a chip that cycles the input power on and off at a high frequency, to get the lower output voltage you desire. The inductor smooths out these pulses into a stable (let's say 5v) supply. They're favored because they produce less waste heat, which is good for battery life and temperature management, and because you can feed them any combination of battery output and DC in, and they'll handle the conversion without further thought.

How To Ask Questions The Smart Way

message edited by Razor2.3


Report •

#7
February 5, 2018 at 14:46:27
Aha, I see that Buck Converter is another variant of switched mode power supply which in their general form have been in the industry for many years:
https://en.wikipedia.org/wiki/Buck%...

Always pop back and let us know the outcome - thanks


Report •

Ask Question