Yousuf Khan wrote:
On 26/11/2017 6:57 AM, Paul wrote:
I checked mine on the Kill-A-Watt. I always wanted one of these,
but had to wait until a retailer here started carrying them.

http://www.p3international.com/products/p4400.html

My battery should be somewhere between 70-80% and
the charging ramped pretty slowly from 0 over about 20 seconds,
before it got to 46W and then the power gradually backed off
to around 32W before I stopped the test. Maybe it's
in topping-off mode (CV) or something ? Before deciding
to do this test, I thought it would still be in CC mode
for the state of charge I was expecting in the battery.

My quick test doesn't have a "characteristic value" to speak
of, and I'd have to drain the battery to do a more "honest"
test of what the value actually is.

And when operating, I don't think my laptop will allow
the adapter to go all the way to 65W. I think it caps
demand at a lesser value. I would expect the battery
to charge slower while the CPU is running.

If I were to guess where the battery is on mine right now,
it's probably right near where the vertical line is at 1.3 hours.
It's in CV mode, and the current flow is declining.

http://batteryuniversity.com/_img/content/ion1.jpg

So anyway, my peak with CPU off was 46W, for whatever
that is worth.

Paul

I was thinking of going for a 90W replacement battery, rather than the
standard 65W, just for some additional capacity just in case. But it
looks like it may not even be necessary?


AFAIK, a three pin 90W power brick should be able to
replace a 65W power brick. It's the laptop design that
reads the three pin, and decides whether the brick is
good enough. So if the laptop is a 65W laptop, a 65W
or a 90W brick should work. If the laptop is 90W and
you offer a three pin 65W brick, the laptop should
"decline it".

Obviously, all the bricks in the previous paragraph,
put out the same voltage. If your laptop used a 14V
adapter, connecting a 19V adapter will ruin it. The
thing is, with SMPS technology, there is no reason
for things to get ruined, but it's the lazy design
inside the laptop that has made it voltage sensitive.
And why the adapter must match within +/-0.5V for
a long life (of the laptop side).

It's hard to say whether the extra capacity means anything
or not. The laptop internal design can only handle a certain
amount of power, MOSFETs are selected for that purpose,
so it doesn't necessarily mean it is going to change
any operating policy when it sees the 90W adapter.

And as for the brick design, while a 90W might be
radically better (active PFC, 80+ efficiency), it's
just as likely to be a $10 crappy design with no
features at all.

Take my adapter as an example. It looks nice on the
outside, but the measured power factor is 0.54,
which means it's completely uncorrected. And might
as well have been designed in 1970 :-(

All that you really want, is an adapter that doesn't
get too hot, to extend the life of it. And that's
where a more efficient design would pay off. I don't
recollect seeing any marketing statements for adapters,
where they mention the efficiency at all, so you'd
never find such a beast without random sampling.

Paul