[ltp] Re: WARNING: Lenovo ThinkPads and 65W power supplies

[Ted Ts'o]

On Sat, Nov 06, 2010 at 02:39:37PM +0000, Pedro Ribeiro wrote:
> 
> My T400 (P8400 and intel GPU) came with a 65W power adapter.
> 
> It never draws more than 45W in full load. But I guess if I'm charging
> the battery and working at full load it can probably go over 65W.

Ditto; I had a T400 with an Intel GPU, and it came with a 65W power
adapter.  *However*, it charged significantly faster with a 90W power
adapter; with the 65W adapter, you could actually see the charging
rate decrease if you did something CPU intensive, such as say building
a Linux kernel.

Also, when I tried using a Igo Juice 65W power adapter, and the
battery was below 60% or so, if the laptop was powered on, it would
attempt to draw a bit too much power running the laptop and charging
the battery, such that after 2-3 minutes, the Igo adapter would trip
its internal circuit breaker, and stop supplying power.  Plugging and
unplugging the adapter would reset it, but then after 2-3 minutes, it
would trip again.  This didn't happen with the Lenovo 65W adapter, and
shortly afterwards I realized that it would charge the battery much
more quickly with a 90W adapter.

So even if you have a newer Lenovo laptop with a 65W adapter, it may
benefit you to have a 90W adapter around.  If I'm at a conference with
plenty of power strips, I'll tend to use a 65W adapter, and try to
keep the battery topped up at all times, just for weight and space
reasons.  If I'm at a conference where power is scarce, I'll carry the
90W adapter, just so I can pump charge into the batteries faster when
I can get access to an AC mains socket.

> Thanks for the warning. The only problem with this is that 90W power
> supplies seem to be unrealiable...

I've not experienced any problems with the 90W adapters, and I use a
combination of 65W and 90W adapters all the time, since I have a
number of Lenovo laptops at home and at work.

						- Ted