[ltp] T530 Claims Wrong Powersupply

[Bjørn Mork]

Bjørn Mork <bjorn@mork.no> writes:

> The initial test looked good.  But I don't know for sure before I've
> tested it with the power supply I have at work.

Now tested.  With an unmodified dongle and a 65W adapter, I saw

$ while true; do grep . /sys/class/power_supply/BAT0/power_now ; sleep 5; done
48972000
48513000
48671000
48770000
48878000
..
50309000
50318000
50345000
50342000
50355000
50363000
0
0


At this point the battery was at about 50% full. Then, after replacing
the dongle with my modified 300 ohm, I got:


45705000
46210000
46449000
46689000
46667000
46734000
46733000
46720000
46636000
46668000
46707000
46722000
46603000
46048000
46111000
46160000
46150000
46266000
46367000
46441000
46453000
46459000
46513000
46546000
46333000
46372000


etc.  So the firmware now limits the power drain at about 46W (probably
excluding some loss), making the 65W power supply survive without
disconnecting. Great!  Thanks for the hint.

I only wish this information was better doumented by the dongle sellers,
preferably with options for the smaller power supplies.  All available
dongles and converter plugs seem to be made for 90W supplies.  I guess
there are limits to what you can expect when spending almost a dollar ;)


Bjørn