Not really a DIY question - Capacitive Loads Query

[SimonH2]

This is the unit I have - bought a load of them from Maplins IIRC when they were offer and gave them away as Chrissy presents.
http://www.prodigit.com.tw/userfiles/admin/files/20140820_102156.pdf

Exactly how accurate it is at low powers I can't say, but whenever I've used it, the readings have been 'plausible'.

 

[jonwestuk]

Intrigued by this and having the test equipment to hand I did a quick test on my laptop power supply.

Testing a Lenovo 90W 20V AC adaptor with a Voltech PM100 I got:

Off load
230.6V
16.4mA
500mW
3.8VA
PF 0.13

On load but with fully charged battery
230.1V
160mA
13.8W
36VA
PF 0.37

The on load readings were difficult to take as they fluctuated quite a lot - probably due to the battery management system

As you can see the PF is far from 1, especially off load. The 38W off load reading taken by the OP is wildly high. Something is wrong here I think.

Amazing, thanks for taking the time to do that.

 

[ericmark]

I simply look at the size of a lap top charger which is not that much difference to the size of a light bulb and you would not be able to touch a 40W light bulb without burning yourself. So clearly nothing like 35W being used by a lap top charger with no output.