Phone chargers are not all the same

When I initially tested the electricity consumption of my phone charger when plugged in but not actively charging, I was pleasantly surprised to see that no electricity was consumed. Since I was running that test with the current cost meter which could only measure to an accuracy of 1 watt, I decided to repeat the test with my new more accurate meter and also I compared three different phone chargers. The three chargers I tested are shown in the picture on the right.

• On the far right is the charger which came with my phone (a Samsung Galaxy II).
• In the middle is a charger that came with my first ever Android phone. I bought the phone from a clone maker in China via eBay because Android phones were not offically available in Ireland. The phone was truly dreadful, but the charger was really cute looking so I hung on to it.
• On the left is a charger which was part of a multi-device charger set I bought in Lidl.

The results of my testing were that the chargers on the left and right truly consumed no power when not actively charging the phone. At least they consumed less than 0.05 watts since the measuring device reported the power consumption rounded to 0.1 watts. Unfortunately the charger in the middle (the cute looking one) consumed about 0.5 watts when plugged in but not charging. This is not going to cost much money (roughly 5 cent per month if left plugged in permanently) but since I have better charges available, perhaps I should consign this charger to its most appropriate use as an ornament.

All of the tests were done with the same phone. Obviously it has logic to stop drawing power once the battery is fully charged, I can't be sure that other phones would have the same feature. Therefore as the saying goes "your mileage may vary".