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Ask HN: On-Demand Phone Charger

2 points by egberts1 ↗ HN
When you have 6 phone chargers around the house, napkin-math is showing me $22.00/month in electric bill.

Not to nitpick, but surely there is a charger out there in the marketplace that can apply electrical load once the iPhone/Android gets connected to the charger. That is assuming that Energy Saving Trust accurately assert that it is eating electric cost wether the device is connected or not. [1]

Perhaps with a big zenier diode or something instead of an always-on wounded transformer coil sucking electricity …

Is there such a thing? I could imagine some type of mechanical (or even electronic) relay to kick in that coiled transformer load but as a tiny consumer product?

Does one exist? If so, how would one search for such a product on search engines?

Napkin Math:

35W/hour (rated phone charger)

24 hours x 365 days (always on)

306.6kW/year, total usage (1 charger)

$0.149/kWh electric rate

$45.68 per charger

or $274.10 annual electric bill for six(6j chargers

of course, Energy Saving Trust claims the chargers are essentially always on, whether you have the device connected or not.

[1] http://monopolybuysellrent.co.uk/advice/energy-saving-tips/

5 comments

[ 5.1 ms ] story [ 21.2 ms ] thread
detaro
what's your napkin math? because switching PSUs if well-done are pretty darn efficient even if idle (and the most efficient topology overall)
egberts1
35W/hour (rated phone charger)

24 hours x 365 days (always on)

306.6kW/year, total usage (1 charger)

$0.149/kWh electric rate

$45.68 per charger

or $274.10 annual electric bill for six(6j chargers

of course, Energy Saving Trust claims the chargers are essentially always on, whether you have the device connected or not.

updated OP.