Charging cordless phones

Fred_Bear_2

I have just upgraded my home phone system from an Amstrad Emailer plus 3 old BT cordless handsets to 4 Siemens ECO handsets. Leaving them all on charge continuously uses 8 watts or 70 kWh per annum compared to the old setup of 14 watts or 120 kWh per annum. To save even more lecky I could leave them all off charge and only charge them when the battery is empty: that would cut the consumption to about 2 watts. The downside is that a handset is likely to be flat when I try to use it. How do other green moneysavers manage their cordless phone charging?

thescouselander

I dont think you'd save much. When you charge the battery you only put in as much as you have taken out. Once the battery if full the phone will stop charging so the charger shouldn't draw as much current.

If you wait until the battery is completely flat (not good if they are lithium based) the charger will be drawing the full charging current twice as long as it would have if the battery was 50% used.

jweb2k

I'd put it on a plug-timer that turns on twice a day for two or three hours. Then you'd just be charging for 4 hours a day, keeping on top and being green.

Simples!

thescouselander

jweb2k wrote: »

I'd put it on a plug-timer that turns on twice a day for two or three hours. Then you'd just be charging for 4 hours a day, keeping on top and being green.

Simples!

Why bother? How do you know two or three hours will be enough to get the battery up to full charge. The phones charger is designed to charged the battery to the correct level and then it will stop. Why not leave it to do its job?

Messing about turning the thing on and off interrupting the charge cycle is a good way to ruin the batteries - not green at all in the end.

Fred_Bear_2

jweb2k- I had thought of this but the cost etc of the timers didn't seem worth it.

thescouselander - You're right, I think the old BT chargers used about 1.9 watts each whether charged or not but these new chargers use 1.3 watts uncharged but only 0.3 watts charged! So with the base my new system should use about 2.7 watts total - that's a great reduction from the old 14 watts.

thescouselander

Yeah, modern devices are a lot more efficient. It would be interesting to know how much power is used when the charger is plugged in but the phone is removed. I suspect some of the power used once the battery is charged is being used to power the phone rather than using power from the battery.

If you use say 50% of the battery when you charge it you will put the same amount of energy back in plus a bit more due to the losses in the charging process. I would guess the most efficient way to use the phone would be to leave the phone connected to the charger with the charger plugged in.

Fred_Bear_2

thescouselander - I've checked the figures with my plug-in meter: 1.3 watts charging, 0.3 watts fully charged and 0.0 watts when the handset is removed. The charger obviously has intelligence! The old chargers were relatively heavy transformers and got quite warm even when there was no handset to charge.

By the way, to everybody reading this, I can strongly recommend the Maplin N67FU plug-in meter. All the other meters I have tried, including the Maplin 2000MU, are useless at measuring power below 5 watts or so. If you are trying to cut your electricity usage then this meter can help you to discover where your electricity is being used. It has helped me to more than halve my consumption since 2004 even though I have more gadgets now eg. breadmaker and garden lighting and power to a shed.