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Humber888 · 15th Sep 2018, 2:49 pm

I just had a look at my electric toothbrush charger where the stated power consumption is 0.4-1.4W at 100-240V. This is much lower than a typical electric shaver which could consume 15-20W when in use. Shaver transformers are designed to respond to over-current demands by rapidly dropping their output voltage to near zero as demand begins to exceed the rated output power. As a consequence their voltage regulation is much poorer than a conventional transformer and a low power draw can result in an output voltage significantly higher than the stated nominal.

I seem to remember seeing a quote that the output could be up to 270V at the nominal 240V socket at very low current draws. This is why you should be careful using a shaver socket (containing an in-built transformer) to feed an electric toothbrush charger. Better to use the 115V output if your charger voltage range will take it. The output voltage will still be higher than nominal, but nowhere near the 240V charger limit.

15th Sep 2018, 2:49 pm	#46
Humber888 Heptode Join Date: Jul 2012 Location: Bromley, London, UK. Posts: 702	Re: Can I use a shaver plug and socket ??? I just had a look at my electric toothbrush charger where the stated power consumption is 0.4-1.4W at 100-240V. This is much lower than a typical electric shaver which could consume 15-20W when in use. Shaver transformers are designed to respond to over-current demands by rapidly dropping their output voltage to near zero as demand begins to exceed the rated output power. As a consequence their voltage regulation is much poorer than a conventional transformer and a low power draw can result in an output voltage significantly higher than the stated nominal. I seem to remember seeing a quote that the output could be up to 270V at the nominal 240V socket at very low current draws. This is why you should be careful using a shaver socket (containing an in-built transformer) to feed an electric toothbrush charger. Better to use the 115V output if your charger voltage range will take it. The output voltage will still be higher than nominal, but nowhere near the 240V charger limit.