Watch out for what an inverter can do (1 Viewer)

Jul 12, 2013
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In Spain this summer, we bought an 800w inverter, not the most expensive pure sine wave type (whatever they are) to charge the batteries on our electric bikes; perfect!
As there was plenty of power available, I could not resist charging my little electric toothbrush. Big mistake! Apparently the shape of the sine wave does matter, well it did to my toothbrush, it destroyed it. ( later I read in the small print that this could happen)
Alan
 

JockandRita

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I cant understand that.

Genuine pure sinewave is as close as it gets to mains leccy....and you use that at home without problems.
John, Alan is saying that it wasn't the most expensive pure sine wave type.
In Spain this summer, we bought an 800w inverter, not the most expensive pure sine wave type (whatever they are)

When I charge my Braun electric shaver via a modified sine wave inverter, the charge never lasts as long as a mains charge, but other than that, it seems to work okay.


Cheers,

Jock. :)

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JeanLuc

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Modified or Quasi-sine wave inverters: i.e. not pure sine wave models, can cause havoc with inductive motors and devices. As you have found out, electric toothbrushes are charged by inductive coupling and don't like square waves. This also applies to other devices that have 'contactless' charging. I have also read that quasi-sine wave inverters can destroy expensive hair tongs (e.g. GHD).
 

Derbyshire wanderer

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In Spain this summer, we bought an 800w inverter, not the most expensive pure sine wave type (whatever they are) to charge the batteries on our electric bikes; perfect!
As there was plenty of power available, I could not resist charging my little electric toothbrush. Big mistake! Apparently the shape of the sine wave does matter, well it did to my toothbrush, it destroyed it. ( later I read in the small print that this could happen)
Alan
I suspect that the inverter is NOT as described. Pure sine wave is exactly the same as mains power. Cooking the toothbrush can only point to it being modified not pure.

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JockandRita

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Feb 24, 2013
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Ah yes I see now (red wine must have muddied the thought from vision process).
I thought it meant a cheaper pure sine wave. Doh

So did I, Jock must be on Alans wave length

(did you see what I did there) :):)

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hilldweller

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Big mistake! Apparently the shape of the sine wave does matter, well it did to my toothbrush, it destroyed it. ( later I read in the small print that this could happen)
Alan

Anything very small is in danger from the rough treatment handed out by big cheap inverters. Their tiny capacitors and suppressors can't absorb the spikes created by the crude waveform.

300W pure sine way here.
 
Dec 12, 2010
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We used to have a teacher we called Sine Wave, he had one leg a bit shorter than the other and couldn't draw a straight line across the blackboard.
 
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Do you remember those experiments at school where you (or teacher :sleep:) moved a magnet in a coil of wire, magically producing electricity? (It went under the heading of "electro-magnetic induction" - work it out!)

The faster you changed the magnetic field, the bigger the voltage produced.

This lesson will probably have led to a discussion of the transformer, where a changing voltage (in the primary coil) creates a changing magnetic field which creates a changing voltage (in the secondary coil).

The inverter provides electrical power to the "charging base": it produces a changing magnetic field which links to the device: a coil inside the device produces the electricity to charge (or fry) the internal battery.

When sinusoidal changing fields are applied, you get sinusoidal voltage changes. However, if you use a wave which suddenly change the field (eg triangular-shaped, or even worse, square shaped) then you get a sudden, large change in voltage (in the secondary).

This is what fries your toothbrush/hair-tongs or, as stated earlier, any "charged by induction" device.

SIMPLES :whistle: - Gordon
 
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rosalan
Jul 12, 2013
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Thank you Gordan, most enlightening for those who know about things like that. I think I too may have been a bit enlightened but Sangria does it better.

Alan
 

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