Toothbrush Charging - will it survive? (1 Viewer)

Armytwowheels

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Finally we have fitted a pure sine wave inverter, but having killed two toothbrush charges this year already (using modified sinewave) I am a tad nervous of risking a third one!

Does anyone know for sure that a pure sine wave 1500w inverter will not melt the inners of the charger?

A minor problem I know but having an electric toothbrush on tour is important to me! o_O
 

Jim

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All the talk I've heard is that your toothbrush will survive. The leccy coming from your inverter should be as clean as that from a house. Let us know though, won't you :)
 
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I charge our braun toothbrushes with a pure sine wave inverter. No problem.
I have also burnt a charger out using modified square wave inverter, but pure sine works fine.

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Munchie

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Yep we lost one on a modified! Now got a 300w pure sine wave but not had the balls to try the toothbrush as yet!
 

Munchie

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I have been told that toothbrushes and other things are an "induction charger" which requires pure sine wave.
We will see!!!
 

funflair

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Ours is fine on Pure sine, as far as I am concerned it is better supply than most sites as it is 240v where a lot of sites abroad especially at the end of the line are well below even 220v.

Martin

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Tootles

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Finally we have fitted a pure sine wave inverter, but having killed two toothbrush charges this year already (using modified sinewave) I am a tad nervous of risking a third one!

Does anyone know for sure that a pure sine wave 1500w inverter will not melt the inners of the charger?

A minor problem I know but having an electric toothbrush on tour is important to me! o_O
Seen this quite a few times with narrowboat inverters, where they have fried cam corder battery chargers. Even pure sine wave generators have done the same, (but never, for some strange reason, a Honda). Maybe mains 240 runs with a smoother wave???
 

Derbyshire wanderer

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Seen this quite a few times with narrowboat inverters, where they have fried cam corder battery chargers. Even pure sine wave generators have done the same, (but never, for some strange reason, a Honda). Maybe mains 240 runs with a smoother wave???
Mains power generation uses rotating generators so the power up and down from 240v follows a smooth wavy curve above and below the 0v line (240 positive and then 240 negative). This is actually done by transformers as the generators work at 33000v and above and transform down in stages to get to 240v. The result is a clean and stable ac supply.
Petrol inverter generators usually use an alternator to make ac voltage (110v 3 phase is common) which is converted to dc which feeds an inverter to make 240v.
It is the inverter type in the generator that deterimes the output quality ie a pure sine wave (as Honda use) will give an output close to the quality of mains supply. Cheaper generators use modified or (rarely) square wave inverters that cause exactly the same damage as if the inverter type was connected to your leisure battery for 240v output.

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Feb 27, 2011
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Pure sine should be fine, however there were a batch of chinese pure sine inverters being sold on ebay and elsewhere recently that were slightly better than modified sine but had lots of artifacts and harmonics that caused problems. I can't remember where I read it now but the guy got an oscilloscope on the output and it was rough.... If you get a descent quality branded one like Sterling or Victron you will be fine as those put out extremely clean power. probably better than in your house as there is no noise being fed back onto the line.
 
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Armytwowheels

Armytwowheels

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OK you have all convinced me to give it a go.

I am afraid the inverter (now bought and installed) is not one of the known good quality ones you mentioned Grommet, rather more a .........erm...... less expensive one from eBay! :rolleyes: So there will still be an element of finger crossing going on.

Both times with a modified sine the charger worked the first time but not the second, I will report back after charging both toothbrushes.
 

eddie

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With inductive charging the polarity changes and produces a tiny current, it has to change very quickly to produce a charge, so quickly that it has to be electronically controlled to ensure that the polarisation produces the correct voltage

Its this that causes the issues, the processor not getting the correct "juice" means that it doesn't work properly and the charging voltage is unstable

If your worried

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Welsh girl

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I've been charging mine from a pure wave inverter for the last 5 years. It's still working fine.

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Why not buy one that uses ordinary AA batteries rather than rechargeable ones. That is what we use when in the motorhome. A couple batteries last both of us at least a month. And then just another couple in when they go flat. And they are much cheaper to buy than the rechargeable ones.

Yes, we use these, too. Find them just as effective as the rechargeable sort.
 
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Armytwowheels

Armytwowheels

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The first toothbrush is in charge today, will it do the 2nd one though, that is the question. :worried:
 

Judge Mental

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back to stone age camping and a tooth brush for me...I cant keep up!:D

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Feb 27, 2011
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With inductive charging the polarity changes and produces a tiny current, it has to change very quickly to produce a charge, so quickly that it has to be electronically controlled to ensure that the polarisation produces the correct voltage

Its this that causes the issues, the processor not getting the correct "juice" means that it doesn't work properly and the charging voltage is unstable

If your worried

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I always thought it was because the modified sign is made of small stepped increments in voltage. In effect giving lots of square waves which have the worst level of harmonic generation possible next to a pure square wave. I thought it was the harmonics that caused the issue with the inductor in the toothbrush charger.

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eddie

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You may be right. I was under the impression that the speed of the polarisation was the critical issue to stabilise the correct inductive voltage. It may be that all of the issues are factor?
 
Feb 27, 2011
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Just did a quick search to see if I could find a comparison of modified vs sine on an osciliscope and found this...



Quite interesting.. worth watching all the way through.
 
Feb 27, 2011
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You may be right. I was under the impression that the speed of the polarisation was the critical issue to stabilise the correct inductive voltage. It may be that all of the issues are factor?
I worked at a transformer factory as my first job. I had to do a BTEC in Electronics while I worked there. It was a long time ago so my memory of the details of electronics has faded somewhat...

I also guess that he harmonics will cause massive eddie currents in the inductor which will be lost as heat. Heat is bad for electronics as you know...

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zac

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we installed a sterlin puresine wave 1600watt in our new motorhome when we brought it last year. this hasnt failed to power anything we have thrown at it. Hair dryer/Curling Tongs/Tassimo Coffee Maker/Microwave/Tooth Brushes all excellent.

If it charges those tooth brushes and being quite the same watts as ours then i dont see you having any issues with what you want to charge. always best to check the watts though as we brought a plug that we use that tells us how many watts the device you want to use takes. Very useful as the hair dryer works perfectly on all settings apart from the top one (which she doesnt need) this sends it over the 1600watts. Worth knowing though just in case :)

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