The Important Differences Between Real and Counterfeit iPad Chargers

[gnasher729]

Important info from the article: The fake charger had in some places a distance of 0.6mm between high voltage and low voltage part, and in a humid area, like a bathroom, it is quite possible for condensation to enter and bridge that 0.6mm gap. Results could be quite bad. So don't use this charger in your bathroom!

 

[Tanegashima]

Transformers are usually a source of high frequency noise. It occurs when it operates too close to its limits and causes it to run warm. Manufacturing variations often result in a few units being noisier than the others. This doesn't necessarily mean it's unsafe, but it indicates that it has the potential to end its life early from constant overheating. Heat is a primary nemesis of all electronic equipment.

I know, I'm a EE engineer.

But hearing that is not good. And should never happen.

Also, cheaper SMPS (AD/DC converters like those) work at lower frequencies, better and more expensive SMPS work at hight frequencies where you cannot hear, and also is key to energetically efficient designs.

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Clearly defective, so take it back to the store and ask for a new one. A charger making noise that stops you from sleeping is defective.

Too lazy for that, but yes, it's defective, but I'm almost sure they would say "it's normal", because the sound is very low, but when you are trying to sleep, you know, your hearing adapts to the silence.

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Perhaps you're addicted to risk taking. If / when it catches fire you may wish you would have taken advantage of the replacement warranty it came with.

I don't use it any more. I use an old LG charger. But's an anecdotal evidence that not only are counterfeit chargers badly designed, but also some from well-known manufacturers.