USB charger exploded

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techocrazy

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#2232655 8-May-2019 08:57

Nate001:

Far out now that one really did go bang. Did it cause any damage to the phone?

I am happy to report that the phone survived just fine :)
USB cable did look a little bit burnt as in your photos.
The fuse in the house circuit breaker did burn out though. Which was impressive and concerning.

I've since changed phones to a Galaxy S8 and use the official charger. Here's hoping nothing else explodes haha.

linw

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#2232666 8-May-2019 09:13

Wonder how the phone didn't get fried??

dacraka

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#2232667 8-May-2019 09:14

Same thing happened to me - and another one broke and stopped working! Another two of them constantly put out a high pitch squeal! They replaced the two that exploded and stopped working.

Rikkitic

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#2232677 8-May-2019 09:34

I haven't had any charger issues but I did have a SATA power cable break down and start a fire that would have burnt the house down if I hadn't heard the smoke alarm from another room. You can't have too many smoke alarms.

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Batman

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#2232699 8-May-2019 10:14

techocrazy:

Nate001:

Far out now that one really did go bang. Did it cause any damage to the phone?

I am happy to report that the phone survived just fine :)
USB cable did look a little bit burnt as in your photos.
The fuse in the house circuit breaker did burn out though. Which was impressive and concerning.

I've since changed phones to a Galaxy S8 and use the official charger. Here's hoping nothing else explodes haha.

I saw a youtube video where someone did precisely this - connecting big voltage and power surges to mobile devices of all sorts. the only things that broke were the lightning ports of i-devices (just the connectors) and the charging port of a tesla. everything android (admittedly they tested branded stuff) had no effect.

Groucho

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#2233017 8-May-2019 14:38

All scary stuff. My partner was using an after market charger with her phone resting on the armrest of the couch. She came back to it some time later and found it had barely charged the phone. Closer inspection found reseating the cable to the phone made no difference. I then discovered the adapter was dead with that dreaded faint burning smell however wasn't enough to trip the circuit breaker.

As it potentially could have been a very serious outcome blowing while sitting on flammable couch cushioning we made a pact to never leave devices charging unattended (within reason). If only I was as successful with teaching her to unplug cables from the wall using the plug and not the cable 🤨

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DarthKermit

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#2233030 8-May-2019 14:58

I'm not an electrical engineer, but it seems to me that in the quest to make these AC to DC chargers and power supplies smaller and smaller, they're now more risky than they used to be. They're all made of plastic with a sealed body with no ventilation holes or slots.

Old fashioned power supplies tended to be a lot bigger and be housed inside bulky metal cases with vent holes.

The power supply I use with my ACER laptop gets so damn warm to hot I have it sitting on top of a glass bowl on the carpet so it's not directly on the carpet and it has a bit of air circulation under it.

Rikkitic

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#2233044 8-May-2019 15:02

Old-fashioned supplies also used transformers, which are inherently safer. The modern gizmos use electronics to drop and rectify the voltage and your house fire is only a capacitor away. Cheap capacitors fail all the time. Ask any Chinese motherboard.

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DarthKermit

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#2233049 8-May-2019 15:08

Yes that too. The good old bulky transformer and four diodes to form a rectifier are pretty much dinosaur tech now.

I've pulled apart a few switch mode power supplies and they have a bewildering array of components inside.

Fred99

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#2233125 8-May-2019 16:18

Rikkitic:

Old-fashioned supplies also used transformers, which are inherently safer. The modern gizmos use electronics to drop and rectify the voltage and your house fire is only a capacitor away. Cheap capacitors fail all the time. Ask any Chinese motherboard.

They still do use a transformer for voltage drop. It's just much smaller as it's much more efficient at high frequency than tiny mains (50Hz) transformers, so they use a switching circuit to feed the primaries in the transformer with rectified mains voltage switched at several thousand Hz. For example, a 10VA 50Hz stepdown transformer probably weighs 250g or so, a complete 5V / 2A Samsung USB wall-wart probably weighs 50 grams at a guess.

The old style simple transformer with bridge rectifier and smoothing capacitor(s) wouldn't be good enough alone, the output needs to be voltage regulated, so they're going to have to be relatively complicated circuits in any case.

There's nothing wrong or inherently "unsafe" with the design. The problem is entirely with implementation / manufacturing quality, with cheap poor quality components used by cheap nasty manufacturers. The most suspect of all IMO would be "knock-offs" of OEM chargers - the manufacturers already demonstrate that they're happy to break regulations by making counterfeit goods, so having them save a few cents per charger by using dodgy components shouldn't be a surprise.

Given how ubiquitous these things are (there's probably a dozen of the things in various forms around our house), the OEM wall-warts seem to be extremely reliable. I think I've only had one fail in recent times - the LG charger that came with my Nexus phone. That didn't overheat, it just stopped working.

KiwiSurfer

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#2234155 9-May-2019 22:15

Batman:

Please let me clarify - the charger was not a Redmi charger but bundled as an extra to your redmi phone

Interestingly the Redmi phone I bought from the Mi Store in Sylvia Park recently didn't come with a Redmi brand charger. It came with a charger made by this company called Switchwerk. Says 'Designed by Switchwerk in NZ / Assembled in China'. Seems to be this product also sold by PB Tech on its own. Should I be worried about this charger?

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Fred99

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#2234300 10-May-2019 09:27

KiwiSurfer:

Says 'Designed by Switchwerk in NZ / Assembled in China'.

That would be more credible if I could find a registered company or trademark or if switchwerk.co.nz was registered or there was a listing in the yellow pages for it.

Were there contact details for this "Switchwerk" on the product or in packaging? They put "www.switchwerk.com" on the packaging, that site is unreachable, it's registered to a Nathan Chen of Kowloon, but there's a .co.nz contact email, but that URL isn't registered.

So yeah - sounds legit - LOL.

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