Very cheap USB car chargers

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Bananabob

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#139536 12-Feb-2014 10:26

ir I was in a $2 shop yesterday and I noticed USB charges that fit in the cigarette lighter in cars. Their price was $3. My question is are they going to be safe for that price or should I follow the "If it is too good to be true" rule?

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#984856 12-Feb-2014 10:30

sounds OK

xpd

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#984863 12-Feb-2014 10:34

Ones Ive used have been fine (as in they do charge the device without killing the car) , but dont expect long term use, they usually just stop working after a while IME.

Ended up paying a few extra $$ for one of these which has been working fine for a year or more now.

http://cdlnz.com/index.html?do=viewproduct&p=POW550&code=PTUSBMINI

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freitasm

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#984868 12-Feb-2014 10:37

Also notice that these might be not enough to charge tablets or larger smartphones. I bought a 2amp one at JB HiFi other day because the .5amp ones I had in the car before wouldn't charge the Nokia Lumia 1200 or any tablet.

aros71

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#984970 12-Feb-2014 11:50

My car (2008 Prius) has an "Aux In" for the audio so I run an iPod Y cable - gets its power from the cig lighter socket through a USB charging adaptor, provides line audio from the iPod to the Aux in. Other end is the standard dock connector.

Problem is that the USB 5V power is horrendously noisy which the iPod doesn't filter at all well. Even if I connect it to a clean 12v battery (eliminating the car's electrics as the source of noise) it's still noisy.

I've been looking for a USB car adaptor that will output clean power suitable for this application... so far the only ones I've tested are ok for charging but don't run anything sensitive from it.

itakestime

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#996285 28-Feb-2014 12:16

You could always put a capacitor across the output of the 5v. That should reduce some of the noise.

richms

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#998864 4-Mar-2014 15:06

It's not just the noise on the power. You are also making a ground loop so you will get all the alternator and injector noise coming thru even if you smooth it to perfect at the lighter socket.

Someone needs to make a totally isolated ciggy lighter charger.

Richard rich.ms

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#998906 4-Mar-2014 16:03

aros71: Problem is that the USB 5V power is horrendously noisy which the iPod doesn't filter at all well. Even if I connect it to a clean 12v battery (eliminating the car's electrics as the source of noise) it's still noisy.

Pretty sure this noise is actually generated by the charging circuit in the iPod / iPhone - I was chasing the very same noise with the same setup, except using an iPhone instead, and managed to rule out noise introduced from the 5v supply.

The fix is either don't charge it while listening, or use a stereo with a USB connection to the iPod / iPhone where the audio is transmitted digitally instead.

As for the cheapie USB adapters, I've had a couple of the 1 amp variety going strong for nearly 18 months, no problems so far.

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#998911 4-Mar-2014 16:06

I've just found the cheap ones mechanically break with either the wire cracking or the plugs needing a wiggle to work then failing totally. None have failed electrically.

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aros71

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#998915 4-Mar-2014 16:10

I simplified my description of the problem ... in fact I *used* to use an iPod in this configuration, but subsequently switched to using a bluetooth audio receiver that has a dock connector.

http://jaycar.co.nz/productView.asp?ID=AA2084&w=bluetooth+receiver&form=KEYWORD

The problem presented with the iPod and with the BT dock connector

So, clearly the dock connector has no internal battery... it is powered currently off a 5V USB adapter plugged into the cig lighter port. This is where all the noise comes from.

If I instead power it off a USB battery - one of the type used to recharge your iDevice on the go... there's no noise whatsoever. But, it doesn't draw enough current for the USB battery to register a load, so its control circuitry shuts down after about 30sec.

I'm pretty sure the USB charger has some sort of Switch Mode power supply to reduce the 12V to 5 and that's where the high frequency audio interference is coming from.

I could have put all this in the original post but decided it would make it too long so I simplified it a bit and just called it an iPod.

Currently it's noisy to the point of unusable, but running off the USB battery is perfect.

richms

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#998916 4-Mar-2014 16:13

Try the same ciggy lighter power supply off a separate 12v supply and see how it goes. Lots of ground difference and other high frequency noise sources in a car.

Richard rich.ms

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#998917 4-Mar-2014 16:14

Ack submitted too early.

Then join the ground of the other source to the ground of the car and see if there is a change in it.

Richard rich.ms

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#1000314 6-Mar-2014 18:31

ive got a $2 one, it wouldn't charge my ipod, so i dont think it'd charge my phone. not really fit for purpose, it should say on the box that it wont charge smart devices.

but for $2 i hardly think its worth waiving the CGA at the poor asian people who run the store i got it from.

*Insert big spe*dtest result here*

richms

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#1000325 6-Mar-2014 18:52

Apple devices need some proprietary sense resistors on the data lines to determine the capabilities of the charger. Unless they advertised ipod or iphone compatibility then you would not have a leg to stand on under the CGA

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hamish225

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#1000383 6-Mar-2014 20:18

richms: Apple devices need some proprietary sense resistors on the data lines to determine the capabilities of the charger. Unless they advertised ipod or iphone compatibility then you would not have a leg to stand on under the CGA

thats silly, why on earth do they need them for?

*Insert big spe*dtest result here*

Dunnersfella

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#1000395 6-Mar-2014 21:11

I was driving a car a few weeks ago, iPod connected via 3.5mm cable, charging my iPhone via the cigarette lighter. When I accelerated I'd get a high pitched whine in the car.
The car charger was from the petrol station, picked up on a whim so I could listen to my almost flat phone on the drive home. It was interesting at the time that it only whined when I accelerated...
The car, at the time was a 6.2l V8.
I've never had the issue in my much cheaper vehicle, a 1.6l Mitsi...
Same adaptor and cable.

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