USB Chargers

[chopnhack]

Does anyone have a source for relatively inexpensive but decent quality USB chargers? Is it cheaper to make them in small scale than it is to buy them ready made? I am looking for a module that would plug into mains power and charge up to four devices. Thanks for any assistance.

 

[KrisBlueNZ]

Random tangential information: There's a company in Auckland (New Zealand) selling the Samsung 2A USB charger, model number ETA-U90HWE, universal input, for NZD 29 (equivalent to about USD 25). That's the one I would go for, assuming they're telling the truth when they say it's genuine Samsung.

I guarantee you won't be able to make an equivalent unit cheaper yourself; probably not cheaper than twice that price.

Of course that unit is only intended to charge one device, though 2A is twice the current of a generic USB charger.

Look into how the USB data lines are used to convey information about the charger's capacity. I've only heard snippets of information, but I believe they are sometimes used by the charger, so the device knows how much current it can draw.

 

[chopnhack]

Thanks Kris, I found this article interesting, but at over 2 years, I figured things may have changed: http://www.eetimes.com/document.asp?doc_id=1279469

I found some inexpensive units at around $14 for 4 ports, but I doubt the quality.

 

[Gryd3]

You can get a kick out of this one:
Has very little info, but gives you more info regarding USB charging.
http://hackaday.com/2014/03/21/dont...here-protect-the-precious-with-a-usb-wrapper/

As far as making a constant voltage source yourself that runs on mains... It would probably be cheaper to buy something and hack it apart if you only need a couple of them.

 

[chopnhack]

You can get a kick out of this one:
Has very little info, but gives you more info regarding USB charging.
http://hackaday.com/2014/03/21/dont...here-protect-the-precious-with-a-usb-wrapper/

As far as making a constant voltage source yourself that runs on mains... It would probably be cheaper to buy something and hack it apart if you only need a couple of them.

LOL, that is a funny article.!

 

[(*steve*)]

This is far less funny.

 

[chopnhack]

This is far less funny.

Yes, I had read reference to that event on the web... very sad and for probably a few cents worth of circuitry...

 

[donkey]

when it comes to anything that plugs into mains power I would highly recommend buying the well built items from well known suppliers. that lady died for a couple dollars.
I recently bought an Ipod charger for my GF when she plugged it in the metal case kept shocking her. that was a lesson I MUST pass on. DO NOT BUY CHEAP. it is your life on the line.
depending on intent of use there are options that you could make at home with far less risk and also save your electricity bill.

 

[chopnhack]

depending on intent of use there are options that you could make at home with far less risk and also save your electricity bill.

Care to elaborate further?

 

[donkey]

car USB charger is a start. as it only peaks at 12volt (13.8 is usuualy a car battery but will say 12volt to make it easier) this is actually a good start
there are hand crank USB chargers that only generate 5 volt, make sure however the voltage is regulated... oh and its exercise.....
solar once again depending on your setup its only 12volt.
battery backup, these things are all over the place simply use a secondary charger then plug it into your USB device.

the big thing to remember is regulated voltage. make sure that it ONLY puts out 5volts. otherwise your device goes black and doesn't work.... and it smells funny too.

http://www.instructables.com/id/Build-a-Battery-Powered-USB-Charger/ for the battery powered one
http://www.instructables.com/id/How-to-make-a-Solar-USB-charger-simple/ for a "regulated" solar version (I personally would make a solar setup with battery then use above link to charge)
http://makezine.com/projects/hand-crank-usb-charger/ hand crank USB charger..

if you want to get into some trouble you can also use the telephone wires in your house that output 12volt and down them to 5 volt regulated.... but that's illegal

 

[chopnhack]

Ah, thanks for clarifying. The intent was to make a piece of functional equipment that would incorporate the USB charger in it. As such, it would need to be powered by mains. Hacking a manufactured unit for the "guts" is the best option at this point.

 

[chopnhack]

I think I found a great candidate for a hack: http://www.leviton.com/OA_HTML/ProductDetail.jsp?partnumber=USB4P-W&section=63493&minisite=10251
A four port usb charger with a built in microprocessor claiming to boost recharge speed. I assume that the manufacturer pre-programmed the micro with the most common handshakes that the major manufacturers use for their proprietary chargers. This would be a cool product to breakdown as the mains entrance and step down is down by a commercially made/certified product. I looked at a close up of the product and it looks like there are some screws that may be able to be backed out

 

[shumifan50]

claiming to boost recharge speed.

Unless the device that is being charged has a very poor charge control circuit, this is an outright lie. The speed with which the battery gets charged is controlled by a circuit in the device and, provided the power source can provide the current, this will determine charge time.
Charging batteries at higher than recommended current runs the risk of damaging the battery or at worst starting a fire.

 

[chopnhack]

This is a product from a very large electrical supplier (Leviton), do you think its just marketing lingo or is it a good product?
This is from the spec sheet:

4-Port USB Charger, 4.2 AMP, 2.1A Max per output
Microprocessor and smart chip designed for recognizing and optimizing the charging requirements of the electronic device

Bear in mind that this is a device that goes into a wall box wired directly to mains, so there are some strict safety regulations that they have to pass through to sell this product.

 

[shumifan50]

A bit of an explanation of what I am saying:
I am not disputing the current the charger can deliver, that is eminently possible. I am disputing that they can speed up the rate at which your device charges, unless your device has a bad charge control circuit, in which case it will deliver too much current that can damage your device or even cause a fire. Sony laptops suffered from this a while back, starting several fires.
The only condition where charging will be quicker is if your original charger did not deliver the current at which the device can be charged, but I find that unlikely.
This does not mean it is a bad charger, it is just an invalid claim and the charger will most likely work as expected.

2.1A is higher than the specification for USB ports and if the device relies on the current being limited to 1A as per the USB specification, then it could get damaged.

 

[chopnhack]

A bit of an explanation of what I am saying

Understood It's a shame that there is a standard for USB, but then there are so many different "proprietary" charging schemes. Great way to sell accessories, but not so great for interoperability!

 

[BobK]

I suspect that the charge speed up is based on the fact that various devices look for certain voltages on the data lines to determine how much current they draw. A charger could, conceivably, try these various voltage combinations, while monitoring the charging current and then choose the configuration that gives the max current. Since they are always supplying 5V, the device itself is setting the charge current and presumably would not set it too high to operate safely.

Bob

 

[chopnhack]

I suspect that the charge speed up is based on the fact that various devices look for certain voltages on the data lines to determine how much current they draw. A charger could, conceivably, try these various voltage combinations, while monitoring the charging current and then choose the configuration that gives the max current. Since they are always supplying 5V, the device itself is setting the charge current and presumably would not set it too high to operate safely.

Bob

That is an interesting thought Bob and quite possible!

 

[KrisBlueNZ]

http://www.usb.org/developers/devclass_docs/batt_charging_1_1.zip
http://www.usb.org/developers/devclass_docs/BCv1.2_070312.zip

 

[chopnhack]

http://www.usb.org/developers/devclass_docs/batt_charging_1_1.zip
http://www.usb.org/developers/devclass_docs/BCv1.2_070312.zip

Thanks Kris! A lot of thought went into the development of that specification with lots of exception handling capabilities.