• After 15+ years, we've made a big change: Android Forums is now Early Bird Club. Learn more here.

All USB cables are not alike

I'm not a fan of bumping, but I'm loath to starting a new thread for this. Can anyone help?
 
Doubt that first one works. From the picture it looks like the wrong connector - The desire uses micro USB, that looks like the chunkier mini USB. But it's not a great photo so I could be wrong.

Edit: Confirmed. The hero etc use the older mini USB connection, so the charger won't work with the desire.
 
This whole problem does seem to defeat the object of standardizing phone usb connections. I much preferred my hero's mini usb because I had several cables from phones, cameras, ereader and even the ps3 controller. Thanks to standardization, phone cables hardly fit anything other than other phones and then don't work to full capacity, brilliant move.
 
Micro USB is a better connector than the old mini usb, much sturdier, and a slimmer profile so it takes up less space. It'll just take time for things to convert.
 
Do you really need a 6 foot phone cable? :confused: They look like they should at first glance, but no promises. Cheap crappy cables are often cheap and crappy.
 
All my cables, chargers are from HTC or RIM.

No problems anywhere. They cost more but they work.

HTC car charger works too with no problem, though I don't use GPS, that might change things.

The inbox HTC charger that came with the Desire has a removable UK plug. I am not UK based. Does anyone know where I can get a European and American plug for this charger?
 
I bought 1 of
1
these and so far its worked quite well, just under
 
First, there are two issues: to charge from a wall charger, the phone needs to know it's a wall charger, and can draw as much as 1A from it. This is done by shortening data pins together. (With iPhone, a small positive voltage at the data pins does the trick.) Some wall and car chargers don't have the data pins shorted, so it charges 0.5A max - which is barely enough to keep the phone afloat when GPS turned on.. The same goes for CL/USB adaptors - though they are rated 0.7 A or 1 A, they charge 0.5 A max. The solution is simple, just solder the data (middle) pins together in the charger..

The issue we have is different though:

I have bought many different MicroUSB cables from eBay / Hong Kong shops, they charge but too slowly, only slightly exceeding the power need of the phone, so they won't charge the phone overnight from a PC.

No idea what does make this difference..
 
Got an idea.. Could you take a multimeter and measure resistence of your cable, say the leftmost / rightnost pins (these are used for charging) and post it here? The resistance is maybe too big to cause loss of current there..?
 
Dilbort said:
Got an idea.. Could you take a multimeter and measure resistence of your cable, say the leftmost / rightnost pins (these are used for charging) and post it here? The resistance is maybe too big to cause loss of current there..?
Click to expand...
Something to watch for is cheap stuff out of China. There have been reports of fake labels as another post noted and as such the cables do NOT comply with standards. Sometimes the cables have inferior wiring that is too small to carry the current load and the cables can get hot. In some cases they have been the cause of fires in some cables like AC extensions, multiple block outlets, etc. Only buy extension cables from reputable sources that carry some kind of known brand name.

I don't think there would be a risk of fire with thin wires in USB cables since the voltage and current are not very high, but it's something to think about.

As for the Nokia branded cables not being compatible, it may have something to do with their phones and limiting current flow. Perhaps there is a small resistor in the cables to increase impedance slightly.
 
HYCAET said:
Can someone help me out with a little request.

I need a USB cable to charge with, but I need it to be about 50cm longer than the one that comes with the Desire (which I think is 1m). Can anyone post a link for one that will do the job? I'm unsure of what will work with the Desire.

Thanks
Click to expand...
i bought one that cost me about
 
bfksc said:
Something to watch for is cheap stuff out of China. There have been reports of fake labels as another post noted and as such the cables do NOT comply with standards. Sometimes the cables have inferior wiring that is too small to carry the current load and the cables can get hot
Click to expand...

Well of course it cheap stuff from China. :)

I have measured the resistence of a goood (original) and two bad cables. The original was unmeasurable (1 ohm which is the same when I short the two measuremend sonds), the bad ones were 2 ohm (3 ohm on display minus 1 ohm).

I am not that good at electronics, but from what I remember - assuming there's a current regulator that won't let more than 0.5 A through the circuit, at zero resistance of the cable there's no voltage loss. At 2 ohms the U = I * R , U = 0.5 * 2 = 1 V. That's a lot to me, I don't know how the current regulator works, but I can assume that it's 1/5 less than the max available current i.e. 0.4 A. That looks like it is exactly the current that charges the phone very slowly or not at all..

So, to summarize, cheap cables have too high resistance to charge the phone. I doubt that it's on purpose (included resistor), I would rather guess that the alloy is a low-grade one, or the wires are too thin. One cannot wonder that cables for 0.5 USD from Hong Kong / China have not much real copper in them.
 
How can one USB cable charge more slowly than another? It doesn't make sense given the tiny amount of current involved.
 
spile said:
How can one USB cable charge more slowly than another? It doesn't make sense given the tiny amount of current involved.
Click to expand...

For DC, R=p*l/A (Should be a rho not a p but still). So the resistance is equal to the resistivity of the wire (Higher for cheap cables due to impure copper/crappy alloys etc) times the length (Some people use excessively long cables such as 2 metres) divided by the area (Cheap cables have a very small cross sectional area to keep the cost down).

As a result, cheap crappy cables can have much higher resistances than a good cable, and as I=V/R and V is constant, the bigger R is, the smaller the current. With all three factors combined it can make a pretty hefty difference I'd imagine.
 
You must log in or register to reply here.
Back
Top Bottom