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Charging: USB and AC differences

I have an older USB cable and it doesn't carry power (probably doesn't have +/- power pins), I can't power my laptop bay fan nor LED light nor external USB hard drives.
 
Hi there!!
I bought an HTC Hero (now is stock android 2.1) about one year and a half ago and it has always been useful for traveling by car (GPS Google Nav..).
I bought some cigarette car usb chargers and with an usb cable almost all of them worked just fine.
Reading this post I've learned about short circuiting data pins and obtaining the 1A.. great.
But now I have a challenge for you hehehe:
- With HTC AC charger, it shows "Charging AC" and battery charges normally.....OK
- With all USB cables and a computer..it shows "Charging USB" and battery charges normally ....OK
- With my new car radio (it has an USB connector) and an USB cable...it shows "Charging USB" and battery charges normally....OK
- With a Car cigarrete 12V-USB charger and any cable ... it shows "Charging USB" ....BUT BATTERY NEVER CHARGES

The amazing thing here is that mobile shows that is charging...but it is really not..WTF :mad:
Do you have some experiences with this?

Car 12V-USB is this

It is really weird..I don't know if it is the cheap charger (but in this post there was people working well with this kind of cheap chargers).

Thanks!!
 
If you install a battery monitor widget which shows you the discharge current of your phone, that will answer your question.

A navigation app almost discharge so much current as USB can charge.

Harry
 
hero_xmm said:
- With a Car cigarrete 12V-USB charger and any cable ... it shows "Charging USB" ....BUT BATTERY NEVER CHARGES
Click to expand...

How do you establish that the "battery never charges"? Do you mean that although the phone shows "Charging USB", its indication of % charge continues to drop? And was Google Navigation running at the same time?

When I first tried my Santok 1A charger (see my post of Feb 27), my HTC Desire showed "Charging USB", but if I had Google Navigation running at the same time, the % charge continued falling, because although the Santok was charging my phone, the Navigation was using the power at a faster rate, so the charger couldn't keep up. However, if I switched off the Navigation (i.e. so that there was much less demand on the battery), then the charge did increase, though of course not as quickly as with a mains charger.

As an experiment, I would suggest you check that your phone's GPS and bluetooth and mobile data and wifi options are all switched off while using your car charger and see if the % charge then increases. If it does then it simply means that your charger is working but, like my Santok, despite its claim of 1A output, the data pins are not shorted together internally and so the phone charges only at the USB rate. And that would mean that to make it charge at the higher 1A "Charging AC" rate, you would need to open up your charger and solder the pins as I did with my Santok charger.

Alternatively, if you have all those 4 options switched off and the % charge does not increase while using your car charger, then I would say that your charger is faulty :(

Hope that helps,
Si
 
Harry2 said:
If you install a battery monitor widget which shows you the discharge current of your phone, that will answer your question.

A navigation app almost discharge so much current as USB can charge.

Harry
Click to expand...

Thanks for the tip.

If I tell you that I've tried with no app running on the phone..and the mobile shows "charging" but really it isn't....and if I put a multimeter it shows no current (0 A) on wirings... as I said..really weird
 
So the charger is faulty :(

EDIT: The phone only detect a charger at the moment of connection of the charger (google for 'enumeration').
When the charger a few seconds later goes down, the phone won't notice it (it will continue to show USB or AC).

Harry
 
Thank you too :),

dj_si said:
How do you establish that the "battery never charges"? Do you mean that although the phone shows "Charging USB", its indication of % charge continues to drop? And was Google Navigation running at the same time?
Click to expand...

I said "it never charges" because the mobile is in "standby" (this means with no app running) and with charger connected and in 20 minutes batery monitor has dropped 2 or 3 %...and mobile shows charging

dj_si said:
When I first tried my Santok 1A charger (see my post of Feb 27), my HTC Desire showed "Charging USB", but if I had Google Navigation running at the same time, the % charge continued falling, because although the Santok was charging my phone, the Navigation was using the power at a faster rate, so the charger couldn't keep up. However, if I switched off the Navigation (i.e. so that there was much less demand on the battery), then the charge did increase, though of course not as quickly as with a mains charger.
Click to expand...
Yes I have some experience with this situation, but this is not the case :p

dj_si said:
As an experiment, I would suggest you check that your phone's GPS and bluetooth and mobile data and wifi options are all switched off while using your car charger and see if the % charge then increases. If it does then it simply means that your charger is working but, like my Santok, despite its claim of 1A output, the data pins are not shorted together internally and so the phone charges only at the USB rate. And that would mean that to make it charge at the higher 1A "Charging AC" rate, you would need to open up your charger and solder the pins as I did with my Santok charger.
Click to expand...

Well...with the pins shorted, it shows "charging AC" but the same is happening.. multimeter shows 0 A and battery (as expected) doesn't charge.

dj_si said:
Alternatively, if you have all those 4 options switched off and the % charge does not increase while using your car charger, then I would say that your charger is faulty :(

Hope that helps,
Si
Click to expand...

It is weird because with a resistor (very low Ohm value) and a multimeter I've been able to supply more than 1 Ampere

Thanksss
 
hero_xmm said:
- With all USB cables and a computer..it shows "Charging USB" and battery charges normally ....OK

- With a Car cigarrete 12V-USB charger and any cable ... it shows "Charging USB" ....BUT BATTERY NEVER CHARGES
Click to expand...

I've just re-read your original post. If the phone is in standby and charges successfully at USB rate from a computer, but then doesn't when using the same cable with the car charger, then IMO it's pretty conclusive that the car charger is faulty.
 
dj_si said:
I've just re-read your original post. If the phone is in standby and charges successfully at USB rate from a computer, but then doesn't when using the same cable with the car charger, then IMO it's pretty conclusive that the car charger is faulty.
Click to expand...

mmmm... the charger works with a Nokia N85.. this is crazy :eek:
It has to be the Hero that does not want cheap chargers or something... but it is annoying to don't know why does not charge ....
 
iynCognito said:
I do believe its actually the data lines on the CHARGER that need to be shorted. THe USB cable can be the same whether for a true AC wall charger or a USB car charger.

Just as sandozer is asking, does anyone have a car usb charger that reads as "AC charging" on the phone / battery when plugged in?
Click to expand...

...but the USB cable is not always the same. For example, I have two rechargeable USB charging units (both Proporta) that came with USB cables that have only 2 cores - therefore not usable for daya. When I connect these to my Desire, it indicates "Charging AC" which would imply that the data connections are shorted in the micro USB plug. In contrast, the HTC standard AC charger must have the data lines shorted at the charger end, because I get "Charging AC" with that when I use a standard micro USB data cable.

Regards,
Tony
 
Tony_J said:
...but the USB cable is not always the same. For example, I have two rechargeable USB charging units (both Proporta) that came with USB cables that have only 2 cores - therefore not usable for daya. When I connect these to my Desire, it indicates "Charging AC" which would imply that the data connections are shorted in the micro USB plug. In contrast, the HTC standard AC charger must have the data lines shorted at the charger end, because I get "Charging AC" with that when I use a standard micro USB data cable.
Click to expand...

To elaborate further...

The phone detects only whether there's zero resistance between the data pins - if so, it'll charge at the AC rate, otherwise at the USB rate. The phone doesn't care whether the short is between the data pins in the micro-USB plug or within the charger. (In fact, it can't tell where the short is.)

The standard HTC mains charger has the data pins shorted internally (I've checked this with a multimeter), so when used with any standard USB data cable this will charge the phone at the AC rate.

If a charger is supplied with a cable that has only 2 wires/cores, then the short must be within the micro-USB plug if the phone is indicating AC charging. A cable like this should never be plugged into the USB port of a computer, as the phone may then try to draw a higher current than the USB port can supply, which could potentially damage the USB port and/or computer! :eek:
 
I haven't had my charger apart yet, I came across this thread when trying to find out why my phone discharges while using Copilot.

So this isn't my experience, just an observation of the seemingly inconsistent problems people are having with different cables.

ru' said:
Wikipedia explains better than I can:

"In Battery Charging Specification,[31] <snip>

The Dedicated Charging Port shorts the D+ and D- pins with a resistance of at most 200&#937;. The short disables data transfer, but allows devices to detect the Dedicated Charging Port and allows very simple, high current chargers to be manufactured.
Click to expand...

So perhaps some cables have greater than 200 ohm resistance across the data pins? ie one cable may have thinner wire in the data lines, therefore the phone could detect more than 200 ohms and assume USB charging mode, even though the pins are shorted in the charger. Could be a dry solder joint in the short, crimped wire in the cable etc...

You would need to measure the resistance from the phone end of the cable, through the charger, and back to the phone end.

Just a thought, hope this helps someone... I'll be interested to see what mine does when I get it apart tonight.
 
Just to add my 2 cents, since I updated to Gingerbread on Tuesday, the CU S420 (CC220) in the car shows as ' Charging (USB)' with the official cable attached to the windscreen dock.
However, if I plug the USB cable from the mains charger directly into the CC220, I get AC charging.
I vaguely remember getting a similar issue when I first bought the charger but it then starting working after a day or two.
Any thoughts?
 
Have belkin micro auto charger with OEM usb cable, everytime i connect droid charge it auto detects as mass storage device...asks me to connect/stop..etc..

I just want it to charge.

Any ideas.. have a Samsung Droid Charge. Belkin Micro Charger is the only one that fits in my armrest and allows it to close properly. Have samsung oem car charger but too bulky and armrest wont close.
 
If your Samsung OEM car charger is seperated in charger and (USB) cable, you should try this cable with your Belkin charger.
With a USB cable without the two data wires the phone can't detect mass storage ;)

Harry
 
The usp device you are plugging the cord in might be lower rating than the cords capability. Try getting a new lighter adapter piece.
 
Today I received two different cigarette lighter USB chargers (Tom Tom and PowerBolt), at least one rated at between 1 A and 2.1 A. I also have the original HTC charger here, the one with the curled cable.

The other cable is a self-made one with the data lines shorted, see How to make a car charging cable for HTC smartphones | Windows Problem Solver .

I fired up my Nexus One (similar to the HTC Desire) and started Google Navigation and My Tracks track recording to create a high load. Battery status was between 70% and 75%.

All tests always yielded the "Charging (AC)" mode in the phone.

Only the original charger with its own cable was able to charge the battery and yield a rising battery level towards 75%. The other chargers saw the battery level slowly sink towards 70% in my short tests.

And here is the surprise. After several conclusive tests I began to switch cables. The final result is that all chargers were able to charge the battery against the high load when used with the original HTC charging cable.

No charger, not even the original HTC one, was able to charge the battery when used with my self-made cable with pins 2 and 3 shorted. I have made several such cables, and they all succeed in taking the phone into "Charging (AC)" mode, but apparently this is not enough.

The secret is in the cable.

To me it now seems as if there are at least two different "Charging (AC)" modes, one in which the phone pulls nearly 1 A and another in which it pulls something around 500 mA, like in the "Charging (USB)" mode.

Unfortunately I don't have a wired micro USB socket, so I cannot measure the HTC charging cable. Perhaps they use the fifth connector for an additional signal to the phone. That would be mischievous on the side of HTC and raise the suspicion that they resort to such trickery to sell a few more of their otherwise rather ordinary chargers that have only one USB socket and no additional cigarette ligher socket like the Tom Tom charger.

If anybody here has that curly HTC charging cable and the means to measure it, please do that and report here what you find.
 
hgmichna said:
... By now I am really curious about what HTC did to signal a HTC cable (and why).
Click to expand...

Actually would be the correct way to use the data wires. Not for to shorten, but to use for the USB protocol for order and delivery of the amount of charging current (Enumeration).

As I know, HTC uses this pin (ID) in the microUSD for to detect docks/car docks (also not the right thing by USB regulations ;) ).

So I'm really curious too what HTC has done to this USB connection and look forwards for measurement outcome.

Harry
 
Nope, the negotiation only works within the USB standard and is only used to negotiate from the default 100 mA up to a maximum of 500 mA.

Chargers never use any negotiation over the data wires (except for Apple products), and anything beyond 500 mA could not be negotiated anyway.

The new standard procedure is to connect the two data lines with a resistance below 200 Ohm, i.e. to simply shortcut them. Indeed this makes HTC phones display "Charging (AC)", but, as far as I can now tell, this still does not make them pull the full current.

Something else must be in the original HTC cable, and I hope to be able to measure it soon. Strange that nobody else has measured it yet, although the question has been open for quite a while.

I'm now worrying that the contacts on the micro USB socket I ordered are so microscopically small and close together that I will not be able to connect anything to them.
 
Oh, I thought the USB regulations are extented for Enumeration up to 2A (because of iPad ;) ), but I'm not sure :)

EDIT: ... or is that only with USB 3.0 ?

Harry
 
The details in a compact form are here: USB - Wikipedia, the free encyclopedia

All I can surmise for now is that HTC uses something in its charging cable that is not mentioned anywhere to increase the current drawn by its devices. So far nobody here seems to know what it is. One vague guess is that they could use the fifth contact in the micro USB plug for their additional signalling. Since the USB cables have only four leads, and a USB charging-only cable needs only two, the extra trick must be located in or near the micro USB plug.

This does not explain how it could work in older HTC phones with mini USB sockets, which have only four contacts. Perhaps the trick is newer.
 
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