If I use my HTC Desire for Google Navigation in the car, with the phone plugged into a USB power adaptor for the cigarette lighter socket with the cable that was supplied with the phone, the battery still runs down.
A dialogue pops up when the battery is getting low saying words to the effect that the phone is using more power than is coming in via the charging cable.
I notice that the phone distinguishes between being charged on AC and being charged by USB. In Settings->About Phone->Battery it says, "Charging (USB)" or "Charging (AC)". I believe that charging from a PC USB socket is limited to <500ma by the USB spec. I guess the phone knows that it can draw more current when connected to the AC charger.
The supplied AC charger must have some way to tell the phone that it is connected. Perhaps it communicates with the phone via the USB data lines, or something simpler like the data lines being shorted together?
The USB power adaptor I have in my car can source 1A. If I can work out how to convince the phone to switch to "Charging (AC)" mode then perhaps it can do Google Navigation and charge the battery at the same time...?
Does anyone know for sure how the AC adaptor identifies itself to the phone?
If I use my HTC Desire for Google Navigation in the car, with the phone plugged into a USB power adaptor for the cigarette lighter socket with the cable that was supplied with the phone, the battery still runs down.
A dialogue pops up when the battery is getting low saying words to the effect that the phone is using more power than is coming in via the charging cable.
I notice that the phone distinguishes between being charged on AC and being charged by USB. In Settings->About Phone->Battery it says, "Charging (USB)" or "Charging (AC)". I believe that charging from a PC USB socket is limited to <500ma by the USB spec. I guess the phone knows that it can draw more current when connected to the AC charger.
The supplied AC charger must have some way to tell the phone that it is connected. Perhaps it communicates with the phone via the USB data lines, or something simpler like the data lines being shorted together?
The USB power adaptor I have in my car can source 1A. If I can work out how to convince the phone to switch to "Charging (AC)" mode then perhaps it can do Google Navigation and charge the battery at the same time...?
Does anyone know for sure how the AC adaptor identifies itself to the phone?
Rob.
Going by pinouts on other USB devices this seems likely.
Throwing caution to the wind, I have just prized open my car cigarette lighter USB power adaptor (currently on special offer at Maplin - Micro DC to USB Adaptor : Caravan & Camping : Maplin), and shorted the two middle pins that were unconnected with a blob of solder.
Now when I connect my phone to it, it says "Charging (AC)".
I'll need to test it on a long trip to see if a) the battery is kept topped up whilst using Google Navigation or other power-hungry apps, and/or b) the car USB power adaptor fails/overheats/catches fire.
I'm hopeful it will be ok. I was impressed to find what looks like a switched-mode PSU inside the adaptor, rather than a linear regulator. Hopefully this will current-limit if the phone tries to draw more than the 1A is is designed for.
Rob.
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One interesting point I've noticed. Been using the Wife's Samsung Spica's charger which is rated at 700mA. Now from 5%, hers (1500mA battery) charged in around 90 minutes.
My Desire was put on at 18% earlier, and is still at 89% after 2.5 hours!
Throwing caution to the wind, I have just prized open my car cigarette lighter USB power adaptor (currently on special offer at Maplin - Micro DC to USB Adaptor : Caravan & Camping : Maplin), and shorted the two middle pins that were unconnected with a blob of solder.
Now when I connect my phone to it, it says "Charging (AC)".
I'll need to test it on a long trip to see if a) the battery is kept topped up whilst using Google Navigation or other power-hungry apps, and/or b) the car USB power adaptor fails/overheats/catches fire.
I'm hopeful it will be ok. I was impressed to find what looks like a switched-mode PSU inside the adaptor, rather than a linear regulator. Hopefully this will current-limit if the phone tries to draw more than the 1A is is designed for.
Rob.
Be careful there Rob, if the regulator cant handle the extra current you may finish up with 12v going straight to the phone, it may work now but be seriously overloaded. As you have shorted the data lines the phone will draw around 800ma (I have measured this ) Be safe and get a yourself a 1amp capacity USB adapter.
Be careful there Rob, if the regulator cant handle the extra current you may finish up with 12v going straight to the phone, it may work now but be seriously overloaded. As you have shorted the data lines the phone will draw around 800ma (I have measured this ) Be safe and get a yourself a 1amp capacity USB adapter.
Be careful there Rob, if the regulator cant handle the extra current you may finish up with 12v going straight to the phone...
Ok, armed with an assortment of crocodile clips, two multimeters, one butchered USB extension cable, a selection of resistors and a Scalextrix speed controller (no, really), I've measured the voltage output of the Maplin car USB power adapter at various currents. I've also recreated the smell of Scalextrix racing and reminisced about my childhood days.
Basically it's starts at around 5.25 volts (no load) and decreases to around 3.6 volts at around 2 amps (double the rated capacity!). Somewhere around 2.5 amps it starts pulsing the power on and off.
Possibly if I'd left it on for longer then it would have started cutting off the power at a lower current level, or gone super-critical and triggered a thermonuclear event.
Anyway, the important thing is that the voltage didn't go higher.
Furthermore, I can now tell you that with D+/D- shorted, my phone draws 750ma from the charger input (whether connected to the car adaptor or the original AC adapter), and with D+/D- disconnected it draws ~450ma. This is when using the lead supplied with the phone, but also connected through the doctored USB extension cable, croc clips, etc.
However, if instead I use another cable which has two pins shorted in the MicroUSB plug itself (I assume the D+/D- pins, but didn't check), then although the phone says, "Charging (AC)", it only draws 500ma.
So the bottom line is that the choice of USB cable does seem to affect the charging current, as does the state of the D+/D- pins in the charger and/or cable.
Rob.
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Ok, armed with an assortment of crocodile clips, two multimeters, one butchered USB extension cable, a selection of resistors and a Scalextrix speed controller (no, really), I've measured the voltage output of the Maplin car USB power adapter at various currents. I've also recreated the smell of Scalextrix racing and reminisced about my childhood days.
Basically it's starts at around 5.25 volts (no load) and decreases to around 3.6 volts at around 2 amps (double the rated capacity!). Somewhere around 2.5 amps it starts pulsing the power on and off.
Possibly if I'd left it on for longer then it would have started cutting off the power at a lower current level, or gone super-critical and triggered a thermonuclear event.
Anyway, the important thing is that the voltage didn't go higher.
Furthermore, I can now tell you that with D+/D- shorted, my phone draws 750ma from the charger input (whether connected to the car adaptor or the original AC adapter), and with D+/D- disconnected it draws ~450ma. This is when using the lead supplied with the phone, but also connected through the doctored USB extension cable, croc clips, etc.
However, if instead I use another cable which has two pins shorted in the MicroUSB plug itself (I assume the D+/D- pins, but didn't check), then although the phone says, "Charging (AC)", it only draws 500ma.
So the bottom line is that the choice of USB cable does seem to affect the charging current, as does the state of the D+/D- pins in the charger and/or cable.
Rob.
Rob, those figures stack up with my results too. I used a Lab powersupply rated at 3Amps set at 5V output.
I found the two charging rates on the phone are 400ma USB only and a shade under 800ma with the data lines tied together.
What is different in this charger than any other 1A cigarette charger? I have one 1A cigarette charger and still when running the GPS the battery is discharging instead of charging.... Is this charger somehow different from any other 1A charger?
that belkin one linked doesn't charge the handset at the full 1amp recommended, found that out at my peril today when driving back from manchester using the sat nav. also checked using the battery status in the phone and in the car it only shows charging usb when connected. must mean that these don't output whats required
btw whats the easiest way of tying the 2 data lines together? tried with a piece of foil on a spare micro usb cable but this didn't seem to work
Last edited by marshalex; May 9th, 2010 at 05:25 PM.
I think the bottle neck is being caused not by the type of charger, but by the supllied USB lead from HTC themselves
I originally posted this on the Google Navigation thread, but it also fits in here
Just carried a little experiment, with interesting results
Last week I bought a car holder and charger from eBay (item no 170467443547)
The holder is a little plasticy but fully adjustable, but what do you want for less than 7 quid delivered
The interesting thing is, that the supplied charger say output 600 - 750ma
I just did a 35min journey, Google Navigation + GPS + Auto screen brightness
According to the battery graph produced by Battery Snap, the charge state rose from 64% to 69% in that 35mins
It would appear that the Desire is able to pull more charge than 400ma, as long as the charger is able to supply it
Maybe the bottle neck is caused by the supplied USB lead from HTC
I've got the same USB car charger from Maplin's, is it the two centre points I've highlighted in red that you need to solder together? (Image attached)
And can you confirm that when using this and the HTC supllied lead it charges the battery whilst using navigation?
I've got the same USB car charger from Maplin's, is it the two centre points I've highlighted in red that you need to solder together? (Image attached)
And can you confirm that when using this and the HTC supllied lead it charges the battery whilst using navigation?
Thanks,
Bruno
so it would appear that i'll have to prise open my new belkin adaptor to make this change then. might drop their cs an email and see what comes back from that
I know this is stating the obvious, so what have I missed.
A normal USB socket on a PC is rated at 500mA. A phone, or any other device, plugged into this shouldn't pull more than 500mA or it risks damaging the PC. Surely this means that the manufacturers of the car chargers are latching onto this & using this over current protection, to stop there 5p voltage regulator from being melted. If you short out the pins & take away this protection, the poor little cig charger is going to give up very quickly, as it's not meant to cope with the sort of current that will be demanded.
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The problem is occurring with 500ma being not enough to power the phone while it is running several app
People are running satnav, gps, plus others and a standard 500ma just cannot keep up so even the phone is plugged into a power supply its still discharging the battery
ebay, belkin verified the serial number when going through their chat system yesterday so thats not a problem. didn't help that the person i was speaking to didn't quite understand the concept of quick charge and the output it was supposed to supply!
The problem is occurring with 500ma being not enough to power the phone while it is running several app
People are running satnav, gps, plus others and a standard 500ma just cannot keep up so even the phone is plugged into a power supply its still discharging the battery
Sorry, Don't think I explained my post to well. I understand what people are trying to do, I don't understand why they they are trying to make a charger do more than it should.
Is it because of using a 'data' usb lead, instead of a 'charge' usb lead?
OK here is the situation, I am using the USB adapter in the car, engine not running.
Case one. My 5 year old Belkin 12 USB adapter, rated at 700ma, part no USB-CLA, 10R-021626. input 12-24Vdc.
As connected to the Desire it delivers 400ma, linking the Data connections, it delivers 700ma. This adapter puts out 5.5V (this data shorting condition is done to automatically charge at a higher rate, detected by the battery manager in the HTC battery).
The BAD news, I bought a new Belkin 12V USB adapter, rated at 1AMP, part no F8Z445ea, #8830-00800ea. This one delivers 400ma, linking the Data connections it delivers 530ma. This adapter puts out 5.2V.
Obviously the current switching trick is something HTC know about, and Belkin dont. So dont put your faith in new USB adapters delivering what you are hoping for! It also explains how the AC charger charges at the higher rate, do a resistance check on the data lines in the AC charger, they are shorted.
I did these tests using a split USB lead and a Fluke DMM, I cannot see how the lead can make any difference in charging. There are 4 wires, two power, two data and a common screen to the outers. It is a one to one connection, no black magic. Anything different you may just have a faulty cable.
If anyone comes up with an adapter that can deliver more than 700ma, in the car, please let me know.
OK here is the situation, I am using the USB adapter in the car, engine not running.
Case one. My 5 year old Belkin 12 USB adapter, rated at 700ma, part no USB-CLA, 10R-021626. input 12-24Vdc.
As connected to the Desire it delivers 400ma, linking the Data connections, it delivers 700ma. This adapter puts out 5.5V (this data shorting condition is done to automatically charge at a higher rate, detected by the battery manager in the HTC battery).
The BAD news, I bought a new Belkin 12V USB adapter, rated at 1AMP, part no F8Z445ea, #8830-00800ea. This one delivers 400ma, linking the Data connections it delivers 530ma. This adapter puts out 5.2V.
Obviously the current switching trick is something HTC know about, and Belkin dont. So dont put your faith in new USB adapters delivering what you are hoping for! It also explains how the AC charger charges at the higher rate, do a resistance check on the data lines in the AC charger, they are shorted.
I did these tests using a split USB lead and a Fluke DMM, I cannot see how the lead can make any difference in charging. There are 4 wires, two power, two data and a common screen to the outers. It is a one to one connection, no black magic. Anything different you may just have a faulty cable.
If anyone comes up with an adapter that can deliver more than 700ma, in the car, please let me know.
i can confirm that as belkin didn't seem to know anything about it and kept trying to fob it off as cable/phone problems. after much perseverance belkin have acknowledged that there may be a problem with the adaptor not using the quick charge which they will have to pass on. unfortunately now this leaves me stuck without a charger that i can use in the car to power the handset. anyone know if the htc car charging kit is the same? need to work out now whether to send it back or not.
i can confirm that as belkin didn't seem to know anything about it and kept trying to fob it off as cable/phone problems. after much perseverance belkin have acknowledged that there may be a problem with the adaptor not using the quick charge which they will have to pass on. unfortunately now this leaves me stuck without a charger that i can use in the car to power the handset. anyone know if the htc car charging kit is the same? need to work out now whether to send it back or not.
That is a good call, anyone know if HTC`s USB car adapter has the shorted data lines? Its a really easy check to do guys!!
and am happy to report the phone detects AC charge, and it supplies enough current to charge the phone whilst using bluetooth, navigation and phone calls. I used the HTC supplied USB cable with it.
Unfortunately I don't have a means of testing the actual output or the voltage with this mod in place, but it appears to do the trick and both charger and phone don't appear to be getting too hot.
hope this helps, obviously I accept no responsibilty for any damage caused!
Not sure if this helps anyone & there's a strong chance I have it wrong of course.
From what I understand, the USB lead doesn't have the data wires tagged together.
This means that if you put the lead into a charger, be it AC or DC, it will only charger at the lower rate of 500mA, as the Desire will treat it as a PC connection.
This is overcome by the Desire's AC charger having the data wires joined internally, so it doesn't matter that the USB lead doesn't.
You too can easily overcome this problem for your car charger by getting another lead & shorting together the data wires. However, if you then use this lead on your PC, the phone may damage your PC, if it's 5V rail is weak. (500mA max for USB remember & the phone may well try to take more). Other than that, the lead obviously won't connect.
Finally, don't take the ratings very seriously on these things. I would imagine the 1A charger mentioned above can't do 1A for long, if at all. By shorting the data wires together, you may well end it's days quickly. Again, this depends on the regulation circuit built into it.
A better test (if someone could be arsed) would be to study the charging current over a fully charging cycle.
Let the battery go flat, then charge the phone whilst not using it.
Then a second test, same flat battery, but use the phone & see what current it draws.
Both these would need to be done on the mains charger.
Third & forth, run the tests again, but using a car charger. I bet the current is less, even with the belkin 1A unit.
If you really wanted to push the boat out, run a fifth test with 5V PSU that is 'really' rated at over 2A. See what current the phone pulls then.
You may find that over the charging cycle, the current demand changes. It all depends how clever the Desire is I suppose.
Sorry for the long post, think I got carried away!
I'm pretty sure the phone actually controls how much current it draws from the charger, so just becuase a charger is rated at say 2A, it doesn't actually output that constantly, thats just what it is capable of supplying.
So in answer to your question, no it won't damage the battery.
If you plugged in something that was a higher voltage, now that would almost certainly cause some damage.
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Quote:
Originally Posted by Newth
Not sure if this helps anyone & there's a strong chance I have it wrong of course.
From what I understand, the USB lead doesn't have the data wires tagged together.
This means that if you put the lead into a charger, be it AC or DC, it will only charger at the lower rate of 500mA, as the Desire will treat it as a PC connection.
This is overcome by the Desire's AC charger having the data wires joined internally, so it doesn't matter that the USB lead doesn't.
You too can easily overcome this problem for your car charger by getting another lead & shorting together the data wires. However, if you then use this lead on your PC, the phone may damage your PC, if it's 5V rail is weak. (500mA max for USB remember & the phone may well try to take more). Other than that, the lead obviously won't connect.
Finally, don't take the ratings very seriously on these things. I would imagine the 1A charger mentioned above can't do 1A for long, if at all. By shorting the data wires together, you may well end it's days quickly. Again, this depends on the regulation circuit built into it.
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?
hi guys.kinda following the jist of the conversation,can i ask if its safe to use wall charger for n97,seems to be same micro charger as desire,also my wife had a small extention for attaching to a normal nokia charger in the event that the main one got lost or broke,i have attached it to a cigarette lighter charger and it seems to charge it ok but is it going to damage my desire battery??i dont know wat what power its ommitting,not that clued up on wattage and power output!!
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?
hi guys,as i stated in my post i took my wifes wee mini charger addaptor for hr n97 which you can connect to any newish or old nokia charger and charge your handset,i just went to my car and plugged it into cagarette lighter and connected it up to my desire,went to settings;battery; and it said "charging ac" hope this helps anyone,if i knew how to upload a pic i would to show what im using and my findings,
From my investigations only a HTC CHARGER gives the Charging AC message on the phone - which I assume means 1A.
My ipod USB charger which is 5v/1A, with both a normal USB lead, and the HTC supplied lead, still says CHARGING USB.
Just the HTC Charger seems to supply 1A..
I bought a Belkin Micro Car charger whose output is 5v/1A, but even with that it still says charging USB..
From my investigations only a HTC CHARGER gives the Charging AC message on the phone - which I assume means 1A.
My ipod USB charger which is 5v/1A, with both a normal USB lead, and the HTC supplied lead, still says CHARGING USB.
Just the HTC Charger seems to supply 1A..
I bought a Belkin Micro Car charger whose output is 5v/1A, but even with that it still says charging USB..
strange.
maybe the nokia charger addaptor is differant than a normal incar charger,i can assure you it says CHARGING AC,if i knew how to put pic up i would kindly show you what the status says and what the charger is im using!
AC, 1AMP, whatever you want to call it then the DATA LINES MUST BE SHORTED AT THE USB CHARGER SOCKET !!!!! The AC charging will be indicated on the phone.
I get the feeling I am repeating this post somewhat.
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the thing is i havent modified anything all im using is a nokia mini usb charger adapter that plugs into an in-car charger.no shorting any wires or anything
the thing is i havent modified anything all im using is a nokia mini usb charger adapter that plugs into an in-car charger.no shorting any wires or anything
If you are getting the CHARGING AC indicated then the data lines must be shorted to tell the battery to go to the Hi-charge mode, think yourself lucky that it does !!
well it must have came that way i havnt touched anything,its just a stock standard in-car charger for a nokia plus the mini adapter charger that came with my wifes n97.if its something thats gona benifit me then i cant complain but its also something for people to look into if it can help some1 else acheive better charging in-car!
From my investigations only a HTC CHARGER gives the Charging AC message on the phone - which I assume means 1A.
My ipod USB charger which is 5v/1A, with both a normal USB lead, and the HTC supplied lead, still says CHARGING USB.
Just the HTC Charger seems to supply 1A..
I bought a Belkin Micro Car charger whose output is 5v/1A, but even with that it still says charging USB..
From my investigations only a HTC CHARGER gives the Charging AC message on the phone - which I assume means 1A.
My ipod USB charger which is 5v/1A, with both a normal USB lead, and the HTC supplied lead, still says CHARGING USB.
Just the HTC Charger seems to supply 1A..
I bought a Belkin Micro Car charger whose output is 5v/1A, but even with that it still says charging USB..
strange.
Sorry that's not correct. I used a tried my really basic car charger (bought for £1.9 on ebay) and it came up AC charger.
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Quote:
Originally Posted by hainman
well it must have came that way i havnt touched anything,its just a stock standard in-car charger for a nokia plus the mini adapter charger that came with my wifes n97.if its something thats gona benifit me then i cant complain but its also something for people to look into if it can help some1 else acheive better charging in-car!
Very interesting! I just want to check. When you say a "standard in-car charger for a Nokia", what kind of end does it have? A mini-USB (like those on a digital camera), or a round Nokia small like this
The HTC Desire is one of the latest high end phone by HTC bringing a huge 3.7" inch high quality AMOLED screen for crystal clear viewing, powered by a 1 GHz Qualcomm Snapdragon processor and runs on, you guessed it, Android.
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Charging: USB and AC differences
