Car charger Modding

[Rusty]

I noticed a few complaints on this forum and others about Goggle Navigation being too much of a drain on the handset even with it plugged into a car charger.

My suspicion is that this is down to badly made car chargers, and on a previous occasion using the Testing menu, I noticed that my own charger was being reported by the phone as USB.

So I set about trying to rectify this, using my awesome rolleyes knowledge of how the phone recognises what it's being charged with and an 'I don't care if I kill the charger, it was free' attitude.

I took it apart and tested continuity between the 2 middle (data) pins on the USB plug, there was none, and the problem was identified. I simply flipped the board over and soldered these 2 pins together and reassembled the charger.

Took it out to the car, plugged it in and lo and behold, the Testing menu now reports that it is plugged into an AC source! As my phone is fully charged and I don't have any trips planned right now I don't know how much real world difference there is, but it's looking promising, at least the phone now knows it can draw 1000mA instead of 500mA, and for 5 minutes 'work' it was worth doing.

 

[inspiron41]

nice work! only if there was a video!! would love to see how it was done

 

[|mpulse]

Care to post up pics?

Nice work!

 

[Rusty]

I didn't bother with a how-to as I figured chances of someone having the same charger as me were slim, but pics aren't a problem:

Here is my universal USB charger with the cover removed:

and the reverse side with the 2 pins soldered together:

Probably doesn't tell you a huge amount unfortunately, but to be honest that's because it really is a simple procedure with not much to tell.

 

[ianr]

I would be slightly careful doing that if I were you, I know some chargers identify themselves to some phones by connecting the two data pins to each other via a resistor, there is a chance you might do some damage by just shorting the pins together. This is with other brands though, I can't recall which one right now. You could quite easily verify that it's safe by measuring the resistance between the data pins on the supplied wall charger, if the two data pins are shorted together on the supplied AC charger then you're most likely safe replicating that, if there's a significant measured resistance then you'd be better off trying to replicate that value in your modified charger.

 

[Rusty]

I just went with Wikipedia's spec that the resistance between the two must be less than 200ohms, which a blob of solder is.

 

[ianr]

OK, probably fine then, I've not checked my leads that identify as AC, so I've not bothered myself, just throwing a note of caution in as I'd not noticed any references to further checking, if you've found something that makes it look legit then great, I won't worry about my own leads either ;-)

Please do some further testing with navigation, so far I've largely done the same thing and found it didn't stop the battery draining during navigation, it would be interesting to know if it works for you, if so then I'll re-investigate my own findings, if you find it also doesn't work for you then that'll be annoying as I'd prefer that it did so I don't have to buy any more official docks!

Do make sure you try an hour or so's driving though, battery meters can be rather inaccurate from what I've seen in small increments, I've seen some odd results when playing with chargers, including a battery going from 85% charged to 100% charged in 20 seconds!

 

[Rusty]

I've a couple of small trips penned in for tomorrow, so I'm going to make sure I don't have a lot of charge when I set off, and see what happens. Hopefully it'll do the job.

 

[ianr]

FYI the standard AC wall charger is rated as supplying 5 volts at 1 amp (so what I reckon is the max micro-usb port charging rate) whereas the official car dock's PSU states that it outputs 5 volts at 2 amps -- although it does have to power the dock as well as the phone so that might be why it needs the extra juice, what with bluetooth and speakers.

When I next go for a trip I'll plug it in to the phone directly, it plugs into the car dock via a micro-usb connector, although there are dire warnings that you must not plug the dock itself into a computer.

 

[Rusty]

5v @ 1A is the standard for microUSB charging, which in turn is the standard for new mobiles. I doubt the phone is set up up take advantage of the 2A charger, but it's well worth finding out.

 

[chqshaitan]

ebay are selling 2a car chargers, i am tempted... mmm

2A USB DC CAR CHARGER FOR HTC Touch Pro2 Pro 2 Touch2 on eBay (end time 06-May-10 11:18:30 BST)

 

[Rusty]

Looks a lot like mine...

 

[ianr]

I've got three of those, 2A rated, so far no difference, still the phone discharges when using satnav.

 

[spongebobnopants]

Based on my 1 week experience I am pretty sure the internal heat of the phone determines charging. too hot = slow or no charge. This is like a built in safety. When the phone is not hot I don't see the issue. I pulled mine off the dash and sucktioned it to my cars nav screen. Its further out of direct sunlight.

 

[spongebobnopants]

Not sure if this helps, but I have a portable Li-Poly battery for charging small electronics and it has listed temperatures for which it will charge. At 113F it will not charge.

 

[ianr]

Right, just been out for a drive in one of my other cars using just the official car dock's charger and a universal phone holder, when the official car dock's charger is plugged into the phone directly, the phone *can* be used with navigation without depleting the battery, I'll do some more messing about (turning up the brightness and using other satnav software) but it looks like it can be done, just need to figure out why the other chargers and leads I have won't make it happen. I'll try and measure across the data pins on the car dock's charger to see if there's a signalling resistor in there.

 

[Rusty]

Fail!

Despite the mod, it's still not enough to charge/sustain the N1 with Google Navigation running (screen on full brightness). Guess it's just not man enough to produce the required 1A.

 

[ianr]

I've got three 2A chargers posted somewhere on this board, one of them never worked, the one I tried today actually *did* manage to sustain charge on the phone while using google nav, while the third didn't. The 2A charger supplied with the dock effortlessly charged the battery, the charge graph on JuicePlotter was quite steep upwards, whereas the supposed 2A chargers I have either didn't make the grade or produced a charge graph that was just slightly above level. So it looks like it can be done, but if a charger says it can supply 2 amps, best take it with a pinch of salt unless the vendor is a big name with kudos to lose.

I'd like to get more of the chargers that come with the official google dock, fat chance of that happening, maybe I can order "spares". But I can say that the 2A charger that comes with the official google dock will charge the phone very effectively while satnav is in full swing, while directly plugged into the phone, i.e. without needing to use the official dock or the special dock connectors.

 

[Rusty]

Might get myself this: HTC: Accessory store: Pocket PC Power Adaptors + Batteries: HTC Desire Car Charger with USB/micUSB Cable CC C200 (1A/5V): Description

Has to be up to it, surely?

 

[macroweb]

I've got three of those, 2A rated, so far no difference, still the phone discharges when using satnav.

Hi,

Could someone confirm for me that "all" micro usb chargers are interchangeable with any phone with a micro usb port? Wondering if I can use the micro usb chargers I have for my LG Dare with my Incredible when it arrives. I'm thinking that the specifications of a micro usb make this work?

Thanks!

Macroweb

 

[ianr]

Maybe, the charger supplied with the car dock is a 2A charger but it has to power the bluetooth and speakers in the dock as well as the phone and satnav. However I have tried satnav with a selection of 1A rated power units including the "minigorilla" from Powertraveller and some of their other products, and it wasn't enough. Powertraveller do good products so I trust them to deliver 1A when asked to. The extra burden of the bluetooth and the speakers in the dock probably don't amount to much and I didn't see much of a change in the recharging graph rates when using the dock as opposed to plugging the dock charger directly into the phone.

However, if the charger's cheap-ish then get one and try it, and report back and I'll follow suit ;-)

 

[ianr]

Hi,
Could someone confirm for me that "all" micro usb chargers are interchangeable with any phone with a micro usb port?

*All* is a big ask, but it should work fine, the USB sync cables I ordered weren't for a Nexus One but they worked fine and the USB charger leads are generic USB to Micro USB cables and all work fine.

Have a look at the charger and check it delivers 5v, ideally at 1A or above. If it lists the output as anything other than 5v then that's a definite no.

The only thing to watch out for is that the phone does treat leads differently depending on how the data pins are wired up when it comes to charging. As Rusty has pointed out in this thread, if the data pins are floating (i.e. not connected to anything) the phone will identify it as USB and charge relatively slowly, if the data pins are connected together then it will identify the lead as AC and suck as much power as it can and recharge as fast as the PSU will permit.

 

[macroweb]

*All* is a big ask, but it should work fine, the USB sync cables I ordered weren't for a Nexus One but they worked fine and the USB charger leads are generic USB to Micro USB cables and all work fine.

The only thing to watch out for is that the phone does treat leads differently depending on how the data pins are wired up when it comes to charging. As Rusty has pointed out in this thread, if the data pins are floating (i.e. not connected to anything) the phone will identify it as USB and charge relatively slowly, if the data pins are connected together then it will identify the lead as AC and suck as much power as it can and recharge as fast as the PSU will permit.

Thanks for the response!

I don't have any skills with electronics, at least technically, how do I tell if the data pins are floating or not?

 

[Rusty]

Multimeter and test for continuity between them.

Or just plug the phone into it and see what it says.

 

[dextroz]

I am using OEM AT&T Car Charger w/ USB Port for Motorola, LG, Sanyo, micro USB 75369 - Nexus One Accessories (Google Phone)

charger for charging TWO Nexus One phones at AC charge speeds simultaneously. I am using the supplied USB cable plugged into the 'split' USB of this car charger and can run navigation/GPS while successfully charging the phone.