I have an old Nokia phone which charges fine from the adaptor, but refuses to charge using a USB charging cable.

USB Nokia USB charging cable.

Note that this isn't a normal USB cable, as you can see from the picture, it's got a USB A connector at one end, and a Nokia DC jack at the other.

What's strange is that even if connect this cable to a beefy 5v power supply, the phone still refuses to charge. I know that power is getting through because I can measure the voltage at the phone end of the cable, and the phone seems to notice when I connect the cable, but still won't charge.

Do Nokia phones have some nasty trick they use to prevent unlicensed chargers working with them?

  • The phones do a magic dance with the charger and the charger must supplu volateg and current within certain mapped areas and not in others. If it does not match anywhere the phone will not charge. The document is around. Rushing now but look for it and if no joy msg me via this answer in say 3 days time and I'll dig out a copy. Grunty supply plus series R MAY work. – Russell McMahon May 31 '12 at 18:54
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    They ought to use the standard USB charging spec method of shorting the D+ and D- lines together with less than 200 ohm impedance as described in How to get more than 100mA from a USB port but I doubt they do that: it seems every manufacturer has their own standard. Note: This is not a question about fixing consumer electronics, it's about designing a charger compatible with a (non-)standard. – Kevin Vermeer May 31 '12 at 20:45
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    @RussellMcMahon - Thanks Russell. I think I found it: Nokia 2-mm DC Charging Interface Specification – Rocketmagnet Jun 1 '12 at 9:01
  • @KevinVermeer - It's nothing to do with that. I'm plugging it into a big power supply, so it can have as much power as it wants. As Russell said, the problem seems to be that I'm able to deliver too much current. – Rocketmagnet Jun 1 '12 at 9:03
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    @Rocketmagnet, the reason he linked that answer is that question is because it has what you must do to have a charging port. The tieing the Data lines together with a short. – Kortuk Jun 1 '12 at 10:48
up vote 3 down vote accepted

The old Nokia phones using a 2mm charging connector will refuse to charge if the supply is not current limited. I can't point you to any reference/datasheet but from my experience in building a home-brewed charger, you need to limit the supply to deliver around 100mA. I don't have my schematics handy right now but the circuit I used was based from LM317.


EDIT:

Here's the schematic for the charger I built (page 22 of the LM317 datasheet): enter image description here

I replaced the 1ohm resistor with a 0.82ohms 5W resistor to get around 300mA of current (which falls within the limits in the Nokia datasheet). Also instead of 1.1Kohm, I used a 5Kohm trimmer so I can adjust the output voltage to 5.5V. Supply voltage is 12V so make sure to mount the LM317 on a decent heatsink. I have over-sized capacitors for input and output as I only have 2,200uF 25V available at that time.

Here's a photo of the kludge charger: enter image description here

On the internet I found a very interesting document, the "Nokia 2-mm DC Charging Interface Specification".

According to Page 17 - "Charger identification method" some voltage levels are banned:

  • Over 9.3V - Illegal voltage.
  • 5.5V to 9.3V - Standard charger.
  • 5.2V - 5.5V - Illegal voltage.
  • 4.65 V to 5.20 V - Special charger.
  • Under 4.65V - Illegal voltage.

But this is not the whole story, also you need limit to current (like in this answer), not more than 950mA and not less than 200-300mA, depending on the voltage level.

i was once experimenting with old nokia, trying to charge it from various sources. I noticed, that voltage has to be more than 6V (didn't try to discover the upper limit :)

what voltage is at your USB charger cable output?

i was successfull charging my phone form 9V battery without current limiting.

  • I assume my USB is 5v. – Rocketmagnet Jun 4 '12 at 0:28
  • theoretically there could be a switching boost regulator in that cable boosting voltage to more than 5v. – miceuz Jun 4 '12 at 7:13

protected by Dave Tweed Aug 8 '14 at 1:14

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