Phone Charging

I think they put a 1k ressitor from the USB+ to D+ so the phone knows its a wall wart, other wise the usb protocol takes care of requesting power from the hub. My Old Razr is setup this way.

Cheers

Mini USB connector. You'll need to add a 200k resistor and short pins

2 and 4:

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

I just realized this connector resistor issue is not likely to be my problem... I think. I can charge this phone using two generic adapters I have. One is a box with six high current outputs, at least two rated for

2.1 amps and the other four rated for 1 amp or maybe 4 and 2 (other way around). The other unit that will work with the phone is a car charger, but then that one is also a high current charger. They are all connected with the same cable and I'm pretty sure the charger end of the cable only has four pins so there is no place to connect the resistor to the "ID" pin.

This phone won't charge from my laptop, so I don't think the phone is negotiating anything over the USB data pins, or maybe it is? I don't think either of the chargers have a USB host built in and the laptop clearly does.

I'm still stumped.

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Rick C 

Viewed the eclipse at Wintercrest Farms, 
on the centerline of totality since 1998

Because you aren't listening to the other responses, those phones need a modified cable to charge. Many of those type also used that mini (micro?) usb jack to use as headphones, standard cable to export the photos and of course to charge it.

Anyway, I doubt your "I can't find it" claim...

seems to be what you need.

-bruce snipped-for-privacy@ripco.com

I have no idea what you read. Of course I have a cable with the mini USB connector. There's no way to plug it in otherwise. I don't know why anyone would bother to tell me that. I said I could charge the phone with two chargers I have using the same cable as used with the two chargers that won't charge the phone. So clearly the cable is not the issue. Further it is clear the chargers don't have the resistor because in the Motorola cable it is on a pin that does not exist in the type A connector on the chargers, so no way to connect it. I said all this in the post you replied to. I think you didn't listen to my post.

"can't be found" is referring to the charger that came with the phone. That is why I am looking for another way to charge this phone. The original charger is MIA.

Thanks for your help.

I've measured the voltage on the different chargers, but didn't write down the numbers as they were all pretty close to 5 volts. One web page did mention the phone would not charge if the voltage was too high or too low. I'm wondering how critical the high voltage is. Or possibly the phone is triggering to not charge because the low voltage is too low and I don't see it on the USB meter because it is too quick to see with the slow update rate? The chargers that work are definitely higher current.

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Rick C 

Viewed the eclipse at Wintercrest Farms, 
on the centerline of totality since 1998

These are handy devices to measure the working capacity of the charger:

The cheapest ones have worked fine for me.

I have a few of those and use them for testing chargers and phones. Very handy. They're especially fun when I connect them all in series and notice that both the voltage and current readings are not even close to each other. If you're using one for measurements, rather than just fault finding, I suggest you make a calibration chart.

I also bought a USB adjustable load: which is useful for testing if a charger can actually deliver the current printed on the label. Most will not or go into oscillation at the rated current. It's not the best quality instrument, but it works for the purpose intended.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Some usb leads for chargers only run the +5 and Gnd - so they can't be used on PC's etc

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John Keiser wrote on 11/20/2017 9:50 AM:

How do they measure the capacity of the charger? They measure the current drawn by the load and the voltage. I have one and when I used it with the phone and charger it indicated a voltage slightly over 5 volts and never registered a current unless the phone would allow charging to begin.

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Rick C 

Viewed the eclipse at Wintercrest Farms, 
on the centerline of totality since 1998

I'm using the same cable in all cases. Only the PC has any smarts attached and I'm not sure the phone even uses the data signals. The PC does make some noises like it might be connecting to the phone though, but I suppose it could be from the power drawn rather than the data signals. I don't know how complex the USB port is in my laptop.

--

Rick C 

Viewed the eclipse at Wintercrest Farms, 
on the centerline of totality since 1998