Car Charger

[azj]

Newegg has a 2A car charger on sale for $6 with free shipping.
Newegg Charger

 

[ace7196]

So question: does a device only pull the current it needs? Seems those 2 amp chargers can charge a phone just as easy as a nook color. Anyone have a good explanation of this stuff? I'm just an ME...EE stuff is a bit beyond me.

 

[Divine_Madcat]

So question: does a device only pull the current it needs? Seems those 2 amp chargers can charge a phone just as easy as a nook color. Anyone have a good explanation of this stuff? I'm just an ME...EE stuff is a bit beyond me.

Yes, a device will only pull what it needs. I have charged an Ipod with my nooks brick, no ill effects. The charger CAN supply 2A, but will not FORCE 2A unless it is requested.

 

[Hosermage]

Well, I wanted to make sure my NC will charge on a long road trip, so I pull the trigger on the BN car charger. The regular nook cable looks to be a regular micro usb cable by the connector, the NC cable connector is bit taller.
View attachment 613232

 

[spdsl]

I purchased the Griffin Technology PowerDuo 2 amp Power Charger for iPad. The Powerduo comes with a 2.0 amp car charger and a 2.0 amp plug in wall charger. Using the Nook oem cable I plugged in the nook to both the Griffin car and wall charger. Battery widget and the cm7 battery app both reported USB charging only. When I plug the nook into the oem nook wall charger the battery widgets report charging / AC.. It seems that charging a nook at the rapid or high amp rate is dependent on the cable, charger and nook syncing together.

 

[DatterBoy]

I am sure it is mentioned somewhere here, but the taller NC cable is how the NC get's it higher voltage and rapid charge. Charging with a shorter cable will basically get you trickle charge.

 

[mrmark93]

So, your post pushed me over the edge. I knew I needed to just cut a cable apart, break open a few chargers and get the gear out and measure stuff--so after your push, I jumped

First thing to measure was the resistance across the data pins (the center two conductors on normal USB connectors) of the three chargers I have:

Stock B&N Nook COLOR wall charger: 0 Ohms
Belkin 12V I-Pad USB Vehicle Charger: 53 Ohms
Harbor Freight 12V USB Charger: 53 Ohms

I had read in the 'is the wall charger special' thread that shorting the data pins is what tells the NC that it is connected to a high-output charger-and indeed, shorting the data pins and THEN plugging the NC into the two 12V chargers makes the NC believe it is plugged into the NC wall charger (reports 'AC Plugged' in the battery widget).

My NC was almost fully charged so the current draw wasn't the full available from none of the three, but was easily able to get both the Belkin and Harbor freight to put out 'normal' of ~400mA; then unplug, short the pins, plug in and both chargers put out over 1000mA as needed by the NC--the same as the wall charger when plugged into that. I definitely got the feeling that the NC was controlling charge current level. The Belkin unit had no problem supplying the higher current, while the Harbor Freight unit (advertised for only 500mA) started to get hot and started to smell like burnt--probably would have a short life used this way, but never failed though.

I don't have the B&N 12V vehicle charger to test so I'm not 100% sure there are only the two modes as reported by Battery Widget (USB Plugged or AC Plugged).

Short version: Charger needs to have data pins shorted to get the NC to change to high rate charge mode.

I'll add more when I have discharged the NC.

Continuing on now that I finally purchased a B&N Nook Color Car Charging kit


Stock B&N Nook COLOR wall charger: 0 Ohms
Belkin 12V I-Pad USB Vehicle Charger: 53 Ohms
Harbor Freight 12V USB Charger: 53 Ohms
B&N Nook COLOR Car Charger 0 Ohms


0 Ohms? I thought to myself, that's what the wall charger measures. How does the Nook differentiate between the Wall (AC) charger and the Car (DC) charger. I re-installed Battery Monitor Widget (it had gone insane so it was uninstalled), fired up the bench power supply, plugged in the B&N car charger, used my ORIGINAL (& somehow fully functional) B&N Nook COLOR micro USB cable, and low and behold: Battery Monitor Widget reports:




wait for it....



building....



AC Plugged


....so there is no difference as far as the NC is concerned between the B&N wall charger and the B&N car charger. If the data pins are shorted, the NC will charge at the higher rate. Well that was slightly disappointing... but no more mystery on the chargers. 53 Ohms across the data pins = iPad charger, 0 Ohms = B&N compatible charger. Now if that spec. was posted on the package, it'd be very helpful!

 

[2devnull]

So, I bought a small USB extension cable and shorted the data pins via a splice and solder job, and connected it to a regular USB to mUSB. The NC states 'AC Charging' however it does not seem to be increasing in %. I have a 2.1A cigarette lighter USB adapter. Will try the original NC USB cable and see if that actually charges it but the fact that the NC recognized this regular cable for AC Charging and not actually charging is disappointing.