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Current Events In Cell Phones: Tales Of My Transition to Micro-USB Power

As described previously, about a month ago I bought a Blackberry 9700 cell phone to replace my vintage Blackberry Pearl. The Pearl and the Motorola Razr that preceded it both used mini-USB type connector for DC power. I had thought that this was something of a standard, but if it was I guess it was short-lived. Early in 2009 the major cell phone manufacturers all agreed to settle upon “micro-USB” as the one standard connector type for DC power in new models.

Someone once said, “the great thing about standards is that there are so many to choose from.” I suspect that it might have been Dilbert.

Hurray for us! We have a standard!! That means that we might get more utility out of that box of AC adapters that we all have hidden away in a closet. I actually have two big boxes of these little beasts. I just can’t stand to discard a perfectly functional PSU, even if the device to be powered is completely D.O.A.

My earliest exposure to the new micro-USB connector was back in early August when bought a Mifi wireless router from Sprint. It came with an AC adapter that was terminated in a micro-USB connector. It did not come with the USB-to-micro-USB cable for using it in a wired fashion. I’m lead to understand that the Verizon Wireless version does come with this cable.


Micro-USB power connector on the Mifi device.

When used in a completely wireless fashion the Mifi supports wifi connectivity for up to five devices. However, when physically connected to a PC it shuts off the wifi radio and acts as a network interface to that one PC alone. Since the PC can charge the Mifi this way I thought that it would be good to have the cable, so I got on E-bay and bought one for under $5.

As fate would have, not long after that cable arrives the AC adapter for the Mifi died. It had the look of an incredibly cheap device so this was not completely unexpected. Since it’s demise I’ve charged the Mifi solely by way of the micro-USB cable. This has not been a problem, even over a period of many weeks.


Micro-USB charging jack on the Blackberry 9700

That was August through to the end of October. In November I purchase the Blackberry 9700 which also uses a Micro-USB power connector. As you might expect that phone came with an AC adapter, and as some others might have expected, I lost it after just a few weeks.

Actually, I didn’t lose it. I left it at the Crowne Plaza Hotel in Indianapolis at 5am one morning in December. I was in a hurry and trying to make a very early flight home to Houston. I should probably call them and see if they might be convinced to send it back to me.

I though to myself, “no problem I’ll just charge the phone using the USB cable, just as I’ve been doing with the Mifi.” That was a nice idea, but it didn’t work. At least it didn’t work much of the time. Over a period of a couple of weeks I have identified the pattern of when the phone would or would-not accept a charge using the USB-to-micro-USB cable.

It turns out that it will charge from the USB ports on my desktop PC or my wife’s desktop PC. It will definitely not charge from the USB ports on my laptop or netbook. It turns out that to charge the Blackberry 9700 requires more current than a single laptop or netbook USB port will provide.

Occasionally, when you plug in into one of these PCs the display on the phone will issue a warning message indicating this fact very clearly. However, just as frequently when I connect the phone to the laptop it changes to the clock display, which is what is supposed to happen when the phone is actually charging.

Though I have at least four Blackberry chargers that terminate in mini-USB connectors, I don’t have any with micro-USB style in my stash of older AC adapters. I seemed doomed to commit another $30-50 to acquire at least two more new style AC adapters. Accepting this conclusion I went off to the T-Mobile store nearest me in search of said power supplies.

However, they didn’t have them. What they had were a generic T-Mobile branded USB style charger kit with the right cable and a little switched mode AC adapter with a standard USB jack. Mechanically it seemed ideal, so I bought it and the similar DC adapter necessary to charge the phone in my car. That’s me out of pocket just shy of $50. Cell phone accessories are such a scam!

When I got home I tried to charge the Blackberry 9700 from my brand new AC adapter. Guess what, it won’t charge! It behaves just like when I tried to charge it from the laptop USB port. The AC adapter is not providing enough current. The phone doesn’t indicate this at all…but it isn’t charging either. When I try charging the phone in my car the same problem arises.


T-Mobile’s generic USB type AC adapter, rear view showing the rated voltage & current output

It turns out that the generic T-Mobile USB style charger is current limited to 500 mA. It seems that the  Blackberry 9700 requires considerably more current to charge. Looking at my old Blackberry chargers they indicate that they provide 5 vdc at 700 mA.

So for the moment I don’t have a reliable means of charging the phone except from the USB ports on our desktop PCs. That’s what I’ve been doing for the past few days. It seems that I need a better solution, especially for when I travel. I typically have two AC chargers; one the stays in my bedroom and another in a pocket on my suitcase. Then a DC adapter in the car….just in case of emergencies.

mini-usb-cable-for-portable-hd-200I am reminded of a few times when I had USB-powered portable hard drives. They often come with a cable that provides two standard USB plugs at the PC end and one mini style at the HD end. This is intended to get around the fact that some USB jacks are current limited.

By connecting to two USB jacks on the laptop the drive can draw twice the current it would otherwise. I’ve seen cases where such a drive would not spin up without both jacks plugged into the host PC. While I’ve seen this happen on laptops I’ve seen it just as often on server class machines where the front panel USB ports were current limited, but the one on the motherboard rear apron were not current limited.

mini-to-micro-usb-adapter-200I’ve also done a little hunting online and found mini-to-micro USB adapters. These little adapters are dirt cheap, less than $1 each, and look like they might let me use my older Blackberry chargers with the 9700 and the Mifi.

I’m also going to try charging the Blackberry using one of the cables from a portable hard drive. I think I have a spare. Perhaps that will let me charge it from a laptop, using two of the USB ports. I’ll report back about that little experiment later in the week.

<time passes and I find myself in a small town in central Texas visiting in-laws>

It’s nice to have the Mifi here in Thorndale as we visit with in-laws over the holidays. There’s no internet access otherwise. However, the Mifi has now fully discharged its battery. We find that none of the laptops present or AC adapters (all rated for 500 mA) will charge the Mifi. Thus it was necessary to make a run to the one appropriate local resource; a Radio Shack.

Happily, Radio Shack had a genuine Blackberry brand charger intended for a Storm2. It puts out the requisite 5vdc at 700mA. As a result the Mifi is now back online and the various spouses on-hand are again amusing themselves online, myself included.


Blackberry AC adapter, rear view showing the rated voltage & current output

When the various other adapters and chargers that I’ve ordered from Amazon eventually arrive I will document their utility. One thing is for certain, I will not be going to the T-Mobile store looking for Blackberry official charging hardware. I’ve already been down that path, paid handsomely for what was supposed to be a solution, and found it wanting.

I’ll close this episode by giving you the moral of the story explicitly; though we might now have arrived at a standard connector for charging cell phones, don’t go thinking that this makes everything simpler. It might, but it doesn’t have to. The very fact that some chargers will or more importantly will not charge some phones (or Mifis) adds a layer of complication. It creates an opening for staff at cellular retailers to recommend charging accessories that might appear to be workable, but in the end don’t do the job.

As in most things technological, there’s real value in tracking the details. It’s important to stay current. Be aware of the charging current you need when looking for a replacement cell phone charger.

This Post Has 4 Comments
  1. You should really get an Apple iPod or iPhone charger. Tiny, reliable, well built, and puts out 1A over USB…


  2. Have you seen the LG mini-USB cable/charger combo? The wall charger can (I think, not in front of me) take a pair of USB cables. Disconnect the cable and you get a nice neat clean little package to drop into the man-bag and the cable can be used like you’d normally use a cable.

    1. I have something similar on order. Part of the issue is that there’s a lot of focus on physical connector type, not so much on current rating.

  3. I use the usb adapter end of my Barnes and Noble Nook to charge my BlackBerry Tour. Its rated at 0.85A. I found it annoying to have to carry around micro-usb charges for the Nook, the Tour, and the Mifi. So one day I checked and found out that all would charge using the Nook charger.

    I am actually waiting for the TruePower UCS Power Outlet With Built-in USB Ports. Hopefully they will come out with a higher power model than 0.6A.

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