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Some charging tests

Discussion in 'Android Devices' started by CKwik240, Sep 14, 2011.

  1. CKwik240

    CKwik240 Well-Known Member
    Thread Starter

    After I learned of the USB dedicated charger protocol last year, I had been wanting perform few simple tests and finally got around to it this afternoon. I tested three chargers with three phones. The phones are a Droid Bionic, a Droid X and a Droid Incredible. The three chargers I tested were:


    powerPLUG - Low-profile USB Car Charger for iPad

    High Powered USB Car Charger | Bracketron

    The first is rated at 1.0A while the latter two are rated at 2.1A.

    First thing I did was test if the data pins were bridged, which is one of the USB specified signals for a dedicated charger. None were. There is another USB spec that I recall reading about, but I didn't understand it upon initially looking at it and didn't study it further to determine what it might actually be doing. The Droid X and the Bionic must recognize that signal as each detected the chargers as dedicated chargers and indicated AC charging. The Incredible did not.

    I bought the Bracketron charger primarily for this test as it had a visible screw that led me to believe I might be able to disassemble it without destroying it. I was right. I pulled it apart and bridged the data pins with solder and tested the Incredible and it finally said it was in AC charging mode. It would appear HTC uses a different protocol than Motorola. While I bought the Bracketron charger primarily for testing, I told my girlfriend to use it instead of the others for her Incredible since it should charge faster with it.

    Next, I decided to test the actual current being passed to the phone. I picked up a cheap micro usb cable. Tested it to make sure it can charge the phones and pass data normally. It appeared to do so just fine. I cut it in half and exposed the leads. I reconnected all the leads using test clips and tested it on each phone to make sure all the connections seemed solid. Then I disconnected the +5V test clip and put a multimeter in its place to measure the current. With both Scosche chargers, the DX and the Bionic pulled up to 0.75A. Both fluctuated quite a bit down to as low as 0.65A or so. Both seemed to register between 0.6A and 0.7A with the modified Bracketron charger. Though, I didn't get to test the current prior to the modification of the charger as I modified it before I assembled my test rig. The Incredible registered a measly 0.4A with the Scosche chargers since the phone wasn't going into AC charging mode. With the Bracketron charger it was pulling 0.85A.

    I was a little disappointed that none of the phones could use the full potential of the chargers. However, I am going to say that these tests were hardly scientific in ruling out other reasons for that. The cable I bought was rather cheap and the wires were quite thin. I also didn't test at different battery levels, with the phone off, or even after a fresh restart and perhaps turning off all radios to try and limit the data to just the charging circuit. I did however, do a quick test using a Griffin Ipad charger (2.1A) and the Incredible's OE charger (1.0A) and there were no remarkable differences except with the Incredible, which pulled 0.75A. I wanted to test an OE 2.1A charger, but my Galaxy Tab 10.1 charger won't charge either of the Motorola phones. I didn't try the Incredible with it. I have a few couple more chargers I can test, but they are currently either behind furniture or permanently attached to my car and I had this all rigged up on my workbench in the garage. Either way, short of the USB cable causing a limitation, it might appear that buying more than the needed amperage in a charger is not necessary.

    I did this for my own edification, but I figured others may find it interesting or useful so I figured I'd share what I found. Enjoy.

  2. kingnut

    kingnut Well-Known Member

    great write up man. i have been trying different chargers and now reading your post has brought some clarity to some gray areas. the highest amp charger ive found to work with my droid X/bionic is the motorola stock chargers 850MA. my buddy had a 1A Belkin usb he charges his iphone with and it wouldnt charge my X. that charger charges his iphone 4 from zero charge to 100% in an hour.

    i would think that the more high tech the phones get, that they would be able to accept a rapid charge of 2A or 3A. actually this should be what R&D of all major mobile phone manufactures is focused on.

    when im using my GPS, NAV, and full screen brightness in the car with my droid X, my car charger can not keep up. i actually lose battery and my phone will shut off if i use it over 6 hours straight in the car from full charge.
    Duckster and DanDroide like this.
  3. CKwik240

    CKwik240 Well-Known Member
    Thread Starter

    Could be reasonable. I don't know how they calculate the mAh of the battery though, but roughly, 1.42Ah (iPhone4's battery size) * 3.7V = 5.25 Watts. Conversely, 5V * 1A * 1hour = 5 Watts. Assuming, the iPhone4 can accept the full 1A, it might be close to an hour, give or take a few minutes.

    I'm sure there is research going on in this area, but I'm thinking we may see bigger advancements made in the automotive arena first. Plug-in electrics are likely to see a lot invested in this area, but even then, there is likely some limit we are going to reach with li-ion technology. As I understand it, the Nissan Leaf may see shortened battery lifetime if the rapid charge mode is used too often. So there is likely some threshold for balancing battery lifetime with charge rates. I do agree that I would like to see faster charging performance though. But currently, I think the drive to and from school will be enough for me to top off enough to last the day. If not, I got in on the 50% off extended battery. I would prefer not to have to rely on it though.

    My DroidX managed just fine. I used the 1A Scosche charger I described above, but I also used a Motorola car charger as well. I got it off amazon for cheap with no packaging and there are no specs for output printed on it so I have no idea what its putting out. I also can't test it without destroying it or buying and destroying a micro-usb extension cable to test with. But mainly using only Pandora for the drive home, I still usually had more charge than I remembered starting with. Honestly though, I never gave it a lot of thought as the phone generally made it through the day.

    Its hard to say without testing to know which chargers will provide enough current to keep from depleting the battery or even allow one to charge while driving and using some of the phone's functionality, but safest bet would be to make sure the phone goes into AC charging mode and the charger is rated to at least 750mA. Given most available aftermarket chargers are in increments of 500mA, a 1A charger should suffice.
  4. SpeakerBox

    SpeakerBox Member

    Just an fyi from what I've learned in the car audio competition scene. Batteries have a sort of memory. To elaborate, you can train a battery to have a higher resting voltage by draining it and charging it over its normal resting voltage. For instance, a wet cell battery rests around 12.5v which no one would recommend trying to over charge these as they have a tendency to pop, but an agnostic or gel cell battery can be trained. They can also be brought back to life much easier which is pretty much the same thing as trying to train one to raise its resting voltage which for these types should be in the 12.7v range. Now, trickle charging them is the best option as it teaches a battery to slowly drain giving you much better performance and life out of the battery. Trickle charging usually charges the battery with 2-4 amps of current over a long period of time(6-12 hours depending on how good and efficient your charger is, I prefer XS Power chargers) teaching that battery how to be efficient in taking the charging supply given in order to reach its maximum capacity as quickly as possible. While charging at a higher amperage is good at times, it mostly causes heat and at some point the battery will start to swell. This is probably what moto had in mind when it came down to the batteries and charging. Only allow so much amperage and voltage in order to keep the life cycle of the battery long and give its best performance. Just my thought about it though, no real data to back that up, just seems like it makes sense to me. Not to mention Li ion batts are a slightly different case but I think its close enough in this aspect.
  5. kingnut

    kingnut Well-Known Member

    so the [FONT=&quot]scosche charger did work with your droid X/bionic[/FONT]? also did the [FONT=&quot]scosche charger come with the micro USB cable?[/FONT]
  6. CKwik240

    CKwik240 Well-Known Member
    Thread Starter

    Yes it works with the X and the Bionic. And no, it did not come with a cable.
  7. Travisimo

    Travisimo Android Enthusiast

    I just want to know what's the fastest charger that will charge the Bionic? The stock Moto charger I'm using takes 4+ hours to charge my extended battery from 5% to 100% if I don't turn off the phone while it's charging. If I fully turn the power off on the phone, then it takes just over 2 hours.

    Given that I'd rather leave the phone on (in case I get a call, etc), is there a different charger that will charge the phone faster than the Moto one that came with the Bionic?

  8. thenew3

    thenew3 Android Enthusiast

    This has more to do with heat then the output of the charger. When you are running GPS NAV, it generates more heat from the CPU and chipset, thus causing the device to be very warm/hot. When this happens, the battery charges very slowly or doesn't charge at all.

    Here's a test I've done, 8 hour drive, droid x, cheap generic car charger, start the trip with a 100% charged extended battery, 6 hours into trip, battery completely drained, charger not able to keep up. Back of phone extremely hot to the touch (it was 108 degrees outside, phone was on car nav dock on the windshield with sun shining directly on it, car AC was set at 72 degrees).

    Next day, same trip, same setting, except this time, the car nav dock is set in a way where the AC vents are blowing cold air at the back of the phone. finished 8 hour trip with phone still at 100% charge.

    Repeated this experiment 3 times, same results. one time tried it with a 2.1A charger, it also could not keep battery charged when hot.

    So as long as I keep the phone and battery cool, the charger is able to keep the battery fully charged while using GPS/NAV and streaming radio.

    Going back to my College circuit design days, transistors don't work as efficiently when the temperature reaches above a certain point, so when it gets hot, they can consume more power. While the difference is suppose to be mostly negligible, when the power consumption level is already low to start with, even a small change makes a big difference.

    Next time you take a trip, try to put your phone in such a manner where it can have cold air blowing on it, this should keep the battery charged regardless of what apps you are running.
    Duckster, DanDroide and kingnut like this.
  9. kingnut

    kingnut Well-Known Member

    awesome post man. i do keep my phone out of the sun. but it does get pretty hot. im not sure the MA rating of my car charger because its not listed on it. its the newest verizon car charger and wasnt even listed on the packaging.

    but i do appreciate the input and the research you have done. i just downloaded an app from the market thats called "battery indicator". its an awesome app that has the battery temperature and voltage. it runs in the status bar and it has a free version. i think this is an app you would thoroughly enjoy.

    thanks again for you post.
  10. thenew3

    thenew3 Android Enthusiast

    No problem. I've also tried it where I had AC blowing at the front of the phone. That slowed the drain from the battery but did not stop the drain.

    So on the Droid X (I imagine other phones as well) the AC needs to keep the back of the phone cool. (makes sense, that's where the battery is, and most of the circuits are on the back as well).

    Now the Droid X has a metal back, which is a better conductor of heat. The Bionic and many other phones have a plastic back, so I'm not sure how well it would work conducting heat away from the circuit board and the battery. But worth a try anyway.

    I'm going to try this tomorrow on a 3 hr drive.
  11. xguy

    xguy Android Enthusiast

    This may very well be my problem- heat! Heat is truly the battery's enemy and I know from just leaving battery powered tools like cordless drills in the sun.

    As I reported that I left on my motorcycle with 100% charge, plugged in to charger and in 2 hours of GPS and Pandora she died!! Even though it was only 80* it was right in th sun. I am in the process of ordering a Moto rapid charger and hope that helps. A lot of people have them on their bikes with no problem- so maybe it's a Bionic thing and I have to get an Ipod or something.:thinking:
    Amazon.com: Motorola Vehicle Power Adapter micro-USB Rapid Rate Charger: Cell Phones & Accessories

Motorola Droid Bionic Forum

The Motorola Droid Bionic release date was September 2011. Features and Specs include a 4.3" inch screen, 8MP camera, 1GB RAM, TI OMAP 4430 processor, and 1735mAh battery.

September 2011
Release Date

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