1. Sheppy01's Avatar
    Hi. New to forum and hope this is the right place to ask. I want to use my Android phone for a slightly different type of application, and have found all the software and tools to do what I need it to do. However, I'm having a problem keeping the mobile continuously charged. I purchased one of these solar chargers which essentially just charges its own internal battery, then when required, transfers the charge to the phone battery via a USB cable. As a boost, I charged the solar up from the mains first, then connected my phone to it via the USB output. My phone was about 50% charged at the start and it charged the phone perfectly, and as expected. I placed the two devices on the windowsill while still connected and left them alone. I assumed that the light through the window would keep the solar charger toped up, and the solar charger would keep the phone topped up, but when I check the battery status, the phone is using power but it's not automatically charging as I expected/hoped. To be fair, it's early days and the phone might start charging when it drops below a certain level but I'm not convinced. I'm pretty sure that if I unplug the charger, then plug it back in again, then the phone would start charging again - but I haven't tried this yet as I want to see what happens when the phone gets really low on charge. Does this whole idea seem viable? Am I missing something? Is there a better way to keep a phone continuously charged in a remote location?
    Any advice would be appreciated.
    01-21-2014 05:09 AM
  2. Sheppy01's Avatar
    For anyone who's interested, I may have answered my own question. Further research implies that the phone will stop charging when it hits 99 or 100% and won't automatically start charging again. This seems to correspond with my test findings so far.
    So I have to find a way of getting the phone to charge again. There maybe some software that'll do this for me, but if not, I'll set up a scheduled phone reboot which I believe will solve the problem. If this doesn't work, then I need to find a way to cut the connection with some kind of timer based relay, so the phone thinks the charger has been unplugged and plugged in again. I'll post more after my findings.
    01-21-2014 06:13 AM
  3. Jeffery Lutge's Avatar
    Yo check the prongs at the bottem. They get bent down i just bet mine up a little charges adap

    Posted via Android Central App
    01-22-2014 06:26 AM
  4. Rukbat's Avatar
    Most phones will do a top-off charge as soon as they drop below 100%. The only problem is that the charge rate of most of these devices is on the order of 0.1A, while the phone draws more than that to operate, so the net effect is just to discharge the battery slower. If the phone will be in a car, it would make more sense to wire the accessory socket to the hot side of the fuse box, so it's constantly powered, even if the car is off, then plug the phone into a car charger.
    01-23-2014 12:13 AM
  5. Sheppy01's Avatar
    Thanks for your reply. I might have got myself into a silly bind anyway, I'm starting to think the solar charger's battery was flat. Also, it seems near impossible to restart an android phone unless it's rooted - but a test last night actually showed that the phone will trickle charge at 100%.
    Anyway, I'm starting a more conducive test tonight with both items fully charged at the beginning, although it might make sense to start the test at the beginning of the day to maximize sunlight, but I'm not sure it'll make any difference. I am starting to think that this won't work in part for the reason you mentioned. That said, the phone will be 'standby mode' for 98% of the time and only coming out to run a couple of tasks. Most services will be turned off to save power, so it might just work. If not, I think I'll have to connect it to a 12v car battery via a 12v car style charger, then run a much larger solar charger on the car battery, pretty much as you suggest. It just seems odd that you can't run a phone on a constant supply. I guess I try to connect a power source direct to the phone terminals and remove the battery, but I'll still have problems with the power source. But I'm not giving up yet :-)
    01-23-2014 03:37 AM
  6. Mooncatt's Avatar
    I would also suggest a larger panel if possible. You may have to go with a general use one with with a 12V or 110V outlet and then use the charger that came with the phone. I think 12V setups are the most common, so may need to look into adaptors too.

    It sounds like the current panel isn't strong enough. Have you checked its output rating to make sure it's at least as strong as the phone's stock charger? Personally I'd go a little overkill on panel output, that way you can still generate enough power even if it isn't optimal sunlight conditions.

    It sounds like yours may just be meant to charge with the phone turned off and not act as the main power supply. I've seen some decent looking ones for campers and hikers (like backpack units) that may better suit your needs. I don't really know much about them other than they exist. I couldn't advise on which ones are good or bad.
    01-23-2014 05:14 PM
  7. Rukbat's Avatar
    It just seems odd that you can't run a phone on a constant supply.
    USB 2.0 specs call for 0.1A maximum supply, so a lot of phones aren't designed to draw much more than that. A phone with a USB 3.0 port (like the Note 3) can draw 0.9A from the USB port, and probably will draw a lot more that that if it's available. The 3.2A battery charges in about 2 hours on the supplied charger, and that's more than 900mA charging.

    Running a constant 3.7 volt supply to the battery terminals, with no battery, might do it. But I'd run it as a UPS, so if the input power glitches, the phone doesn't shut off.
    01-23-2014 06:16 PM
  8. Sheppy01's Avatar
    Thanks guys. Yes I think you might be right on the solar panel. I do have a larger one that I can test but it's not at the house. It's a 12v 2.4w so I feel this should be up to the task. I need to find a car style charger that has some circuitry inside which stops it sending out a voltage when the power input is too low. I believe most do this, and assuming so, then I should be ok. I.e the phone will use about 10% of overnight, but in the morning, the solar panel will ramp up to 12v, thus kick starting the car charger, which should fully charge the phone battery in very little time, then just trickle charge. Again, I have to prove this but I think the theory is sound.
    01-24-2014 03:58 AM
  9. Rukbat's Avatar
    Oh, it's definitely sound. I worked for a company that made burglar alarms that used cellphones (well, the insides of them) to call the central office. (That way you couldn't cut the phone lines and break in unannounced,) The phones were powered by 5 volt power supplies that fed off small 12 volt batteries that were floated on the AC power line (a kind of specialized UPS). They ran for years. The batteries had to be replaced every few years, but everything else lasted forever.
    01-24-2014 11:54 PM

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