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  • wall wart question

    My buddy just bought a new tablet which comes with a charger that says it's rated for 2000mA. He asked me today if it would be safe for him to charge his phone with that charger. The charger that came with his phone is rated for 1000mA. I thought about it for awhile and realized I really didn't know.

    So what's your take? Yes? No? Can't tell?

    metalmagpie

  • #2
    As long as the voltages match, that is, the charger's rated output voltage and the voltage that his cellphone requires during charging are the same, it will be fine.

    Of course the plugs need to be a mechanical match also.

    The batteries will draw the required current during charging, there will be no harm from the fact that the new tablet charger is capable of delivering more current that required.

    If it provides more voltage than the cell phone is designed for, THAT will be a problem.

    Think of it like the battery in your car, if it's 12 volts and the factory battery was a 105 Amp Hour rated one, and you replace it with a higher quality 12 volt 120 Amp Hour battery, you just have more reserve capacity, but no harm will be done to the car's electrical system.

    The old analogy for voltage and current being compared to water through a pipe is another way to think of it. Voltage is like the water pressure through the pipe, and current is like the gallons per minute flow volume through the pipe.

    If the pipe is emptying into a tank like one on an older style toilet, once the bucket is full the float valve shuts it off. Once the battery is full , it stops accepting more current. But if the voltage is too high, just like having too much pressure in the pipe or the tank, bad things happen. The battery will heat up, swell, possible burst, etc.

    With the cell phone, if the voltage is too high, the really bad thing that happens is all the magic smoke gets let out of it. And that's next to impossible to stuff back in there.
    Steve
    NRA Life Member

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    • #3
      There is not enough information to answer the question. 2000 Ma is a current rating. The voltage is the critical factor. Also the polarity of the adapter as well as the connector. If the voltage, polarity and connector are compatible, the current rating is not the critical factor. All devices with LiPo batteries contain charging circuits that control current to the battery during the charge cycle.
      https://www.youtube.com/channel/UCIF...7S66kX1s8rd0qA

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      • #4
        The tablet probably charges through a micro-usb port, just like most phones do.

        Yes, it'll be fine.

        Comment


        • #5
          As mentioned, if all it requires is a voltage source, then it would be fine if the plug and polarity are satisfied.
          However, if it is a charger and not just a voltage source, then the battery technology should be the same in both cases, i.e. LiPo and NiMh etc require different charge techniques.
          Max.

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          • #6
            One other item to be aware of. IF the voltages match, and IF the connectors match, it is okay to charge the phone from the table charger, however, IT IS NOT okay to attempt to charge the tablet from the phone charger. As stated before, MORE capacity is good, LESS is BAD.
            Kevin

            More tools than sense.

            Comment


            • #7
              As stated above voltage and polarity matter. But your question does not ask that. It asked about current. So simply the phone battery will only consume 1000mah. Thus the power supply will only be working at half it's capacity. And that is only when the phone battery is accepting 100 percent. As the battery is charges the current into the battery, as well as the current drawn from the power supply lessens

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              • #8
                The OP mentions Charger, NOT supply, they can be two different things, especially where battery technology is concerned.
                Max.
                .

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                • #9
                  this topic kinda hits home, iv ran into a little "confusion" waking up in the morning before I have my coffee and shorting out my electric razor,,,

                  it's a remington and I also have norelco beard trimmer, but the two plugs are almost identical, there is a huge voltage difference and yet also their polarity is reversed,



                  here's the thing - the norelco's plug fits into the remingtons receptacle like it's a glove...




                  here's the other thing - and this is not a one time fluke as it's happened many a time, when my razor is running low and is on the last red increment ( there's about a half a dozen greens above it before it gets down to red) I then grab one of the two plug ins coming out of the wall socket, if not careful I forget and grab the wrong one, the split second I try to plug it into the remington hear a strange sound, disconnect and then see I grabbed the wrong plug, but get this, the remington now has what appears to be a full charge - all the lit up greens are telling me that, and,,,,,,,, the shaver acts like it, it will act like it just got a full charge within a split second of reverse polarity, and will behave as such... go figure,

                  overunity ???

                  Comment


                  • #10
                    Originally posted by A.K. Boomer View Post
                    overunity ???
                    Overload!
                    https://www.youtube.com/channel/UCIF...7S66kX1s8rd0qA

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                    • #11
                      A.K. Boomer, you should not be shaving. It is just a waste of time amounting to more than a week over your entire life. Be a man.

                      Comment


                      • #12
                        If it is a usb connection you can plug either device into either charger. The tablet looks for something on the data lines that tell it that a high capacity charger is attached and will charge at a high rate. if it does not see anything on the data lines it will charge at USB default of 500ma. If you plug the phone into the tablet charger it will just charge at it's standard high charge rate limited by the charging chip in get phone.

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                        • #13
                          If his phone is a smart phone, it should be fine although it will be charging the battery at twice the rate it is designed for, which will shorten its life somewhat. If it's a dumb phone, most likely it will simply not charge. Mine doesn't (700mA charger normally), just beeps and disconnects. Going the other way, sure you can charge a tablet with a 1000mA wall wart, if it will let you. It'll just be a lot slower. Most likely though it just wont charge - my Nexus 7 won't charge off either a 700 or 1000mA wall wart. It needs a 1.5-2A charger. It's not just charging slowly, it doesn't charge at all.

                          Although the voltages and plugs are the same, the current supply is designed to match the capacity of the li-ion/ li-po battery inside the device. Standard lithium batteries (high zoot RC ones and power tools excepted) don't like being charged or discharged above 1C (i.e. if it has a 2000mAh battery, don't charge or discharge it above 2000mA), which is why you have 700mA, 1000mA and 2000mA chargers, for 700mAh (dumb phones), 1000mAh (smart phones) and 2000mAh (tablets) batteries. Best to stick with the charger it came with or its equivalent.

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                          • #14
                            Originally posted by macona View Post
                            If it is a usb connection you can plug either device into either charger. The tablet looks for something on the data lines that tell it that a high capacity charger is attached and will charge at a high rate. if it does not see anything on the data lines it will charge at USB default of 500ma. If you plug the phone into the tablet charger it will just charge at it's standard high charge rate limited by the charging chip in get phone.
                            my experience suggests that, although that would be the right way for device makers to do it, many of them don't. I've found that iPhones charge much more quickly (not sure 2x, but noticeably faster) on 2A power supplies and the tablets (and bike lights, believe it or not) that I've tried it on aren't interested in anything under 1.5A, plus there's my crappy phone which won't even look at a 2A charger. Given that there's no guarantee that the device maker followed specs, I think it's just wiser to use the right amp charger for the device.

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                            • #15
                              A reply for Boomer and Magpie...

                              Boomer, when you plug the 12 volt, .4 amp charger into the shaver that is designed for 2.3 volt at .1 amp it is providing a huge power surge. If there is a diode bridge it will allow a .4 amp surge at 12 volts to charge the battery quickly. This will drastically decrease the lifespan of the battery.


                              Magpie....

                              The rating of the charger is the max that it will provide if the cell phone or tablet tries to suck that much current from it. An ipad will charge faster on a 2000ma charger than it will on a 1000ma charger, but it will charge from both if it's not running an app that is eating up all the power. The amount of current that is drawn from the charger is dependent on the load that the tablet presents to the charger.

                              Dan
                              At the end of the project, there is a profound difference between spare parts and extra parts.

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