All you ever wanted to know about battery chargers

[sperho]

I was glad to see that the Samsung "cube" charger, i.e. the one that came with the Galaxy Nexus, did a pretty good job. I have about 5 of them because back when I bought them from Amazon, they were about $6 apiece, cable included. And they are tiny!

 

[stoli40]

I wish someone with a degree in this would state their qualifications and give us true facts. There are too many opinions here to really know what is safe to use and what isn't.
IDUNNO says, A/C Chargers - This is where the most variation is as far as power output, they will all put out an acceptable voltage (4.75-5.25 volts)
Then why does the one I purchased say, Output 7.6 volts-1000mA?
Someone says 2 amps turns the phone into a bomb but others say it's the volts or amps that affect it and damage it.

Tis the nature of the internet and forums. Anyone can post anything. Up to the reader to fact check.

I suggest you do a bit of reading about the basics of electricity so you have a better idea of what's going on especially the difference between volts (voltage), amps (current), and watts (power).

The short story is that you should match the voltage of a charger to the voltage of the device you're charging. Plugging in a charger with a higher voltage than is specified will damage your device. There are exceptions to this rule, but unless you know what you're doing and understand electronics, best to stick to this rule.
I don't know what the charger you bought is designed for or whether it is safe to use unless you post a specifications sheet.

The question here is not about volts, it's amps. The more current a charger can provide, the faster it can charge. However, charging produces heat. This then can cause many different issues as generally electronics and heat don't match.
So, most phones have a built in current regulator to avoid charging the battery too quickly and producing too much heat. So even if a charger can produce say 2A, most phones will only charge at 1A. Tablets have more robust batteries, circuits and wiring so their regulators allow 2A charging or even more.

The end game is that buying a charger with a high current charging rate won't make a difference to a device that has a current regulator.

I have a Galaxy Note v1. When the battery is low (less than 15%), it only draws 650mA on charge. After that it draws the maximum 1000mA (1A) current from the charger. Using a charger that could provide 2A would make no difference to this.

Oh and I have a Bachelor of Electrical Engineering, and these are FACTS not OPINIONS. =)

 

[mllyou]

This is an informative thread. Thanks to all, and Stoli40 particularly.

So my understanding is that as long as a charger (AC, car charger, or whatever) has the same voltage as the original charger, you can plug it into a phone, a tablet, etc. (with the right plug, USB, or one of those barrel connectors). If the amperage of the charger is higher than required, it will do no harm to the charger or the battery/device: it will charge at a suitable rate determined by the battery and regulator. If the amperage of the charger is less than required, it will not charge at a maximum rate, but a lower rate, or not at all if there is not enough juice, so to speak; and again, there is no harm to the charger or the battery/device.

I have one of the newer tablet pc, the Cube U30GT2 (a very nice Android tablet for the price of $300, more or less; my questions below are not specific to the Cube), but the 12V 2A charger that came with it was DOA. I have a Seven Star SS105 18Watt power supply that can be set to output 12V with the right plug and polarity for the Cube. The SS105 is rated at max 1A (1000 mA). However, if I measure the open load voltage at 12V setting with a multimeter, I get 18 to 19V. I can also set it at 9 V (or maybe it is 7.5 V) and the measurement would then be about 12V (the numbers just for easier illustration). At 9V, the power supply should be able to source 2A.
Questions: (1) Is there a difference between what we normally call an AC charger or AC adapter (as supplied by phone and tablet manufacturers), and an AC-DC power converter (which the SS105 is)?
(2) Is it safe to use the SS105 as a "charger" to the Cube (or other LiIon batteries/devices)?
(3) If it is safe, which setting should I use, the 9V or 12V?
Note that because the Cube has a barrel connector (2.5mm OD/0.8mm pin), there is no need for a USB charging cable.

If it is not safe, instead of buying a new original charger, I plan to buy a LiPo balance charger (for all rechargeable battery types) which not only have the regulation for charging, but also an LED screen to display the charging (or even discharging) progress. Another question:
(3) Is it okay to charge the Cube from such a balance charger? My concern is the duplication of regulators, one from the balance charger, and one from the battery/device itself (if it has one).

If that is not okay, then I have a third proposition: Use a regulated switched mode power supply from an old PC that supplies a steady 12V at up to at least 10A, and connect the molex connectors to the right plug, observing polarity.
(4) Would that be safe to charge the Li-Ion or Li Polymer batteries in an Android tablet that have specs for 12V 2A?

I am a newbie. There have been a lot of reported problems with charging (even with manufacturer's charger) on Android tablets due to upgrade to Android 4.2 (for example, Nexus 7) and some solutions have to do with bypassing the battery built-in control circuits. That's what brings me to this forum.

Many thanks.
Mllyou

 

[Outatime]

If I am not mistaken, isn't it the phone that determines the amperage that it "accepts"? I was under the impression that if you put 1, 1.5, 2.0 amps to the phone, it will only accept a max of 1.0 amps.

You are correct. Too much misinformation thrown about as fact by people that do not understand electricity.

Edit: Wow. Just looked at the date. Holy necro.

 

[steven yit]

Hey...if that charger is over 2 ampere..like 2.1 or 2.4....will it still suitable to charge the galaxy note 2 ??

 

[Dngrsone]

Hey...if that charger is over 2 ampere..like 2.1 or 2.4....will it still suitable to charge the galaxy note 2 ??

Yes.

 

[vishalreddy]

My Samsung galaxy tab pro wall charger is only picking up as charging in USB mode even when connected to wall outlet,inaddition it shows a red X on my battery indicator.the output voltage of adapter is 5.3v and output current is 2A .The adapter works fine with other usb cables which are designed to 750mA or below but the usb and adapter are getting too hot.I bought the device in usa and I use it in India.I think this should not be an issue.please help me out.Iam worried

 

[Dngrsone]

It sounds like you have a bad cable. Try and find yourself a more robust data cable to use with that charger.