USB charge meters

[tinpanalley]

Is there ANYthing I can buy to measure the amount of amps I'm getting of charge into a mobile device, tablet, or phone? I just want to do some experiments with some of my chargers. I've spoken to Qualcomm about their QuickCharge and they say that although they've tried to offer a list of devices that are QuickCharge compatible, obviously there are lots of devices out there with Snapdragon processors that they don't know about. Plus, there are other devices like my Asus Transformerbook T100 that has a BayTrail but are CLEARLY charging faster when I plug it into a QuickCharge desk charger I have. It's a remarkable difference. So I'dlike to plug in some meter that tells me exactly what's happening.

Does this exist? Is what I want to do possible? Thanks!

 

[Kelvrick]

http://www.amazon.com/DROK-Multimeter-Voltmeter-Capacitance-Charging/dp/B00J3JSEG6

 

[tinpanalley]

I'm curious about something, and one question kind of leads me to another...

1. Do these meters absorb (don't know if that's the right term) any current when they're connected between a charger and a phone for example? Or does the current pass through unaltered and give you a perfectly clean reading of EXACTLY what's coming out of the charger?
2. If you wan't to measure different kinds of chargers (regular, quickcharge, etc) is there a USB cable gauge specification at all in the world of USB cables? I mean, can ANY crappy, thin little USB cable carry the amperage of a 1 mA charger all the way up to a stronger amperage charger properly without bottlenecking or choking?

I'm asking question 1 because there's a guy on Youtube who reviews his Drok meter with what he says is a charger that has 1.2A output. But when he plugs in the phone that charger belongs to, he only gets .55A. Doesn't that seem wrong or do I not know my electricity specs?

 

[gorcorps]

I'm curious about something, and one question kind of leads me to another...

1. Do these meters absorb (don't know if that's the right term) any current when they're connected between a charger and a phone for example? Or does the current pass through unaltered and give you a perfectly clean reading of EXACTLY what's coming out of the charger?
2. If you wan't to measure different kinds of chargers (regular, quickcharge, etc) is there a USB cable gauge specification at all in the world of USB cables? I mean, can ANY crappy, thin little USB cable carry the amperage of a 1 mA charger all the way up to a stronger amperage charger properly without bottlenecking or choking?

I'm asking question 1 because there's a guy on Youtube who reviews his Drok meter with what he says is a charger that has 1.2A output. But when he plugs in the phone that charger belongs to, he only gets .55A. Doesn't that seem wrong or do I not know my electricity specs?

To my knowledge, any decent multimeter accounts for its own internal resistance and gives you the real value

 

[tinpanalley]

To my knowledge, any decent multimeter accounts for its own internal resistance and gives you the real value

Thank you! Of all the ones I've seen, the OLED ones look good for the money. Now, is there any way I could get my backup USB battery/charger connected to this to see its remaining charge in mAh and see at what amperage it's feeding my phones and tablets? Is that possible?

 

[gorcorps]

Thank you! Of all the ones I've seen, the OLED ones look good for the money. Now, is there any way I could get my backup USB battery/charger connected to this to see its remaining charge in mAh and see at what amperage it's feeding my phones and tablets? Is that possible?

Current? Yes, easily. You just need to put the positive and negative probes on the corresponding points of the USB port on the battery (Google which pins are the positive and negative)

Capacity is a tough one. I believe you'll have to measure the potential (voltage) of both the fully charged battery and then a completely depleted one. Then you'll just have to do some math every time you measure to get the estimated charge capacity left (it'll be in percent obviously, not a specific unit)

 

[stormkroe]

Current? Yes, easily. You just need to put the positive and negative probes on the corresponding points of the USB port on the battery (Google which pins are the positive and negative)

Capacity is a tough one. I believe you'll have to measure the potential (voltage) of both the fully charged battery and then a completely depleted one. Then you'll just have to do some math every time you measure to get the estimated charge capacity left (it'll be in percent obviously, not a specific unit)

Placing the leads on the positive and negative will measure voltage, not current. You can measure VERY small currents with the probes by placing them in series with the load, but the best way to do it would be to make a short extension cord with the hot wire exposed from the outer cable jacket (but still covered in its own black insulator!) and then use a clamp on ammeter while it's under load. A good meter can like fluke can give you several decimal places and then it's just a matter of P=IE. Charger output will be the same wattage as input minus losses, so without knowing the inefficiency it would mostly be good for comparing between different chargers.

 

[gorcorps]

Placing the leads on the positive and negative will measure voltage, not current. You can measure VERY small currents with the probes by placing them in series with the load, but the best way to do it would be to make a short extension cord with the hot wire exposed from the outer cable jacket (but still covered in its own black insulator!) and then use a clamp on ammeter while it's under load. A good meter can like fluke can give you several decimal places and then it's just a matter of P=IE. Charger output will be the same wattage as input minus losses, so without knowing the inefficiency it would mostly be good for comparing between different chargers.

I guess you're right... without being connected to anything there's no current to measure. Didn't really think that through