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Phil23
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Joined: 27/03/2016
Location: Australia
Posts: 1664

Posted: 01:15pm 02 Sep 2017

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I've got a few of the inline USB Testers that measure Voltage/Current etc...

Just stumbled across these ones though; a bit more advanced.

Review here.

And a couple of listings, here and here.

Cheeers.

Alastair
Senior Member

Joined: 03/04/2017
Location: Australia
Posts: 161

Posted: 05:53pm 02 Sep 2017

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Phil,
Interesting - looks useful. I especially like the albeit limited graphing of the voltage and current.

Some time ago I purchased a simple similar device which just displays voltage and current. It does this quite well and accurately. What caught me out was that the signal lines are not connected through which makes it useless for seeing the current variation as the connected device is operated. I have been meaning to open it up and see if the connection can easily be made. Can't understand why they didn't do it.

cheers

Cheers, Alastair

Phil23
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Joined: 27/03/2016
Location: Australia
Posts: 1664

Posted: 08:12pm 02 Sep 2017

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Alastair said What caught me out was that the signal lines are not connected through which makes it useless for seeing the current variation as the connected device is operated. I have been meaning to open it up and see if the connection can easily be made. Can't understand why they didn't do it.

Are you aware that in some chargers the two data pins are shorted together & in many cases pulled to a voltage to make the charged device draw a higher charging current.

My Samsung Tab, for example, needs the data pins shorted, & pulled up to 1.2V, in order to accept a 2A charge.

I've got a few of these devices & one has a data/charge switch.
Not quite sure what it changes.

Phil.

Alastair
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Joined: 03/04/2017
Location: Australia
Posts: 161

Posted: 08:58pm 02 Sep 2017

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Phil,
No did not know that. I had wondered how the high/low charge rate was arbitrated so now I understand. Sounds like there is no reason not to open up my device and connect the wires.

Is there any danger in doing this? Can't see one as it is just like and extension cord with the current monitor bit. I will check the resistance of the power wires to make sure the shunt is low ohms. Too cheap for it to have been Hall effect.

cheers

Cheers, Alastair

Phil23
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Joined: 27/03/2016
Location: Australia
Posts: 1664

Posted: 10:59pm 02 Sep 2017

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Alastair said I had wondered how the high/low charge rate was arbitrated so now I understand. Sounds like there is no reason not to open up my device and connect the wires.

The Guy that reviewed it has some good info on charge rates on this page.

Phil.

Alastair
Senior Member

Joined: 03/04/2017
Location: Australia
Posts: 161

Posted: 05:04pm 03 Sep 2017

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Phil,
that link shows just how an original simple idea gets complicated and could cause potential incompatibilities. I have always been wary and tried to use the power supply that comes with a device. With usb I thought one could relax more but it still looks a worry. I have one device with a usb c connector that will not charge properly other than with its own unit. The cable coming out of the charger is fixed so I assume it has a proprietary connection. I have avoided using it with anything else.

cheers

Cheers, Alastair

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