Let's talk about those little in-line USB ammeters.  What's the good one? - Page 1
Forum section: electronics / testgear

author: cvanc
author_rank: Frequent Contributor
timestamp: October 23, 2015, 10:31:23 pm
content: I'd like to investigate the current draw of several USB peripherals, and have come across these tiny current/voltaqe meters. There seem to be several different ones available; can I get a recommendation for a decent one? A reliable source would also be most welcome. Thank you.Examples:http://www.amazon.com/gp/product/B00J3JSEG6?keywords=usb%20power%20meter&qid=1445639365&ref_=sr_1_1&sr=8-1http://www.amazon.com/gp/product/B00ORN78WE?keywords=usb%20power%20meter&qid=1445639365&ref_=sr_1_9&sr=8-9http://www.amazon.com/gp/product/B00JW50M5M?keywords=usb%20power%20meter&qid=1445639365&ref_=sr_1_13&sr=8-13http://www.amazon.com/gp/product/B00GC9I61I?keywords=usb%20power%20meter&qid=1445639365&ref_=sr_1_15&sr=8-15

author: Ryano
author_rank: Regular Contributor
timestamp: October 23, 2015, 10:41:29 pm
content: Those would all work if cost is a key factor. We have several of the fourth one listed around work and I can tell you they weren't very cost effective after I had to repair them all.I've been looking to pickup one of these for sometime now.http://store.hackaday.com/products/usb-tester-2-0

author: sleemanj
author_rank: Super Contributor
timestamp: October 23, 2015, 11:14:08 pm
content: Quote from: Ryano on October 23, 2015, 10:41:29 pmI'd be interested to know what the failure was.

author: mtdoc
author_rank: Super Contributor
timestamp: October 24, 2015, 02:05:01 am
content: If you're willing to spend a bit more,thesefrom forum member Franky's eBay store are excellent. I have one of the older version and it works very well and has several additional features - excellent value given all its features..I also have one ofthese from PortaPow. It is a full featured, high resolution meter and is excellent - it also costs alot more. PortaPow makes several inexpensive USB volt/amp only meters as well.

author: eas
author_rank: Frequent Contributor
timestamp: October 24, 2015, 03:23:14 am
content: I tried out ~5 different kinds, but never pulled the trigger on a YZX Studio meter. I'd say this one is probably the best I tried:http://www.ebay.com/itm/New-LCD-Dual-USB-Mini-Voltage-and-Current-Detector-USB-Charger-Tester-Meter-/131342420072Its reasonably accurate and easy to use and doesn't drop a lot of voltage. There is similar, earlier "white tail" USB meter. This one is better. The memory feature is easier to operate the display is larger and easier to read, the lead has reasonable guage conductors, and it has two output jacks, one of which has a USB negotiator chip to get the attached device drawing its max current, and the other passes through.

author: billfernandez
author_rank: Regular Contributor
timestamp: October 25, 2015, 03:40:33 am
content: I've bought 5 of these $40 Port-a-Pow units:http://www.amazon.com/PortaPow-Premium-Monitor-Multimeter-Ammeter/dp/B00LZ07BG0/ref=pd_sim_sbs_468_1?ie=UTF8&dpID=41JZ7oyd4TL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&refRID=02E0YS8KK5QS1SG3H315Here's my review on Amazon:KEY ADVANTAGESThe key advantages of this unit over the other, cheaper USB power meters are that:(1) it has it's own internal, rechargeable battery that lasts for many hours of use.(2) It measures HOW LONG (in hours, minutes and seconds) that current has been flowing through it. And it stops counting time if current flow is interrupted, then restarts the count if current flow resumes. This means that it reports the true amount of time that current was actually flowing through it.(3) It measures the total amount of POWER that has flowed through it, both in Watt hours and Amp hours. And it remembers this reading until you turn it off or the battery runs down; so you can let an experiment run and come back hours later to view the readings. And, like the time count, you can start and stop the current flow and it will start and stop measuring the power consumption, giving you a true measure of the total power that has flowed through the meter.(4) It is quite accurate.FURTHER COMMENTSI did a series of experiments with four of these meters to determine how well they met their specifications. I found that voltage and current measurements are typically within 0.1% of the true value (as measured by a high precision digital multimeter), which is an order of magnitude better than the 1% accuracy claimed by the manufacturer. I also found that the voltage burden with half an Amp flowing through them was only about 55mV.I did not measure battery life, but I have run overnight experiments with these units with no problems; and I think that in one of my experiments a unit ran for two days before the battery ran out. And remember that these can be recharged from any USB port that supplies power.The units have the look and feel of a home-brew device. Of the five I've bought, one came with a banana jack that internally had a loose locknut because the threads were poorly formed on the jack. I had to find a matching locknut, open the unit, unsolder the back of the jack, screw down the first locknut, then add a second one behind it, then re-solder the banana jack. Other than that they have all been fine.Although marketed for USB measurements, the specs say these meters will measure up to 50 Volts, up to 5 Amps, and up to 250 Watts; so they should be useful for lots of other projects. With this in mind the units come with digital multimeter style test leads and some general-purpose connectors so that you can use them for lots of general electronics projects.

author: HighVoltage
author_rank: Super Contributor
timestamp: October 25, 2015, 08:49:42 am
content: I got one of these:"Charger Doctor OLED Display USB Amper Volt Meter power Strom Spannung mess gerät"http://www.ebay.de/itm/181703964276And it works very well

author: crispy_tofu
author_rank: Super Contributor
timestamp: October 25, 2015, 10:15:34 am
content: Here's a comparison too:(some of them aren't in-line, though)

author: Ryano
author_rank: Regular Contributor
timestamp: October 25, 2015, 04:37:33 pm
content: Quote from: sleemanj on October 23, 2015, 11:14:08 pmUSB connectors shearing off the board. Nothing a little trace scrapping and superglue couldn't fix.

author: motocoder
author_rank: Unknown
timestamp: October 25, 2015, 05:19:22 pm
content: Also keep in mind that most of the YZXStudio units, including the USB 3.0 one shown a couple of posts above, are not available at the moment. There is some shortage of the OLEDs, so the only one available at the moment is the yellow LCD model.I own the YZXStudio LCD model, and I like it with two caveats: 1) My eyesight isn't what it used to be, and it's really hard to read the display on this thing without good lighting (it does have a backlight - doesn't help me much); 2) Because it does not have a cord, it may be upside down and unreadable. This is easily fixed with a USB extension cord.If the OLED units were available, I would get one of those from forum member Franky. Hopefully they'll be back in stock soon.

author: 5ky
author_rank: Regular Contributor
timestamp: October 25, 2015, 06:57:50 pm
content: Drok sent me this one to review and it was pretty legit. Nice OLED display and it'll record mAH or WH into one of ten memory slots, along with showing live voltage, current, and power. It's USB male A on one end and USB female A on the other end. The display can be turned 180 degress (digitally) if you're using it in a manner where the display is upside down. TGranted, they have a MUCH cheaper usb 2.0 version if you don't need high pass-through data speeds. The USB 2.0 version is only $14usb 3.0 oled:http://www.amazon.com/DROK-Multimeter-DC0-000-3-000A-3-700-13-00V-Capacitance/dp/B00XL2Y8L6/ref=sr_1_2?ie=UTF8&qid=1445799147&sr=8-2&keywords=drok+usb+3.0usb 2.0 oled:http://www.amazon.com/DROK-Multimeter-DC0-000-3-000A-3-700-13-00V-Capacitance/dp/B00XL2Y8L6/ref=sr_1_2?ie=UTF8&qid=1445799147&sr=8-2&keywords=drok+usb+3.0BTW, you can find those with other brand names on ebay for a couple dollars if you don't mind waiting on shipping from China. There are other brands out there but some of them don't show as much data on the screen at once time, and some of them don't have the ability to keep track of mAH or mWH. (not that doing the math manually would be hard, but it's nice that it'll do it for you and show it at all times)

author: Fraser
author_rank: Super Contributor
timestamp: October 25, 2015, 07:14:31 pm
content: I have a few of these devices and found the white tailed model referred to earlier in this thread to work fine. I see there is a new version 2 out now.The really cheap units in translucent blue did not seem to have a high enough sampling rate to cope with modern pulse charging systems so read almost no current draw when there was in fact plenty of current flowing.Fraser

author: djQUAN
author_rank: Frequent Contributor
timestamp: December 06, 2015, 03:31:36 am
content: I just got my Portapow USB power meter.I didn't turn it on, I took it apart. Then modified it slightly.more pics and details onmy blog/site.

author: Electro Fan
author_rank: Super Contributor
timestamp: December 06, 2015, 03:49:12 am
content: I have these - both do what they say they will do - the fascination wore off pretty quickly... YMMV depending on what you have in mind for them.http://www.amazon.com/gp/product/B00J3JSEG6?keywords=usb%20power%20meter&qid=1445639365&ref_=sr_1_1&sr=8-1http://www.amazon.com/PortaPow-Monitor-Version-Multimeter-Chargers/dp/B00NTU18KY/ref=sr_1_1?ie=UTF8&qid=1449373604&sr=8-1&keywords=usb+power+meter+portapow