Measuring Current Through USB Port or Connection

Mountain DonMountain Don Solar Expert Posts: 494 ✭✭✭
Not directly related to Solar Power, but this could be of interest to folks....


If you have ever wondered just what the voltage at a USB port is, or just how many amps, or fractions thereof, are passing through, this little device is a handy tool.

Product Name: Xtar VI01 USB Current/voltage detector

Review of product:

Detector only @ Amazon

Detector and single cell charger (Li-ion)

Detector and single cell charger, plus one 18650 Li-ion cell
Northern NM, 624 watts PV, The Kid CC, GC-2 batteries @ 24 VDC, Outback VFX3524M

Comments

  • PNjunctionPNjunction Solar Expert Posts: 762 ✭✭✭
    That is actually VERY useful to solar! Well, for small camping style panels that is. Anker / Goal Zero, that kind of stuff.

    It helps make sure the camper actually aims the panel for best affect, and shows how hanging a panel off their backpack is a total marketing joke!

    It can also help identify bad cabling between a panel and a battery pack (the typical li-ion cellphone external packs), where it either doesn't charge, or the cabling is wired in a way that the device just falls back to a very low input. Ie, with proper cabling, one might be able to get 2A from the panel, but with funky cabling, the most that will pass might be the old usb standard of 500ma - limited by the cable, not the panel.

    Quite useful actually for those that deal with small camping solar panels with 5v usb outputs.
  • dropkickdropkick Registered Users Posts: 23
    USB meters are quite fun! I have one similar to above (USB drive sized) and also one of these:

    www.amazon.com/PortaPow-Premium-Monitor-Multimeter-Ammeter/dp/B00LZ07BG0

    which serves as a quick multimeter and can be wired in via those green terminals so you dont have to hold probes on things while u turn solar panels. haha All good for calling BS on alleged "high speed" usb chargers and other marketing nonsense.
    6 250W Renogy panels / Morningstar TriStar MPPT 60 charge controller / 8 Costco CG-2 batteries @ 24V / Samlex PST-1000-24 inverter / Samlex SDC-23 24/12V converter and BG-60 LVD / Midnite Solar boxes, breakers, etc.
  • AlexAlex Registered Users Posts: 12
    Nice, I'm gonna try that on my next outdoor trip!
  • PNjunctionPNjunction Solar Expert Posts: 762 ✭✭✭
    Actually the old 500ma usb standard has been surpassed for many years now. My own Anker panel / Anker battery setup easily surpasses that to about 2A under good sun, as verified by one of the inline volt/ammeter dongles.

    The problem is that not all usb cables are wired the same, and there is some cross-wiring / paralelling going on either inside the cable housing or the device case. If that cable does not meet the manufacturer's spec, sometimes they try to be kind by just falling back to the old 500ma usb standard, even if the charger is capable of much more.

    In the old days, that meant I had to hack together specially wired "charge only" cables to get the higher output. What I like about Anker is that their "smart iq" usb port makes a very good attempt at doing the logic connections to get that higher charge current with a strange cable. For the most part it works, but some combinations can still be troublesome. Still, it beats me having to cut usb cables apart and rewire them.

    So yes, there ARE high speed usb chargers - as long as the cable isn't weird, or the device itself is doing it's own current limiting, you can get a pretty fast charge from a 2.1a port.

  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    The really high power options (>5V, >2.1A) pretty much require an actual digital data dialog between the USB port and the device being charged.
    That is probably part of what the inline gadget fakes out.
    The older/current now USB 2.x standard is definitely limited to 5V to avoid damaging equipment on the other end.
    SMA SB 3000, old BP panels.
  • JoshKJoshK Solar Expert Posts: 232 ✭✭
    I cann't imagine needing this more than once, so here's a cheaper solution... You can just take a spare USB extension cable and peel back the coating like it's a banana. Then hook your multi-meter up like you normally would. Power is red, ground is black.
  • BB.BB. Super Moderators, Administrators Posts: 29,489 admin
    I bought a couple USB current/voltage meters. Found bad USB cables and a power brick.

    Really difficult to debug charging problems otherwise (USB devices have very poor error messages, if any).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PNjunctionPNjunction Solar Expert Posts: 762 ✭✭✭
    JoshK wrote: »
    I cann't imagine needing this more than once, so here's a cheaper solution... You can just take a spare USB extension cable and peel back the coating like it's a banana. Then hook your multi-meter up like you normally would. Power is red, ground is black.

    For freaks like me that might carry a cute tiny import version of a palm-sized Fluke 106, that works too, and is how I used to do it. I got a lot of squirrel-cred that way. :)

    Lose that cable in the woods, and the Anker smart-iq port with any other cable you find laying around might be a more practical solution for those of us that don't take multimeters camping. Or just forget all this and take a big pre-charged 15000mah Anker with you.

    The inline usb dongle meters have saved me a lot of frustration too with funky cabling, bad supplies - especially those that overheat, but initially meet spec.
  • dropkickdropkick Registered Users Posts: 23
    Anker stuff works! I have several of their 12V input 5-port USB chargers (IQ) on my small backup batteries and in the trailer which work everytime at full device power. And their batteries are good too.

    Re: cables. With meters like above, I've verified and purged all crappy USB cables that block proper charging. Or moved them to data-only use. Yup, sometimes the manufacturer's ones included with the device are junk too.
    6 250W Renogy panels / Morningstar TriStar MPPT 60 charge controller / 8 Costco CG-2 batteries @ 24V / Samlex PST-1000-24 inverter / Samlex SDC-23 24/12V converter and BG-60 LVD / Midnite Solar boxes, breakers, etc.
  • BB.BB. Super Moderators, Administrators Posts: 29,489 admin
    I like the Anker stuff too. The only USB charger that I will buy (at the moment). But they do on occasion put out a bad product. And they also have an 18 month guarantee (I returned one of their 5 port chargers, I think they had a design problem where it slowly cooked a component--Very quick and easy exchange via email / mail).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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