Micro usb male to female 1 to 2 Splitter Phone sync data charge Cord Y Splitter (WHL #23)

Uuuh, I’m lazy today. Let’s review an USB cable :mrgreen:

Well, it’s not one of your standard A to B cables. It’s a splitter extension cable for Micro USB, basically violating all USB specs :cool: . I bought it as I’ve been using two phones in parallel for quite a while now – I can’t let go of my N900 with the nice QWERTZ hardware keyboard and full system access, but I’m also running a Galaxy S5 for all that modern Android rubbish (including BLE support for my GoFar). So this cable acts as a Y splitter from Micro USB (female) to two Micro USB males, effectively saving me the standby power (and socket space) of one charger. It’s also providing data lines for one device (the one on the longer cable), but I honestly didn’t try until now. The cable was 0.81€ in late December 2016 at AliExpress.

Total length is a tad more than 30cm, while the shorter end is around 19cm (more than advertised). I’ve been using the thing for around 1.5 months…until the shorter one broke. Well, the USB of my Nokia does sometimes have contact problems, but the Samsung has problems charging as well, so I just had a go with my multimeter. As Micro USB is a bit fiddly, I remembered I had some OTG adapter gift in one of my many padded envelopes from CHAINA (25 cents otherwise)…and it’s really neat for measuring such things:

Soldering all pins of a SMD female connector together makes measurements of the power lines a round trip. While my measurement leads usually have stable 0.13 to 0.15Ω resistance when using the (once again!) great Half Ohm adapter, measuring the short with this contraption gives me 0.2 to 0.3Ω total resistance. Let’s set that on 1/4Ω as baseline for the following measurements, which includes all contact resistance, lead resistance, thermal effects and what have you not.

Measuring the longer cable clocks in at 0.38 to 0.44Ω, which, well, is better than I expected. Considering the offset, that’s only 0.13 to 0.19Ω (without load!), round that up to 0.2Ω. This isn’t too bad for 2x30cm of China wiring and two more contacts. Remember the fancy 4mm Hirschmann banana connectors? They have 3mΩ guaranteed contact resistance for the plugs and another 5mΩ for the jacks, and that’s a huge 4mm barrel (200mm²!) made from even more fancy beryllium copper compounds specifically designed for good contact performance. Here’s two piss-end China “gold” contacts covering 0.40 x 1.35 mm² = 0.54mm² of contact area…

The other one?

Well, 200MΩ. A tad different from the previous 200mΩ, but that’ll do. Yes, it goes down to some similar value when wiggling it around, but that’s clearly broken. Meh.

Would I buy it again? Not so sure. While it is actually very handy in slowly charging two mobile phones with one charger, it’s not ideal. Not so much because of the premature failure after 1.5 months (someone at the Wan Hung Lo factory did a lot of research to make that happen so late after purchase!), but the cable length isn’t ideal and also the female connector is a bit loose and tends to disconnect easily. Let me show you why the length isn’t ideal:

And that’s which a pretty small phone on the shorter end, the N900 is only 3.5″ in screen size or 111×60 mm² in absolute size. The S5 in comparison is 5.1″ / 142×73 mm² – that’s three more centimeters in length, and the S5 isn’t even a screen size monster compared to today’s phones. So having a wider spread would be great, as phones would not clash into each other and leave marks. Sure, bending one cable around to spread them onto opposite sites is an option, but that leads us back to the problem of planned obsolescence and AWG…28? wiring (60cm of AWG 28 copper is ~0.13Ω)..

So I have this type of cable on my watch list, but I won’t buy the exact model again. However, I will try a repair with the male Micro USB solder adapter that I just ordered…we’ll see where the cables have snapped and if the adapter is stable. I guess that’ll make a mini-project as well (yeah, I’m lazy, told you so!).


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