Fast charge affected by cable length?

[netnerdvana]

Battery fast charge seems to be affected by the USB cable length. See attached screen shot from Battery Monitor Widget Pro.

Plugged in the Nexus 7 when it was down at 40% (first vertical bar) using the shorty 3' cable that came with the tablet and a 6' USB extension cable (high speed USB 2.0 Cable by MediaBridge). The outer insulation is fairly thick 3/16". Not sure about the inner wire gauge.

I let it charge for almost an hour and it got up to 58% (just before the second vertical bar) and BMWP reported about a 800mA charge during that time. Then I took off the extension cable at had it just plugged into the same nexus 7 charger with only the stock short cable. I let it charge up all the way.

The charge appears to go much faster like around 1300mA. Also the % available curve steepens until the battery goes into absorb phase at around 90%.

Any suggestions? Are USB3.0 extension cables spec'd to have bigger wire? Do they prevent this effect on Nexus7 fast charge?

 

[stridermt2k]

A very thin gauge wire will have a higher resistance over longer distances, and USB cables can have pretty thin wires inside despite how thick the outside is.

Some companies make their cables with very thick insulation on the outside knowing that some people equate that with quality in a cable.

My bet is one of cable quality. A higher quality cable will use thicker wires which will reduce the amount of drop over the distance you are trying to cover.