Originally Posted by EarlyMon
The following won't help, but may be useful information in the future.
All charging is DC, not AC. High speed charging mode is often called AC charging because it's achieved when the data lines are shorted, as happens with a proper AC charger. That's done, as you've noted, by providing current above 500 mA.
I use the original HTC cable and a 6-footer from monoprice and note no noticeable difference in charging time. Resistance can be higher on the longer cable, but ought not be enough to have a material effect. A better cable will use a larger gauge (smaller number) cable.
PS - my MHL adapter with an HTC charger is enough to just barely maintain charge on an Evo 3D, usually it just slows the loss. Same hardware with with an Evo 4G LTE, running the same services, will charge the phone.
I doubt that HTC went backwards on the MHL chip from the LTEvo to the One. As you note, some software is poorly written.
I hope it's just a software thing. I wonder if people have tvs that does not put out enough power via MHL to the phone. If that's the case, I would suppose an update could resolve the problem on a tv.
This stuff really racks my brain because I couldn't resolve the lack of adequate power problem. Oh well. Thanks everyone for inputs.
So I charged my 3D up to 100%. The MHL converter has held the battery at 100% through two HBO episodes of the Sopranos. I'm seeing your results now EarlyMon. I'm thinking the same thing should work for the One.