My new Clip has yet to arrive from Amazon, but I would like to get some additional information about using external chargers, including AC, car, and even the battery-powered “Minty” charger.
In going over other posts on this subject, I see that some chargers seem to work, and others don’t. I wonder if this is because of the new (March, 2007) USB spec for “dedicated chargers” as described here:
Basically it says that dedicated (i.e. - dumb) chargers should identify themselves as such by having the two Data pins shorted together. Data+ and Data- are the two middle pins in a standard type-A four-pin USB socket. That lets the charging device know that it need not try to communicate or negotiate with the “host”, but can just start drawing current and charging.
Since there was no standard before that time, older chargers could have their Data pins left in any of a number of states - pulled up to +5VDC, or pulled down to ground, or one of each, in any case through a wide variety of resistors, or even completely unconnected to anything. It occurred to me that since the Clip is a new device, if it in fact does follow the new spec and if the charger is of an older design and does not have shorted Data pins, and if the Clip also cannot negotiate a real USB connection, then it may just refuse to charge even though there’s plenty of current available.
If there’s a SanDisk person here who might check with the pocket-protector guys about this, I would very much like to know:
1. Does the Clip care what the state of the Data pins is on a dedicated dumb charger?
2. If it cares, what Data pin states will work? Specifically, will it work if they are shorted? Any others?
3. When the battery is almost fully discharged, how much current should the Clip draw from a dedicated charger if it is actually charging at it’s maximum charging current.
I’m going to build an AC charger and a Minty charger mostly from parts in my junque box, so it would really be helpful to understand all of this. But I also thought that others might like to know about this Data pin thing in case it turns out to be relevant.