Hi. I have a Motorola V3xx Razr phone. It has a USB Mini-B jack for charging.

http://en.wikipedia.org/wiki/Mini-US...cro_connectors

I tried charging it with a BlackBerry wall wart. I can't make out the
model number of the wall wart due to the small size of the type. I can
come up with that later. When I plugged the BlackBerry wall wart into
the phone, the phone came on, but the battery did not charge.

I tried another wall wart. It's a Verizon wireless model PW-1BGT
charger, which can source 800 mA at 5.0 V. When I plugged it into the
phone, the phone's "charging battery" screen lit up. It did charge the
phone's battery pack. When I disconnected it, the phone turned itself
off.

The pinout chart at Wikipedia makes me think that there is difference in
the way pin 4 is wired, rather than an inability of the BlackBerry
charger to source sufficient current.

http://en.wikipedia.org/wiki/Mini-USB#Pinouts

Am I right?

Perhaps, but my guess is that the problem is elsewhere.

Read down a bit further to the "Charging ports and accessory charging
adapters" section.

My guess is that the Razr phone has a different method/protocol to
determine the amount of charging current available from the "upstream"
device than the BlackBerry wall wart. As a result, the Razr isn't
able to identify the wart as a source that can supply the amount of
current that the Razr's charging circuitry requires.

A USB-connected device is supposed to behave as a "low power" device
(drawing no more than one 100 mA unit load) unless/until it
successfully negotiates with the upstream device and is granted
permission to draw more power, or unless it successfully identifies
the upstream device as a dumb "dedicated charger". My guess is that
neither of these things happens when you connect to the BlackBerry
wart, and so the Razr is "playing by the rules" and is drawing only
the minimum amount of power.