OK, here's the update on the 2 TomTom chargers.
Charger A
Manufacturer: AK Technology (see label)
TomTom part # 4A00.182
Does not work with Kindle 2: symptoms are (1) fails to charge (2) leaves "lightning" symbol on battery after charge lead removed (3) Kindle becomes unresponsive ie keys have to be pressed for some time before anything happens.
Resistance across data pins (D+/green D-/white): infinite (ie they are not connected)
Picture below:
Charger B
Manufacturer: Phihong
TomTom part # 4A00.181
Works fine with Kindle 2 (ie just like the Amazon charger)
Resistance across data pins (D+/green D-/white): about 5.7Kohms
Picture below:
I may be wrong, but I suspected that charger B works with the Kindle because of the resistance across the data pins. It would be interesting if people could check this on other chargers. However, the Amazon charger itself has a
much lower resistance between the data pins - I measured 1.2 ohms (not Kohms) - which is close to having the 2 data pins actually shorted.