This is caused by Dell trying to stop people from using third party chargers. If the charger found not working properly, the problem lies not in the laptop nor the power brick itself, but the cord that runs from the charger to the laptop, due to the infamous "exploding battery" incidents companies started to use a 3-wire conductor, Ground, V+ and a data signal, this last one tells the laptop the electrical specs of the charger and if its a OEM one, if it is it charges, if not it disables charging the battery. so the problem is that the manufacturers makes this data signal cable hair thin and it usually breaks after some time, so the laptop doesn't get the charger info and disables the charging circuits,,,, but the charger itself is good. To solve the problem what i do is to open the charger (it is glued hard, and have to literally break it apart), and replace the cable with a thicker 3 or 4 wire one or cut the damaged length of wire if break found near one end, but you also have to adapt the plug from the original cable. 3rd party charger usually only have the ground and V+ conductors and no data signal one so the laptop will never charge.
DELL AC power adapter used for my DELL Latitude D610 has an Identification wire, which is the tiny center pin in the power plug. Trying to figure it's function from the outside proves to be futile. When detached from the laptop it carries no signal, voltage, capacity or resistance. It seems like a dead wire leading no where. So it's time to figure out where this AC Adapter Identification wire is going. After cracking the case of the DELL AC power adapter, brings about a mystery electronic component. It's a transistor shaped component with 3 pins. The middle pin is connected to the AC Adapter Identification wire, the other pin to V- of the power plug. The 3rd wire is not connected.
DALLAS 2501 component - connected to the 3rd wire in the AC power adapter cord
The casing of the transistor shaped mystery component has markings; "DALLAS - 2501 - 0613D2 - +571AA". Not the typical markings on a transistor. Weird!!
Pretty strange for a transistor, where all 3 pins are usually all connected.
MAXIM component, the transistor shaped device is a UniqueWare™ Add-Only Memory, known under type DS2501, DS2502, DS2505 or DS2506. The difference is the size of the memory. The DS2501 seems to be 512 byte memory. The memory is accessed using a 1 wire communication protocol known as "1-wire".
At least there is DALLAS as the manufacturer ID. This is synonym for MAXIM semiconductor.
I was able to identify the power adapter I.D. circuit in the dead power adapter. In my case it was three components on a 3/8" x 5/8" 'perf' board. (one 330 Ohm resistor, one diode looking device across the single line memory I/O port (probably surge suppression) and the single line memory device in a plastic transistor case, with only two wires connected to anything. I removed that circuit assembly from the dead adapter, and moved it from between the third wire and the minus power supply reference in the old adapter to the place in the d.c. cable where I spliced 2 wire cable into the 3-wire plug-tail from the old Dell cable, (on the adapter side of the ferrite RFI suppressor).
Without this adapter I.D. circuit, the two-wire adapter would power and run the laptop fine, but the error message indicated there was trouble with the adapter. After the I.D. circuit was added to the cable, the error message concerning the power adapter cleared and the battery charges.
So the DS2501 in the DELL AC Power Adapter contains the identification info of the power adapter. The DELL laptop reads the identification info during startup of when it's connected while started. Power for the memory device comes from the laptop which is the same AC Adapter Identification wire, indicated as a "parasite power circuit".
A new DS2501 can be soldered and programmed, with a "1-wire" programming kit and a PC with an ole RS232 jack. This is described in the Dallas Semiconductor application note 177. For electronics enthusiasts that's just a bit of fun with a soldering iron and a few low cost components.
When the programming kit is ready, next is to read the identification data from a working DELL AC Power adapter and clone it into a new DS2501 chip, already soldered into the DELL AC Power adapter.