The problems caused by failures of the DELL battery charging system in DELL laptops is lingering on for many years already. Little public information is available about the root cause why so many DELL Laptop AC adapters cause the infamous "AC adapter not recognized" message. And specially not from DELL who introduced the battery charging system in their laptops. Now, it seems that DELL has indirectly released public information through a patent intended to improve the DELL laptop battery charging system.
DELL comes forward with a "Patent Application Publication" in April 20, 2006 known as:
Patent US 2006/0085658 Apr, 20 2006: PSID and remote ON/OFF functions combined.
The information can be found at http://www.patentstorm.us or by clicking on the link above The interesting section is found at page 7 of the PDF (registration required), identified by , or in directly accessible website text by click the links below.
The interesting sentence, among others;
"..by the presence of higher-than-rated voltages on the data channel..".
(click to read)
"...accidental coupling between an outer pin carrying higher-than-rated voltage and the center pin..."
(click to read)
This seems to indicate DELL is aware such case can happen and seemingly the battery charging design is not robust enough to anticipate such occurrences. Hence the improvement attempt described in patent number US 2006/0085658 dated Apr, 20 2006 ??
The data channel (PSID) is connected to the poor MAXIM DS2501 chip, the memory component which died in so many cases. The chip tells the DELL laptop the AC adapter type. When the AC adapter type is unknown, battery charging is shut down.
The MAXIM DS2501 is found in DELL AC Power adapters supplied with the DELL Latitude D610 laptop.
PSID = Power Supply Identifier (The data channel connected to the center pin of the charger lead)
IHS = Information Handling System (Laptop, PDA etc)