How to charge Dell laptop from 12V cigarette socket

[kje]

I wanna charge a Dell Latitude E6500 laptop from the cigarette socket (12V), and have now tried two Vanson laptop adapters (SDR-100W and SDR-120W). Both deliver a weak beeping and does not charge the laptop battery.

According to the regular power adapter the Laptop need 19.5V and 4.62A. On the laptop battery it says 19.5V and 3.5A minimum and 4.62A max.

Vanson SDR-100W http://www.ebay.com/itm/Vanson-Auto-Power-Adaptor-100W-with-adaptors-for-laptops-phones-mp3-players-/220998067364?pt=Laptop_Adapters_Chargers&hash=item337482e4a4 delivers 4.5A at 18/19/20V (you can switch between 18,19 and 20V). The plug fits into the power socket on the laptop and have "positive tip polarity."


Vanson SDR-120W http://www.clasohlson.com/no/Batteri...0W/Pr381383000 delivers up to 6A and can switch between 18,19 and 20V.

I bougth both the Vansons on a local shop here in Norway called Claes Ohlson.

Why do none of these charge my laptop battery?

[heathyoung]

Easy - the Dell laptop chargers have a 3 pin IC that identifies itself to the laptop as a genuine charger.

You to find one that is Dell compatible, they did make one for use on planes + cars (Dell).

[dnmun]

if you have the dell laptop adapter, you can get a 12V DC-120V AC inverter and run the dell adapter from that. i knew someone who used that to keep a lot of things charged while in his car.

[kje]

Easy - the Dell laptop chargers have a 3 pin IC that identifies itself to the laptop as a genuine charger.

You to find one that is Dell compatible, they did make one for use on planes + cars (Dell).

I think mine has just two... plus and minus. This is my usual wall adapter:

I have another wall adapter; Vanson SMP-120W like this:
,
and that works with the same connection into the laptop as I tried with the SDR-100W and SDR-120W.

So why won`t the SDR-100W or SDR-120W charge the laptop? Is it because of wrong power spesifications? Or is it the plug?