[Don Tuite]

The internal battery's rated at 14.8 V. The AC adapter's rated at 19. What are the implications for using an external battery?

Obviously, an automobile with the engine running delivers a voltage in the specified range, with the usual transient caveats.

Any opinions on how long, absent a boost switching regulator in the line, would a mini 9 would stay up while attached to a car battery?

(I'm assumng this can be extrapolated from other platforms.)

Don

[PM5K]

I don't understand the question at all...

[acabtp]

Your laptop is not like a car where the battery is charged directly off of alternator/charger voltage. If you want to replace the power adapter, you'll need one that does right around 19v at at least the current provided by the stock charger, not something between the battery and charger voltages.

[UnaClocker]

In my experience with Dells in the past, they've just about always used a 19v power supply, and they really don't like running off, say, 16v that a Thinkpad power supply puts out.. So they're definitely not going to want to run off the 13.8-14.5v that the car puts out. It's easier for the electronics to step the voltage DOWN than up.. Hence the 19v power supply with a 14.5v battery, when the computer is running off 5v and below.
I don't know if the plug on this laptop is the same as older Dell laptops, but if it is, any of the readily available Dell car adapters on Ebay will work fine.. I had an Inspiron 1200 that took a plug alot like this one, not totally sure it's the same though. And it put out 19v, and more than enough available amperage. I don't have it anymore though. Loaded OS X onto that Laptop and made a mint on Craigslist..