My solution to the laptop battery problem:

I have a portable jump starter (a portable battery pack that has a cig. lighter outlet on it as well as jumper cables attached to the side).

I just make sure that is charged up, run my inverter off of it (instead of the car's cig. lighter), and plug my computer in. I've logged for 1.5 hours at a time without stopping, and that battery pack was JUST starting to get low. My laptop never even went to its own battery.

They aren't cheap (~$80), but I really like having it 'cuz it really does jump start cars well (granted I've only used it once for that purpose - the rest of the time it powers my laptop ).

 

Good idea. I have a portable battery charger and never thought of powering the inverter from it.

 

I always Highly advise AGAINST using the cig lighter
1)...cig lighter wiers are too small....
A).... it shares a fuse with the OBD2 Port....and a bunch of other stuff as well

My laptop is such a power house(I bought it to be a desktop replacement) that it pops the fuse for the cig lighter... I run a separate wire over to the fuse panel on the drivers side dor side of the dash.... and use the bolt that holds down the passenger seat as a chassis ground....I make sure I use one of teh extra plug in spots in the panel...and make sure its tied to a 25 amp fuse(dont use the blank thats tied to the 10 amp guage cluster fuse..LOL)

The Problem is that cig lighter has such puny gauge waires that it cant properly hold current(its the whole ohms law and resistance of wire/size/length). with the small wires it creates a lot of heat... the fuses arent really based on amperage....they will pop from the heat caused by amperage(hencforth the guage and type of material inside directly reflects fast or slow blow fuse)..or they will pop from heat if there is enough heat for a long enough time...
In my case the inverter was only drawing about 2.8 amps through proper gauge wires(measured with an amp meter)... but through the cig lighter wires it popping the fuse from the amount of heat it created..
at one point I unpluged the cig lighter adapter and accidentally touched the end of it with my finger and it burned me so bad that a blister the size of a dime poped up within seconds...and the part that touched me was just the little center tip.

I also used to have problems with it getting enough juice at idle..the inverter would beep at me telling me that It was starving for power...

now with the new 10 gauge wire run I can sit with the car off and still get plenty of juice when the battery has a good fresh charge on it(freshly stopped...not sitting overnight)and I never have power problems at idle

 

kbracing96 suggested to use the cig liter outlet on his self contained battery charger (a 12 volt battery power source) external and completely disconnected from the 12 volt electrical system of the car.