Power supply for laptop

[reddoss]

I am starting to get into autoguiding and have an Opticstar PL-130M guide camera which is USB powered and connected to my HP pavilion laptop which runs the PHD software. I guess the battery time of the HP while running the camera lasts just over an hour. I am thinking of getting another 12 V 17 amp hour car starting battery and a 12 V laptop adaptor from Maplins. As the mains power supply for the HP delivers 18 V, I am just wondering if the set up I am considering would be OK for getting a longer period of time out of the Lap top for autoguiding? Does any one else do this?

PS I have no option of using a mains supply as I live in the centre of Cardiff and have to set up in the sticks.

[Photosbykev]

I use this one to power my toshiba i7 laptop 120W Laptop Car Adaptor : InCar Power Adaptors : Maplin.

Be aware if you try to extend the lead on the cigarette plug side you will need to use heavy guage cable to avoid excessive volts drop on the input to the adaptor.

[Bizibilder]

You would be better off getting a "leisure battery" - these are designed for slow drain over time - a car starter battery is not. Amazon and Ebay both show suitable adaptors for laptops. Note to save confusion: a "12v" battery is 13.8v when fully charged!

[reddoss]

Thanks for the advice guys!

[antimorris]

I got just a simple Belkin laptop charger (I will look for the link and edit it in if I find it - its been a while) from Amazon that I plug into a spare port on my Celestron portable power supply. It has worked great for my trips out into the sticks!