I was going to ask about your battery life but I did not.
Battery packs can get expensive, Never buy a used one. They are sold used for a reason.
Normally you can get a much better computer for about half of what that one cost you.
You may want to check out Fry Electronics for a nice computer at a good price.
Http://www.Frys.com
if you are not a Costco member, Frys may beat their price anyway.
Bob, Owns Costco and I own Frys.
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April Fool...