Laptop batteries only last a limited time and often go dead long before you want to replace your laptop. The problem is, replacement laptop batteries can cost over a third of the price of a new laptop. The simple and cheap way around the problem is to make your own external laptop battery pack that connects straight into the power socket of your laptop. Use LiPo batteries to make a laptop battery. They are rechargeable, lightweight, durable and produce 3.7 volts per cell. Wire five LiPo batteries in a series and you have a battery pack to power your laptop.
Check the bottom of your laptop to see what voltage it requires. It's clearly labelled. Most laptops need 19 volts: some operate on slightly less.
Get five LiPo batteries, if your laptop operates on 19 volts. If it operates on less, simply divide the input voltage of your laptop by 3.7 and round the answer down to the nearest whole number. For example, if it operates on 14.9 volts then the answer is 4.02, so round it down to four and that's the number of batteries you need.
Lay the five batteries flat on a suitable surface with the positive terminals facing the same way. Rotate two batteries 180 degrees -- so at one end you have three positive and two negative terminals, and at the other end, two positive and three negative terminals.
Label the batteries 1 through 5. Wrap electrical insulating tape around the batteries to form a neat battery pack.
Cut six strips of wire using a small knife. AWG gauge 16 or similar works fine. Cut two strips so they can reach between your laptop and your battery pack comfortably. The other four need to be short since they only attach to the battery terminals.
Remove ¼-inch of plastic from the end of each strip of wire to expose the inner copper metal wire. Use wire strippers or a small knife. Label one long piece of wire "+" and the other "-." These will attach to your laptop power jack.
Use a strip of electrical insulating tape to attach the long "+" wire to the positive terminal of battery 1, and then attach the second long "-" wire to the negative terminal of battery 5 using the same method.
Attach a short wire strip to the negative terminal of battery 1, and the opposite end to the positive terminal of battery 2. Attach a short strip of wire from the negative terminal of battery 2 to the positive terminal of battery 3. Continue using short strips of wire to attach to the negative and positive battery terminals in numerical sequence, until the final end of the last strip of short wire is attached to the positive terminal of battery 5.
Wrap the complete battery pack in electrical insulating tape. Make sure you cover the terminals, but make certain the two long, labelled strip of wire protrude from the battery pack.
Unscrew the cover from your power jack. It needs to be the same size as the power input socket. They're widely available from electrical stores. If you're not sure, take you laptop to the store so you can compare input and output sockets. Slide the cover over the two labelled wires.
Turn on your soldering iron and let it get hot. Place the wire labelled "+" on the positive terminal of the jack. Touch the wire and terminal with your soldering iron and solder. Let the solder melt and coat the terminal and wire. Remove the soldering iron and solder, and allow to cool completely. Repeat the process by attaching the "-" wire to the negative power jack terminal. Let the jack cool and turn off your soldering iron.
Slide the cover down the wires and screw onto the power jack. Insert the jack into your laptop power socket and turn your laptop on.