How to Make an External Laptop Battery

Written by stephen benham
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How to Make an External Laptop Battery
Make your own external laptop battery to power your laptop. (www laptop image by Photoeyes from

Make an external laptop battery using lithium polymer (LiPo) batteries wired in series. Wiring in series combines the output from each battery while maintaining endurance. LiPo batteries are high capacity, durable and light and are the battery of choice for remote control enthusiasts. The output from a LiPo battery is 3.7 volts when fully charged. Making an external laptop battery, wired in series, is easily done and requires few tools and equipment.

Skill level:

Things you need

  • LiPo batteries
  • Electrical insulating tape
  • Wire (AWG 16)
  • Knife
  • Wire strippers

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  1. 1

    Check the base of your laptop to find out its operating voltage. The voltage is clearly labelled. Laptops generally require 19 volts, although it does vary.

  2. 2

    Divide the laptop input voltage by 3.7 and round down the result. For example, if your laptop operates on 19 volts, the answer is 5.13, so round it down to 5, meaning your need five batteries.

  3. 3

    Place your batteries flat on a suitable surface with the positive and negative terminals alternating. If you're using four batteries to make your laptop battery you have two positive and two negative terminals at each end.

  4. 4

    Label each battery numerically. Using four batteries, label them 1 through 4. Wrap electrical insulating tape around the batteries to form a tight battery pack.

  5. 5

    Use a knife to cut strips of AWG 16 wire. Cut two strips long enough to reach from your battery to your laptop. The other strips can be short, as they connect between the battery terminals. The number of strips you need depends on the number of batteries, but the simple rule is you need to cut one strip fewer than the number of batteries. If you are using four batteries, you need three short strips.

  6. 6

    Strip ¼ inch of plastic from the end of each strip of wire using wire strippers, so you have ¼ inch of metal wire exposed. Label one of the long wire strips "+" and the other "-." Attach the wire strip labelled "+" to the positive terminal of Battery 1 and the other to the negative terminal of the last numbered battery. Attach the wires to the terminals using a short piece to electrical insulating tape.

  7. 7

    Attach a short strip of wire to the negative terminal of Battery 1 and attach the opposite end to the positive terminal of the battery. Continue repeating the process of attaching wire to the negative and then positive terminals until you reach the positive terminal on the last battery.

  8. 8

    Wrap electrical insulating tape around the entire battery pack ensuring you cover all the battery terminals. The pack should look neat and tight with only the two labelled long wires protruding.

Tips and warnings

  • Connect the external battery to your laptop by wiring a power jack. They can be purchased in most electrical stores. Attach the positive and negative wires from your laptop to the positive and negative terminals on the power jack. Get one with screw connectors so you don't have to use a soldering iron and solder.
  • Laptops consume electricity quickly. To increase capacity but maintain voltage, build two packs wired in series then connect the two packs in parallel: this will double your capacity. Simply attach the positive wire from one pack to the positive wire of the other pack. Repeat for the two negative wires. The wires then feed to your laptop in parallel.
  • The voltage output of your battery must never exceed the input voltage for your laptop. You will seriously damage it.
  • When the batteries need charging, ensure your charger matches the voltage requirements of your LiPo battery pack.
  • Never connect two different types of battery, such as LiPo and NiCad.

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