Introduction: LiPo/LIon Batteries From Laptop Cells

Many people want to get into the hobby of flying RC planes or driving RC cars, but they are unable to do so because of the price of LiPo or LIon batteries. On the other hand, millions of laptop batteries get thrown out every year because one of their cells fail or the owners get rid of the laptop. The cool thing is, old laptop batteries can easily be turned in to fully functional batteries to be used for RC applications with very little time and effort. They will also be able to be balance charged thereby prolonging their lifespan. In this instructable I will go through the process of recycling and building an RC grade battery from old laptop cells. The video below will compliment this instructable by giving a visual demonstration of what this instructable shows. Lets get started.

Step 1: Finding the Laptop Batteries

To find the needed laptop batteries for this project, you can look almost anywhere. Ask around for broken laptops or go dumpster diving to find them. I got the laptop battery that I used in this instructable from a laptop in which the motherboard toasted. Since the actual laptop was not in use anymore, I extracted the battery.

Step 2: Extracting the Cells

To extract the laptop cells, You need to use a screwdriver to pry open the battery at its seams. Laptop batteries are glued shut, not screwed, so it makes it a little bit more difficult. After the battery is opened, cut the connections and wires in between the cells to free all the individual cells. After these are free, we can start building the RC battery.

Step 3: Materials:

For this project, you will need;

  • 3, 3.7 volt lipo or lion cells.
  • Heavy gauge wire
  • Connector opposite of the connector in the RC plane you are building.(I got mine on Amazon for 3 dollars)
  • Balance charger connector(I found a matching one in an old VCR)
  • Solder
  • Electrical tape

Step 4: Tinning the Batteries and the Wires

To start building the battery, tin all of the wires and the positive and negative poles of the batteries with a soldering iron. To tin, hold the iron to the surface you want to tin for 5 seconds, then touch the solder to the surface, not the tip of the iron.

Step 5: Taping the Batteries Together

Before soldering any wires together, first tape all the batteries In a triangular shape. Make sure two of the batteries are facing the same direction and 1 battery is facing the opposite direction. This makes it easier to connect the batteries in series. Then, wrap the batteries in electrical tape.

Step 6: Connecting Batteries in Series

To connect the batteries in series, solder the positive and negative poles of the batteries together with small lengths of wires. Make sure to leave one positive and one negative pole open to connect to the battery connector.

Step 7: Soldering the Battery Connector

To solder the battery connector on, attach a length of wire to male type battery connector that matches the connector of the RC vehicle that you are building. Then, solder the wire lengths to the remaining negative and positive poles on the battery pack. Remember the polarity.

Step 8: Adding the Balance Connector

To solder on the balance connector, solder the 4 connector wires to each point on the battery according to the the schematic above. Make sure the balance charger connector has enough slack.

Step 9: Covering the Battery Pack

The final step in this project is to cover the battery with electrical tape to cover the electrical contacts, secure the wires, and to make it look aesthetically appealing. To do this, take electrical tape, and wrap the whole battery. Make sure to cover the front and back contacts with electrical tape. Also, make sure to secure the wires. After this, the battery pack should be done.

Step 10: Charging and Testing

After the battery is done, plug it into a balance charger and set it to the type of battery that was used to make the battery pack, if you do not have a balance charger for the type of batteries used, remember; a lipo charger should work with a lion pack because the same charging procedure is used. Always make sure that the cell voltages of the batteries used in the pack have the same or a higher voltage than the balance charger can provide. This prevents the pack from exploding. To test these batteries, connect them to the RC vehicle they will be used in and have fun! I used these batteries in my home made RC plane. Thanks for reading and good luck! The video below shows a test of the plane with the battery, It crashes because of design flaws, not the battery.

Disclaimer: this project deals with volatile lithium batteries that have the probability of exploding. I am not responsible for any damage cause to the reader and his/her property as a result of building this project.

Comments

author
hanelyp made it!(author)2016-08-26

A word of warning: the LiPo batteries sold for RC vehicle use are made for high discharge rates, as high as 60C (discharge full capacity in 1/60 hour) for high performance RC aircraft. Laptop batteries are designed for a much slower discharge rate, typically 1C. Drawing excess current from the battery can damage it.

author
abhilash_patel made it!(author)2016-09-22

these cells are extreamly good for RC transmitter

author
signOnthe made it!(author)2016-08-26

I believe you will need rarely high C batteries for airplanes. If you say for quads or hexas OK, but for planes I dont think you will need that high C rating.

author
TechMartian made it!(author)2016-08-27

Depends on your props. If you have a 10x4.5 for example that can draw 20-30A, so you will still need a high discharge rate battery. Using LiOn batteries would be dangerous and could blow up -- same thing happens with LiPo where they get bloated.

author
signOnthe made it!(author)2016-08-27

There are 30A Li-Ions out there..

author
TechMartian made it!(author)2016-08-27

Yes there are. Sorry if I wasn't clear before, but my point is the ability to discharge about 30A continuously. You can use 9V batteries in parallel until you have 30A but if it cannot discharge this continuously it would be quite useless. 30A LiOn batteries could be because it has a high mAh but low discharge rate like Rx LiPo batteries - these must not be used for flight (though it will fly it will get bloated and is an extreme fire hazard. The amperage draw is simply >= mAh * discharge rate. So I can have a 20C lipo with 1000mAh that can give 20A, and a 1C LiOn with 20,000mAh, that is still 20A. However, the former can sustain an RC plane while the latter cannot.

author
signOnthe made it!(author)2016-08-27

Samsung 30Q 18650 got 15A CDR (datasheet http://www.nkon.nl/sk/k/30q.pdf)

Samsung 25R 18650 got 20A CDR, also got 100A momentary pulse (datasheet https://www.powerstream.com/p/INR18650-25R-datash...

LG HG2 18650 got 20A CDR (datasheet https://www.imrbatteries.com/content/lg_INR18650H...

LG HB6 18650 has 30A continuous discharge (CDR) rate.

Also, there will be more lithium based high discharge rate batteries announced soon (including high-end titanium).

Have a nice day,

Mehmet

author
hanelyp made it!(author)2016-08-30

Granted, some Lithium Ion cells are capable of high discharge rate. But to assume that random salvaged cells can deliver such performance is risky.

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