|A Brief Process for Making Battery|
|Step 1: Preparing Cells
||Step 4: Assembling
|Step 2: Setting up Nickels
||Step 5: Adding up A Battery Management System
|Step 3: Welding Cells Together
||Step 6: Sealing
Let us learn how you can make an inexpensive 18650 battery pack from scratch.
If you are interested in making custom battery packs then you have landed at the right place at the right time. This guide will take you through a complete and detailed step by step procedure that anyone including amateurs can use to end up with a custom battery pack that can help them do whatever that they want. There are many companies out there that can help you make a custom 18650 battery pack if you want it that way but we would like to assure you that you do not need all that because after reading this guide you will be able to do it yourself. The battery has helped so many people in the world today.
Before you start doing anything, it is always very important to set your goals clear. So what are your goals in this project? Do you want to make a battery pack just for the sake of it or you want the process to be successful? The process of DIY your 18650 battery pack should only begin after answering the questions above. The advantage of doing this is in order to keep you focused from the word go. You don’t want to leave your project halfway just because you do not have goals to meet. Set your goals clear and let the work begin.
You should also know how you will use the battery pack once you have completed the project. Is it for domestic or commercial use? Do you know anything about this particular project? Do you comprehend all the safety measures involved in this project? These questions are very important and anyone who wants to have a successful project making this type of battery should be ready to answer them.
Part 1: Something You Need to Know First
Before we proceed to the process of making your battery let us first look at some important words you need to know about.
Amperage (A): Amps is the amount of current your battery will produce once you make it. Multiplying the amount Amps and Volts gives the amount of wattage.
mAh output: Milliamp hour stands for your battery’s total capacity in milliamp hours. If your milliamp value is higher your battery will stay longer before you recharge it.
Voltage output: This is the amount of energy your battery produces if current is allowed to flow. Ohm’s law defines the relationship that exists between current and voltage.
Watts: Stands for electric power. They are determined by volts and amps. W = Volts x Amps. The unit for watts is j/s or joule per second.
Charging Time: This is the time your battery will take to charge fully. This is determined by how you will use it. What is the end use of the battery you are making?
Weight: This is very important. You should know the weight of the battery you are expecting. If it’s something that you will use on the go then you definitely have to make sure that it is light enough to allow you move with it from place to place.
Safety: Safety always comes first when doing a project like this. Make sure that you stick to safety requirements that are set by relevant bodies. Do not forget to consider safety when making an inexpensive battery.
Now we go direct to the process of making your battery. Relax and get a pen and a paper if you need them and take notes. We are going to take you through the entire process of making a battery pack for commercial or domestic use. Isn’t it just amazing next time you will be riding a bike with a battery that you personally sat down and made?
Part 2: Prepare These Things
Top Materials needed in this project:
· Goggles(for safety purposes)
· Gloves (latex)
· Nickel strip(original)
· Spot welder
· Glue gun
· Soldering iron
· Tape (Non-static)
· Battery management system(BMS)
· Silicone wire
· Foam padding
· Heat Shrink
· Hair dryer or heat gun
· Electrical connectors.
These cells are used in different type of electric appliances and they are the main cells used in in making battery packs. Gone are the days when there were mediocre 18650 cells. 18650 cells that are used these days are much better than what was there initially. These cells are being used in different places and since their demand increased, we started seeing some amazing 18650s even in electric vehicle industry.
So why are they that best when it comes to making a battery pack? 18650s are distinctive and come in a cylindrical shape ideal for use in such projects. The number of cells you will use depends on the size of the battery you intend to make. If you plan to make a bigger battery then you will have to use hundreds of these cells but if you want a small battery you will only need a dozen or so.
18650 cells come in different types. So it’s upon you to decide what to go for but some of the big names known to manufacture some of the best 18650 cells are Panasonic, LG and Sony of the world and FST, OptimumNano and BAK of China. If you get cells from these companies then be sure to make a good battery as long as you stick to the right procedure.
ICR18650B4 are one of the best cells to use in this type of project. These cells are not expensive to acquire and as long as you want the project to be successful.
Some people like going for cheaper options but this will not give them a good battery at the end of the project. Do not be one of those people who get tempted easily to buy cheap 18650 cells. If you never knew, the truth of the matter is that some of the cheap cells that people go for are nothing but a rejected lot from the manufacturer which end up in companies that are ready to sell them to desperate buyers.
Most 18650 cells don’t deserve a look-back because those are one of the rejects that will end up disappointing you. Good batteries that will serve you for long are made from cells that are sold by companies that we saw earlier. But the best cells that are easy to recommend are usually by LG.
To get good cells you can either buy them locally or import them directly from the seller. The best option here that is easy to recommend is ordering directly from the manufacturer. Direct ordering will help you save some money that you would have used somewhere else. Even if it means that you will have to pay for shipping just go ahead and ship because the truth of the matter is that you will be in a position to get good quality cells at an affordable price. There are many payment options available online that you can use. Just make sure you go for a payment option that is secure and in case the cells turn out to be something you never expected, you will still be able to get your money back.
Nickel Strip: It must be pure
It’s not an easy task making a good battery. You must consider all the required steps without missing even one. The work of nickel strip is to hold the cells in position. You should then work with nickel that is pure and nothing less. However, if you want to use a cheaper option you can go for steel strips that are coated with nickel. The advantage of using pure nickel is despite the fact that it costs more is that its resistance is lower meaning that there will be less energy wasted and more energy will be produced by your final battery. Pure nickel ensures that almost all the energy is used and that there is minimal wastage of energy.
When buying nickel, be careful because you might end up with nickel coated steel instead of pure nickel(yes, they look the same). This is something that many vendors out there are doing and many people have already fallen in their trap.
If it’s your first time making a battery, it is advisable to buy a small amount. Some sellers have good prices for small buyers. So it’s upon you to try and find the best pure nickel seller out there.
Dimensions considered, the best measurement of nickel to use is 0.15mm or 0.1mm in terms of thickness and 8mm in width. If the welder you will be using can weld a thicker nickel then well and good but if your welder cannot do thick nickel plates then it’s advisable to consider thinner strips that are easy to weld together.
If you will need more current then that means you will make a longer connection that will hold together more cells.
Spot Welder: Is it Necessary Really?
Using or not using a Spot Welder will depend on whether or not you want your 18650 cells to get damaged. Before you decide on using a Spot Welder you should first comprehend that your cells can get damaged by heat. The cells are joined together using a spot welder because of one main reason – to avoid exposing them to a lot of heat.
Soldering is possible but this has a negative effect to your cells because it adds more heat to your 18650 cells hence killing them. When your cells get in contact with heat, it activates reactions within the cells and as a result the performance of your cells decreases. The cells should therefore not be exposed to heat when making a battery pack.
When buying a spot welder to use in your project just ensure that you go for something that will get the job done. Do not go for a professional spot if you don’t have a lot of work to do. Go for a spot welder that is not expensive and can serve you for the time you will be making your battery.
SAFETY TIPS BEFORE STARTING
Your working area must be clean
Clear and clean the area where you will be making battery from. Only have items that are needed in the project within your working area. Do not put yourself in a position that will lead to accident happening in the course making battery.
This is a must. You can use any type of gloves from latex gloves, work gloves, welding gloves or mechanic gloves as long as you feel comfortable working in them. Do not put yourself at a risk of coming into contact with high voltage in the process of making battery.
Get rid of Jewelry that is metallic
Anyone who has experience making batteries will give you this advice for free. Do not wear your jewelry while making battery. If your metallic jewelry come into contact with the batteries and by mistake you complete the circuit believe it you will not like the experience. The contents of 18650 cells can also affect your jewelry if they come into contact. Let’s say you are married and that happens to your wedding ring. How will it feel?
You definitely do not want anything to happen to your eyes. Wearing goggles shield your eyes away spikes flying into your eyes. If you seriously don’t want anything bad to happen to your eyes then make sure that you put on goggles when making battery.
Wearing long sleeved cloths is also recommended when making an 18650 battery pack. Do not put yourself at a position where the spikes damage your skin when welding.
Part 3: It’s now time to make our battery
It’s now time to make your battery. What’s the configuration of your dream battery? This is where to start from.
Let’s assume we are making battery for a bicycle. Bicycle batteries mostly fall between 24volts and 48volts and in increments of 12V. There people who can go as high as 100V.
Let’s assume you are making 36V7800mAh battery. The principles will still remain the same nothing changes except the voltage.
For a 36v battery you must get many Lithium-ion battery cells and connect them together. These cells are mostly rated between 3.6 and 3.7 volts. This therefore means in order to get 36 volts you will have to connect together about 10 of these cells. So this will be a 10 series pack battery of 36 volts.
The next step involves using the 18650 cells. These are connected in a parallel manner in order to get the desired capacity. Depending on the cells you use you will find that they have varying mAh value. Let’s assume we are using cells with 2600mAh value. Arrange 3 cells in parallel manner such that the total Ah value is 2.6Ah x 3 =7.8Ah. The abbreviation for parallel arrangement is P and that of series is S. Therefore this would mean that the final configuration for the pack would be 10S3P pack. This configuration will have final specs of 36V7.8Ah(30 cells).
A good number of 36 V packs that are available in the market are 10Ah. What does this mean? We will have a smaller pack. The configuration you decide to go for will be determined on the level of your project. You will go for a higher configuration if you want a bigger battery. If you are just getting started in this project it is advisable to start small as you get the skills to make a good battery.
Get a paper and a pen or you can use a computer to prepare a plan of your final configuration. This plan will work to guide and show you the final layout of your pack. This will include dimensions, shape and size. Prepare a simple plan and layout such that the columns of cells (3) get a parallel connection and the other 10P get aligned correctly.
Step 1: Preparing Cells
After drawing a plan or layout of your final configuration, the next thing is to work on your cells and prepare them. Remember you are working on a clean and clear area where the only items available are the ones you need. Make sure you have your safety gear on because this is where the real making starts.
Start by preparing each and every 18650 cells one after the other. So how do you do it? Start by finding out the voltage of each and every cell to make sure that the voltage is the same from the first cell to the last. Now this is where you will realize that it is better to order your cells direct from the manufacturer rather than a local seller. If your 18650s were shipped from the same manufacturer then they should have the same voltage and if there is a difference then it should not be big. You will find some of them have a slightly higher voltage because the manufacture set them like that just in case they get exposed to factors that might affect their voltage.
Should you find a cell that has voltage that hugely varies from the rest do not use it. Isolate it. Make sure that you only use cells that have similar voltage. This is advisable because if you connect cells that have a higher voltage with cells that have a lower voltage then there will be excess current flowing to cells with lower voltage hence affecting them. This situation can sometimes lead to spikes and fire because of the overload. If you have to use a cell with a higher voltage you can either reduce the voltage to the right level such that it matches other cells or just isolate it altogether if this cannot happen. Whatever you do in the process of preparing your cells just make sure that you do not include a cell which will end up damaging other cells leading to wastage of resource and your precious time.
Chances of encountering voltage differences in cells are minimal if you order directly. However, if you buy unbranded cells then get ready to find such cells with varying voltage.
After matching all your cells put them together and start arranging them as per your planned orientation. Do this while considering the plan or layout that you had prepared earlier. This will give you a rough size and shape of your final battery pack minus wrapping and padding which will act as a shield to protect the cells.
Step 2: Setting up Nickels
So now you have prepared your cells and arranged them to give you the shape of your final battery, the next thing to do is to have the nickel ready.
Cut the nickel early enough to make the process easy and fast. Measure the size of nickel needed to hold the cells together before you start welding. Cutting pure nickel is easy not unless you decided to use nickel coated steel. You can even use scissors to cut the nickel. You should avoid bending the nickel while cutting it because it is better if it remains flat.
The next step after preparing your nickel is to weld. As you weld it is good to make sure that the cells get aligned and remain on a straight line. If doing this is difficult you can use a jig to hold the cells in position as you do the welding. Another working option is gluing the cells so that they stay on a straight line.
Once the cells are on a straight line, you can use a strong magnet and place it on the backside of the magnets to hold the cells.
Step 3: Welding Cells Together
Welding is not a difficult thing to do as long as you follow instructions. You will have to follow a plan if you want this process to be successful. Start by parallel welding of cells. You can start with 3 cells or 2 by welding the bottom and the upper side. Do this to ensure that the negative and positive ends of the cells are shared by all the cells you are welding together.
Place copper plates or electrodes on the arms. Depending on the welding machine you use, there are some that come with arms that can be useful in placing copper electrodes at the right place.
Place the nickel over the cells that have been welded together and make sure that the three terminals are covered. Start welding only after correctly adjusting the current. Place the copper strip and battery cells under the probes as you lift the arms of the welding machine until you confirm that a weld has actually happened. Once you have done this, two dots will be seen indicating that the welding took place.
How do you know that the weld is good? This is simple. Just try to lightly pull the strip to see if it detaches from the weld. If the strip remains strong then that is an indication that the weld was okay. Regulate the current once you discover that the surface of the strip is hot. This can affect your cells.
Repeat another welding process on 3 cells and follow the same process. After finishing the welding process on the top side of the cells, it’s now time to turn to the bottom side. Repeat the same welding process of working with 3 cells at a time and welding them together.
Continue making these parallel groups for all the cells that will fit in your early prepared plan.
Step 4: Assembling
After finishing the welding work it is now time to assemble these different groups in series to make your final 18650 battery pack.
There are different ways you can layout your cells. The first layout is known as liner and the second method is known as offset.
Start by gluing parallel groups in an offset way as you make sure that the ends are opposite use nickel strips to bridge two cells. Then place the positive side of the 1st parallel group upwards and the negative side of the 2nd parallel group upwards. Place nickel strips on top of each of the sets of cells and bridge the positive ends of the 1st parallel group with the negative ends of the second group.
Put another set of welds on every end of each cell of the 1st parallel group and ensure that they take the three strips in place. Add another set of welds on all the negative ends of the 2nd parallel group. This will lead to 5 sets of welds.
After doing this, make sure that the connection is okay and contact also. Hot glue the third parallel group and follow the same process as outlined above. Turn the whole thing upside and repeat the same process of connecting terminals using the nickel strips. Make sure your series connection is in such a way that positive is connected to negative then to positive to negative as you alternate between these two. Add the 4th parallel group and glue it together making sure that you follow the steps accordingly.
Step 5: Adding up A Battery Management System
The main work of this system is to ensure that current flows and the battery can charge and discharge. It monitors the parallel groups for safety power cut off after charging. Make sure the cells are balanced and it should not be over-charged. Make sure that you buy the right BMS for your battery.
When connecting BMS you must first find out the first sense wire. Find out wires that need to be numbered on one side of the board. Connect the sense wires from the right direction.
Consult the wiring pattern of your BMS if you want it to be successful. The first wire should go on the negative terminal of the 1st parallel group. The other wires should go to the positive terminal of the successive parallel group.
Before you wire the battery management system, glue it to maybe a piece of foam in order for it to insulate the bottom contacts of your board and then hot glue the foam to the battery end.
Take a B1 sense wire and solder it on the positive terminal of the 1st parallel group. When doing the soldering of the wires, you should solder between two cells and avoid soldering them directly on top of a cell terminal.
After that, take the 2nd sense wire and solder it on the positive terminal of 2nd parallel group. Continue with the same process with the sense wires and when you get to the last one, solder it
on the positive terminal of the 10 parallel group.
Finally add the discharge and charge wires. Solder the positive charge and discharge wire on the positive terminal of the 10 parallel group.
Solder the negative charge wire on the C-pad on the battery management system and the negative discharge wire on the P-pad. Add one more wire from the terminal of the 1st parallel group to the B-pad on the Battery Management System.
Step 6: Sealing
Use a heat shrink to seal your batteries. For better protection wrap your battery in a foam padding/layer. Wrap your battery and seal it using an electrical tape. The next process involves using a heat shrink to cover your battery. Buy the best heat shrink if you want your battery to be protected.
The last thing to do after ensuring that your battery is protected is to add connectors. These connectors can be added earlier or when you have finished making your battery.
Now you have your 18650 battery pack ready.