EBike Battery Pack || DIY or Buy || Electric Bike Conversion (Part 2)

In the last episode of this video series I showed you how to create your own ESC sensor For power wheel electric bike with low voltages But since the rotational speed achieved was very slow And not many people would like to create their own ESC to convert e-bike Let's move on to the console that is included in the set To test it I got myself a new lab bench power supply which can produce up to 60 volts So I tied its output to the controller input And slowly began to raise the voltage and approximately about 40.6 volts The console started working how it was supposed to Now by moving the voltage more The wheel started to spin faster and faster Until I reached the limit of my power supply This means we will need a battery pack that can cover Voltage range no less than 40.6V, maximum 61.5V A suitable choice for batteries would be 18650 lithium ion cells Because it provides a large energy density of volume and gravity Can provide enough current And let's face it everyone uses them to pack E-bike batteries But while searching for a compatible battery pack on eBay I noticed the prices were rather high which made me wonder Whether using your own E bike battery pack will be cheaper Even in this episode of DIY or BUY Let's find out what goes into creating Lithium-ion battery pack for your bike And whether it is really cheaper in the end Let's get started [INTRO] This video is sponsored by JLCPCB One fact about them JLCPCB was the first PCB company to cut the price from $70 to $7 On a 2-layer PCB 10 years ago Download Gerber files to order 10 professional PCBs for only $2 When examining the datasheet of most lithium ion cells Then we can see that they got a nominal voltage of 3.6 to 3.7 V And the maximum charging voltage of 4.2V There is almost no capacitance left when discharged to 3V This means that we have a voltage range of 3V to 4.2V per cell Thus for our control voltage set it makes sense to put 13 cells in series To create a battery voltage range from 39V to 54.6V With a nominal voltage of about 48.1 volts Which is not surprising is the recommended voltage of the controller Next we need to know the maximum current required of the controller Unfortunately despite my dry test with a lab bench power supply Didn't give an exact answer And the product page doesn't mention the current either But fortunately it provides 1000 watts at 48 volts which is equal to a current of about 20.83 amperes The next best combined lithium-ion cell which can produce 20A continuously Samsung INR 18650-25R was Capacity 2500 mAh But just to be on the safe side and double the battery pack capacity I decided to use two of these cells in parallel Which is ultimately equivalent to the 13S2P lithium ion package Capacity 5 amp hours And the nominal voltage of 48.1 volts A constant current output current of 40 amps So I applied and ordered 30 of these cells From a trustworthy German seller How do I know it is trustworthy? well after receiving the cells and visually inspecting them I measured the voltage of all of them And they noticed that they were all very close to each other Which just wasn't a very good sign But also indispensable Because we want to connect two cells in parallel If they have a large voltage potential difference الجهد Parallel connection may lead to large current flow and destroy the cell But anyway to turn 26 of these cells into a nice looking battery pack I will use those plastic spacers which can hold 2 cells each So you connected 13 of them in series through the help of an interlocking system Put two batteries in the same direction in the first row Continuously changing the direction of the next two cells While filling in all commas Once that was done I added the remaining spacers to the top of the battery pairs They are connected as well through their interlocking system To connect cells to each other I got this nickel strip 7mm wide and 0.3mm thick which can handle up to 30 amps So I started making 26 smaller pieces of nickel bar that was long enough to connect all parallel cell pairs Now to create the actual connections I wanted to avoid soldering this time But as you know I recently failed to build my own battery spot welder Thank God though the viewer sent me a solution to this problem The so-called kWeld It is basically a very advanced battery spot welder After doing a bit of assembly It can be powered by LiPo .

Battery Thus it can create suitable welding spots without problem According to its manual, 100 joules of energy is recommended for 0.3mm nickel strips Which I use as a standard value for all the welds of my battery pack And as you can see creating the seams is really not that complicated Simply press the electrodes to the metal with a distance of approximately 3 mm to each other push the foot switch and Here you are! :Dr Now I created two pairs of spot welders for each battery terminal Resulting in a total of one hundred and four welds And once that was done It's time to measure and cut 24 nickel strips for chain connections Which need to get in touch with parallel batteries In the order shown here So I created another 96 welds for chain connections Same way you did for parallel cellsخلايا However our 13S2P battery pack is basically finished It should provide us voltage within the previously calculated voltage range which i did 🙂 The only question left is: How is it shipped? The data sheet of our used lithium-ion cells Provides constant current constant voltage method With 1.25 amps and 4.2 volts If we multiply these values ​​for a 13S2P battery pack We'll get 54.6 volts and 2.5 amps This means that I can set the voltage limit for our lab bench to 2.5A Reducing the voltage to 54.6V Simply connect it to the battery terminals Which you soldered thicker 10 AWG pre-color-coded wire Not surprisingly, the charging process worked like a charm مثل But once I closed the target voltage The charging process was interrupted to measure the voltage of each battery pair As you can see the voltages are still very close to each other But let's imagine that we repeat this charging process several hundred times Since no two batteries are exactly the same The voltage gap between cell pairs will grow and grow Even one will eventually give up What we need to prevent such an event is this BMS Also known as battery management system Not only does it keep all cells in balance voltage at 4.18 volts But it also adds a price increase over-performing and short circuit protection To use it, its balance connector wires must simply be soldered to the battery According to her label This means B1 to ground potential B1 + to 3.71V potential B2+ to 7.4V potential B3 + to 11.1V potential And so on, and on…

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Even B13+ connects to 48.1V Finally, we simply connect the battery ground wire to the B And add two black wires to the P- and C-terminal Now to charge the battery We reconnect the positive voltage But connect the ground potential to the C-terminal This way the battery charges now as before كان But simultaneously charging the battery itself through BMS Once all the red lights are on Shipping was complete Thus we can connect our load through the P- terminal And the usual positive voltage wire from the battery pack And such a creation of a complete DIY E-bike battery pack 🙂 But one question remains… Was it cheaper? Well according to ebay prices was actually cheaper! But only very little 🙁 But again if you add labor costs and battery spot welding cost Then it will be cheaper if you plan to make more than just one battery pack and personalization care So, all in all, I declare both DIY and BUY the winners of this episode! However, I hope you are looking forward to the final chapter of our e-bike conversion project! As always don't forget to like, share and subscribe Be creative I will see you next time!

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