When you start to DIY a battery pack and get the BMS to wire, you may feel quite confused about the many wires on the BMS. And if you make a mistake about the wiring, it will likely burn the BMS and you will feel frustrated.
In fact, it is not difficult to wire the BMS correctly to the battery pack, here we are going to show how it’s done step by step.
1- Confirm you’ve got the right BMS
First of all, you need to know what kind of BMS suits your battery pack, there are many suggestions we will not mention in this article. One important thing is you need to know how many wires you need from the BMS. If your battery pack is 7S, then the BMS wires need to be 8 wires. BMS wires quantity has to be one more than your series quantity of the battery pack.
2- Do the wiring without BMS connected
It is very important that when you do the wiring, do not connect the BMS. You need to disconnect the wires from the BMS first.
3- Do the wiring carefully
Confirm the negative wire on the BMS. It would be best if you started from the negative of the battery pack, and connect the BMS negative wire to it. Usually, this BMS negative wire has a different color than other wires. Make sure you connect the right wire to the battery pack negative. (In this example, the black wire is to the negative pole, red wires are to the positive pole)
Then connect the first red wire to the positive of the first series battery, or you can find the connection point on the nickel strip that connects the 1st and 2nd series of the battery. Then the 2nd red wire to the 2nd series battery positive pole, the 3rd wire to the 3rd series positive pole, the 4th red wire to the 4th series positive pole…
Finally, you have the last wire left, you need to connect it to the positive of the battery pack.
4- Test the voltage of each battery series
Put the tester pen between the neighboring pins on the connector, you can test the voltage of each battery series, make sure each series battery’s voltage is the same, and the difference is less than 0.1V. If you find one voltage is extremely higher than others, you probably have the wrong wiring connection, you need to recheck the wiring order.
5- Connect the wires to the BMS and test the resistance
Put the tester pen on the BMS wire B- and P- and test the resistance value of it. Normally the value is within 0.2Ω
6- Connet the BMS to the battery pack and test
Connect the B- wire of the BMS to the negative of the battery pack. You need to make sure the voltage of the battery pack individually is the same as the voltage of the battery pack with BMS connect. Use a multimeter to test them. Normally the value difference is within 0.1V.
Skya Power designs & produces BMS for electric bicycle battery packs. Contact us for custom or production.
