BMS from China?

ESK8 Electronics
1

Hello, i want know if bms from china (aliexpress, ebay, banggood) is good enough for electric skateboard. and if you have do you have some problems?

thank you for yuour time :wink:

2

Several times, I have read on this forum something like : “You can buy a cheap power supply but always take a good BMS anyway”.

My own experience :

  1. I bought a BMS from aliexpress last year (20 euros), it worked for a long time but then I used it a bit harshly (outside of the skate, without any case, so totally my fault I guess) and a resistor burnt.

  2. 2 days ago, I ordered a cheap BMS from ebay just because I need one quickly but after the event I need one for, I will buy a good BMS from Bestech or BatterySupport.

My advice : Get a good BMS :slight_smile:

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3

It is not a Matter of stores. Aliexpress has a lot of garbage and also very good bms. Depends on the model/manufacturer/seller…

4

Thank you, and another noob question, you can control output of bms like voltage and amp, or bms have to be a specific for your type of battery and your xP exemple: 12S1P

5

It has to be specific for most cases. Some Smart bms can tweak parameters via pc or phone. Depends on the bms. 10s 20a 6$ for example… That’s exactly what you’ve got. The only choice available is bypass the bms. I do not recommend you that option if you are still unfamiliar with the bms world.

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6

@Deckoz runs powerful 13s builds and I think he runs like a 20$ bms from ebay.

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7

thank you, i searching about bms. and i understood bms have a limited discharging, so, if the discharging (from battery to vesc) max is 20 A is useless have a VESC with max discharging 80A because my max will be 20A

like this

8

Exactly. That one could be used only bypassing the discharge. Or used like that with a very low performance. Also make sure you understand the difference between lifepo4 and lipo/li ion. They have different voltages so they are not compatible. That one you posted is lifepo4. Good for street legal ebikes.

9

I use cheap BMS as @Blitz said. But I bypass discharging, and use them for charge only.

I don’t use discharge bms for various reasons…

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10

@Deckoz I’m new to bms’s. I have a $9 bms from china and am really worried about using it. I actually used this video https://youtu.be/_yrYG5skwvs to help me connect my power switch and vesc to it. Is this setup to bypass discharging? Sorry to sound like a noob!

11

Where can i learn more about bypass? i gonna need a 12s bms soon so i should probably research

12

All you got to do, is make sure that your charging wires are connected to the BMS. Either to the C- or the P- on your BMS depending on design, since some BMS’s don’t have separate charger/VSS ports. Then solder 2 ground wires from your battery to the BMS B- and another to your anti-spark/VESC. Then your P- or C- to charger port.

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13

Bypass means you take the discharge directly from the battery ignoring the bms. So you can use smaller/cheaper bms at full power. Example of bypass:

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