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Hole in PCB for BMS not Right Size for Current???

YoshiMoshi

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Joined
Oct 26, 2024
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Hello Freinds
1735357832829.png
I have a power tool BMS whose rated continuous discharge current is 35 A. So per Matador's ampacity table that is cited on these forums in many places, 0.1 mm thick by 10 mm wide strip, 13 of them stacked would give me 36.48 A.

Now the B- and B+ holes within the PCB, can't fit 1.3 mm thick nickel strip
1735357989017.png
The most I could get in there was about 0.8 mm, or 8 strips. So what is a guy supposed to do? Is there like a surface mounted connector that I can mount to this area? Please send a link to one. Thanks for any solutions! I know the small surface mounted connectors are typically rated at 0.5 A.

Looking at other power tool BMSs, they also seem to have a really small hole. Additionally, looking at manufacturer created BMSs, I think they have really thin nickel, like 0.3 mm thick... Interesting. I see people get lots of current out of them though! Much more than what 0.3 mm nickel is rated for per Matador's table, I guess enforcing the idea that if it is only for a few seconds, than don't worry about it.
 
Looks like you need special connectors. All the bms I see have screw post connectors for the battery. Solder a connection, especially a high amp connection, to a pcb board at your own risk.
 
Looks like you need special connectors. All the bms I see have screw post connectors for the battery. Solder a connection, especially a high amp connection, to a pcb board at your own risk.
What is the risk? Do you have a good connector that might work?
 
That looks like a BMS from a power tool battery pack, not anything that can handle more than 10 amps.
 
That looks like a BMS from a power tool battery pack,
Yup, I should hope so 🤣
Hello Freinds

I have a power tool BMS whose rated continuous discharge current is 35 A.

Looking at other power tool BMSs, they also seem to have a really small hole. Additionally, looking at manufacturer created BMSs, I think they have really thin nickel, like 0.3 mm thick... Interesting. I see people get lots of current out of them though! Much more than what 0.3 mm nickel is rated for per Matador's table, I guess enforcing the idea that if it is only for a few seconds, than don't worry about it.
Is this a drop on replacement that copied the original form factor? I'd just copy what they did.
If not, make the best connection to the board that you can and up the conductor size outside of the board.
 

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