1.  
Thicken the current-carrying terminals to provide a larger cross-sectional area, due to prevent the temperature rise of more than 30°C of when switching currents. 

2.  
By widening the terminal to increase the cross-sectional area, to prevent the temperature rise of more than 30°C when the current is turned on. 

3.  
When the battery connection to the board and electrical system, In order to prevent spark phenomenon,so negative terminals need to be longer than other terminals, that let the electron flow of the negative electrode to be grounded preferentially due to the electric concept. 

1.  
In order to prevent poor contact due to loose connection, that set base snap design to keep setting. 

2.  
Let negative terminals longer than other terminals to keep preferentially grounded on electron flow due to the electric concept.  

Each terminal connection wire, that per terminal current flow is proportional with wire diameter on the same rated voltage.

Dun-Pu supplied wire’s spec of AWG24~AWG28 with 7pin/ 8pin/ 12pin WTB connector for customers to choose from / between different demands.

p.s. AWG number is spec of wire diameter, that number smaller be thick.