T.9.2 Low Voltage Batteries

T.9.2 focuses on the specifications for Low Voltage Batteries at large with guidelines regarding mounting, overcurrent protection, insulation, wet-batteries, lithium chemistry, and documentation. A synopsis of each section is as follows:

As for T.9.2.3, this rule requires that the hot terminal of our battery be insulated so as to prevent shorting the positive and negative terminals. In our case, the wires attached to the positive and negative terminals of each cell are insulated. 

T.9.2.4 refers specifically to wet batteries, which, also known as a flooded battery, are a type of battery that contain liquid electrolytes. The electrolyte is a mixture of water and acid, and the battery also has lead plates and separators. When the battery is connected, the acid bonds to the lead plates, triggering a chemical reaction. This rule specifies that the casing on these batteries must contained in a non-conductive marine type container. 

But why marine type?

For context, batteries in boats are housed in waterproof plastic boxes so that water spills into the hull and cannot short the battery terminals, which could otherwise potentially start a fire or render the battery inoperative. 

For our purposes, this is helpful because it also means the battery acid cannot spill out if a vehicle flips over, which prevents injury to the driver.

T.9.2.5.a and T.9.2.5.b are rules specific to Lithium-type batteries. Firstly, T.9.3.5.a specifies that the housing for cells of this type must be designated Non-Flammable as defined in F.1.18.

And as stated for T.9.2.5.b, batteries must be commercially available and designed as an Original Equipment Manufacturer (OEM) style replacement. This rule prevents teams from designing potentially unreliable battery chemistries, or from sourcing batteries from Non-OEM sources. These are made by a different company that reverse-engineers an original battery and starts producing copies which may have functional discrepancies from the original design.