Battery modules from Model S and Model X cars come in several revisions, known as Rev A, Rev B, and Rev C. They look very similar in photos, but the balance wire connections differ. Use this guide to identify your revision before ordering a BMS kit.
If you have the chance to remove the old Tesla BMS board, It’s easier to see the differences.
Misidentification or Misrepresentation?
Unfortunately it seems to be quite common for sellers of these batteries to send a different revision, or even show photos of different revisions on the same eBay listing. If you end up with a different battery that doesn’t match your BMS kit, contact email@example.com and we will exchange the adapter board.
For example, I found these photos on eBay- one shows a pallet of Rev A modules, and the next photo is a close up of a Rev B module:
Tesla battery capacity
Each car battery can be broken down into 16 modules. Each module is a 6 cell Lithium-ion battery that puts out 24 volts, and they weigh about 65 pounds each (30kg).
The capacity of each module when new can be found by dividing the car’s advertised battery size by 16. Example: for an 85kWh (kilowatt-hour) battery pack, each module holds 5.3kWh when new. The capacity degrades with age, as all batteries do.
We have also seen examples of modules that were damaged by leaking coolant, which corrodes the bond wires to each of the individual 18650 cells. Modules in this condition will have a significantly lower capacity than a healthy module from the same car.
Model 3 / Model Y batteries
Model 3 and Model Y cars have a different type of module. The car battery contains 4 large modules, each of them has 24 cells and they put out about 96 volts. We do not recommend these modules for DIY projects due to the extreme danger of working with 96 volts DC.