The Tesla Model S propulsion battery pack is one of this centuries most innovative breakthroughs.
A collection of thousands of small form factor 18650 Lithium Ion cells, assembled into parallel connected bricks, inside modules, is what propels a Tesla Model S for often hundreds of miles.
As batteries age, they naturally lose capacity. This, in turn, gradually shortens driving range. LI-Ion batteries age with use, or age with time, even if not used. The number of charge cycles also affect battery life.
Out of thousands of cells, occasionally one declines in performance, going resistive as it fails, and becoming parasitic. Since the battery architecture is a combination of parallel and series connections, any cells in a "brick" of parallel connected cells, is affected by the one parasitic cell, pulling down the voltage.
The Tesla drive train warranty, which includes the battery system, is warranted for 8 years, and battery pack replacement is free during the warranty period. Tesla does not repair main battery packs in the field or Service Centers. For out of warranty vehicles, a battery replacement is their only option, around $20K.
At GMC, we are able to go inside the battery pack, repair what is wrong right down to component, or cell level. If the failure is cell related, we isolate the declining cell(s), neutralize them, and restore full functionality for a fraction of replacing the entire main battery pack.
As Li-Ion battery packs age, they become less resilient, and have a harder time bouncing back. For battery packs nearing end of life, we recommend limiting high amperage rapid charging, especially supercharging. Although convenient, it takes a toll on the cells and can hasten their demise.
Battery Pack Pull and Enclosure Disassembly
To remove a 1200 lb battery pack from a Tesla Model S requires a car lift with specialized hydraulic equipment, and a movable battery table capable of handling this weight.
The pack is cleaned, the top blanket is removed, and a large top sheet metal cover is then peeled off to expose clusters of LI-Ion modules containing cells, 7,104 in an 85KW pack.
We carefully inspect the tub for any water ingress, coolant leakage, etc. before removing the battery module with the declining or failing cell(s).
Cell Isolation and Neutralizing
Diagnostic software identifies which of the 16 modules has a declining cell, in a brick. This module is then extracted from the pack, and moved to our cell isolation lab.
Using very sensitive measuring equipment, the declining cell is isolated, often only one out of 7104, and the dying cell is then neutralized.
This is followed by a combination of charging/discharging and load testing to verify a successful module/brick repair.
BMS Repairs
Each module also contains electronics as part of the Battery Management System (BMS) which controls and monitors charge rates, bleed rates for cell balancing, all part of the intelligent management of sophisticated battery management.
At times, component failures in the electronics also causes pack failure. Gruber Motor Company routinely repairs complex electronics down to component level, and resolves problems stemming from this section of the battery pack.
Module Replacement
Although rare, if enough cells have been compromised in a battery module, the next option is replacement of the module from donor packs which we maintain a supply of.
Each module contains 6 Bricks, or groups of parallel connected cells, and there are 16 of these Modules in each 85KW battery pack.
Gruber Motor Company (GMC) is part of Central Dispatch, a service that manages hundreds of automotive transporters all over north America. The members are all licensed, insured, and bonded transporters, skilled in auto transport.
Both specialized enclosed transport, and more common open transport are available. We provide bids for the vehicle owner to review, and handle payment, coordination, scheduling, for a seamless customer experience.
Upon vehicle receipt, we thoroughly clean it before it enters our state-of-the art Service Center.
