Big numbers are one way to appreciateTesla’s gargantuan Nevada Gigafactory.

Operating 24-hours per day in shifts, workers produce enough battery packs and drive units in a week to power 5,300 of Tesla’s Model 3 sedans.

Tesla says at 5.4 million square feet, roughly equivalent to 50 Home Depot stores, the factory is just 30 percent of its potential size and is already producing more batteries than all other carmakers combined.

With more than 7,000 Tesla workers, the factory is responsible for increasing manufacturing employment in the Reno-Sparks area by 55 percent since 2014, according to the Governor's Office of Economic Development.

Another way to appreciate it is to feel it through your ears and toes. On Dec. 3, the Reno Gazette Journal got a rare glimpse inside the factory.

Hallways, production areas and even the offices and conference rooms seem to exist in a state of steady vibration that, depending on your location in the building, is punctuated by loud warning beeps from autonomous vehicles or whirring from robots large and small.

“It is not elaborate, mahogany offices here, this is where work gets done,” said Chris Lister, vice president of operations for the Gigafactory.

Lister was speaking from a carpeted work area stocked with hundreds of sparse workspaces where design engineers and teams from planning, production and engineering work side-by-side at tall tables arranged in long rows.

That factory floor is a hive of activity by human workers, robotic arms, conveyor lines and autonomous vehicles. They're working together to assemble battery cells into configurations that will power Tesla Model 3 sedans and other energy products.

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Panasonic makes the cells, which look a little like oversized AA batteries, in one part of the factory before Tesla's human and robot workforce assemble them to be used in cars and batteries that power homes and businesses.

The noise and vibration that seeps from the factory floor into the office area is a constant reminder that every corner of the Gigafactory is part of what Tesla CEO Elon Musk refers to as "the machine that builds the machine."

With that machine under constant refinement as Musk and others chase ambitious production goals it makes for an environment filled with Sturm und Drang.

A living machine: How the Gigafactory works

When Tesla officials cite advantages of the Gigafactory they often discuss elements of design and logistics.

Design-wise, the factory is built for an automated workforce.

Long, unobstructed and straight corridors are referred to as “spines,” where autonomous vehicles can move parts about. Its orientation is set to true north to make it easier to use GPS in programming vehicles or automated processes.

Even the exterior wall panels are modular, so they can be removed and reinstalled as the factory expands.

Tesla still plans to make the factory energy independent by continuing to add solar panels to the roof.

Unlike corporate campuses developed or under development for high profile tech companies like Apple or Facebook, Tesla’s Gigafactory appears spartan by comparison.

From the outside there is little to no landscaping. The building, in its current configuration, is an “L” shape with right-angle corners.

There are no awnings or patios outside. Vehicles park on pavement or dirt that goes to the edge of the structure.

The sheer size of the building and volume of work inside its walls makes it difficult to grasp what’s going on inside the Gigafactory from a single vantage point.

That’s why when trying to understand how the factory works, it’s helpful to consider each of the three, major functions it performs.

They include battery cell manufacturing, battery pack assembly and drive unit production, key components that are shipped to Fremont, Calif., where Tesla builds the Model 3 and other vehicles.

“This is really like 10 manufacturing plants in one,” Lister said.

Here's how it all works.

Where it all begins: making battery cells

This part of the factory, operated by Panasonic Energy of North America, is where some of most sensitive operations take place.

The entire Panasonic portion of the Gigafactory is off-limits to photos, video and audio recording and people walking through can only view areas of production that are visible through small windows from the hallway.

Panasonic invested $1.6 billion in the $5 billion Gigafactory. The company is the exclusive cell provider for Tesla and converts , raw materials such as refined lithium and steel into the cells Tesla uses to create a Model 3 battery.

Panasonic already produces cells for Tesla’s models S and X vehicles in Japan, but at nowhere near the volume that the Model 3 requires.

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Panasonic President Allan Swan said there are already 11 battery cell production lines in operation and two more under construction.

The two incoming production lines, he said, will produce double the output of the older lines.

With each Model 3 battery pack requiring more than 4,000 cells, Panasonic needs to churn out more than 3 million cells daily to keep pace with Tesla's ambitious production schedule.

“This is just a completely different scale,” Swan said..

Although lithium ion batteries are commonplace in everything from mobile phones to unmanned aerial vehicles to electric cars, Panasonic zealously guards the specific processes and ingredient mix it uses for its cells

Swan flashes a chart to visitors to explain the process, but he won’t distribute copies.

The chart depicts a process that includes mixing the material that goes into each cell, coating the metallic sheet that’s wound like a cinnamon roll into a cylinder, cutting, or slitting, the sheets to the appropriate size for the Model 3 cells, then assembling the cells and enclosing them in casings from H&T Nevada, which manufactures them on-site.

The secrecy is important as manufacturers Panasonic seeks to maintain its advantage.

At least one electric vehicle expert, Jack Rickard of EVTV, said Tesla’s batteries are superior to those in use by Volkswagen, Nissan and GM.

“I would venture that no one … has anything that can approach it,” said Rickard during a nearly 90-minute video in which he disassembles and analyzes a Model 3 battery pack. “This is probably the finest battery in the world.”

Secrecy isn’t the only thing Panasonic cherishes when it comes to cell manufacturing. Cleanliness is also high on the priority list.

Workers on the lines wear masks, protective booties, gloves and head coverings and the rooms where they work are hermetically sealed with special filters that control the air quality.

The measures are precautions to protect the cells which can be ruined by dust or other contaminants.

“Any contamination whatsoever, we basically have to scrap the batteries,” Swan said.

Putting it all together: Module and pack assembly

This is where Tesla workers and robots receive cells via autonomous vehicles from Panasonic and assemble them into Tesla products.

This handoff is what Lister refers to as the “handshake” between the partners.

From here, using a combination of human and robot labor, Tesla assembles the cells into long rows Lister calls “bandoliers,” because of the way the cells are arranged around a cooling tube. The tubes are also manufactured on-site by the company Valeo.

Bandoliers are then grouped side-by-side and placed into modules. The modules then go through more machines that, with help from people, use wires to bond the electrical connections. The bonding enables cells within modules to work together as part of a cohesive energy bank to power a Model 3 or any of Tesla's stationary products, such as the Powerwall home battery or the Powerpack, it's industrial cousin.

For Model 3s, four modules are placed in large, clamshell-type enclosure that contains and protects the battery pack in place at the bottom of the car.

The pack gets topped off with a “penthouse,” which is what Tesla calls the assembly of computer hardware that manages the pack.

Once a pack is complete it's ready for shipping to Fremont where workers will assemble it into a Model 3.

Although the Model 3 gets most of the attention from the public, Tesla is hard at work seeking to triple it's stationary storage power business with products like the Powerpack, which the company has deployed in disaster areas when traditional electrical service is disrupted.

“A lot of the discussion has been around Model 3 production, but the energy products are a significant part of our business,” Lister said.

The pack and module lines are among the most human-intensive areas of the Gigafactory.

That’s due in part to the nature of some of the components. Pieces that are firm and require simple, straight-line movements to install can be done by robots.

But other parts, such as wires and tubing, require manual dexterity and higher-level decision-making to install and are better done by humans.

The process of figuring out that people are better than machines at some jobs was part of the reason behind bottlenecks that caused headaches last year as Tesla struggled to meet Model 3 production goals.

“We had to make some quick drastic decisions on the fly to take areas that may have been over automated at first design and create a manual station to unlock a piece of the bottleneck,” Lister said, adding that safety was another factor in decisions about where to automate.

It was a process that’s been repeated throughout the factory, Lister said, as each fix that sped up a line at one place exposed a slow spot elsewhere.

“We look at the slowest unit operation and we apply all the resources and mind power that we can and solve that bottleneck,” he said. “Then we move on to the next bottleneck.”

More than just batteries, the Gigafactory also makes drive units

Although the Gigafactory is most often described as a battery factory, it’s also where Tesla produces another important component: drive units for the Model 3.

The drive units are what convert electrical power from a motor into force that moves the wheels of a vehicle.

Each all-wheel drive versions of the Model 3 requires two drive units and rear-wheel models use just one.

The drive unit area is separated from the battery manufacturing and assembly area by walls. And with about 90 percent of the work done by machines, it’s the most automated portion of the factory.

“Most of the operations here do not require manual interventions, it can just run,” Lister said of the automation, which has capacity to produce drive units at a rate of as many as 10,000 per week.

The motors include stators and rotors, gearboxes, and inverters. Parts move by elevator and conveyors, mostly from the third floor, and are assembled into housings.

After the drive units are tested, conveyors, autonomous vehicles and robots stage the units for shipping to Fremont.

“The robots are loading the final drive units into the shipping rack,” Lister said.

What is it like to be an employee there?

Although the factory has an elaborate and extensive food and beverage operation, the Gigafactory doesn’t have gyms, drugstores or other conveniences found in some high-profile tech campuses.

The list of amenities for employees includes outdoor fitness programs such as running, hiking and mountain biking. Employees get free snacks including cereal, oatmeal, crackers, pretzels, coffee, tea and other beverages.

The Gigafactory also provides private pumping space for breastfeeding mothers.

For transportation, the factory offers free commuter shuttles with Wi-Fi from various locations such as Reno, Sparks, Fernley and Carson City in addition to vanpools.

A Tesla spokesperson said the shuttle program has grown from about 150 users in January to about 1,700 today. Including the vanpool, more than 2,000 employees are using alternative transportation to arrive at the factory.

Given Tesla’s ambitious goals, it’s likely the number of people arriving at the factory will continue to grow.

“The biggest thing we need are folks with enthusiasm and passion and drive and scrappiness,” Lister said. “This family keeps growing bigger and bigger every single day.”