Tesla Motors has halted production of the Model S electric car while it upgrades the assembly line for its next vehicle--the Model X crossover.

A two-week production hiatus will give the firm enough time to complete a full $100 million upgrade to the plant, before production restarts at increased speed.

According to Bloomberg, the upgrade will add 25 robots and allow Tesla to build the Model X on the same assembly line as its sedan sibling.

The upgrade is the "single biggest investment in the plant since we really started operations", spokesman Simon Sproule explained.

When the plant comes back online, Tesla will have the ability to boost production 25 percent. That should help the company meet Elon Musk's goal of producing 1,000 cars per week at the Fremont facility, up from 700 per week at the end of the first quarter.

During the plant's down-time, workers are taking vacation time and coming to the plant for maintenance and training shifts.

MORE: Tesla's Lithium-Ion Battery Gigafactory: What You Need To Know

The upgrades are part of a huge push by Tesla to prepare for its future vehicles--one that also includes the building of a battery 'Gigafactory' to ensure it's able to supply lithium-ion batteries as demand for electric cars increases.

The gigafactory is expected to cost as much as $5 billion to build, and could employ as many as 6,500 people--with the aim of reducing the cost of batteries by 30 percent.

That will prove essential in readying Tesla for its third-generation car, the aptly-named Model III, or 'Model three'. Previously known as the 'Model E', the smaller Tesla sedan will sit on an all-new platform and cost about the same as a mid-range BMW 3-Series.

Several potential locations have been chosen for the battery site, though Tesla will break ground at two sites so the firm is prepared for any last-minute changes.

Green Tech Media suggests one of those sites could be near Reno, Nevada--where hundreds of earth-movers have been recently spotted clearing a large site. For now though, Tesla's participation is merely rumored, and the company itself has not commented.


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