Over a year ago, Tesla (NASDAQ:TSLA) announced a way owners could have a full charge in less than 90 seconds: battery swapping. The new technology would be dramatically faster than the current charge rate of 20 minutes for a 50% charge and 40 minutes for an 80% charge at Tesla's Superchargers. But since the announcement, the technology hasn't yet been made available to owners. Here is what we know about the missing technology and why investors shouldn't be concerned.

Model S charging at a Supercharger location. Image source: Tesla Motors.

What is battery swapping?
In about half the time it takes someone to fill up an internal combustion vehicle, Tesla's battery swapping technology would replace a Model S owner's battery with a fully charged one -- all while the driver remains in the vehicle. Tesla said the cost of switching batteries would be around $50 and that owners would eventually have to return to retrieve their battery.

Every Model S sold is capable of getting its battery swapped -- it's just a matter of Tesla actually building the stations. The stations will cost around $500,000 to build, Tesla says. That's up considerably from an estimated $150,000 for its typical Supercharging stations.

The Model S battery is built into the floor of the vehicle. Image source: Tesla Motors.

Even at a cost of $500,000, however, it would only take 10,000 swaps for Tesla to break even on its initial investment. Of course there will be maintenance and depreciation costs, but they are likely to be nominal.

So, what happened?
Summing up the few comments Tesla has made on its plans for battery swapping since the technology was announced last summer, the company's priorities have shifted.

"We're a little late on [building a battery swapping station] because we got preoccupied with other issues," Tesla CEO Elon Musk said at the California Public Utility Commission's Thought Leaders program in February.

The most recent comment from Tesla on its battery swapping comes from Tesla's vice president of business development, Diarmuid O'Connell, who responded to Jalopnik in June: "We diverted most of our team and resources to expanding [the Supercharger] network as quickly as possible. It was mostly a reprioritization of efforts."

But Jalopnik's Damon Lavrinc pointed out that the reprioritization "came at a suspicious time."

Shortly after Tesla announced its battery swapping initiative, the California Air Resources Board decided to nix the extra zero-emission vehicle, or ZEV, credits for "fast refueling." To qualify for fast refueling, the state would grant extra ZEV credits to vehicles that could "refuel" to 285 miles in under 15 minutes. Tesla, which sells its ZEV credits to auto manufacturers that need them to meet their ZEV requirements, had a financial incentive to rapidly launch battery swapping stations. But with the program nixed, there was less incentive. And given all the items on Tesla's plate, the lack of extra credits may have made other items more important.

But this argument loses credibility when you consider that Tesla was already predicting ZEV credits to decline as a percentage of total revenue, making them less meaningful to earnings, before battery swapping was announced. And, indeed, this is exactly what has happened. Straight from Tesla's 2014 second-quarter 10-Q filing, the company illustrated their diminishing importance:

We recognized $129.8 million in ZEV credit sales in 2013 which contributed to our gross margin. Although ZEV credit revenue was strong in 2013, over 90% of ZEV credit sales were recognized during the first half of 2013, including $51.5 million during the three months ended JuneĀ 30, 2013. During the three months ended JuneĀ 30, 2014, we recognized $10.0 million in ZEV credit sales and we expect the contribution of ZEV credit revenue to remain low in the future relative to our automotive sales as we continue to grow our sales outside the United States.

Notably, however, Tesla still said in the filing that it "will pursue opportunities to monetize ZEV credits we earn from the sales of our vehicles." But the company "[does] not plan to rely on these sales to be a contributor to gross margin and our business model and financial plan are not predicated on such ZEV credits."

A smart move?
There is no doubt Tesla management has their hands full. Current areas of focus include Gigafactory construction, the Model X launch, international expansion, the Supercharger network rollout, and recent quality issues that needed to be addressed. Execution is incredibly important.

Model X (right) next to a Model S. Tesla plans to launch the Model X early next year. Image source: Tesla Motors.

Just isolating one of these items as an example, Tesla's Supercharger network, it's clear that prioritization really is key to progress for the company, as management asserts it is. Since the very first Supercharger, the company has been installing the charging stations at an accelerating pace. Since Tesla first showed off battery swapping last year, the company's Supercharger network has grown from about 10 locations to 178 globally.

Today, owners in the U.S. can drive across the country, up and down the West and East coasts. Further, Tesla has made significant progress with its network in Europe and has begun a network in Asia and Canada. The network of free charging has significantly boosted the value proposition for Tesla's vehicles.

If it really is about prioritization, the execution the company has displayed since it announced battery swapping over a year ago now is undoubtedly valuable enough to justify dropping the project.

Model S. Image source: Tesla Motors.

Battery swapping would be great, but there's no rush. For now, Tesla will fare just fine without the technology -- and there are plenty of other areas the company needs to focus on executing expertly in order to live up to the market's lofty growth expectations.