Lifestyle
EV Basics – What’s a kilowatt hour?
So what’s a kilowatt hour or shall we ask Watts a Kilowatt hour?
As more car buyers take the plunge into owning an electric vehicle (EV), it’s important to educate on the EV specific units of measure which differ greatly than your traditional gas burning vehicle. What is a kilowatt hour? How does it differ from a kilowatt? And why does this even matter?
Background
First, let me preface everything by saying that much of what I’m about to write is based on US specific units of measure since that’s what I’m familiar with. For instance, miles vs km and US dollars versus Euros. I’m also over simplifying and breaking things down to basic laymen terms so please cut me some slack if you already know all this!
If you receive a utility bill for your residence then you should probably be somewhat familiar with, or have heard of, a kilowatt (kW) and kilowatt hours (kWh) since that’s what electricity bills are measured on. Your EV is no different and uses these same units of measure although it’s probably something you haven’t paid much attention to in the past.
kW and kWh Units
Depending on the EV display you may see watt hours (Wh) or kilowatt hours (kWh) in some places and watts (W) and kilowatts (kW) in others. The kilo or k is a standard prefix meaning a thousand. So 1 kWh is 1,000 Wh. If you own your EV long enough you may just get to the next level, megawatt hour (MWh) which would be one million Wh!
Now for the fundamental definitions:
kW is a measurement of power and kWh is a measurement of energy.
Energy is the amount of work that can be performed. kWh, calories, joules are all units of energy. A slice of pizza has 285 calories which is 0.33 Wh of energy that can be derived from that substance. Energy can be converted and change in form. For instance we can convert that slice of pizza to heat by setting it on fire. The fuel is the pizza, but don’t try converting it in your EV!
Power is the rate at which energy is generated or used. kW is a unit of power. When you accelerate in your EV you’re using power and when you decelerate with regenerative braking you’re generating power. The Model S dedicates half the speedometer display to the unit of power on the right side. There you can see how many kW you are using (indicator is orange) or generating (indicator is green) at any instance in time. It’s great to be able to see this however you can’t easily convert this into a cost. In order to do that, you’ll need to measure it over time and convert it into a unit of energy.
Power is similar to your speed. 50mph is your speed, but you have to maintain that for an hour to travel 50 miles. Similarly, 40kW is how much power you’re using and you’ll have to maintain that consumption for one hour to use 40kWh. If you spend half that hour at 40kW and the other half at 20kW you’ll end up consuming 30kWh. Power usage is constantly changing and will depend on driving habit as well as usage of onboard amenities such as your seat heaters or A/C unit.
A 100W incandescent light bulb used over 1 hour will consume 100Wh of energy. If you use that 100W bulb for 8 hours every day, it will consume 800W or 0.8 kWh per day. After 30 days, it will have consumed 0.8kWh x 30 = 24 kWh. After 365 days it will have consumed 292 kWh. Measuring your EV is done in a similar fashion but keep in mind that an EV can both use and generate power (regenerative braking) over periods of time. The difference or net power used (used – generated) is what you see reported on your EV display.
Units for Charging
Charging your EV you transfers energy back into your battery so you’re effectively storing kWh for later use. EVs report charging in different ways but the most common is to report by kW and kWh added. So a charge rate of 6 kW is storing 6kWh for every hour of charge. If you’re charging at 6kWh and charge for 2 hours you’ll have an extra 12kWh added at the end of your charge.
When it comes to driving, we’re trained to think in terms of miles, but not all miles travelled are the same when it comes to energy usage since there are variations in terrain and elevations. Weather also plays a factor for each mile travelled. A kWh stored, on the other hand, is always the same. The main difference is how you use that kWh.
The Model S offers the option to display charge rate by kW and kWh or by miles. Not surprisingly most Tesla owners choose to display charge rate in terms of miles. However it’s important to note that there’s a huge assumption being made about how many miles you can drive on a Wh and that assumption needs to account for charging efficiency. Tesla uses their proprietary algorithm to compute this value.
On Tesla’s online calculator they assume 300Wh/mile average use and a 90% charging efficiency. My own measurements show the average Wh/mile usage to be a bit higher (306 lifetime average) and the charging efficiency to be slightly less (81% last month).
What about Volts vs Amps?
Now you may be wondering how all this relates to volts and amps. This gets us back to the basics. One can calculate watts by multiplying volts with amps. W = V x A. So if you’re at a public charger and it’s charging at 199V and 30A (reference picture above), you’re essentially charging at 199V x 30A = 5,970W or about 6kW. This equates to 6kWh added after an hour of charging, but as we all know this is based on an ideal world where it charges at 100% efficiency with no loss. At 199V and 30A, the Model S is reporting this as a rate of 16 mi/hr.
Lets check that math:
5,970W/300Wh/mile standard assumption = theoretical 20 miles/hr charge rate. But that doesn’t account for charging efficiency. The Model S is reporting 16 mi/hr so its assuming an 80% charging efficiency (16/20) under these conditions.
Cost
Utility bills price per kWh. Your electric company may break it down by distribution vs generation, time of use, etc. and then associate a different cost per kWh on each pricing tier. It seems complex but you can simplify this.
To figure out your total cost per kWh just take your total amount of the bill and divide it by your total energy usage for the same period. That may include the various service fees, taxes, etc. but in the end you’re paying the electric company that total amount for those kWh regardless of what it’s derived from. Knowing this will help you calculate the costs for your road trips based on the kWh used.
Summary
Elon Musk
The FCC just said ‘No’ to SpaceX for now
SpaceX is fighting the FCC for spectrum that could put satellites inside every smartphone.
SpaceX was dealt a new setback on April 23, 2006 by the Federal Communications Commission (FCC) after the U.S. government agency dismissed the company’s petition to access a Mobile Satellite Service spectrum that would allow direct-to-device (D2D) capabilities.
The FCC regulates communications by radio, television, wire, and cable, which also includes regulating D2D technology that lets your existing smartphone connect directly to a satellite orbiting Earth, the same way it would connect to a cell tower.
Elon Musk’s SpaceX has been building toward this through its Starlink Mobile service, formerly called Direct-to-Cell, in partnership with T-Mobile. The service officially launched on July 23, 2025, starting with messaging and expanding to broadband data in October of that year.
T-Mobile Starlink Pricing Announced – Early Adopters Get Exclusive Discount
It’s worth noting that SpaceX is not alone in this race. AT&T and Verizon have their own satellite texting deals with AST SpaceMobile, while Verizon separately offers free satellite texting through Skylo on newer phones.
The regulatory foundation for all of this dates to March 14, 2024, when the FCC adopted the world’s first framework for what it called Supplemental Coverage from Space, allowing satellite operators to lease spectrum from terrestrial carriers and fill gaps in their coverage. On November 26, 2024, the FCC granted SpaceX the first-ever authorization under that framework, approving its partnership with T-Mobile to provide service in specific frequency bands. SpaceX then went further, completing a roughly $17 billion acquisition of wireless spectrum from EchoStar, which gave it the ability to negotiate with global carriers more independently.
Starlink’s EchoStar spectrum deal could bring 5G coverage anywhere
This recent ruling by the FCC blocked SpaceX from going further, protecting incumbent spectrum holders like Globalstar and Iridium. But the market momentum is already in motion. As Teslarati reported, SpaceX is targeting peak speeds of 150 Mbps per user for its next generation Direct-to-Cell service, compared to roughly 4 Mbps today, which would bring satellite connectivity close to standard carrier performance.
With a reported IPO targeting a $1.75 trillion valuation on the horizon, each spectrum fight, carrier deal, and regulatory win or loss now carries weight beyond just connectivity. SpaceX is quietly becoming the infrastructure layer underneath the phones of millions of people, and the FCC’s next move will help determine how much further that reach extends.
FCC Satellite Rule Makings can be found here.
Elon Musk
Elon Musk talks Tesla Roadster’s future
Elon Musk confirmed the Roadster as Tesla’s last manually driven car, with a debut coming soon.
During Tesla’s Q1 2026 earnings call on April 22, Elon Musk made a brief but notable comment about the long-awaited next generation Roadster while describing Tesla’s future vehicle lineup. “Long term, the only manually driven car will be the new Tesla Roadster,” he said. “Speaking of which, we may be able to debut that in a month or so. It requires a lot of testing and validation before we can actually have a demo and not have something go wrong with the demo.”
That single statement is the entire Roadster update from yesterday’s call, and while it represents another timeline shift, it comes as no surprise with Tesla heads-down-at-work on the mass rollout of its Robotaxi service across US cities, and the industrial scale production of the humanoid Optimus.
The fact that Musk specifically framed the Roadster as the last manually driven Tesla is significant on its own. As the rest of the lineup moves toward full autonomy, the Roadster becomes something rare in the Tesla-sphere by keeping the driver in control. Driving enthusiasts who buy a $200,000 supercar are not doing so to be passengers. They want the physical connection to the road, the feel of acceleration under their own input, and the experience of controlling something with that level of performance. FSD, however capable it becomes, removes that entirely. The Roadster signals that Tesla understands this distinction and is building a car specifically for the people who consider driving itself the point.
Tesla isn’t joking about building Optimus at an industrial scale: Here we go
The specs for the Roadster Musk has teased over the years are genuinely unlike anything in production. The base model targets 0 to 60 mph in 1.9 seconds, a top speed above 250 mph, and up to 620 miles of range from a 200 kWh battery. The optional SpaceX package takes it further, rumored to add roughly ten cold gas thrusters operating at 10,000 psi, borrowed directly from Falcon 9 rocket technology. With thrusters, Musk has claimed 0 to 60 mph in as little as 1.1 seconds. In a 2021 Joe Rogan interview he went further, stating “I want it to hover. We got to figure out how to make it hover without killing people.” Tesla filed a patent for ground effect technology in August 2025, suggesting the hover concept has not been abandoned. The starting price remains $200,000, with the Founders Series requiring a $250,000 full deposit. Some reservation holders placed those deposits in 2017 and are approaching a full decade of waiting.
With production now targeted for 2027 or 2028 at the earliest, the Roadster remains Tesla’s most audacious promise and its longest-running delay. But if what Musk is testing lives up to even half of what he has described, the demo alone should be worth waiting for.
Elon Musk says the Tesla Roadster unveiling could be done “maybe in a month or so.”
He said it should be an extraordinary unveiling event. pic.twitter.com/6V9P7zmvEm
— TESLARATI (@Teslarati) April 22, 2026
Elon Musk
Tesla isn’t joking about building Optimus at an industrial scale: Here we go
Tesla’s Optimus factory in Texas targets 10 million robots yearly, with 5.2 million square feet under construction.
Tesla’s Q1 2026 Update Letter, released today, confirms that first generation Optimus production lines are now well underway at its Fremont, California factory, with a pilot line targeting one million robots per year to start. Of bigger note is a shared aerial image of a large piece of land adjacent to Gigafactory Texas, that Tesla has prominently labeled “Optimus factory site preparation.”
Permit documents show Tesla is seeking to add over 5.2 million square feet of new building space to the Giga Texas North Campus by the end of 2026, at an estimated construction investment of $5 billion to $10 billion. The longer term production target for that facility is 10 million Optimus units per year. Giga Texas already sits on 2,500 acres with over 10 million square feet of existing factory floor, and the North Campus expansion is being built to support multiple projects, including the dedicated Optimus factory, the Terafab chip fabrication facility (a joint Tesla/SpaceX/xAI venture), a Cybercab test track, road infrastructure, and supporting facilities.
Credit: TESLA
Texas makes strategic sense beyond the existing infrastructure. The state’s tax structure, lower labor costs relative to California, and the proximity to Tesla’s AI training cluster Cortex 1 and 2, both located at Giga Texas and now totaling over 230,000 H100 equivalent GPUs, means the Optimus software stack and the factory producing the hardware will share the same campus. Tesla’s Q1 report also confirmed completion of the AI5 chip tape out in April, the inference processor designed specifically to power Optimus units in the field.
As Teslarati reported, the Texas facility is intended to house Optimus V4 production at full scale. Musk told the World Economic Forum in January that Tesla plans to sell Optimus to the public by end of 2027 at a price between $20,000 and $30,000, stating, “I think everyone on earth is going to have one and want one.” He has previously pegged long term demand for general purpose humanoid robots at over 20 billion units globally, citing both consumer and industrial use cases.
SpaceX Board has set a Mars bonus for Elon Musk
Tesla’s biggest rivals fights charging wait times with a modern approach
