Tesla's LFP (iron) batteries compared. Which one should you buy?

For the first time, you have a choice of battery for your new Tesla. Not battery size, you've always had that choice. Now you have a choice of which chemical elements you want. Here are some thoughts about how you can choose intelligently. It all depends on your financial situation, your plans for long-distance travel, and the geography of your area.

Elon Musk explains Tesla's LFP Battery strategy for US Model 3 SR+.

There's a delay in delivery times for the Model 3 SR+. This is August 2021. Delivery dates are some time in 2022. If you're buying one of the more expensive models or one of the bigger battery sizes, you can take delivery sooner, but the Model 3 SR+ might be the one you want. It's the one I bought. I knew that road trips would take a bit longer with the shorter-range battery since I'd have to pull off the road to charge more often. So far, I haven't had the opportunity to take a multi-day road trip. There's a pandemic after all. But I knew that would eventually become an issue. I really like road trips. But I have to say, even when I took lots of road trips, most of my driving was local.

Had I opted for the long-range Model 3, I'd have paid an extra ten thousand dollars in order to get 90 miles of extra range. That extra ninety miles of range would come into play only 30 or 40 days each year, and the time it would save me would be about an hour each day of a multi-day road trip. It didn't make financial sense.

Now that Tesla is experiencing the same production delays as are all the other auto manufacturers, they're giving their shorter delivery dates to buyers of the more expensive, read higher profit, models. But they're making an exception and giving shorter delivery dates if you buy a Tesla with an LFP battery rather than an NCA battery.

So what's the difference? Both batteries are actually lithium-ion batteries. They both use lithium. So that's not a difference. But the NCA battery uses nickel, cobalt, and aluminum in addition to lithium. The LFP battery uses Iron and Phosphate (phosphorus combined with oxygen) in addition to lithium. The main differences for you to consider are that the LFP battery has a slightly shorter range, 253 miles, as opposed to the NCA battery, 263 miles. But that slight difference in range is deceptive. The NCA battery probably shouldn't be charged to 100%. Fully charging the battery causes damage to the battery making it likely to deteriorate over the years of ownership. It's perfectly fine to charge the LFP battery to 100% so the driver experience is pretty much the same except for a couple caveats.

The LFP battery is heavier. That's why the range is slightly lower on the ordinary battery test cycle. The extra weight causes extra rolling resistance. That's why the range is reduced. There's probably also some extra wear on the tires. The problems of extra weight and extra rolling resistance are probably not all that bothersome for most drivers.

But, if you live in an area where there are lots of hills so that you're changing your elevation every time you drive, you're going to notice a much more pronounced decrease in range with the heavier LFP battery. You can experience the difference more intimately by getting a wagon or a wheelbarrow. Roll it around on level ground. Then put a heavy object in it and roll it around some more. You'll notice a bit more rolling resistance, but you'll be able to deal with the extra rolling resistance easily.

Now do that same experiment on a hill. Pull the wagon or push the wheelbarrow up the hill empty. No problem, right? Then put in the heavy object and go up the hill again. Big difference. Your car feels the same way. You'll get a bit of extra regenerative braking going down the hill with the heavier battery, but it won't be enough to make up the difference. The second law of thermodynamics causes that. That pesky high school physics topic, entropy, strikes again.

LFP batteries are also much more environmentally friendly.

There's also one more issue, cold weather.

LFP batteries charge more slowly in cold weather than NCA batteries and their range decreases somewhat more than NCA batteries in cold weather. Keep in mind that both NCA and LFP do worse in cold weather. It's just that LFP batteries get more of a cold weather effect than NCA batteries. When you're on a road trip and navigating to a Supercharger, your car will prewarm its batteries. That will alleviate the slower charging problem to some extent, but you'll be at the Supercharger six or seven minutes longer in winter with LFP batteries. That will be a problem if you plan to use your car in such a way as to need to do lots of cold weather supercharging. It won't matter at all if you're just going to charge your car overnight in your garage.

So flatlanders will be fine with the LFP battery. If you live in a hilly area, you may want to wait for the NCA-equipped Tesla Model 3 SR+. But remember, the lower range problem is only a problem for people planning to do lots of mountain driving. In that case, you actually ought to invest the extra $10K in the long range Model 3.

One last issue about the LFP battery. Remember, earlier in this article, I mentioned that you shouldn't fill the NCA battery up to 100% charge, but you should fill the LFP battery up to 100%? That's true at home, but it's not true on road trips. On road trips, you want to minimize the amount of time you're stopped. The way to do that is to never charge the battery to 100% no matter which kind of battery you have. When you plug your car in at a modern high voltage supercharger, you'll see your car adding four to five hundred miles per hour of connection. That doesn't mean you'll be up to 100% in a half hour. You won't. As the battery gets charged, the rate of charge drops significantly for both the LFP and the NCA batteries. Once you get above 80%, the battery charges very slowly. So figure out how much charge you need to get you to the next place you're going to charge up and give yourself enough charge to get you there with a twenty or thirty mile cushion. Charging your battery more than that is a waste of time. Your travel time.

Tesla's Battery Day

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A Closer Look at Tesla's Updated Energy App - What's Changed

Not a Tesla App

One of the big undocumented changes in Tesla’s 2024 Holiday Update was the changes to the Energy app. While the Model S, Model X, and Cybertruck received the Consumption tab in the Energy app for the first time, the changes made for those models also carried over to Model 3 and Model Y.

The Consumption tab lets you view your vehicle’s consumption over recent trips as well as view projected range estimates based on historical usage, but it now offers different options.

Sadly, legacy Model S and Model X vehicles produced before the 2021 refresh still don’t have access to the Energy app at this time.

Energy App

Tesla’s Energy App previously let you view a lot of in-vehicle data on what is consuming energy and how to improve your energy consumption. It was previously refreshed in 2022 and brought Drive, Park, and Consumption tabs to help compare actual vehicle energy consumption versus what you’d expect from the EPA ratings.

The old Energy App's consumption page.

Not a Tesla App

Key Changes

The Energy App has seen a lot of changes - mostly in the name of simplicity and reducing confusion. Some changes reduce functionality, but others bring even more. All of these changes impact the Consumption tab - the Park and Drive sections are unchanged.

Distance

Previously, you were able to switch the graph on the Consumption tab to show the last 5, 15, or 30 miles. Instead, it is now a static display of the last 200 miles (or 300km). This means your last 200 miles of driving - whether it's a single trip or multiple trips. Your range prediction and energy usage are now based on 200 miles of driving instead of the previous selectable distance.

This allows for a more reasonable range prediction as small bursts of high-energy usage, such as time spent accelerating to highway speeds from an offramp, are now less of an impact and are instead averaged out by regular driving.

However, for those who love to take their Teslas to the track or tow regularly, this makes the consumption significantly less useful because you can no longer see your actual energy usage for the type of driving you’re doing. This could be fixed with a reset button or by adding the ability to select your distance — similar to before.

Projected Range and Average Wh/mi

Unfortunatley, the Instant Range button has been removed, and the graph is now locked on what was previously the Average Range. Essentially, you cannot view your real-time range based on current instantaneous consumption - but you can view the overall projected range.

Additionally, average Wh/mi and projected range are still displayed - but in different areas compared to before. The projected range is displayed on the center-left side of the graph, while the average Wh/mi is now displayed at the top of the screen.

Not a Tesla App

Compare Vs EPA

Another new feature is that the average range is now compared to the EPA estimated range in terms of wh/mi. You’ll be able to see whether your driving style and conditions put you over or under the EPA estimate in a pretty quick way, which is helpful.

This new comparison is located just under your average Wh/mi.

Small and minor adjustments to your driving style - like not taking off like an electric lightning bolt at every red light - will make a big difference to your range. Don’t worry - we know its hard, we love doing it too! Other things - such as driving downhill versus uphill, will have an impact that you can’t necessarily avoid unless you’re old enough that you went to school uphill both ways.

Total Vehicle Consumption

The final new feature is a total vehicle consumption number at the bottom left, under the chart. It will tell you how much energy you’ve consumed over the distance you’ve driven so far. This is a convenient way of seeing exactly how much energy you’ve used.

Bug

There’s currently a bug in the way the Y-axis is labeled. The yellow area of the graph means the vehicle is using energy, while green means the vehicle is generating energy through regenerative braking. However, the Y-axis is currently mislabeled and shows generated energy as using about 100-200 Wh/mi.

The confusion appears to be due to the dark gray line, which looks like “0” on the Y-axis but actually represents the vehicle’s rated range. We would expect this to be Y-axis 0, since above the line the graph is yellow, and underneath it, the graph is green. However, this line is at about the 240 Wh/mi mark but will vary depending on the vehicle.

Due to this bug, it’s currently not possible to see how much energy is being generated.

Dynamic Y-Axis

The Y-axis in the Consumption tab is now dynamic - it will expand and contract automatically based on the driving data. We’ve seen it go from 400 Wh/mi all the way up to 800 Wh/mi. You likely need to be in a Model S Plaid or Cyberbeast with Launch Mode to see numbers much higher than that.

We’re sad to see the X-axis get locked to 200 miles, but being able to see total vehicle consumption and comparing average consumption against what’s rated is equally, if not even more valuable.

Overall, the new and improved Consumption tab is simpler and doesn’t require user input. While it takes away some features, it makes it easier for drivers who may not use it regularly. The most important piece is the projected range, which is now easier to see and understand unless you're towing and need the historical usage erased because it’s now irrelevant to your current drive. Hopefully, Tesla will allow you to scrub the graph horizontally in the future, adding the ability for the user to adjust the X-axis dynamically.

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Tesla Smart Voice Assistant Coming - Vehicle Responds for First Time

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If you hop into your Tesla and say ‘Hi’ or ‘Hello’ after pressing the Voice Command button, there is a good chance it’ll reply with “Hello!” This is the newest and most interesting piece of news pointing us to the conclusion that a Tesla voice assistant is on the way.

Previously, if you tried this, it would simply return “Command not understood.” This is the first time the vehicle is responding and interacting with the user.

Experience It Yourself

You’ll need to have your vehicle language set to English. Once that’s done, you can use the voice command button on your steering wheel or yoke - for the Model 3 and Model Y, push the right wheel button, and for the Model S, Model X, and Cybertruck, press the button. Then go ahead and say Hi or Hello.

The Hello! response may even have regional differences. For a German Tesla owner, after setting his language to English, the response came back as “Hallo.” We’re interested to see what the responses may be in other regions, so let us know if you notice anything interesting.

We’ve tried a few other basic things, but it seems that, for now, the vehicle only replies to a simple greeting. Asking it what time it is or the $TSLA stock price doesn’t seem to do much yet - unless you’re in China with the updated Smart Assistant.

Not a Tesla App

Server-Side Update

This update appears to be happening over Tesla’s voice system backend and doesn’t require the Holiday Update. Users who aren’t on the Holiday Update are reporting that they’re getting this new response as well.

We already know that Tesla interprets speech remotely, and the driver’s voice is not processed in the vehicle. Instead, the voice snippet is transmitted to Tesla’s servers, where Tesla processes it and sends a response back to the vehicle so that the vehicle can interpret it. This is unlikely to change with a smart assistant, as Elon Musk has already said that Grok will still process data server-side instead of on-device.

Many users recently also noticed significant improvements to voice commands, saying that the system understands them better and that responses now come back faster.

All of these things point to a new backend system for voice processing that Tesla is testing. It’s not unusual for a company to switch to a new backend process but keep the capabilities the same as the legacy system until it’s ready to roll out the new features. At that point, it’s simply a flip of a switch to allow the new capabilities.

The new smart assistant that was rolled out in China is mostly a backend change, with the in-vehicle experience largely remaining the same. The activation method (button press) and user interface remain the same. What changed is the response that comes back from the server, and the assistant gained a voice. The new voice we receive with a smart assistant could very well be the new voice users are experiencing in the navigation system in newer vehicles.

Below is a video of the voice assistant in China:

Vehicle Support - Intel?

When China received the Smart Assistant, it was locked to cars equipped with AMD Ryzen processors only. Shortly after its initial launch, it became available to older cars with Intel Atom processors as well.

However, we’re not sure whether it would apply to legacy Model S and Model X owners. A legacy vehicle owner had their vehicle report “Command not understood” when they tried the ’Hi’ voice command.

Grok for Tesla

Elon has previously mentioned that Tesla vehicles would receive Grok AI. Grok, as of yet, still doesn’t have live speech support like other LLM models such as OpenAI’s ChatGPT or Google’s Gemini. However, a major update to Grok just brought massively improved image generation via a new model called Aurora.

xAI has been hard at work improving Grok, and we’re sure that live speech support is on its way soon. Once that feature arrives on X, Tesla will likely be well-positioned to enable a Grok-powered smart assistant fleet-wide with a flick of a switch.

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