Tesla Built Room for Cheaper LFP Cells Into the Cybercab Battery Pack. What the Engineer Said, What He Did Not, and Why Your Model Y Pack Is Different
By EV Bandit | Updated October 29, 2026 | 6 min read
Key takeaways
- Tesla battery engineer Robert Sumpf said in a Munro Live interview that the Cybercab pack has unused space so Tesla can move to a lower-energy-density chemistry as it scales, per Teslarati and InsideEVs.
- The Cybercab uses Tesla’s 4680 cells with a nickel-based chemistry today.
- Sumpf gave no date for an LFP version, named no cell supplier and did not say what it would do to range.
- The pack is four individually sealed modules; the Model Y’s pack is structural. Nothing here changes a Model Y you already own.
Tesla designed the Cybercab’s battery pack with empty room inside it, and an engineer says the room is there so cheaper lithium iron phosphate (LFP) cells can go in later. The comments come from a Cybercab deep dive on the Munro Live YouTube channel, reported on October 27 by InsideEVs and Teslarati.
It is an engineering design note, not a product announcement. Here is what was said, what was not, and what separates this pack from the one under a Model Y.
Tesla “protected this pack to go to an even lower energy dense chemistry as we scale.” Robert Sumpf, Tesla, on Munro Live, as quoted by Teslarati
What was said, and what was not
| Topic | On the record | Source |
|---|---|---|
| Spare room | Unused space beside and beneath the modules | InsideEVs, The Next Web |
| Why it is there | Lars Moravy, Tesla VP of vehicle engineering: part of the room exists because “we didn’t need as many batteries as we thought we did” | Teslarati, InsideEVs |
| Chemistry today | 4680 cells, nickel-based | Teslarati, InsideEVs |
| LFP trade-off | LFP stores less energy for its size, so more cells would be needed to offset lost range | Teslarati, InsideEVs |
| Release date for an LFP Cybercab | Not given | Teslarati |
| Cell supplier | Not named | Teslarati |
| Range impact of switching | Not stated | Teslarati |
We have not watched the full Munro Live video; every quote here is as relayed by the outlets named. Teslarati also recalls that Tesla said in early 2025 it was targeting a Cybercab pack under 50 kWh with close to 300 miles of range. That is an older target, not a spec of the pack discussed this week.
Why LFP is the interesting part
InsideEVs describes LFP cells as generally more thermally stable and more durable over many charge cycles, which suits a car meant to run all day, and notes that Tesla engineers say the Cybercab is designed to last 500,000 miles. InsideEVs also says LFP’s lower cost would help hold down the price of a car Tesla plans to build in large numbers, and that Tesla briefly sold LFP-based Model 3s in the U.S. The Next Web adds that LFP became the world’s most used EV chemistry last year.
None of that is a Tesla commitment to switch. It explains why leaving room is a cheap option to hold.
Cybercab pack versus Model Y pack
| Feature | Cybercab (as described) | Model Y |
|---|---|---|
| Layout | Four separate, individually sealed modules, so a failed module can be replaced without replacing the pack (Teslarati) | Structural pack with glued cells (InsideEVs) |
| Serviceability, per Tesla engineers | Eric Earley, Cybercab chief engineer: replacing a whole pack “before half a million miles is a killer on cost” (Teslarati) | Sumpf rated the Model Y structural pack “a grade D” on this point (Teslarati only) |
| Trade-off | Sumpf estimated a fully structural pack gains about 10% more cell volume, but said “the issue is the service cost” (Teslarati) | The structural design is why a Model Y pack is harder to repair module by module |
The “grade D” rating and the 10% figure appear in Teslarati’s write-up only, so treat them as one outlet’s account of the video until you see the clip yourself.
What this means for owners
If you drive a Model Y, your pack does not change. The story is about a purpose-built robotaxi designed around a long service life and cheap pack replacement, and about Tesla leaving itself a path to cheaper cells. For owners, the signal worth watching is whether LFP shows up in more Tesla products over time, which Tesla has not said. Tesla VP Lars Moravy separately said the Cybercab line is “currently outpacing our deployments,” per The Next Web and Teslarati, which fits the fleet counts we examined in our Texas registry piece. Whether your own car will ever join a ride network is a separate question we answer in our seven-question explainer.
Frequently asked questions
Is the Cybercab getting LFP batteries?
Not announced. An engineer said the pack was built with room to move to a lower-energy-density chemistry as Tesla scales. No date or supplier has been given.
What battery does the Cybercab use now?
Tesla’s own 4680 cells with a nickel-based chemistry, per InsideEVs and Teslarati.
Why would Tesla use LFP?
InsideEVs says LFP cells are cheaper, generally more thermally stable and last through more charge cycles, at the cost of lower energy density.
Does this affect my Model Y?
No. The Cybercab pack is a different design from the Model Y’s structural pack.
How we reported this
We read the InsideEVs (via Yahoo Autos), Teslarati and The Next Web write-ups in full and quote only short, attributed passages. The original source is the Munro Live video, which we did not review. Where a detail appears in only one outlet, we say so. Spot an error? Tell us in the group below and we will correct this page.
Would a cheaper LFP robotaxi change how you feel about Tesla’s fleet plans? Tell us in the Tesla Model Y Owners group.
Sources
- Teslarati: Tesla’s Cybercab battery design could make robotaxis even cheaper (Oct 27, 2026)
- InsideEVs via Yahoo Autos: Tesla Designed The Cybercab To Use LFP Cells In The Future (Oct 27, 2026)
- The Next Web: Tesla built the Cybercab’s battery pack with room for cheaper LFP cells (Oct 27, 2026)