EV Battery Recall Explained: What Under-Torqued Means

Fourteen vehicles. That is the size of NHTSA recall 26V625000, filed by Rivian on October 2, 2026. One fastener on a high-voltage battery pack had been “under torqued” by an automated station on the assembly line, and a manufacturing operator noticed.

Here is the EV battery recall explained properly, because the phrase “poorly tightened” sounds trivial and the physics underneath is not. A loose bolt on a high-current connection does not just rattle. It heats up, and the heating scales with the square of the current.

Key Takeaways

• Recall 26V625000 covers approximately 14 Rivian R2 vehicles after a fastener on the high-voltage battery pack was found to have been under-torqued by an automated assembly station.
• The stated consequence is specific: the defect “can cause a loss of power while driving.”
• Rivian “is not aware of any customer reports, accidents, injuries, or fatalities related to this issue,” and reprogrammed the assembly station to reject improperly torqued fasteners.
• Torque is only a proxy for what actually holds a joint together, which is the elastic stretch of the bolt. Most of the torque you apply is lost to friction, not stored as clamping force.
• Fourteen vehicles qualifies for a recall because the threshold is unreasonable safety risk, not scale, a principle worth teaching a teenager once.

What Rivian filed

The defect was discovered on September 17, 2026, when a manufacturing operator found that one fastener had been “under torqued” by an automated station on the production line. Fasteners on the high-voltage battery pack may not be properly tightened on affected vehicles.

The consequence Rivian stated: the defect “can cause a loss of power while driving.”

The remedy: Rivian will “repair or replace damaged components on customer vehicles as needed” at no cost. Affected vehicles are at service centres “being inspected to properly torque the fastener or replace damaged components.” The company reprogrammed the assembly line station so it rejects improperly torqued fasteners going forward.

Rivian said it “is not aware of any customer reports, accidents, injuries, or fatalities related to this issue.” This is the R2’s second recall since deliveries began in June 2026, during a period when Rivian aimed to ship 20,000–25,000 R2s by year end to reach profitability for the first time. The same reporting week noted the R2 had set a sales record.

What a bolt is actually doing

This is the part that gets skipped, and it is the whole story.

A bolt does not hold a joint together by being in the way. It holds it together by being stretched. When you tighten a bolt, you pull it elastically, it gets slightly longer, like a very stiff spring, and that stored tension squeezes the two parts together. Engineers call that squeeze preload or clamping force.

Torque is how you create that stretch, and it is a surprisingly poor measurement of it. When you apply torque to a fastener, most of it is consumed overcoming friction: friction in the threads, and friction between the bolt head or nut and the surface it presses against. Only a modest fraction, commonly in the range of ten to fifteen per cent, ends up as tension in the bolt.

Which means a torque reading tells you about the total resistance you encountered, not the clamping force you achieved. A dry thread and an oiled thread at the same torque end up with very different preload. This is why precision assembly often uses torque-plus-angle control: after the joint is snug, the number of degrees you turn is a direct measure of how far the bolt stretched.

So when a recall says “under torqued,” translate it as: the bolt was probably not stretched enough, so the clamping force is lower than specified.

Why a loose high-voltage bolt is not a small problem

Now add current. A high-voltage battery pack in an EV moves hundreds of amperes during acceleration.

A bolted electrical joint conducts across the contact area between two metal faces. Clamping force determines how much of that area is in real metal-to-metal contact. Reduce the clamping force and contact area falls, so electrical resistance rises.

Resistive heating follows P = I²R. The current is squared. At 400 amperes, one extra milliohm of contact resistance dissipates: 400² × 0.001 = 160 watts

One hundred and sixty watts in an area the size of a coin. That is a soldering iron, inside a battery pack. Managing exactly this is part of what a battery pack engineer actually does.

What happens next is a feedback loop that engineers specifically design against. Heat causes thermal expansion and contraction cycles, which relax the joint further, which raises resistance, which produces more heat. Meanwhile vibration from the road works on a joint that no longer has enough preload to resist it.

The practical symptom is exactly what Rivian described: intermittent or lost power delivery while driving. A connection that cannot carry the current reliably will interrupt it.

What goes wrong at each level of tightness

Condition	What happens to the bolt	What happens to the joint	Typical symptom
Far too loose	Barely stretched, no preload	Parts can move relative to each other	Rattle, rapid loosening
Under-torqued	Stretched less than specified	Reduced contact area and clamping	Rising resistance, heat, intermittent power
Correct	Elastic stretch within design range	Full clamping force, stable contact	Nothing. That is the goal
Over-torqued	Past elastic limit, permanently deformed	Clamp force unpredictable	Delayed failure, bolt may snap
Far too tight	Threads strip or bolt yields	Joint cannot be relied on at all	Immediate assembly failure

There is a window, not a direction. More tightening is not safer, which is the counterintuitive fact at the heart of fastener engineering and the single best thing to teach a kid out of this story.

How to Teach Your Kid About Torque and Why Recalls Happen

Ages 5–8: the jam jar window

Hand them a jar with a screw lid. Have them close it so loosely it leaks when tipped, too loose fails. Then have an adult close it so tightly the child cannot open it, too tight fails too, for a different reason. Then find the setting in between.

That is the whole concept: there is a correct amount, and both directions away from it are wrong. No vocabulary needed at this age beyond “just right.”

Ages 9–12: measure torque with a scale

You need a spanner or wrench, a bolt in a vice or a sturdy fixture, and a luggage or fishing scale.

Hook the scale to the wrench at a measured distance from the bolt, say 20 centimetres. Pull until the bolt just turns and read the force. Torque = force × distance. If the scale reads 5 kilograms, that is about 49 newtons, times 0.2 metres, giving roughly 10 newton-metres.

Then repeat with the scale hooked at 10 centimetres. The force needed roughly doubles for the same torque. Your kid has just discovered why a longer wrench feels easier, and why a torque specification is meaningless without stating where you measured it.

Ages 13+: the stretch and the squared current

Two steps for a teenager.

First, the preload idea: have them look up what fraction of applied torque becomes bolt tension and find out why torque-angle control exists. The answer, friction eats most of it, and angle measures stretch directly, is real mechanical engineering and takes twenty minutes to understand.

Second, the heating calculation. Give them P = I²R and ask what one milliohm of extra contact resistance does at 100 A, at 200 A and at 400 A. The answers: 10 W, 40 W, 160 W, show the squaring immediately. Then ask why electric vehicles care about this more than a petrol car’s 12-volt system does.

The question to ask: “Why does a bolt that’s too loose fail, and a bolt that’s too tight also fail?”

If they can explain both directions, not enough stretch versus too much stretch, they understand elastic deformation without having been taught the term. That concept carries into materials science, civil engineering and anything structural.

What to do at home

Run your VIN, once a year

NHTSA’s recall tool takes a 17-character vehicle identification number and tells you whether that specific vehicle “needs to be repaired as part of a recall.” The 14-vehicle Rivian case is exactly why checking by make and model is not enough, recalls are frequently limited to very narrow production windows. Pair the check with a date you already remember.

Know that the repair is free

NHTSA states plainly that owners should contact a dealership “to fix the recalled part for free.” Manufacturers “will notify registered owners by first class mail within 60 days of notifying NHTSA of a recall decision,” so if you have moved recently, the letter may never find you.

Read the consequence line, not the headline

Every recall filing states a consequence. Rivian’s was “can cause a loss of power while driving.” That one sentence tells you how urgently to act, and it is more useful than any amount of commentary. A loss-of-power consequence means do not postpone the appointment.

Treat a small recall as a good sign about the process

Fourteen vehicles, caught by an operator on the line, with the station reprogrammed to prevent recurrence, filed publicly with a number. That is a quality system working. The worrying recalls are large ones discovered through field failures, not small ones discovered in the factory.

What not to do

Do not tighten anything yourself to “be safe.” Over-torquing is a real failure mode that permanently deforms fasteners, and high-voltage battery enclosures are not user-serviceable at any skill level. The correct action is the service appointment, and the distinction between a voluntary company pause and a formal recall is covered in how autonomous vehicle recalls actually work.

What to Watch For Over the Next 3 Months

• Week 4: Watch whether any additional R2 recall appears. Two recalls in four months of deliveries is not alarming for a new model, but a third within a quarter would suggest process issues beyond a single station.
• Month 2 red flags: Watch for recalls where the defect was found through customer reports rather than internal inspection. Rivian’s was found by a manufacturing operator before any customer complaint, which is the better of the two discovery paths by a wide margin.
• Month 3 self-check: Can anyone in your household find the VIN on your car without help? It is at the base of the windscreen on the driver’s side and on the door jamb sticker. That is the one fact that makes every future recall notice actionable.

Frequently Asked Questions

What does “under torqued” actually mean?

That the fastener was tightened with less rotational force than specified, so it was stretched less than designed and therefore clamps the joint with less force. Since torque is mostly consumed by friction, a shortfall in torque usually means a larger shortfall in clamping force.

Why would that cause a loss of power?

A bolted electrical joint conducts across the metal-to-metal contact area, which depends on clamping force. Less clamping means less contact area and higher resistance. Heating follows P = I²R, so at high current a small resistance increase produces substantial local heat, and the joint can interrupt current delivery.

Is 14 vehicles really worth a recall?

Yes, and that is the principle worth understanding. The threshold for a recall is whether a defect “creates an unreasonable safety risk or fails to meet minimum safety standards”, not how many units are affected. A loss-of-power consequence on fourteen vehicles clears that bar.

Should I be worried about EV batteries generally?

This recall is about a bolt, not about battery chemistry. High-current bolted joints exist in any electrical system; EVs simply run far more current than a conventional car’s 12-volt accessories. The failure mode is well understood by the industry and is exactly what torque monitoring on assembly lines is designed to catch.

How do I know if my vehicle is affected?

Run the VIN on NHTSA’s recall tool, and expect a letter if you are the registered owner at your current address. Rivian stated affected vehicles were already at service centres for inspection.

Does this say anything about Rivian’s quality?

A small recall discovered internally, with a corrected assembly process, is evidence of a functioning detection system. It is Rivian’s second R2 recall since June 2026 deliveries began, during a ramp toward 20,000–25,000 units by year end. Ramps produce defects; what matters is whether they are caught in the factory or in the field, and this one was caught in the factory.

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About the author

Ricky Flores is the founder of HiWave Makers and an electrical engineer with 15+ years of experience building consumer technology at Apple, Samsung, and Texas Instruments. He writes about how kids learn to build, think, and create in a tech-saturated world. Read more at hiwavemakers.com.

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Sources

1. TechCrunch. (2026, October 2). “Rivian issues R2 recall for poorly tightened battery packs.” https://techcrunch.com/2026/10/02/rivian-issues-r2-recall-for-poorly-tightened-battery-packs/
2. National Highway Traffic Safety Administration. “Recalls.” https://www.nhtsa.gov/recalls
3. U.S. Department of Energy / EPA. “Electric Vehicles: Energy Efficiency.” fueleconomy.gov. https://www.fueleconomy.gov/feg/evtech.shtml
4. U.S. Department of Energy. “Electric Vehicle Basics.” Alternative Fuels Data Center. https://afdc.energy.gov/vehicles/electric-basics-ev
5. TechCrunch. (2026, September 23). “Zoox grounds Atlanta test fleet after workers report toxic gas exposure symptoms.” https://techcrunch.com/2026/09/23/zoox-grounds-atlanta-test-fleet-after-workers-report-toxic-gas-exposure-symptoms/
6. NGSS Lead States. “Appendix I — Engineering Design in the NGSS.” https://www.nextgenscience.org/resources/ngss-appendices