Cannonball Run EV record attempt in a modified R1T

[Dark-Fx]

One really important metric that the video didn't talk about is at what average C rating they charge. The extended Rivian might charge at 500kw overall, but it also has to fill a battery that's over 3x the size of the Taycan. 500/310 = 1.61C. A max pack truck is already pretty close to this C rating: 220kw / 141kwh = 1.56C

The Taycan can charge at 320kw, and it just needs to fill a 97kwh battery. 320/97 = 3.29C! For an equivalent C rating charge, the extended Rivian would need to charge at 1 megawatt! The area under the charging curve is also what matters, but this is just napkin math. I'm not even considering the charging overhead associated with plugging into two chargers and configuring the truck to accept it. It does look like part 2 will reduce that overhead though.

They're also not getting 500-600 miles every stop, as that would require full batteries. They do get a jump ahead with both batteries fully charged though. Realistically they'd be getting up to 80% at each stop, though I'm guessing all EV cannonballs have charging cycles like this.

The real elephant here is that American infrastructure isn't ready for two digit C charging like China is starting.

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[Dark-Fx]

Probably not. There, I just answered the central question in the video and saved everyone 10 min.

Not modified enough. Definitely needs to not be R1T shaped.

 

[CharonPDX]

Summary: They bought two original R1-Large battery packs, ripped them apart to be 6-modules each, combined them into one 12-module pack (basically making the original "Max Pack") and mounted it in the bed, with control circuits and DC-to-DC converters shoved into the spare space behind the stock pack and the Gear Tunnel, using the DC-to-DC converter to feed power from the add-on pack to the stock pack.

When they get to a charging station, they plug the Rivian's main pack into one charger, and the add-on pack in the bed to a second charger. (Which charges at higher power since it's at higher voltage!)

The big problem is that the add-on pack is…. "kludgey". The charging circuitry hangs out on the tailgate when the tailgate is open, so they can't recharge in the rain - and they hit a torrential downpour during what was supposed to be their second charge stop. And the BMS doesn't provide any useful information while there is power flowing in or out - only when the pack is "resting." Which means they really couldn't tell how full the pack was when driving.

And the fact that the add-on pack is just constantly feeding power to the Rivian's main pack while driving (which Rivian's vehicle control system has no problem with,) it *DOES* mean that the vehicle's calculation of efficiency is thrown right out the window, so they had *NO* idea how efficient they really were, or how far they could actually go.

They thought that in theory they could go ~600 miles on a charge, but chickened out and stopped at only ~400 miles, and they had plenty of battery left when they got there.

But the rainstorm at the second charge stop caused them to abandon the run.

They teased *MAJOR* changes for the next attempt, including some noticeable modifications to the vehicle itself. (The first one had almost no modifications to the vehicle, just adding things nondestructively.)

(This summary hand-typed by a human who watched the video - any mistakes are pure human error, not AI hallucinations.)

 

[KRIV_ian]

The Rivian Roamer leaderboards had some crazy efficiency numbers for a truck a couple of months ago so I'm wondering if this was the canonball attempt.

R1T 2022

7.43 mi/kWh

446.4 mi

-290 ft

Oct 17, 2025

 

[mkhuffman]

One really important metric that the video didn't talk about is at what average C rating they charge. The extended Rivian might charge at 500kw overall, but it also has to fill a battery that's over 3x the size of the Taycan. 500/310 = 1.61C. A max pack truck is already pretty close to this C rating: 220kw / 141kwh = 1.56C

The Taycan can charge at 320kw, and it just needs to fill a 97kwh battery. 320/97 = 3.29C! For an equivalent C rating charge, the extended Rivian would need to charge at 1 megawatt! The area under the charging curve is also what matters, but this is just napkin math. I'm not even considering the charging overhead associated with plugging into two chargers and configuring the truck to accept it. It does look like part 2 will reduce that overhead though.

They're also not getting 500-600 miles every stop, as that would require full batteries. They do get a jump ahead with both batteries fully charged though. Realistically they'd be getting up to 80% at each stop, though I'm guessing all EV cannonballs have charging cycles like this.

They made it clear in the video that they are not worried about stress on the auxiliary pack. As long as it doesn't blow up.

They monitor the pack temp and control the current to keep the temp in the safe range, but at a much higher rate than would ever be used if you cared about long term battery health. And since they use two chargers to charge both batteries at the same time, 400 kW is easily achieved as an average charge rate for the truck. They hit 300 kW on the aux pack and can maintain that for as long as they keep the battery temp in the safe range.

The challenge was knowing when to stop the charge when they can't measure SoC with their equipment. I think attempt 2 will include the ability to monitor aux battery SoC and allow them to use most of the battery before stopping to charge. It will also help them know when to stop charging.

If they can cut down on the aux pack setup time, because that added a lot of downtime before charging could start, they have a great shot at the fastest Cannonball BEV time.

 

[madhat]

I think it's cool that they were able to do this without the truck freaking out.

 

[Rivian Roamer]

The Rivian Roamer leaderboards had some crazy efficiency numbers for a truck a couple of months ago so I'm wondering if this was the canonball attempt.

R1T 2022

7.43 mi/kWh

446.4 mi

-290 ft

Oct 17, 2025

Not during the attempt but yes. Same truck.

 

[Rade]

If they can go 500-600 miles between charges, and charge at an average speed of 400-500 kW, they should win.

...unless you have a bladder that is only good for 150 miles tops...

 

[beatle]

They made it clear in the video that they are not worried about stress on the auxiliary pack. As long as it doesn't blow up.

They monitor the pack temp and control the current to keep the temp in the safe range, but at a much higher rate than would ever be used if you cared about long term battery health. And since they use two chargers to charge both batteries at the same time, 400 kW is easily achieved as an average charge rate for the truck. They hit 300 kW on the aux pack and can maintain that for as long as they keep the battery temp in the safe range.

The challenge was knowing when to stop the charge when they can't measure SoC with their equipment. I think attempt 2 will include the ability to monitor aux battery SoC and allow them to use most of the battery before stopping to charge. It will also help them know when to stop charging.

If they can cut down on the aux pack setup time, because that added a lot of downtime before charging could start, they have a great shot at the fastest Cannonball BEV time.

If they average an aggregate 400kw charging speed, that's an average 1.29C, which means it'll take 46 minutes to fill the 310kwh batteries. The Taycan will do 10% to 80% in 18 minutes. That's an average of 226kw, or 2.32C! The Rivian just charges very slow relative to the size of its battery, and it's way less efficient with its energy than a smaller vehicle. Even a flat 500kw (2.77C) charging of the aux pack is isn't enough to make up for the slow charging of the main battery.

But with all that extra capacity, the Rivian can go further on each charge. Let's say both vehicles can do 70% of their rated range per stop. That puts the Taycan around 200 miles, and the extended Rivian around 400. The Cannonball is a little under 3k miles, but let's say 3k due to a less optimal route due to charging stops (and because I'm still using a napkin for this calculation). After the first full battery is drained, the Rivian needs to go another 2500 miles, Porsche will go 2700. Rivian needs 7 stops, Porsche needs 14. But each stop with the Rivian takes 46 minutes because it charges so slow relative to its battery capacity. So the Rivian spends 7*46 = 322 minutes charging (not including setup) and the Taycan is 14*18 = 252 minutes. That's much better than a stock truck, but it's still behind, even before we start to consider the charging stop overhead being much higher.

This doesn't take into account battery efficiency, and what the right balance of speed vs. efficiency is, since everyone knows faster travel speed will crater your efficiency. I think the Rivian will be worse here due to its overall drag, but I have run out of napkin for more math.

I am no Porsche fanboy, but I still think adding battery capacity has limited returns for an EV cannonball run. I will still watch part 2 to see what they can do though.

 

[mkhuffman]

If they average an aggregate 400kw charging speed, that's an average 1.29C, which means it'll take 46 minutes to fill the 310kwh batteries. The Taycan will do 10% to 80% in 18 minutes. That's an average of 226kw, or 2.32C! The Rivian just charges very slow relative to the size of its battery, and it's way less efficient with its energy than a smaller vehicle. Even a flat 500kw (2.77C) charging of the aux pack is isn't enough to make up for the slow charging of the main battery.

But with all that extra capacity, the Rivian can go further on each charge. Let's say both vehicles can do 70% of their rated range per stop. That puts the Taycan around 200 miles, and the extended Rivian around 400. The Cannonball is a little under 3k miles, but let's say 3k due to a less optimal route due to charging stops (and because I'm still using a napkin for this calculation). After the first full battery is drained, the Rivian needs to go another 2500 miles, Porsche will go 2700. Rivian needs 7 stops, Porsche needs 14. But each stop with the Rivian takes 46 minutes because it charges so slow relative to its battery capacity. So the Rivian spends 7*46 = 322 minutes charging (not including setup) and the Taycan is 14*18 = 252 minutes. That's much better than a stock truck, but it's still behind, even before we start to consider the charging stop overhead being much higher.

This doesn't take into account battery efficiency, and what the right balance of speed vs. efficiency is, since everyone knows faster travel speed will crater your efficiency. I think the Rivian will be worse here due to its overall drag, but I have run out of napkin for more math.

I am no Porsche fanboy, but I still think adding battery capacity has limited returns for an EV cannonball run. I will still watch part 2 to see what they can do though.

Using your rough math, the ER R1T will lose by 70 minutes, assuming travel speed is the same and efficiency is the same. It is hard to imagine the truck running as efficiently at the Taycan.

Another option is to charge the aux battery at 500 kWh until it is full and then leave the station regardless of what the SoC of the main pack is. That gives them a better shot because now they are not slowed down by the speed of the main pack. It is practically irrelevant. It means more stops, but each stop will be much faster.

If they can charge all 180 kWh of the aux pack at 500 kW, they will only need 22 minutes to fully charge it. The setup time will be key.

 

[beatle]

I also didn't factor in the routing/speed "penalties" associated with the additional charging stops the Porsche would have to make, though it also sounded like routing to stations with two independent chargers was going to be a challenge for the Rivian.

The Lucid Gravity would be a great cannonball candidate based on this article. It charges crazy fast and has a larger battery which yields more range than the Taycan, despite lower efficiency.

I didn't watch the OOS cannonball video to see what kinds of hurdles they faced that napkin math won't account for. There is always a bit of luck involved in cannonball runs. 46 minutes is not nothing, but it's possible to overcome with some good luck, unless the OOS guys min-maxed everything perfectly.

 

[ElGuano]

One really important metric that the video didn't talk about is at what average C rating they charge. The extended Rivian might charge at 500kw overall, but it also has to fill a battery that's over 3x the size of the Taycan. 500/310 = 1.61C. A max pack truck is already pretty close to this C rating: 220kw / 141kwh = 1.56C

It looked like they charge the main pack and the aux pack separately and in parallel (plugging into two chargers at once), so while they're still limited by the charging time of the slowest pack, it's not like they're doubling charging time by feeding a 2x-sized pack through one charger.

It's definitely a fun idea so an engineering achievement; I hope they really demonstrate what it's capable of in the Part 2 video.

 

[beatle]

It's true, they're still limited by the slower pack, though the one in the bed is also 50% bigger. @mkhuffman's suggestion to charge the secondary pack to full and then leave regardless of the main pack SoC would be worth computing. When the secondary pack is full, at that point, the effective C rate will plummet as only one pack is being charged, and it'll be the slower one at a higher SoC anyway.

I bet the team has a bigger napkin than I do to figure this stuff out.

 

[NeedSumCoffee]

Seems dumb to select a EV with poor efficiency, poor charging curve and speed limiter for a cannonball run. Seems like Lucid Gravity would be a much better option for vehicle to attempt the run.

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