Turtle Mode (Cold Weather Warning)

[Mach-Lee]

Curious about cold testing of LFP battery versus NCM.

Yes, would love to get my hands on one for testing...

What is the limit for Tesla vehicles?

Tesla allows significantly more voltage sag than Ford. On a Tesla Model 3 (also 400V), I've seen reports of the pack voltage getting as low as 240V under load (vs. Ford's 310V limit). Granted the sag may be less than that when the battery is under similar conditions (low SoC and cold temp), but I believe Tesla would almost always allow sag below 300V. On Bjørn's videos I see it go down to 280-290V pretty regularly.

So in summary, Ford limits to only 3.3V/cell, but Tesla routinely allows 3.0V/cell and even down to 2.5V/cell under extreme load.

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[Jimrpa]

Clarification: This applies to cold climates with temperature below 20°F/-6°C. You don’t need to worry about this in the southern states or if you’re not discharging the battery below 30%.

Warning: If your battery is cold, your car may unexpectedly enter turtle mode (power limit) with as much as 30% battery left. You will suddenly have a severe power limit and will not be able to maintain freeway speed, nor accelerate through intersections or on-ramps safely. This has happened to myself and several others in the cold during the past few days. It's a really severe power limit and is pretty scary when it happens.

Yellow Turtle:

Red Turtle:

The colder the battery, the sooner you will get turtle mode. The power limit will get progressively worse as you keep driving until you are no longer able to maintain speed. It will start with yellow turtle warning "Performance limited due to cold battery" then progress shortly after to the above red turtle mode "Severely limited performance due to cold battery". At this point you have almost no power.

To avoid this, you must precondition/set a departure time, and plan your charging stops for no less than 20% battery in the cold. The GOM will still say you have many miles to go, but your car will be at a crawl long before it gets to 0%. I preconditioned and got turtle mode at 9% because my battery had cooled off enough while driving. Cold battery + low % SoC charge triggers turtle mode.

If you get yellow turtle, you need to take action immediately and find the nearest Level 2 charger regardless of what the GOM says. Slow down 20 MPH and/or get off the freeway ASAP before you have no power left. Your car will only have about 50 horsepower to accelerate, wait for all traffic to pass at stop signs and do not pull out on anyone.

What is the yellow lane keeping symbol with a pentagram in it?

 

[Mach-Lee]

What is the yellow lane keeping symbol with a pentagram in it?

With the snowflake, that's the low outside temperature warning, nothing to do with lane keeping. I think it turns on below 39ºF. Around here that means it will be permanently on for the next four months.

 

[Jimrpa]

That's the low outside temperature warning, nothing to do with lane keeping. I think it turns on below 39ºF. Around here that means it will be permanently on for the next four months.

Thanks! I’ve never seen that symbol, but I do appreciate all the info about cautions with the battery when it’s cold. It does routinely drop below 30 in the Philadelphia suburbs.
Can this problem be avoided by preconditioning (setting a departure time) and just keeping the battery charged above .30%? That’s what I’m taking from the discussion?

 

[Mach-Lee]

Thanks! I’ve never seen that symbol, but I do appreciate all the info about cautions with the battery when it’s cold. It does routinely drop below 30 in the Philadelphia suburbs.
Can this problem be avoided by preconditioning (setting a departure time) and just keeping the battery charged above .30%? That’s what I’m taking from the discussion?

Yes that helps, but if it's cold enough the battery will cool down while driving even if you do a departure time first. It also impacts your ability to do winter road trips if you can't go below 30%. That means you'd have to stop every 75 miles or less. This popped up a bunch during Christmas and New Years holiday travel last year. A lot of cars have the updated software now due to the recalls, so I predict it's going to happen to even more people this year. Primarily affects people that have to drive in temps below 20ºF/-6ºC.

 

[Jimrpa]

Yes that helps, but if it's cold enough the battery will cool down while driving even if you do a departure time first. It also impacts your ability to do winter road trips if you can't go below 30%. That means you'd have to stop every 75 miles or less. This popped up a bunch during Christmas and New Years holiday travel last year. A lot of cars have the updated software now due to the recalls, so I predict it's going to happen to even more people this year. Primarily affects people that have to drive in temps below 20ºF/-6ºC.

So, I think one of the big questions in the room is “will the heat pump help?” You did say that the battery will cool down while driving under certain conditions. Will the heat pump help prevent this?

 

[mg_gti]

Wonder if the 2023.5 models (with the cooling system redesign) behave any differently?

 

[Byrus]

Wonder if the 2023.5 models (with the cooling system redesign) behave any differently?

I have a 24 model but really afraid to test this! ?

 

[Mach-Lee]

So, I think one of the big questions in the room is “will the heat pump help?” You did say that the battery will cool down while driving under certain conditions. Will the heat pump help prevent this?

At 15ºF the heat pump will probably help improve output a little bit and keep the battery a little bit warmer. But in extreme cold -20º it will probably be the same.

Wonder if the 2023.5 models (with the cooling system redesign) behave any differently?

2023.5 adds additional heat recovery from the motors to help keep the battery warmer, but it's the same battery, so if it gets too cold or too low I think the same thing will happen.

It's part of the battery strategy.

 

[Norcolboulder]

Thank you all for the feedback and your driving impressions. We should all be aware of cold temps and the potential turtle mode occurrences. Interesting to see 2025 ( heat pump ) and 23.5 improvement impressions. .

 

[Billyk24]

Thanks! I’ve never seen that symbol, but I do appreciate all the info about cautions with the battery when it’s cold. It does routinely drop below 30 in the Philadelphia suburbs.
Can this problem be avoided by preconditioning (setting a departure time) and just keeping the battery charged above .30%? That’s what I’m taking from the discussion?

I'm in the southwestern part of the state. Lost 11f of battery temperature driving 60 miles of 55 to 65mph on divided 4 lane highway (422-I 79-I-80) today in 27f weather. Turned on pre-conditioning by selecting a dcfc charger and picked up 22f of battery temperature in 25 miles. Seems like doing this every 40 minutes while road tripping might be helpful but it will also reduce range.

 

[Wes8398]

Joining this thread because we have been giving some serious consideration to an MME-X for my wife's commute to work (220km return), but our winters see at least a few good stretches of NEGATIVE Fahrenheit temperatures and definitely plenty of time under 20*F. Threads like this and posts on MME sub-Reddits are causing us some serious pause.

Also, what is it about people drawing comparisons or offering experiences to down right balmy conditions in posts that are specifically targeted at ACTUAL WINTER TEMPERATURES? Get outta here with your "mine didn't do this when I was out driving in "cold" 40*F temps yesterday" ?

 

[GarageWarrior2023]

Tesla allows significantly more voltage sag than Ford. On a Tesla Model 3 (also 400V), I've seen reports of the pack voltage getting as low as 240V under load (vs. Ford's 310V limit). Granted the sag may be less than that when the battery is under similar conditions (low SoC and cold temp), but I believe Tesla would almost always allow sag below 300V. On Bjørn's videos I see it go down to 280-290V pretty regularly.

So in summary, Ford limits to only 3.3V/cell, but Tesla routinely allows 3.0V/cell and even down to 2.5V/cell under extreme load.

@Mach-Lee do you know what the allowed voltage sag in the Mach-E was before Ford made the software change?

@Ford Motor Company @Ford of Canada this 3.3v limit represents locking customers out of an additional 30% of the battery capacity of their vehicles in winter. The software blocks needlessly turn our vehicles into a road hazard and make them unsafe and unreliable past that SOC. As customers we have sized our vehicle batteries according to our summer and winter needs, taking into account normal winter range losses of up to 40%. Removing an additional 30% capacity means winter losses in the Mach-e are up to 70%. Nobody purchasing their Mach-E took into account that a software update would steal an additional 30% of their winter range after they purchased the vehicle.

When will a corrective update be released to fix the issue? Can it be a Christmas miracle update?????????????

 

[VindictivePantz]

@Mach-Lee - Curious what the "Energy Usage" display is showing before/during the Turtle Mode events.

I just checked mine (I was down to ~60% SOC) and range was impacted by ~5% climate, and about the same ~5% for exterior temperature. Temperature was 23F-25F for me, and the car had cooled down as it had parked for 2+ hours outside.

The reason I'm asking is that I am assuming that Ford should show a steady increase in "exterior temperature" as it gets closer to Turtle mode. We all know how unreliable their reporting/dashboards are, so it would not surprise me if it's no indicator that one might be trending towards Turtle Mode but am hoping it becomes a larger factor over time; if so, then perhaps we could see it happening and plan accordingly.

I was going to take the car to MI this weekend, but stopping every 75-100 miles without the ability to precondition and with the thread of Turtle Mode will have me driving our ICE vehicle instead.

 

[luckie]

So, I seem to recall in the past year(?) a 3rd party vendor who was marketing an underbelly insulation add-on for the Mach-e. To increase insulation of battery. Anyone else remember this?

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