Featured 2021 Toyota RAV4 Prime recalled for potential stalling in cold weather

This thread is not about justifying bad buying decisions. It's not about fudging the numbers. It's about unanticipated behavior of the 2021 model year Rav4 Prime in very few cases and the proactive recall that Toyota launched.

While it would be nice to have instant fixes that are safe, It's even better to have fewer errors in design and execution so that OTA is not needed.

 

Most safety recalls are proactive with just a few occurrences of the problem.

Toyota's quick response here could easily be compensation for their less proactive response to Prii stalling.

 

Wondering if this recall 'remedy' will mean that the ice will run more frequently in cold weather like many other PHEV's.
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Running the ICE more often to protect the battery would be one solution. So would be using some of the battery power to heat the battery pack. Or just issuing a warning while limiting the power drawn from the battery under those extreme conditions.

 

What does the Rav4 Prime have in way of battery heater? Just 'freeze' protection like the Prius Prime, or can it condition the pack?

 

It occurred to me that Toyota could have done something equivalent to what our older vehicles did. The Tach showed the red line, and when you over revved it either a) engaged a governor or b) let you ruin the engine if you wanted to, up to and including burned pistons, broken rods, etc.

The EV equivalent would be a notice on the screen warning that battery damage is eminent if you don't slow down.

Was it the Ford Mach E that had a minor problem which surfaced shortly after being introduced? I recall that repeated drag races tended to melt the contacts within the high voltage wiring. What was the fix in that case?

The toyota hybrids that I've owned, rented and borrowed in the last 20 years had the accelerator pedal mapped to a power curve that did not tax the battery unduely.

 

Take a look at the attached PDF.
Because it is liquid cooled, it uses the heat pump to cool it but also contains electric heating elements like the Prius Prime. Page 4 has the details.

 

The car is putting up a warning before shutting down.
https://static.nhtsa.gov/odi/rcl/2023/RCLRPT-23V041-3277.PDF
"Due to certain characteristics of the software logic, the HV battery output may not be limited as required to protect the battery."

The system is letting the battery be overdrawn at low temperatures in EV mode. It might mean the car doesn't have the available energy to fire up the ICE when the driver suddenly calls for more throttle.

So the heating element is there to warm the battery over 0C for charging? Using it to warm the battery up for better operation parameters likely isn't a fix for this issue in that case.

 

The battery heating is like the Prius Prime's. First you have to activate it on the Charging Settings on the MID. So you select it to On and when the AC charging cable is connected it'll automatically turn on at the same temps as the Prius Prime. It's actually a 12V heater that uses about as much energy as the seat heaters which is why it gets turned on when the AC charging cable is plugged in. And you're correct, it won't fix the OP issue.

 

That actually make a LOT of sense. If a traction pack is in a serious deep freez environment - the heat pump essentially becomes useless, as there has to be some degree of heat to pump from. Not so, if it's too cold. Resistance heat, though less efficient - will at least be able to warm up &/or defrost a cabin when driving below freezing temps.
Here's a pretty nice chart that show the least amount of lost energy to heat in various EV's. It's kind of surprising;



Study: Winter & Cold Weather EV Range Loss in 7,000 Cars

Mustang, Bolt & ID4 ??? You seriously SUCK (amps) ... in cold weather.

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I don't think the heat pump refrigerant lines a plumbed in a way to heat the battery at all.

With it drawing heat off the battery, the Rav4P's heat pump could warm the cabin better than the PP's

Neither do the Bolt or Mach-E. Heat pumps would be a must for those getting a BEV where winter is a real thing.

 

The best modern home heat pumps can still function with twice the efficiency of electric resistance, down to -15F to -20F. With much better performance at +20F.

Though I do suspect that the necessary cost and equipment size and weight for that performance level won't be justified for cold climate versions for quite some time still, and likely never for milder climate zones.

 

Looks like Audi is going to lose its freezing weather energy loss champion status all because of outsourcing;

Audi No Longer Putting Heat Pumps In Q4 e-tron.
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This is likely, but not a bad solution. It wouldn't A) reduce epa since they don't test these things, or B) use that much gas because there are very few primes on the road and many of these are not in cold weather often. They can likely address it in a design change for future phevs after looking at the problem now.

 

Kudos to Audi for informing their customers with a reservation for the car. They could have said nothing. Maybe put a plastic cover over it.

 

you mean like gunning up Cajon Pass or the Grapevine in the winter time? or up towards wrightwood? Or arrowhead? Or big bear? Or tahoe? Or mammoth? Yeah no one from SoCal does that.