If you happen to’ve adopted my articles, you may bear in mind the issues I’ve had with the 2018 Nissan LEAF I used to personal. Dwelling in Phoenix on the time I purchased it, the car would overheat simply driving down the freeway in the summertime temperatures there. Even in cooler temperatures within the fall and winter, the battery would nonetheless overheat throughout DC quick charging classes, making for street journeys which can be painfully gradual.
Even with software program updates, my final try to take a brief street journey within the car was painfully lengthy, with two-hour charging stops as charging charges plummeted. As soon as once more, warmth buildup on repeated charging stops would kill charging speeds, largely as a result of the LEAF had no cooling system.
You’d suppose that charging issues like this may be utterly solved by liquid cooling programs, however a current video on the Out of Spec Evaluations YouTube channel exhibits us that this isn’t at all times the case.
Within the video, Kyle Conner tells us about a few of the thermal administration issues he’s come throughout testing his Rivian R1T pickup truck. Whereas he’s lately spent plenty of time speaking about issues with charging infrastructure (particularly reliability of Electrify America stations), this time, he’s having issues with the truck.
He factors out that he’s had issues with the truck in the summertime, however he waited to see the way it carried out in winter, and sadly, it’s nonetheless increase an excessive amount of warmth and charging extra slowly than it often does.
He begins out stating that in lots of circumstances, slower charging than you need to get is usually brought on by different drivers. At most Electrify America stations, individuals with slow-charging automobiles just like the Kia Niro or Chevy Bolt typically plug their automotive in at a 350 kW stall when slower 150 kW stalls can be found. When individuals who pull as much as the station with a automotive able to sooner charging pull up, they’re left with the slower stalls.
So, youngsters, don’t do this! If you happen to’ve acquired a slower automotive (like I do), cost within the slower stalls. Depart the sooner stalls for the individuals who can really get essentially the most from them.
Again on the subject at hand, he factors out that not all cooling issues are brought on by the identical points. Typically, it’s the electrical motor or energy inverter that heats up. In his case, he has managed to overheat the Rivian inverters on steep downhill segments with a heavy trailer. When the inverter overheats, it shuts off the regenerative braking, which will be considerably harmful because it’s not a good suggestion to handle downhill segments with simply friction brakes (as a result of they, too, can overheat).
In relation to charging, the Rivian can get as a lot as about 220 kW charging charges, however he then explains that there are two methods to get an EV to not obtain its finest charging.
One factor you are able to do is drive the crap out of it. Racing, a lot of onerous acceleration and braking, and different onerous driving cycles (like mountain towing) could cause plenty of warmth buildup that thermal administration programs can wrestle to maintain cool, or fail to maintain cool. To stop injury or hearth, the automotive ultimately cuts again how a lot energy it may ship — or cost. That is often an inverter or motor subject, however batteries can overheat ultimately.
An inverter or motor doesn’t have plenty of thermal mass, so they need to be capable to cool off pretty rapidly as soon as they’re not requested to work so onerous. However, batteries are one other factor fully. As soon as warmth builds up in them, it may take an overworked or insufficient cooling system a while to take away the warmth. The issue is, should you’re freeway driving, you go straight from driving quick to the charging station, and also you arrive with a battery that’s already too scorching.
So, the automotive throttles charging speeds again to guard the battery from injury or unplanned inside combustion. Within the case of the Rivian, he’s seeing it throttle charging speeds that ought to exceed 200 kW get reduce to as little as 90 kW. And, this may occur in winter temperatures — in Colorado!
The battery charging velocity doesn’t begin out gradual, however after a couple of minutes of charging it drops speeds, exhibiting that warmth had constructed up throughout the cost and exceeded the allowable temperatures for max charging speeds. He figures that the car most likely isn’t working the cooling system as aggressively because it might early within the cost or when pulling as much as stations.
What He Thinks Rivian May Do To Repair This Downside With out Rebuilding Battery Packs
He thinks that the battery pack most likely has just a few cells that aren’t getting nearly as good a cooling as the remainder of them. It’s an enormous, complicated “double stack” battery pack, and there’s most likely some nook of the pack that’s getting scorching first. However, they might probably permit the utmost temperature to increased (which can be dangerous) or pre-cool the pack extra aggressively to attempt to get forward of the portion of the pack that’s getting too scorching first. Some mixture of the 2 is feasible, too.
For now, it won’t be a good suggestion to not precondition the battery for the primary charging cease on a street journey with a Rivian in winter. Future software program updates might repair this.
Rivian Has Made It Harder To Collect Knowledge On This
Prior to now, Rivian automobiles had a secret menu the place you possibly can get all the car’s information, together with issues temperature sensors for various elements. However, with a software program replace, the key menu and app disappeared. House owners knew prior to now that the automobiles wouldn’t go above 45 levels (C), which is fairly aggressive cooling. However, they will not get these figures.
We’re Nonetheless In The Early Days of EVs
One factor to bear in mind is that we’re nonetheless within the early days of EVs. Some producers could have extra issues than others, and a few (particularly Tesla and to some extent GM) have much more expertise than others. Each producer goes to have to determine one of the best ways to chill their designs, and ultimately common information of the right way to finest do cooling will turn into the norm.
Featured picture supplied by Rivian.
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