Impact on battery in Desert temp

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Mikeyb

New member
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Feb 23, 2018
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I live in the so. cal Desert. Summer temp averages between 105 and 115. My garage averages around 100 degrees during the day. My concern is if the heat in the garage will effect the battery range and life.
 
The BMW i3 uses active liquid cooling and heating to help minimize issues. The original Leaf did not, and it definitely had issues. People have not mentioned problems with their i3 under those conditions. Up to a point, a warm verses cold battery can produce more power. What you might experience is a delay to recharge while the car cools the pack some prior to charging. If it does, you'll spend more on battery conditioning verses those in more moderate conditions. You'd also hear the compressor running more.
 
Even though the i3's battery pack is liquid-cooled, this cooling occurs only when the car is running or when the battery pack is being charged or preconditioned. So while an i3 is parked in a hot garage, its battery pack's temperature would increase to that of the surrounding air which could cause increased battery cell degradation.

I believe preconditioning during cold weather can take as long as 3 hours. Do we know whether a similar time limit exists when preconditioning during hot weather?

To minimize battery cell degradation, I would probably precondition our i3's battery pack if we lived in a very hot climate. Although the battery pack would still become very hot before preconditioning starts, the amount of time it would be at a hot temperature would be reduced.
 
The Leaf's heat problem was compounded by having both ambient heat and usage current internally generated heat. The i3 worst case only sees the ambient heat because it is actively cooled during use. My understanding of the lithium battery chemistries is most can function perfectly well up to about 120F, which is likely the most the i3 cells will ever see, even in a desert environment, where the Leaf cells could easily see over 140F. Serious damages require 160F or more.

Also, the i3 will limit acceleration (and deceleration, as it does not matter which direction the current is flowing with respect to internal heat generation) whenever the heat pump cannot keep the batteries within a safe operation temperature. It will limit acceleration when hot to avoid generating additional heat, and it will limit acceleration when cold by default as very cold cells simply cannot provide full current. The power display meter shows the power being limited with greyed out charge/discharge bars near the ends of the range on either side.
 
Thanks for the info. My friend just bought a 2015 with range extender and I found it fun to drive. Surprising acceleration! Probably won’t buy until the lease is up on my Q5 - a year from now.

Also wondering if the range extender is worth it if I only drive around town. Extra maintenance and extra cost. Some of the posts said they hardly ever used it. On the other hand my friend drove from LA to the desert and stopped for gas twice to keep it going. That leads me to believe that if you are willing to fill it up every 20-40 miles you can keep going forever!
Comments?
 
alohart said:
Even though the i3's battery pack is liquid-cooled, this cooling occurs only when the car is running or when the battery pack is being charged or preconditioned. So while an i3 is parked in a hot garage, its battery pack's temperature would increase to that of the surrounding air which could cause increased battery cell degradation.

I believe preconditioning during cold weather can take as long as 3 hours. Do we know whether a similar time limit exists when preconditioning during hot weather?

To minimize battery cell degradation, I would probably precondition our i3's battery pack if we lived in a very hot climate. Although the battery pack would still become very hot before preconditioning starts, the amount of time it would be at a hot temperature would be reduced.


Cooling happens via the AC, It will normally happen only when charging or usage or cabin pre conditioning. The AC is relatively decent size for normal charging and driving conditions.

Heating in i3 happens by a 1000 watt separate heating element. As you can image its under powered for the thermal mass of the battery. So it takes 3 hours to precondition slowly. The battery can also get warm by usage anyways .while in use or charge

Most other cars (except leaf and VW) use the liquid cooling and heating with the same pipes. The volt has 1750 watt heater to heat the water first

The i3 wont charge, if battery temp goes above 50C
 
Mikeyb said:
Thanks for the info. My friend just bought a 2015 with range extender and I found it fun to drive. Surprising acceleration! Probably won’t buy until the lease is up on my Q5 - a year from now.

Also wondering if the range extender is worth it if I only drive around town. Extra maintenance and extra cost. Some of the posts said they hardly ever used it. On the other hand my friend drove from LA to the desert and stopped for gas twice to keep it going. That leads me to believe that if you are willing to fill it up every 20-40 miles you can keep going forever!
Comments?

I too struggled with whether to spring for a ReX vs BEV. Ultimately it came down to whether I was going to use my i3 as a simple town runabout or as an occasional replacement for my ICE vehicles. I decided that it made more sense to buy something that I could use as an occasional ICE replacement, so went for a ReX.

As for the 20-40 miles between fillups, it's closer to 60-80 miles.

Good Luck!
 
I use my i3 for running around town, and it's a BEV...works great for me. I find it comfortable. But, if I had the REx, I'd still probably not use it for longer trips except in a major pinch...the combination of inconvenience of having to stop essentially every hour (and maybe more often, depending on where you can find a gas station or charging location), lack of significant storage, and overall comfort does not match that of my ICE (which sits in the garage most of the time!). Yes, it is a luxury to have two cars, one rarely used, and I realize not everyone can do that. To me, it would depend on the proportion of times you really needed the REx. It does cost more to buy, and to maintain verses the BEV...you could pay for a lot of days of a rental if you couldn't borrow a more suitable vehicle. People seem to indicate somewhere between 34-39mpg when actually using the REx...my ICE gets over 30 on a trip unless it's super cold out...not much of a savings, and I can go over 500-miles before I have to stop (at least for the car!).

This past winter (and maybe more to come), we've had some quite cold spells...highs in the single digits (F), with overnight lows below zero F. Even with preconditioning, the car didn't have great range (maybe 55% of my more temperate value)...part of that is because it could not use the heat pump and needed the resistance heating (the only heat the REx has), and I don't really like to be cold in the car! On one day, my i3 had been parked in the garage...it got moved outside to swap in my ICE...sitting outside in that frigid temp it 'lost' 20-miles, even with preconditioning the next day. Battery temp does make a difference.

FWIW, there are several battery prototypes that can self warm, and it uses less electricity than an outboard heating system. In the next few years, you may start to see those...won't do anything for cooling though.

If your normal pattern is to use the car during the day, and recharge when you get home in the evening...the i3 will be cooling itself during the day while in use, in the morning if you precondition, maybe at work before you leave if you're lucky, and again while it is charging at what may be the hotter time of the day especially after use.

If one believes the e-book on the i3, degradation is more from the number of discharge cycles, and 10 discharge cycles of 10% equals one from 100-0.
 
I would buy the i3 / rex in hot climate , as the AC works well. It works , even when the engine is stopped, compared to ICE.
I just carry a gas can for longer drives.

I would prefer the volt in very cold climate , as in i3 , the expensive heat is lost e.g when temp is below 20, th REX may be very inefficient to heat electric element, when the heat lost could do the same thing.

overall i would buy large battery electric. The bigger the battery the better , due to multiple reasons. at the end of the day ,with current tech, the battery is always the bottleneck , and not the electric motor. Fast charging reliable network would be the key
 
I haven't experienced any slow down when it's 115 in AZ. What I do see is every time you turn on the air (or heat) your mileage will drop 8-12 miles. Turn off and you'll gain some of that back. That doesn't happen in my 2017 Volt. But, the Volt doesn't recharge while braking anywhere near what the I3 does.
The other issue with the I3 is when you park and go shopping and then come back you lose mileage! Just being parked for a short time and lose a few miles. Not so in the Volt.
I can spin the tires at takeoff every time in the Volt, not in the BMW. Not a big deal but I get a kick out of that. :p Have done so with the I3 but usually off of a sandy start.

Anyway, I have the Rex and love it, though, I rarely use it. Since May of 2016 I've put in less than 3 gallons. Most that is when it goes into maintenance mode because I rarely use gas. If you're going longer distances in and around town get the Rex. Otherwise, at least here in AZ, if you have an all battery version, you get an the HOV lane plate. Can be handy.
 
I was watching a video today discussing the battery management of the Leaf, and he was comparing it to the Bolt and Volt. The newest Leaf still does not have liquid cooling and the operating manual has a page or so of warnings about maximizing the life of the battery pack. The Bolt and Volt will run the heating/cooling of the battery pack while off but plugged into an EVSE.

From what I've seen, the i3 will only cool a hot battery prior to charging it, and condition it while plugged in if you set a departure time, but not, continually manage the battery's temperature like the Bolt or Volt. If it's particularly cold, it will limit the initial charging rate, until the battery pack warms up from that charging. The battery chemistry may be different. The i3 uses liquid cooling, but an electrical heating element(s). It appears that Chevy heats or cools their liquid. The Leaf's battery temperature management only works while the car is running and warns about leaving it in extremely hot or cold situations.

For me, the biggest variation in range reported is associated with the outside temperature...it definitely goes down when it's colder out, and goes up when it's warmer. Setting a departure time does help. On the REx, preconditioning while on an EVSE can save a significant amount of range...much more so than on the BEV version. I wonder if the temperature change as the battery sits after being used is what may be affecting the variations in range reported when coming back to the vehicle. If not fully hot, whatever heat is there will spread while it sits, or if cold out, the heat will more quickly radiate out, requiring things to be rewarmed to achieve optimum operation.

EVs react differently than an ICE with the temperature changes...cold isn't as great an impact, as the internal combustion process has a lot of wasted heat to use to warm the cabin...an EV essentially has none. The air is denser regardless of the propulsion method, and that can affect the range on both types. An ICE may have a drop as it gets warmer and the a/c is run, but on the BEV, the heating load or a/c load is similar, so that isn't as big of a factor.
 
engineear said:
I can spin the tires at takeoff every time in the Volt, not in the BMW. Not a big deal but I get a kick out of that. :p Have done so with the I3 but usually off of a sandy start.
Anyway, I have the Rex and love it, though, I rarely use it. .

One thing to keep in mind is that FWD cars actually burn out easier than RWD, and that is for a couple reasons. The first is as you accelerate, the center of mass acts more towards the rear of the car. This is called load transfer. What it means is the weight of the car is always acting more on the rear tires during acceleration (and front tires during braking). So for a front wheel drive accelerating, the traction with the front tires decreases more as you accelerate faster.

Secondly, since the tires the are rotating to accelerate the car are also the tires that turn the car, you have a limited amount of traction that can go to accelerating the car or turning the tires. If you accelerate and turn it will reduce the available traction for each. When you accelerate in a turn in a FWD car it tends to cause the car to understeer, or push to the outside of the turn because your traction force is exceeded in the front when you ask the tires to both accelerate and turn the car.

So the i3 REx has a 45% front 55% rear while not accelerating on a level surface. As you accelerate the weight will shift back, the harder you accelerate, the more downward force and more traction you will put on the rear tires. Even though the Volt is front biased, gen 2 is around 60/40, but the harder you try to accelerate less force will push down on the front tires, making it spin out easier. Also, the Volt has light weight forged wheels with low traction tires. When I switched to an aftermarket wheel and high performance tire, I wasn't able to spin the tires in the Volt 1 anymore. My REx has performance summer tires that won't spin easily.

Braking is the opposite, so the i3 REx will be fairly neutral weight distribution on braking, meaning all 4 tires will provide similar stopping power, but the Volt will be very front heavy in braking, meaning your rear wheels aren't really helping much (hence the massive front brakes on almost all FWD cars with tiny rear brakes).

A lot of racers love the 45/55 weight distribution and why mid engine cars are popular with that crowd. It means better braking and better accelerating and can put power down coming out of a turn. What it also means is oversteer, which is why the weird tire pressures on the i3, a front of 33 and rear of 40 or whatever it is, this reduces oversteer make it safer. Part of the twitchiness of i3 at speed comes from this weight distribution I believe.
 
The desert can get quite cold once the sun goes down. The REx makes all cabin heat with resistance heating...the BEV (unless it is REALLY cold) does it with a heat pump, so when you add up the extra weight of the REx and the penalty when you want some cabin heat, that explains most of the differences in overall efficiency between the two versions.

Whenever you can, it is a good idea to set a departure time, and if that's not possible, precondition the cabin while plugged in...then, you will not see as big of a hit when you try to do that entirely on battery power alone.
 
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