Impact Of Temperature On BMW i3 Battery Performance -Video

OCT 10 2015 BY ELECTRICCARSTV 17

i3 Battery

i3 Battery

“In this video, learn how the intelligent heating and cooling system in your i3 keeps the battery within ideal temperature range for consistent energy efficiency and range performance.”

Outside ambient temperatures do impact range, but the effect is not the same for all of the electric cars on the market.

For example, the BMW i3, with liquid cooling¬†a cooling system of inert gas refrigerant (R134a), and “intelligent heating” should fare better over a wider spread of temperature fluctuations than the air-cooled Nissan LEAF.

Additionally, most electric cars with liquid heating/cooling can be preconditioned so that cabin temps are too your liking prior to departure.  Preconditioning typically uses grid power to achieve a comfortable cabin temp, which can save on battery usage as you disconnect and drive on down the road.

Hat tip to franky_b for clarification on cooling system!

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17 Comments on "Impact Of Temperature On BMW i3 Battery Performance -Video"

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The BMW i3 doesn’t use liquid to regulate the temperature. It is using an inert gas.

Yes indeedie Fanky_B,

Will add that point/clarification into the story now(and a hat tip to you as well of course)

/thanks

R134A is only a gas AFTER it has entered the evaporator. A mechanical compressor and condensor will condense this ‘inert gas’ to an ‘inert liquid’. Inert is really the wrong word here, it is not one of the Noble Gases, and it, much of the time, is a liquid. Refrigerants work by changing states twice per roundtrip cycle – boiling in the evaporator (heat extraction) , and condensing (back to a liquid) in the condensor (heat dissipation). So inert gas is wrong terminology. Liquid cooled was better, as long as it is realized that the ‘liquid’ does its work by boiling. So why are refrigerants so much more effective at cooling? Lets take plain old water.. Heating 1 pound of water from 32 degrees fahrenheit to 212 degrees (at atmospheric pressure) absorbs 180 British Thermal Units. But if you continue to heat the water at 212, it will change state (boil away), absorbing 780 BTU. Anyone who has ever watched a tea kettle heat on a stove has seen the kettle quickly rise to boiling temperature and then a much LONGER time for all the water to boil away. In a closed system, if a condenser releases 780 btu, this… Read more »

That link just can’t be right. The pressure required of R134a would be around 50 – 100 pounds/square inch, and therefore if the refrigerant actually touched the battery instead of being in a heat-exchanging tube, the whole battery assembly, including all perferations into it (wires, hoses, etc) would have to be able to withstand this pressure, and be hermetically sealed.

It seems easier to me to make a leakproof heat transferring tube than it does to hermetically seal the entire battery compartment.

Here’s another reason why its highly doubtful they just spray the refrigerant directly on the batteries.

In the refrigeration compressor, lubrication oil is at ‘suction side pressure’, and is in intimate contact with the entering refrigerant gas. Since R134A is ‘miscible’ in oil (forming a homogenious solution, in other words 99.9 % refrigerant and 0.1 % oil), the oil circulates 100% of the time with the refrigerant, and helps lubricate the expansion valve, besides forming an oil seal on the piston rings if the compressor is of the reciprocating style.

If you’ve ever had a refrigerator or air conditioner leak a bit, no doubt you’ve seen a bit of oil around the spot of the leak. This proves that there is oil moving around with the refrigerant. If there is a leak the refrigerant will escape to the air, while the oil makes a mess.

So, in a battery that was just ‘flooded’ with refrigerant gas, the end result would be an oily mess. Any customer who asked to look at his batteries with the cover off (which would of course loose the entire refrigerant charge), would be greated with a drippy, oil-soaked mess.

Correction: Its been too many years since Ive worked on refrigeration systems. The latent heat of vaporization of water ‘From and at’, so to speak, 14.7 PSIA (i.e. absolute presure) is 970.4 BTU/LB. So where I said 780 replace each occurence with 970.

So obvious! I noticed that error myself instantly and was appalled, just didn’t want to point it out and embarrass you!

/just kidding

…I mean really, who knows that sort of thing? Only you, lol. I’m pretty sure no one would have ever been the wiser if you didn’t say anything, but appreciate your precise nature, (=

Haha, the big question is why that link said they cool the batteries directly from the ‘inert gas’. Here’s one possible mixup: WHen people talk about DIRECT EXPANSION refrigeration systems, they mean, in so many words exactly this. Bear with me and you’ll see the issue involved. The year is prior to 1931, the year Carrier invented Freon-12 (used for decades in refrigerators, and car air conditioners, and also used by the TON every day at GM and other car makers as a general cleaning solvent since it would just evaporate away with no cleanup!!!). We have a 1000 seat theatre we want to air condition. So we use CO2 in a DIRECT EXPANSION system. Its not that carbon dioxide is blown directly into the air, but that the evaporator piping where the air blows by is cooled by CO2 and nothing else. Ammonia is a much better refrigerant, usually requiring the compressor only being 1/3 the size of a carbon dioxide system, so why not use that in a Direct Expansion system? The reason is, if the Evaporator ever developed a big leak, the Ammonia would kill all 1000 in the theatre. Too risky. But since Ammonia works so… Read more »

This is a BMW ad. I hope they paid for it.

Yupe this is a BMW produced spot (pretty evident given the BMW logo on it). That being said, we pass along new ads and spots (with no compensation) on pretty much all EVs:

Volt:
http://insideevs.com/chevrolet-releases-first-2016-volt-commercial-video/

LEAF:
http://insideevs.com/nissan-leaf-video-talkers-versus-doers/

Soul EV:
http://insideevs.com/kia-soul-ev-electrifies-dogs-video/

Ford:
http://insideevs.com/look-who-is-back-ford-gives-the-focus-electric-an-ad-spot-video/

etc., etc.,

And we pass them all along for “free”, lol. Like our stance on taking no “freebies”, trips, chotchkies, food – InsideEVs accepts no compensation for stories of any kind. But that doesn’t mean we won’t pass something along voluntarily if we think some readers might want to see it.

Thanks, Inside EVs. I appreciate the information, even if it’s supplied by an automaker.

I also enjoy the various TV and video ads of EVs that Inside EVs posts. We don’t actually get to see many of these ads given the rarity of EV marketing these days. Keep it up!

And for those of you offended by automaker supplied EV information and advertising, move on to the next article. You aren’t actually forced to read this article.

Thanks Jay. like the video and other links.

I’m with Forever Green, since when does insideevs.com post advertising as “news”?

The content of this video is worthless. Where’s the actual car fleet data from the past year showing the actual impacts of temperature?

Yeah, well, its an ad, but at least it shows some subtle differences between vehicles.

My GM products apparently just use fan cooling most of the time, and then use refrigerant cooling when trying to charge in hot summer weather.

Its interesting because charging in my Volt and ELR take much longer in very hot weather, no doubt because some of the charging power is used to run the ‘refrigerator’.

I really appreciate the information on the battery. BMW never mentioned this as I was one of the first to own an i3 at our local dealership. I’m sure it’s somewhere in the manual- but I much rather get in and drive than read the manual. I had my i3 condition the batteries for the winter- making my batteries operate at optimal temperature. Always learning something new with these electric vehicles. Thank you again.

Dan

The i3’s battery cooling system is part of the cabin airconditioning/heating. The BEV version can be ordered with a heat pump option, to minimize energy consumption from the battery when using the AC or heating.