Leaf in the tropical north

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JeffB
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Leaf in the tropical north

Post by JeffB » Sat, 28 Sep 2019, 07:02

We live in Kununurra where summer temperatures reach 40+ and don't drop much below 30 even at night. The batteries will obviously degrade just standing in the garage, but how important will the lack of active cooling be?
We have a 20km drive to town, about 80% of that at highway speed (say 80km/h) which may heat the battery too much.
It would only ever be slow charged overnight.
There are lots of Leafs for sale with 5-6 years and 50 000km, but if the battery fails after two years because of overheating they will be poor value.
Any thoughts?

antiscab
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Re: Leaf in the tropical north

Post by antiscab » Sat, 28 Sep 2019, 08:00

Any chance of air conditioning your garage?

For the distances you propose. Maybe a conversion ev would be better.

Lifepo4 batteries used in most conversions (up until recently) are not as sensitive to heat as the nmc batteries used in production cars.

I note there's a BMW 318i up for sale at the moment.
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells

JeffB
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Re: Leaf in the tropical north

Post by JeffB » Sat, 28 Sep 2019, 08:39

"Garage" is a euphemism for any shady spot, though I have considered the possibilty. Since we only aircondition one room of the house it would be pretty funny airconditioning a garage.
I read the iMiev uses its airconditioner to cool the battery while charging, and there is a 2010 model for sale, but its battery must be getting close to the end of its life. I will look at it when I get to Perth.
The low km BMW looks very nice but out of my price range.

Currently we use electric bikes to commute but the wet season really boils us even with the assistance.

antiscab
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Re: Leaf in the tropical north

Post by antiscab » Sat, 28 Sep 2019, 10:17

imiev only uses aircon to cool the battery when it's fast charging
Though given the hardware is there, it may be possible to modify it to run whilst charging or driving.
likely would just have to apply 12v to the right spots to get everything to start

the BMW I had in mind was this one:
viewtopic.php?f=34&t=6196

about the same price as an imiev, with the same range and possibility of attaching a tow bar to tow stuff
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells

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jonescg
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Re: Leaf in the tropical north

Post by jonescg » Sat, 28 Sep 2019, 11:13

I was doing research on the sandalwood plantations up there during my PhD and post-doc. The latest I was ever there was October, and that was pretty rough! I agree it will be difficult to keep the battery cool. Matt's probably right - a conversion with LiFePO4 batteries will handle the heat much better than the chemistry's being used in all current production EVs. Some kind of cooling whenever the vehicle is charging or driving will also help the battery last a lot longer, but in these circumstances, short of an air conditioned garage, a more robust chemistry is probably the best solution.
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bladecar
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Re: Leaf in the tropical north

Post by bladecar » Sat, 28 Sep 2019, 11:40

Hi
I have learned not to have a "specialist" car unless I am a specialist.
If you are not a hobbyist in the appropriate fields, avoid like the plague any transport which cannot be repaired by a commercial organisation in your reasonable vicinity.
Aside from a non-commercial vehicle not having any of the "it just does it" ability, equipment for it is very specific and not conveniently available with regard to time or knowledge.
I tell you, people here go on about modifications but these are people who can, like to, and do this stuff. If you simply want an ev to drive and you are not one of those people (you will know), ignore any advice on how to "make it happen" regarding vehicle performance. This is one of the perils of mixing up tech people with modern people who, for various reasons, realise that an Electric Vehicle is the type of vehicle they would desire to drive.

I have a 2012 imiev. I don't even stress it with highway speeds most of the time. My slow speed range seems to be around 100 km with a 73% reported battery capacity after this time.
I have not learned the true range capability of the car because I just don't/won't use it that way. Also, without having tested anything, I'm going to guess that full-time use of air/con in the car while driving will significantly reduce your driving range. I'm pretending that you will drive flat roads but if you go up significant hills in high temperatures while using aircon, that could also be very significant for a 100km range vehicle. It seems, without having looked into it, that a better 2nd hand leaf, say, might be ok for you if you drive properly and really only want it for 20 km each way. It would go much further than that and you would know just how much further after having owned a car and learned about it. I'd say the imiev would work except that I do not know just how influential higher ambient temperatures Brisbane/vs/outback would be.

You'd need to ask yourself how far away Nissan or Mitsubishi service centres are and would they want to know if you have issues with the car. The odds are that the cars would go for a long time without problems, but there is that issue to remember.

If you really want an ev, obviously a kona type vehicle would be perfect (500km range?), though it is a little early to be very sure about the vehicle (and where is the Hyudai service centre). At the approx $50k price, it seems a lot. It might be better to buy a 4wd for $90k or $120k for REAL VALUE. They have their place, but not many of them do.

I've been a little bit silly at the end because only some of us really can afford those things and so I already said it at the start :)

Edit: Added the word "how"
Last edited by bladecar on Sun, 29 Sep 2019, 06:49, edited 1 time in total.

mikedufty
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Re: Leaf in the tropical north

Post by mikedufty » Sat, 28 Sep 2019, 12:00

I agree with most of the above, but wouldn't be concerned about running air con full time in an i-Miev. We pretty much did that with ours in Perth. I'm pretty sure it would be more in Kununurra. Knocks 10% off the guessometer range, but doesn't seem to reduce actual range that much. I'd be more concerned that if the air con is cooling the batteries it might not be available for cooling the cabin sufficiently, but admit I don't know how the system works. Only ever used a fast charger once for about 10 minutes just to try it out.

T1 Terry
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Re: Leaf in the tropical north

Post by T1 Terry » Sat, 28 Sep 2019, 12:17

Something I've always wondered, if heat rises and cold falls, wouldn't blowing cold air above the battery pack and exhausting it below the battery pack a better method for cooling? I see all these cooling plates the cells sit on, but wouldn't that be the coolest part of the cell?
Tesla run pipes up one side of their cells to transfer the heat out of the cylindrical case, but doesn't that only cool the outer layers of the cell while the centre stays hot?
How effective is active cooling?

T1 Terry
Green but want to learn

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jonescg
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Re: Leaf in the tropical north

Post by jonescg » Sat, 28 Sep 2019, 12:53

T1 Terry wrote:
Sat, 28 Sep 2019, 12:17
Something I've always wondered, if heat rises and cold falls, wouldn't blowing cold air above the battery pack and exhausting it below the battery pack a better method for cooling? I see all these cooling plates the cells sit on, but wouldn't that be the coolest part of the cell?
Tesla run pipes up one side of their cells to transfer the heat out of the cylindrical case, but doesn't that only cool the outer layers of the cell while the centre stays hot?
How effective is active cooling?

T1 Terry
Convection (the rising of warmer, less dense air) is a pretty slow way to move heat compared to conduction, which is what all the EV cooling systems rely on. So a solid, highly thermally conductive (but critically, electrically insulating) material binding a large surface area with a big delta T between source and sink will result in the most effective thermal management system. In Teslas case they are cooling the side of a cell through a rubbery material with a thermal conductivity of about 1.0 W/m.K (typical for the job) but the fact that it's only touching 1/4 to 1/3 of the cells radius is not a big deal. The thermal conductivity of the cells in that plane is not great, but the flow of heat actually follows the conductors quite well.
radial heat conductivuty.png
radial heat conductivuty.png (14.05 KiB) Viewed 391 times
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antiscab
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Re: Leaf in the tropical north

Post by antiscab » Sat, 28 Sep 2019, 15:20

bladecar wrote:
Sat, 28 Sep 2019, 11:40
I have learned not to have a "specialist" car unless I am a specialist.
If you are not a hobbyist in the appropriate fields, avoid like the plague any transport which cannot be repaired by a commercial organisation in your reasonable vicinity.
This is solid advice
How comfortable are you working on electric vehicles? would you be willing to learn?
T1 Terry wrote:
Sat, 28 Sep 2019, 12:17
Something I've always wondered, if heat rises and cold falls, wouldn't blowing cold air above the battery pack and exhausting it below the battery pack a better method for cooling? I see all these cooling plates the cells sit on, but wouldn't that be the coolest part of the cell?
That is precisely the method the iMiev uses, though I'm not sure where the exhaust comes out. Just pulls cabin air into the battery, and charging chademo tells the car to run the aircon.
I have heard of leaf being modified in this way too, at least to achieve battery warming.
Who want's to be the first to do the mod to achieve battery cooling?
I know of a leaf down to 60km range that may be a good candidate for testing some ideas out

20km round trip isn't overly onerous, it is a shame that all the vehicles that have active battery cooling have 300km range and cost $50k+
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells

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jonescg
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Re: Leaf in the tropical north

Post by jonescg » Sat, 28 Sep 2019, 16:31

I hope to have a Leaf to play with soon. Only after a while though, Katherine would need to give her blessing :)
If nothing else, pulling air conditioned cabin air through the battery would make a world of difference.
AEVA National Secretary, WA branch chair.

JeffB
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Re: Leaf in the tropical north

Post by JeffB » Sat, 28 Sep 2019, 22:19

Many thanks to all of you for you input.

Bladecar has hit the nail on (my) head - while I like the idea of engineering an electric car, the fact is I lack the time, inclination, and abilty to build such a vehicle. Thanks for the reality check.
However I do have some technical skill, and there are many people on this forum willing to share their knowledge. Which might be useful given the nearest Nissan dealer is 800km away in Darwin, and the nearest dealer with EV experience is probably 3000km away in Perth.

So I think the summary is:
I'm not a specialist so I need a production car with its less than ideal chemistry.
The battery will have a shortened life due to the high ambient temperature.
Active battery cooling will help but by how much?
With reduced life there is no point in buying more battery than I need.
My commute is 20km to town plus running around, say 40-60km. 20kWh is sufficient with a margin for degradation.
And I can still use the air conditioner. Phew!

I had not thought of trying to cool the Leaf's battery using it's air conditioner, I wouldn't have thought there was sufficient space between the cells to allow air flow, but if someone has managed to heat one then maybe I should have a crack at cooling one (except I'm not a specialist right).

We have to buy an EV because we rather blow our carbon budget flying to Perth for family. Also our other car is a Hilux - good for getting us into the bush, but bad form for shopping. When a serious 4WD EV becomes available we will have to get a mortgage and buy one.
Kununurra runs mostly on hydro power so home solar doesn't make much environmental sense, but an EV really does.

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bladecar
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Re: Leaf in the tropical north

Post by bladecar » Sun, 29 Sep 2019, 07:25

Hi JeffB

Of course the "specialist" term is not designed to be a put-down, but to work on ev's is to be a "jack-of-all-trades", but forget the "master-of-none" bit. This would be disastrous.
The way I have looked at it is to remember there are lots of older codgers who have continued to climb ladders to attach photos to walls, to clean their rooves etc and who have fallen off those ladders with disastrous consequences. This was because you don't ask someone to do these simple things, that you have done all your lives, and then you fall off the ladder.
This sort of argument sounds stupid but emergency services, the racq etc have treated ev's extremely seriously because they can't afford to benefit from the sort of voltage that ev-s use. Very rigorous methods have to always be adhered to, where underlying knowledge determines those methods. There's a video of a US ev drag racer (forget the name - White Something) with a dc drag car that was doing 9 second or 8 second quarters, who accidently dropped some metal across some terminals and was lucky to be able to push the vehicle out of the building before everything went up in flames. Injury was also avoided.
So, I decided that acquiring skills is only part of the scene. You have to have deeply ingrained understanding to deal with high voltages. Young people with new careers can do this, and determined any-other-agers also, if they so desire.

Here, I believe our best interest is served by freely giving up any relevant information about the new Electric Vehicles which will give us economical knowledge (we didn't have to give over thousands to learn these bits of knowledge), will help us determine which Makes to promote (buy, talk about), which Makes are old-world or simply continuing to look after themselves, and to properly serve the transported masses instead of contemporary business, ie expensive cars, accepted expensive services, no vehicle value after 10 years regardless of vehicle quality etc.

This is the hope :)

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