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Discussion Starter · #1 ·
On a recent quick two day trip from Scotland to Cheltenham and back I managed to get south without any battery overheating problems, possibly because traffic was heavy. Coming back the next evening, with the outside temp at 18C, I was running into ten bars, just short of red, after a mere two rapid charges, and starting to get seriously concerned if I could get home.
The outside temp dropped slowly as I drove North. I reduced speed down to 60 mph, and by midnight it was about 8C outside. The car never got into the red, but I was getting very nervous.
No charger failures at all, but I would be concerned about repeating this journey in July or August.
 

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I wouldn't worry. The 30 will always be prone to heating up quicker compared to the 24 due to the charging characteristics being changed. The 30 will charge at a higher rate for a longer period of time and only tapers the charge towards the upper end of the SOC.

Drive the car and don't worry about it. The BMS should look after the battery if it's too hot. I would have thought it would reduce the charge rate before actually not allowing you to charge.
 

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As per the previous reply I wouldn't worry about it. I've driven long distances with multiple rapid charges and the battery temp showing 10 of 12 for much of the way without issue. I would suggest only taking action like letting it cool down for a bit if it actually goes into the Red. You might find rapid chargers will stop charging if it's in the red. The BMS should if working correctly keep it in the white :)
 

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My 24 doesn't get as hot, but takes longer to cool down.
I borrowed a 30 two weeks ago.
On Friday I Drove it from Reigate to Croyde in North Devon, then to Newquay in Cornwall and back to Croyde then the next day drove around in Devon then Sunday back to Reigate, so essentially the car was either driving or on charge.
The car was touching red the entire time, with no issues.
 

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The car was touching red the entire time, with no issues.
Yet!

Does anyone know the actual battery temperature (from LeafSpy) when touching red? What are the battery temperature specs for damage?

We've always been told heat damages the battery - just look at early US hot State owners. Is the 30kwh battery just a little too big to have no active battery temperature control?
 

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not sure about the OP, but in my case I stopped at 90 as the 30 hits 90% in the same time as my 24 hits 80, despite being red.
 

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I charged a couple of times to 95 over the weekend and it didn't add any heat at all... it was a pretty warm day too. I'm a bit surprised to read people saying the 30kw overheats as I've never seen any evidence of it. There must be some other difference - different generations of 30kw, different driving styles..?
 

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Wonder if B mode use would make a difference? If you use active regen then does it heat the battery more or less than if you don't? Is it different in Eco or Normal? There's definitely a lot to experiment with.
 

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Discussion Starter · #12 ·
I definitely drive the 30 K faster than the 24k, mainly because my range anxiety has reduced to about zero.
 

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Yet!

Does anyone know the actual battery temperature (from LeafSpy) when touching red? What are the battery temperature specs for damage?
Pretty sure I was on all blue bars lit when I grabbed this.
After my 300 mile trip I came to the conclusion I was adding a lot of temperature by charging in to the 90's%.
With the high battery temp I was still getting around 40kW at nearly 90% charge.


Text Font Parallel
 

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Discussion Starter · #15 ·
I really cannot believe that Nissan doesn't know all this stuff already, so why don't they share their own advice here rather than force us to have to find out for ourselves? I want an algorithm that I can save into my memory as a rule of thumb: e.g: for every 5C reduce speed by 5%, or: when it gets above twenty, 80% charge is plenty.
 
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I really cannot believe that Nissan doesn't know all this stuff already, so why don't they share their own advice here rather than force us to have to find out for ourselves? I want an algorithm that I can save into my memory as a rule of thumb: e.g: for every 5C reduce speed by 5%, or: when it gets above twenty, 80% charge is plenty.
This is why the leaf needs active cooling so this never arises.
 

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I really cannot believe that Nissan doesn't know all this stuff already, so why don't they share their own advice here rather than force us to have to find out for ourselves? I want an algorithm that I can save into my memory as a rule of thumb: e.g: for every 5C reduce speed by 5%, or: when it gets above twenty, 80% charge is plenty.
It just might be much better than we imagine. Perhaps the new cells are less prone to damage if at high temperatures. We have to know if we are comparing like with like or not before it is possible to draw any conclusions about 24 v 30 kWh battery temperatures and the effects on battery life.
 

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Discussion Starter · #18 ·
Well, as my own Leaf is a lease car, I can probably fry the batteries to buggery and still hand it back at no personal cost, but that isn't my style: I would rather the next person who buys it is happy with their purchase.
 

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I really cannot believe that Nissan doesn't know all this stuff already, so why don't they share their own advice here rather than force us to have to find out for ourselves? I want an algorithm that I can save into my memory as a rule of thumb: e.g: for every 5C reduce speed by 5%, or: when it gets above twenty, 80% charge is plenty.
Nnnnoooooooooooo why would they? :)

The last thing Nissan want to do with technology they're trying to take mainstream is make people memorise a matrix of battery temperature, speed, range, charging rate, ambient temperature, upcoming elevation changes, B mode use and driving style! A total show stopper for all but the most techno geeks (in the nicest way possible). And will make people think the car is really unreliable unless you stick to certain laid down parameters....and that's just not the case.

Do road cars come with a matrix of oil grades, petrol RON, RPM, and gear selection to help with efficiency....or tell you not to go screaming down the road at 30mph in 1st gear to prevent overheating?

The engineers have decided what's a tolerable temperature, based on the millions of miles of data and degradation they have from 5 years of leafs running about in all climates. And the testing they will have done with pre-production 30kWh Leafs.

If the cars were regularly refusing to charge due to excessive temperatures then they should provide tips on preventing that situation, but I just don't see it as a problem. Has anyone encountered this yet?
 
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