TonyWilliams
Well-known member
TRONZ said:As far as I can tell the most technically savvy on MNL are not even sure of the usable capacity in a LEAF.
Because it doesn't have a single value.
TRONZ said:As far as I can tell the most technically savvy on MNL are not even sure of the usable capacity in a LEAF.
I am in Phoenix and I see no reason for the added complexity of active thermal management. My battery temperature has ranged between 4 and 8 bars during the past 11 months and 10,000+ miles.SanDust said:How many people still think a thermal management system for the battery pack is unnecessary?
According to this article, the lithium hexafluorophosphate in Li-ion batteries breaks down even at room temperatures and the effect accelerates as the temperature increases:Smidge204 said:Until it's actually proven that temperature is the cause, or even a major contributing factor,...SanDust said:How many people still think a thermal management system for the battery pack is unnecessary?
If the battery in the LEAF contains lithium hexafluorophosphate, and I'm betting it does, then temperature is a significant contributing factor. Does anyone know? (BTW, the battery Leyden Energy is developing looks like it might make a GREAT replacement for the current LEAF battery some day!)Leyden's battery replaces lithium hexafluorophosphate, one of the components of a lithium-ion battery, with imide salt. Unlike lithium hexafluorophosphate, it does not react with water inside the battery cell, a reaction that significantly degrades the cycle life of a battery. Lithium hexafluorophosphate also starts to decompose at room temperature and loses its effectiveness more significantly when the temperature hits 55 °C. Imide salt doesn't start to decompose at higher temperatures.
I agree the jury is still out on the issue of thermal management systems, however. When it is 105 degrees F in Phoenix, do we expect the car to run a compressor to cool the battery below ambient temperatures. At some point, you just need a higher-temperature battery solution.Smidge204 said:...there is no reason to think thermal management would have prevented the problem. Jury is still out.
=Smidge=
RegGuheert said:When it is 105 degrees F in Phoenix, do we expect the car to run a compressor to cool the battery below ambient temperatures.
GerryAZ said:I am in Phoenix and I see no reason for the added complexity of active thermal management. My battery temperature has ranged between 4 and 8 bars during the past 11 months and 10,000+ miles.SanDust said:How many people still think a thermal management system for the battery pack is unnecessary?
Gerry
thankyouOB said:I have become really concerned in the past few days as my battery temp, which always used to be at 5 bars, is now occasionally at 6 bars after charging in the sun.
Yes, and a LEAF battery soaking at 105F in the shade would approach 105F. That is likely hotter than the current technology will withstand for long considering Nissan says no more than 24 hours at 120F. If soaking in the sun at those temperatures, the battery could get well above 105F.TonyWilliams said:105F would be ambient in your example.RegGuheert said:When it is 105 degrees F in Phoenix, do we expect the car to run a compressor to cool the battery below ambient temperatures.
Unless, of course, the cost, weight, energy and power density of the high-temp technology were such that it's easier and better to actively cool the pack. Everything is a tradeoff...RegGuheert said:Regardless, my point stands as written. I don't think having to run a compressor to be able to cool a battery makes much sense. Better to apply a high-temperature battery technology. They exist now with higher capacity.
It's not weight or energy density, since those are shown. Manufacturing cost appears decent since it can be manufactured on standard equipment. Licensing cost could be an issue. I suspect you are right on about power density, since I can find absolutely NO mention of it on the website and there is a mention of "light" electric vehicles.Smidge204 said:Unless, of course, the cost, weight, energy and power density of the high-temp technology were such that it's easier and better to actively cool the pack. Everything is a tradeoff...RegGuheert said:Regardless, my point stands as written. I don't think having to run a compressor to be able to cool a battery makes much sense. Better to apply a high-temperature battery technology. They exist now with higher capacity.
=Smidge=
Smidge204 said:Until it's actually proven that temperature is the cause, or even a major contributing factor, there is no reason to think thermal management would have prevented the problem. Jury is still out.SanDust said:How many people still think a thermal management system for the battery pack is unnecessary?
=Smidge=
TonyWilliams said:TRONZ said:As far as I can tell the most technically savvy on MNL are not even sure of the usable capacity in a LEAF.
Because it doesn't have a single value.
TRONZ said:TonyWilliams said:TRONZ said:As far as I can tell the most technically savvy on MNL are not even sure of the usable capacity in a LEAF.
Because it doesn't have a single value.
Yes. It is surely very difficult to shoot at a moving target. Which also leads me to a question.
If a LEAF charging overnight on a cooled pack is also finishing its charging during the coolest part of early morning, does that give the "impression" of capacity loss if you then take it out of this cool charging environment into a noticeably warmer daytime asphalt environment? Ex; You keep the same amount of water in the pool but the pool gets bigger (capacity) later in the day?
Someone made the comment that they did not want to charge a pack at higher temps and then put the car in a cool environment for risk of "overcharging". If this is true, then would the reciprocal happen going from cold to warm and creating "undercharging".
edatoakrun said:And if you then let the car sit overnight for the battery to cool down to the lowest ambient temperature the next morning...
TRONZ said:Someone made the comment that they did not want to charge a pack at higher temps and then put the car in a cool environment for risk of "overcharging". If this is true, then would the reciprocal happen going from cold to warm and creating "undercharging".
thankyouOB said:I have become really concerned in the past few days as my battery temp, which always used to be at 5 bars, is now occasionally at 6 bars after charging in the sun.
TonyWilliams said:Because it doesn't have a single value.
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