Battery temp management for new leaf

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Oils4AsphaultOnly said:
DaveinOlyWA said:
Oils4AsphaultOnly said:
I was thinking more like apt dweller who can now consider a leaf, because they can fast charge once a week while grocery shopping. QC'ing isn't just to make a long distance trip.

not sure there is any evidence that shows short duration heat being a significant cause of degradation. if it was, I would have lost about 7-8 bars by now! Been in the red a few dozen times but been at 9-10 TBs "at least" 100 times....

But the apt dweller with his 40kwh leaf QC'ing during grocery shopping, isn't doing a short-duration charge. This would be his weekly charge from 20% to 90%, because he doesn't have charging at home. This use case is most definitely long-duration QC.

Edit: By the way, 150 mile range isn't comatose driving, that's a 2-hr trip to san diego or to visit friends for a day. A QC will be needed for the return trip in case there's no L2 at the destination.

The "comatose" comment has to do with the LEAF, not the driver.

As far as a monster charging session once a week? hmmm, I think your gas roots are starting to show :)
 
DaveinOlyWA said:
Oils4AsphaultOnly said:
DaveinOlyWA said:
not sure there is any evidence that shows short duration heat being a significant cause of degradation. if it was, I would have lost about 7-8 bars by now! Been in the red a few dozen times but been at 9-10 TBs "at least" 100 times....

But the apt dweller with his 40kwh leaf QC'ing during grocery shopping, isn't doing a short-duration charge. This would be his weekly charge from 20% to 90%, because he doesn't have charging at home. This use case is most definitely long-duration QC.

Edit: By the way, 150 mile range isn't comatose driving, that's a 2-hr trip to san diego or to visit friends for a day. A QC will be needed for the return trip in case there's no L2 at the destination.

The "comatose" comment has to do with the LEAF, not the driver.

As far as a monster charging session once a week? hmmm, I think your gas roots are starting to show :)

And I think you're failing to account for the change in use-cases as the customer pool expands. How else would you see an apt dweller charge if they don't have home/work charging and still want to get an EV? There isn't an L2 charger in every parking lot yet.
 
Oils4AsphaultOnly said:
DaveinOlyWA said:
Oils4AsphaultOnly said:
But the apt dweller with his 40kwh leaf QC'ing during grocery shopping, isn't doing a short-duration charge. This would be his weekly charge from 20% to 90%, because he doesn't have charging at home. This use case is most definitely long-duration QC.

Edit: By the way, 150 mile range isn't comatose driving, that's a 2-hr trip to san diego or to visit friends for a day. A QC will be needed for the return trip in case there's no L2 at the destination.

The "comatose" comment has to do with the LEAF, not the driver.

As far as a monster charging session once a week? hmmm, I think your gas roots are starting to show :)

And I think you're failing to account for the change in use-cases as the customer pool expands. How else would you see an apt dweller charge if they don't have home/work charging and still want to get an EV? There isn't an L2 charger in every parking lot yet.

I would imagine that they would have to charge MUCH more often. Sure its conceivable that they live 10 miles from work and don't have much of a life so they don't need much more than 200 miles a week but even if that was the case, I still can't see the logic of charging for at least an hour when opportunity charging is available to simply grab enough to insure you have a day or two's worth.

But then again, I am a different shopper. I always use self check out for one and rarely in the building for 30 mins.
 
DaveinOlyWA said:
Oils4AsphaultOnly said:
DaveinOlyWA said:
The "comatose" comment has to do with the LEAF, not the driver.

As far as a monster charging session once a week? hmmm, I think your gas roots are starting to show :)

And I think you're failing to account for the change in use-cases as the customer pool expands. How else would you see an apt dweller charge if they don't have home/work charging and still want to get an EV? There isn't an L2 charger in every parking lot yet.

I would imagine that they would have to charge MUCH more often. Sure its conceivable that they live 10 miles from work and don't have much of a life so they don't need much more than 200 miles a week but even if that was the case, I still can't see the logic of charging for at least an hour when opportunity charging is available to simply grab enough to insure you have a day or two's worth.

But then again, I am a different shopper. I always use self check out for one and rarely in the building for 30 mins.

That's the difference right there I think. The cities around here aren't full of chargers everywhere. Opportunity charging is also dependent on the driver's lifestyle.

My co-worker lives in an apt and he desperately wants to dump his prius, he commutes ~15 miles each way per day. A few days charge for him would be ~25kwh, which means the 40kwh is almost a viable option for him (cost of the charge is the remaining issue). There's a large untapped pool of future EV owners out there, and what works for us charge@home types won't work for them.
 
Well, EVs are not going away so we will have MUCH more charging options or an all out war...

The ideology that long range EVs removes the need for public charging is completely wrong. Public charging only allows opportunity charging to cover more transportation options.
 
Here's why you are going to want/need an active TMS. All this talk about the internal resistance started me to wondering about what are the actual losses while driving and charging. Assuming 60 mph and 16 KWH per hour, that works out to 42 amps current across the internal resistance. 42*42*.115 = 202 watts internal loss. About 650 BTU's an hour. However if we are charging at a level 2 that's only 16,5 amps at 400 VDC. 16*16*.115 = about 32 watts internal loss or about 100 BTU's per hour. That's pretty negligible in my opinion. What happens when we DCFC at 40KW? I typically see 106 amps while fast charging. 106*106*.115 = 1292 watts or around 4000 BTU's per hour. Quite a difference there. What happens if we upgrade to 100KW charging so we can charge our 60 KWH 2019 Leaf in 30-40 minutes? Now we're talking 250 amps at 400 VDC. If we assume no changes to the internal resistance then we are looking at 7200 W loss and 25000 BTU'S an hour. Even if you can somehow cut the internal resistance by 75% you are still looking at 6000 BTU's an hour and that kind of reduction isn't likely. If you want to charge at high rates you are going to have to cool the battery somehow.

You can quibble over what the actual values are for internal resistance. The fact remains that fast charging will generate a lot of heat and if you can't get rid of it, you will cook the battery. Larger batteries make the situation worse simply because higher currents are necessary to keep the charge time reasonable. If you can park your car overnight while charging, you might not need TMS for that. Of course, that might not be viable in Phoenix or Dallas or even east county San Diego. It appears that months of high temps take a toll in any case. Since Tesla's don't seem to have this problem, either the battery chemistry is better or active cooling works or both.
 
Just out of curiosity, I checked my battery temps before and after L2 charging. Battery temp before charging was 81 degrees and after 3 hours charging ( 24%-100%) it was 85 degrees. Ambient at start was 81 degrees at start and 87 degrees at the end. the battery didn't generate enough heat to even keep up with the change in ambient temps. If I get the chance I'll try to repeat this with a DCFC just to see what the difference is. I know that it will add a couple of bars to the temp gauge but that is so inaccurate that it's next to meaningless. I've always wondered why they didn't assign fixed increments to the temp gauge rather than the overlapping ranges they use. Or even better a digital readout! For Christ's sake, it's an electric car with a screen in place of the gauges, Why not just give me the facts instead of guess-o-meter gauges with simulated analog readouts.
 
johnlocke said:
Just out of curiosity, I checked my battery temps before and after L2 charging. Battery temp before charging was 81 degrees and after 3 hours charging ( 24%-100%) it was 85 degrees. Ambient at start was 81 degrees at start and 87 degrees at the end. the battery didn't generate enough heat to even keep up with the change in ambient temps. If I get the chance I'll try to repeat this with a DCFC just to see what the difference is.
It would also be interesting to know how much the battery heats up in those conditions without any charge.
I'll guess very little -- perhaps a degree.

That is the battery heat capacity in play, but it also means that cool-down is slow
 
johnlocke said:
It appears that months of high temps take a toll in any case. Since Tesla's don't seem to have this problem, either the battery chemistry is better or active cooling works or both.
I gather that the Volt uses battery and a chemistry very similar to the LEAF albeit with a TMS, and has not been associated with much if any range loss.

There are some five people left outside of Nissan who are skeptical of the utility of a good TMS, but for everyone else the debate is over. And frankly, I expect those five to become fierce TMS advocates the day that Nissan includes one in their EVs
 
SageBrush said:
johnlocke said:
Just out of curiosity, I checked my battery temps before and after L2 charging. Battery temp before charging was 81 degrees and after 3 hours charging ( 24%-100%) it was 85 degrees. Ambient at start was 81 degrees at start and 87 degrees at the end. the battery didn't generate enough heat to even keep up with the change in ambient temps. If I get the chance I'll try to repeat this with a DCFC just to see what the difference is.
It would also be interesting to know how much the battery heats up in those conditions without any charge.
I'll guess very little -- perhaps a degree.

That is the battery heat capacity in play, but it also means that cool-down is slow

You both need to use LeafSpy and not guess or rely on cluster bars graphs, and/or indicate data measurement source.
 
OK I did a DCFC today from 37% to 100%, I started at 82 degrees battery temp with 74 degree ambient. ended at 100.2 degrees battery temp with ambient still at 74 degrees. For whatever good it does, the temp gauge went from 6 bars to 8 bars.

I have in the past pushed the battery to 11 bars (112 degrees according to Leaf Spy). It was really hot day and I had to DCFC to get home but I wouldn't recommend it.

As an interesting note, I was still charging at over 30 KW even with the battery at over 95% and was still drawing 13 KW even at the end.
 
johnlocke said:
OK I did a DCFC today from 37% to 100%, I started at 82 degrees battery temp with 74 degree ambient. ended at 100.2 degrees battery temp with ambient still at 74 degrees. For whatever good it does, the temp gauge went from 6 bars to 8 bars.

I have in the past pushed the battery to 11 bars (112 degrees according to Leaf Spy). It was really hot day and I had to DCFC to get home but I wouldn't recommend it.

As an interesting note, I was still charging at over 30 KW even with the battery at over 95% and was still drawing 13 KW even at the end.
You have a 30 kWh battery Leaf, right?

This is even more evidence beyond what I already had w/24 kWh Leafs that the "80%" DC FC "unwritten rule" as to when to yield and change to L2 is incorrect. When I had a Leaf w/CHAdeMO, I've been past 90% w/the rate still being higher than my car's max L2 rate of 6.6 kW.
 
johnlocke said:
OK I did a DCFC today from 37% to 100%, I started at 82 degrees battery temp with 74 degree ambient. ended at 100.2 degrees battery temp with ambient still at 74 degrees. For whatever good it does, the temp gauge went from 6 bars to 8 bars.

I have in the past pushed the battery to 11 bars (112 degrees according to Leaf Spy). It was really hot day and I had to DCFC to get home but I wouldn't recommend it.

As an interesting note, I was still charging at over 30 KW even with the battery at over 95% and was still drawing 13 KW even at the end.

is that a typo? Because that is significantly different than what I am seeing. Now I have 3 sensors where 2 are close but one is generally 5-10º cooler. Is this the lowest sensor you are referring to?
 
DaveinOlyWA said:
johnlocke said:
OK I did a DCFC today from 37% to 100%, I started at 82 degrees battery temp with 74 degree ambient. ended at 100.2 degrees battery temp with ambient still at 74 degrees. For whatever good it does, the temp gauge went from 6 bars to 8 bars.

I have in the past pushed the battery to 11 bars (112 degrees according to Leaf Spy). It was really hot day and I had to DCFC to get home but I wouldn't recommend it.

As an interesting note, I was still charging at over 30 KW even with the battery at over 95% and was still drawing 13 KW even at the end.

is that a typo? Because that is significantly different than what I am seeing. Now I have 3 sensors where 2 are close but one is generally 5-10º cooler. Is this the lowest sensor you are referring to?
Not a typo unfortunately. I was referring to the highest value shown in Leaf Spy but my sensors usually don't have more than a 5 degree spread. And yes I do own a 30 KWH 2016 currently at 73% SOH and 268 GID's full charge. To be fair, it was a 90+ degree day and the battery started at 8 or 9 bars (I don't remember which) but I had to get home so I charged it anyway.
 
johnlocke said:
DaveinOlyWA said:
johnlocke said:
OK I did a DCFC today from 37% to 100%, I started at 82 degrees battery temp with 74 degree ambient. ended at 100.2 degrees battery temp with ambient still at 74 degrees. For whatever good it does, the temp gauge went from 6 bars to 8 bars.

I have in the past pushed the battery to 11 bars (112 degrees according to Leaf Spy). It was really hot day and I had to DCFC to get home but I wouldn't recommend it.

As an interesting note, I was still charging at over 30 KW even with the battery at over 95% and was still drawing 13 KW even at the end.

is that a typo? Because that is significantly different than what I am seeing. Now I have 3 sensors where 2 are close but one is generally 5-10º cooler. Is this the lowest sensor you are referring to?
Not a typo unfortunately. I was referring to the highest value shown in Leaf Spy but my sensors usually don't have more than a 5 degree spread. And yes I do own a 30 KWH 2016 currently at 73% SOH and 268 GID's full charge. To be fair, it was a 90+ degree day and the battery started at 8 or 9 bars (I don't remember which) but I had to get home so I charged it anyway.

interesting. I generally don't hit "10" bars until after 124º F 11 bars around 128º

Sounds like the "temperature" bars take other things into account other than temperature.

I would venture to say that your "11 bar temperature turn on" has been creeping downwards with your range.

Granted this was a while ago but I just repeated this trip in Mid Sept with nothing significantly different including temperatures despite average temps in the upper 70's... check out the temps for my car.

http://daveinolywa.blogspot.com/2017/03/road-trip-adventures-of-9-tb-journey.html
 
OT: Dave, are those the usual Ecopias? What is your cold inflation temp?

I just replaced original tires with Ecopia Plus a few weeks ago. I expected that losing the worn, thinner, and so presumably more supple tread would cost me efficiency, and indeed I seem to be off by a half mile per kWh. I have been staying at the sidewall max of 40 PSI cold. I'm probably going to push past that a bit since my driving is all a low speed and, for the next 7-8 months, low temps.
 
BuckMkII said:
OT: Dave, are those the usual Ecopias? What is your cold inflation temp?

I just replaced original tires with Ecopia Plus a few weeks ago. I expected that losing the worn, thinner, and so presumably more supple tread would cost me efficiency, and indeed I seem to be off by a half mile per kWh. I have been staying at the sidewall max of 40 PSI cold. I'm probably going to push past that a bit since my driving is all a low speed and, for the next 7-8 months, low temps.

Those are OEMs and my cold pressure target is always the Max sidewall pressure. Can't remember the last time I saw a passenger tire with 40 PSI listed. (if ever?)
 
johnlocke said:
Just out of curiosity, I checked my battery temps before and after L2 charging. Battery temp before charging was 81 degrees and after 3 hours charging ( 24%-100%) it was 85 degrees. Ambient at start was 81 degrees at start and 87 degrees at the end. the battery didn't generate enough heat to even keep up with the change in ambient temps. If I get the chance I'll try to repeat this with a DCFC just to see what the difference is. I know that it will add a couple of bars to the temp gauge but that is so inaccurate that it's next to meaningless. I've always wondered why they didn't assign fixed increments to the temp gauge rather than the overlapping ranges they use. Or even better a digital readout! For Christ's sake, it's an electric car with a screen in place of the gauges, Why not just give me the facts instead of guess-o-meter gauges with simulated analog readouts.

Psychology and obfuscation. The same reason the last SOC bar is so much wider than the others or why the first capacity bar is so much wider than the others. Carmakers are like Col. Nathan Jessup -- they don't think you can handle the truth.

And sometimes they're right. I remember my original Miata had a functional oil pressure gauge, which was useful for judging when the car was warmed up. But too many owners weren't familiar with how viscosity changes with temperature and would freak out either over the high initial pressure, or the big drop when warmed up. Mazda got tired of the inquiries and complaints and in future vehicles chose a unit that was an idiot-light masquerading as a pressure gauge.
 
Right in the manual it states that the temp bars represent a range of values and that the range for a given bar can overlap the ranges for other bars. What that depends upon is anybody's guess! The highest temp I ever saw was 117 degrees and still 11 bars. If I recall correctly, the system will throttle back output if the temp exceeds 122 degrees.
 
johnlocke said:
Right in the manual it states that the temp bars represent a range of values and that the range for a given bar can overlap the ranges for other bars. What that depends upon is anybody's guess! The highest temp I ever saw was 117 degrees and still 11 bars. If I recall correctly, the system will throttle back output if the temp exceeds 122 degrees.

Been over 122º dozens of times and only saw one "possible" time that the speed of the fast charge might have been throttled. Was expecting roughly 45-46 KW and it was only running at 30 KW. I think I only had 9-10 bars at the time
 
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