derkraut
Well-known member
+1 Well said Dreesdrees said:
How can I measure the battery pack temperature?
- Thread starter chennu
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WetEV
Well-known member
ksnogas2112 said:
I've been at 5 bars almost the entire time I've had my Leaf. I've seen 6 bars after a QC, and sometimes in the afternoons on the drive home.
This morning it was 21 C in the garage, and I've seen 6 bars in the morning for the first time. Heat wave (near 90 F!) is going to last through today, might see this again tomorrow morning.
If 10C warmer for a day removes a day of life from the battery pack, then reducing the temperature in the garage by 5C in the summer is worth money, even in a cooler location. Consider the following:
Assume price of battery pack replacement = US$10,000
Assume life at current conditions = 8 years.
Assume summer is 4 months, and by putting a fan and or vents in the garage the average temperature of the garage in the summer is 5C lower.
Assume the car is in the garage 2/3 of the time.
Extra life would be life / fraction of time cooler /extra life fraction /time in garage = 0.67 years
Value of extra is roughly Price/life*extra life = $830.
This is a very rough calculation. YMMV SDD SRA.
DaveinOlyWA
Well-known member
WetEV said:
for those of you that have solar, i would find it very difficult to believe that you did not have at least a "whole house" ventilation fan which i am guessing could be installed DIY for less than $500. its mounts in ceiling and draws air into the attic. it allow several air exchanges per hour and essentially can cool garage to outside air temperature (or near it depending on how much heat is stored in floor) within minutes.
this morning i measured temps in garage and it did cool down quite a bit more this morning than yesterday morning but still only 23C (73.4F) but better than yesterday morning (25 C) where i had 6 TBs without any charging to add heat.
This actually sounds like a good idea to me, so I ordered one of these this morning.EVDRIVER said:
When it gets here I am thinking that I can just open the access hatch on the center tunnel and put the temp probe in there. Has anyone tried this before and how accurate do think the readings will be with this method?
Sure would be nice if Phil would get the Leafscan finished so we could get some real data.
DaveinOlyWA
Well-known member
WetEV said:
for those of you that have solar, i would find it very difficult to believe that you did not have at least a "whole house" ventilation fan which i am guessing could be installed DIY for less than $500. its mounts in ceiling and draws air into the attic. it allow several air exchanges per hour and essentially can cool garage to outside air temperature (or near it depending on how much heat is stored in floor) within minutes.
this morning i measured temps in garage and it did cool down quite a bit more this morning than yesterday morning but still only 23C (73.4F) but better than yesterday morning (25 C) where i had 6 TBs without any charging to add heat.
davewill
Well-known member
I'm not sure why solar owners would automatically have such a thing... Are you actually venting your garage into your attic? Moisture and carbon monoxide and all? A proper ventilation system should vent directly outside, not into the attic.DaveinOlyWA said:
TonyWilliams
Well-known member
davewill said:
No, the whole House fans go to the attic to lower that temp, and drawing in cooler outside air through the house. Obviously, not so good if the outside temp is hot.
DaveinOlyWA
Well-known member
davewill said:
your attic is vented and probably one of the best designed venting systems on the planet if done properly. your attic has the advantage of extreme thermal dynamics. if you doubt the "extreme" part, just take a stroll thru there on a moderate summer day.
anyway; what we frequently see is the floor of the garage retaining heat for several hours after the sun goes down making the garage much warmer for much longer.
i have seen whole house fans which are very popular in the NW simply because most people dont have A/C (average high temps for August is 76 so who needs it?) but we still get those "Cali-like" days when the weather shifts from its normally eastward wandering ways and heads north like it is today.
so houses will build up heat during the day (mine was at 87º at 9 PM yesterday OAT 77) and stay that way long after the temperature has started to drop.
in the house i built which was two story, a 10º difference or more from upstairs to downstairs was common. after two years of that, i put one of those fans in and it cooled my house down in 10 minutes. i open the windows and it sucks cold air into the house, vents hot air into the already hotter attic and out the roof vents it was unreal how fast it worked. now, keep in mind; mine was either manual or timer and it does not work if its still hot outside
ebill3
Well-known member
Anyway, back on topic, sort of. :roll:
Earlier, I sort of pooh-poohed high temps for two or three days. I must admit I have made a concession and today asked my wife to not park her really hot ICE SUV in the garage next to the cool LEAF.
Earlier, I sort of pooh-poohed high temps for two or three days. I must admit I have made a concession and today asked my wife to not park her really hot ICE SUV in the garage next to the cool LEAF.
dandrewk
Well-known member
Dave - still not sure why solar panel owners should or would have attic fans over and above anyone else. If it's for the clean/free power to run the fan... power is power. If every solar panel owner installed the fan, that's just that much less power for the home to use or excess power pumped back into the grid.
DaveinOlyWA
Well-known member
dandrewk said:
i see a lot of concern over the cost of running any electrical appliance here and its not groundless. my statement was only made because the cost of the materials is small, it is not a difficult DIY project for most people and if you have extra electricity to burn, why not?
i am hardly recommending it to "only" solar people. i think it is a great option for those people who live in an area where A/C may not be financially feasible like i do or people in Coastal Cali. as i said; i had it in the house i built and immediately my first reaction is why doesnt every house in the Pacific Northwest not have it because it does work that well!
Randy3
Well-known member
davewill said:
I have solar and a whole house fan, but the fan doesn't do anything for the attached garage. It draws air from the living quarters of the house into the attic.
So, are we concluding that keeping the garage below a certain temp may help with battery degrading? If so, what temp and for how long per day?
As stated earlier, every 10C cooler you can keep your battery will result in double the calendar life.Randy3 said:
But, unless you air condition your garage, you probably aren't going to reduce the temperature there by more than 10F or about 6C at most unless your garage really holds heat in.
And typically, you're probably parked in the garage about 12 hours/day - but you probably won't see a significant temp difference with fan cooling for half of those hours.
Personally, I'm going add a gable vent to my garage at the highest point about 20ft up the wall - vaulted ceiling - it already has 4 vents - 2 at ground level and 2 at about 10 ft, but you can't feel any air flowing. I'm hoping that another vent near the highest spot where there's a greater temperature difference (typically 5-10F warmer at the top than the bottom of the garage) will help draw air in at the lower vents through convection. If not, it will be easy to add a fan at that point.
But I don't think it's going to make a huge difference in battery life.
Parking in the sun during the day when temps are higher probably accelerates capacity loss enough to where reducing the min temp a few degrees at night gets lost in the noise.
DaveinOlyWA
Well-known member
since it was nice enough to be hot the last few days i did check temps and during the heat of the day when afternoon sun shines on garage door. keeping door shut made it about 4-5 º cooler inside and prevented radiant heat spikes which were 10-20 º hotter. all measured at 30".
with garage door closed and temps measured at ceiling about 102" temps were usually 10-15 higher. with door open, 2-5 higher. i have no ventilation which is common in WA for attached garages and garage is finished sheetrock.
i also checked to see how well heat was retained. with garage door open, as OAT went down, garage stayed 1-4 warmer as measured 8 ft from door for about first two hours then nearly equal after. with door shut temp was 3-6 warmer for first hour after sundown (measured thurs at 9:15) 10-12 warmer 2 hours after sundown and 10-15 º warmer 3 hours after sundown
morning temps were 6-8 warmer with door closed.
with garage door closed and temps measured at ceiling about 102" temps were usually 10-15 higher. with door open, 2-5 higher. i have no ventilation which is common in WA for attached garages and garage is finished sheetrock.
i also checked to see how well heat was retained. with garage door open, as OAT went down, garage stayed 1-4 warmer as measured 8 ft from door for about first two hours then nearly equal after. with door shut temp was 3-6 warmer for first hour after sundown (measured thurs at 9:15) 10-12 warmer 2 hours after sundown and 10-15 º warmer 3 hours after sundown
morning temps were 6-8 warmer with door closed.
WetEV
Well-known member
drees said:
For a car in a hot place that parks in a covered or shaded spot for 9 hours a day, drives a half an hour each way, and parks in an air conditioned garage (swamp cooler) the rest of the time, what sort of battery life increase might be expected?
Assume X = life of battery at 20C
Assume that the garage temperature without the swamp cooler is 30C
Assume that the garage can be cooled by the swamp cooler to 20C
Assume that the temperature during the day is 40C
Assume that the temperature during the morning drive is 30C
Assume that the temperature during the evening drive is 40C
Here I get to a point that I have to warn the reader. I don't have a very good guess as to heat transfer rates in the above cases. The above can be easily changed to match the conditions in your area. But heat transfer rates are more than somewhat unknown. I might make a WAG, but a swamp cooler is a larger investment than a vent and a fan, and a window AC larger still. So I ran an experiment overnight. After starting to write this reply, I went and checked on my experiment. I put a box fan in the side door of the garage and pointed it at Leaf's front right side just in front of the front wheel starting at about 9 PM last night. The outside temperature was 20C then, was 15C overnight and is 17C at 9:30AM. The garage temperature was 19C this morning, and that matches what the Leaf's temperature display shows 67F. The Leaf still shows 6 TBs this morning at 8:30, several hours after the end of charging. I expected that this garage temperature and cool airflow under the car would cool the battery pack to 5 TBs. The result isn't what I expected. Perhaps the Leaf requires airflow from the front to exchange heat with the battery?? What does the heat transfer path from the battery really look like?? To this point, I moved the fan to blow air on the front of the car and rechecked the TBs in an hour (9:30). This gave 5 TBs for a few seconds, then increased to 6 TBs!? I suspect that airflow into the front grill is needed. But I really don't have enough information. What I really need is a real temperature gage on the battery. Can any of the CAN bus devices do this today? TBs are just too coarse for the limited range of temperatures I see.
Sorry for the stream of consciousness reply. I have to stop and say I don't know enough right now to even make a reasonable guess as to heat transfer. Putting a fan or a duct from the AC/swamp cooler to have airflow into the grill at the front of the car might matter a lot. I'm starting to wonder if the drive time temperature might be more important due to airflow than parking or garage temperatures.
If any CAN bus monitor can give me battery pack temperature (even if not yet ready for public release), please send me a PM.
DaveinOlyWA
Well-known member
EVDRIVER said:
have to agree. i have one with a sensor so can read temps in two different places and its surprising how much heat is simply nonconforming. i see 3-5º temp differences as little as 3-5 feet apart so a probe measuring the ambient temp less than 6 " from the pack can give you information that can be nearly useless.
Yeah, without knowing actual battery temp - temp bars are fairly useless - you can only reliably tell when the battery exceeds a certain temp.WetEV said:
If you examine the underside of the car, the battery pack is completely covered (see Underneath the Beast; a Tour of the Dark Side for great pics from Tony) - airflow around the pack primarily comes from front-to-back (which I find curious since running the A/C will end up heating up the pack more) - so if you're going to point a fan at the car with the goal to cool the pack, it's best to point it at the grill.
Without access to the internal temp sensors, probably the best you can do is to tape a sensor to the battery pack shell (I would cover the sensor with insulated tape to help make sure that you're reading as close to pack temps as possible).
