Lost Battery Capacity and Range / Autonomy, Page 2

[davewill]

Nope. The amount of power the Air Conditioner uses is quite modest. The heater uses far more.

And both are modest compared to the power used by the motor. Neither is likely to seriously affect degradation, unless you're in the habit of leaving them running until the battery is dead.

 

[DaveinOlyWA]

Nope. The amount of power the Air Conditioner uses is quite modest. The heater uses far more.

And both are modest compared to the power used by the motor. Neither is likely to seriously affect degradation, unless you're in the habit of leaving them running until the battery is dead.

sorry but never gonna believe that A/C power usage is insignificant in an area that averages 110º in the shade

 

[davewill]

Nope. The amount of power the Air Conditioner uses is quite modest. The heater uses far more.

And both are modest compared to the power used by the motor. Neither is likely to seriously affect degradation, unless you're in the habit of leaving them running until the battery is dead.

sorry but never gonna believe that A/C power usage is insignificant in an area that averages 110º in the shade

Insignificant in that it's not going to degrade the battery faster. 1-5kW vs. the motor's 20-80kW. It will certainly have an effect on range, but the reports, even from AZ and TX is that the AC is much more manageable than the heater is in cold areas.

 

[surfingslovak]

Insignificant in that it's not going to degrade the battery faster. 1-5kW vs. the motor's 20-80kW. It will certainly have an effect on range, but the reports, even from AZ and TX is that the AC is much more manageable than the heater is in cold areas.

I would have to agree. Isn't heater and A/C use baked into the energy economy figure, and by extension the nice annual battery report everyone gets? If I used a lot of energy and taxed the battery more heavily than I should, I would expect to hear about it. That's what these printouts are here for.

 

[azdre]

sorry but never gonna believe that A/C power usage is insignificant in an area that averages 110º in the shade

Depends how you use it. Auto will suck lots of juice, but low fan, and a reasonable 76-78 degrees on the temp, and you're using just a sliver.

 

[tokenride]

For anyone here keeping track I lost another bar over the long weekend. That is two so far. I have just over 25k miles on it. I have have not contacted Nissan.

 

[ydnas7]

anyone see the disconnect between theory and practise

the idea was that because of the thermal mass of the battery pack, it would be around the average ambient temperature

the theory was that the ambient would be the average of the reported monthly min and max

the practise was that the ambient was elevated inpart due to an elevated minimum temperature by the vehicle being indoors during the cool of the night.

the theory works for Honolulu but not Phoenix (even though Honolulu has a higher average, annual temperature.)

 

[ydnas7]

Driving on a dirt road this evening, returning home from some hiking, we almost hit a deer. It jumped right in front of us. Whether you're actually any more likely to hit a deer in an EV is hard to say, though.

By the way, I now know a sure-fire way to reduce the indicated battery temperature - drive through a stream that completely soaks the underside of the car. Went from six temp bars to five in minutes, and it never climbed back to six. And we have a nice coat of dust and mud on the LEAF.

Heres an idea, would a weekly or fortnightly car wash disrupt the battery loss in Phoenix to make a noticeable difference?

http://www.yelp.com.au/biz/clean-freak-car-wash-phoenix" onclick="window.open(this.href);return false;

 

[Nubo]

sorry but never gonna believe that A/C power usage is insignificant in an area that averages 110º in the shade

Depends how you use it. Auto will suck lots of juice, but low fan, and a reasonable 76-78 degrees on the temp, and you're using just a sliver.

I keep seeing a lot of posts about using "low fan" to save energy with the AC. Not sure how much that matters. The bulk of the energy use is in compressing the refrigerant. And the amount of that work is driven by the cabin temperature and external heat load. At a given cabin temperature the compressor will work just as hard on low fan setting as it does on high. And the energy consumption of the cabin fan itself is pretty insignificant. The only exception I can think of is if the fan setting is low enough to where the cooling doesn't keep up and you save some energy by virtue of the cabin actually being warmer than the selected temperature.

In fact I'd think the case could be made for a higher fan speed being more efficient by allowing more efficient heat exchange and also allowing you to be more comfortable at a higher cabin temperature setting.

Or am I missing something?

 

[TonyWilliams]

sorry but never gonna believe that A/C power usage is insignificant in an area that averages 110º in the shade

Depends how you use it. Auto will suck lots of juice, but low fan, and a reasonable 76-78 degrees on the temp, and you're using just a sliver.

I keep seeing a lot of posts about using "low fan" to save energy with the AC....
Or am I missing something?

For folks with Phil's climate control modification, the fan can run without the compressor or heater being powered. If they don't have the modification, then I agree with you, the high voltage air conditioning compressor is the big power consumer, and where you place the fan speed won't matter much.

 

[DaveinOlyWA]

i agree which is why my A/C runs on high fan a lot. granted i dont have the temps to be concerned about but i do see 1400-2000 watts consumed when A/C is first turned on. here in mild Pac NW, that only lasts 5-10 minutes. guessing that is not true for Phoenix meaning A/C could easily be using more than 10% of your pack if you are not on the freeway.

i call that significant.

 

[LEAFfan]

sorry but never gonna believe that A/C power usage is insignificant in an area that averages 110º in the shade

Depends how you use it. Auto will suck lots of juice, but low fan, and a reasonable 76-78 degrees on the temp, and you're using just a sliver.

I keep seeing a lot of posts about using "low fan" to save energy with the AC. Not sure how much that matters. The bulk of the energy use is in compressing the refrigerant. And the amount of that work is driven by the cabin temperature and external heat load. At a given cabin temperature the compressor will work just as hard on low fan setting as it does on high. And the energy consumption of the cabin fan itself is pretty insignificant. The only exception I can think of is if the fan setting is low enough to where the cooling doesn't keep up and you save some energy by virtue of the cabin actually being warmer than the selected temperature.
In fact I'd think the case could be made for a higher fan speed being more efficient by allowing more efficient heat exchange and also allowing you to be more comfortable at a higher cabin temperature setting.
Or am I missing something?

I'm with azdre. I set mine to 60F, low fan and it only uses a sliver. When I increase the fan speed, the KW go up. And the low setting is with the high temps during the day.

 

[LEAFfan]

i agree which is why my A/C runs on high fan a lot. granted i dont have the temps to be concerned about but i do see 1400-2000 watts consumed when A/C is first turned on. here in mild Pac NW, that only lasts 5-10 minutes. guessing that is not true for Phoenix meaning A/C could easily be using more than 10% of your pack if you are not on the freeway.
i call that significant.

It's only significant if it happens. It doesn't happen here. You see up to 2kW for 5-10 minutes!? When it's over 100F here, mine set at 60F and low fan speed only uses that for about a minute before it drops to a sliver. So your guess is incorrect. I wouldn't call a sliver (-0 to -1 mile) anywhere near 10%, let alone over 10%. Once again, please stick to what you know in WA, and refrain from telling Phoenix FUD.

 

[Nubo]

I'm with azdre. I set mine to 60F, low fan and it only uses a sliver. When I increase the fan speed, the KW go up. And the low setting is with the high temps during the day.

Maybe the computer is "generating" those values using fan speed as part of the equation, instead of directly measuring current? Pretty sure it does that for the 12V stuff, not sure of AC.

Also, with a higher fan speed I would expect the compressor to have shorter but more intense duty cycles, so maybe something is just measuring peaks during a given interval, etc.. I'm not going to throw the laws of thermodynamics out the window just yet based on the LEAF's instrumentation, of all things. :lol:

 

[LEAFfan]

I'm with azdre. I set mine to 60F, low fan and it only uses a sliver. When I increase the fan speed, the KW go up. And the low setting is with the high temps during the day.

I'm not going to throw the laws of thermodynamics out the window just yet based on the LEAF's instrumentation, of all things. :lol:

Ok, where does it say in the laws of thermodynamics that increasing fan speed will lower your kW usage? :lol: Azdre and I know that with using the low fan speed, it barely makes a dent in our range.

 

[TonyWilliams]

I'm with azdre. I set mine to 60F, low fan and it only uses a sliver. When I increase the fan speed, the KW go up. And the low setting is with the high temps during the day.

I'm not going to throw the laws of thermodynamics out the window just yet based on the LEAF's instrumentation, of all things. :lol:

Ok, where does it say in the laws of thermodynamics that increasing fan speed will lower your kW usage? :lol: Azdre and I know that with using the low fan speed, it barely makes a dent in our range.

One possibly; the LEAF probably isn't doing much with climate control at 70F ambient temperatures, and we know that lithium batteries will increase in cacpacity with heat, that just happens to correspond to you climate control use.

Might be a wash. I know that doesn't address fan speed, just limited impact to range with light A/C use in hot weather.

 

[Nubo]

I'm with azdre. I set mine to 60F, low fan and it only uses a sliver. When I increase the fan speed, the KW go up. And the low setting is with the high temps during the day.

I'm not going to throw the laws of thermodynamics out the window just yet based on the LEAF's instrumentation, of all things. :lol:

Ok, where does it say in the laws of thermodynamics that increasing fan speed will lower your kW usage? :lol: Azdre and I know that with using the low fan speed, it barely makes a dent in our range.

The work being done is moving the heat from the cabin to the outside. A low fan speed does not change the amount of heat that needs to be moved to maintain a set temperature.

But the efficiency of heat transfer is a function of the difference in temperature between the two mediums. A higher fan speed can put more heat into the evaporator coil per unit time. If you introduce a hotter refrigerant to the condenser coils, there is a possibility of that more heat per unit time can be moved. If more heat is moved through the condenser, there is less work for the compressor to do per unit of heat moved. So that is one possible efficiency avenue.

Now this all depends on the size and capacities of the coils. It may well be that even at a low fan speed, the refrigerant is already reaching ambient temperature before leaving the evaporator coils, and again reaches ambient in the condenser coils. In which case the higher fan speed won't make any difference to the compressor.

But still, thanks to skin cooling, a higher fan speed will cause more air movement in the cabin and keep the occupant equally comfortable at a somewhat higher temperature, allowing the set point to be raised. So that is a second avenue for efficiency.

In any case, the fan itself consumes a low amount of power from the 12V system which is not a range issue and isn't even being directly monitored by the instrumentation.

And finally, the main thrust of my argument was not about higher fan speed being more efficient, but that I don't see any mechanism for a low fan speed to be more efficient, and certainly not profoundly so.

 

[DaveinOlyWA]

I'm with azdre. I set mine to 60F, low fan and it only uses a sliver. When I increase the fan speed, the KW go up. And the low setting is with the high temps during the day.

Maybe the computer is "generating" those values using fan speed as part of the equation, instead of directly measuring current? Pretty sure it does that for the 12V stuff, not sure of AC.

Also, with a higher fan speed I would expect the compressor to have shorter but more intense duty cycles, so maybe something is just measuring peaks during a given interval, etc.. I'm not going to throw the laws of thermodynamics out the window just yet based on the LEAF's instrumentation, of all things. :lol:

once again another gauge we can not really rely on. why am i not surprised?

also, its 84º today so probably last warm day of the year (high temp for Sunday forecast for 70) and i tried the A/C and guess the high current draw only lasts about 3-4 minutes but once again that was with fan on high so who knows what power was actually used?

 

[theaveng]

[corrected]
In the R/C airplane world, we don't overcharge past 4.2V (per cell) or undercharge below [3.2V] per cell. Either case would damage the cell and potentially make it catch fire. Does the Leaf follow similar limits per cell?

 

[TonyWilliams]

In the R/C airplane world, we don't overcharge past 4.2V (per cell) or undercharge below 3.7V per cell. Either case would damage the cell and potentially make it catch fire. Does the Leaf follow similar limits per cell?

The cells can technically take 4.3v, but are stopped at 4.1v per cell. There are 192 cells, with 96 in parallel, and 96 in series.

96 * 4.1 = 393.6 volts

The cells go well below 3.7v on discharge.