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Re: Questions before I buy

Posted: Thu May 09, 2013 6:52 am
by RegGuheert
TimLee wrote:None of the LEAF batteries have any cooling. Strictly heat conduction through the case and into the ambient non-moving air.
When the car is driven, it will conduct heat to the air which is moving across the bottom of the battery.

Of course if it is hot outside, this will *heat* the battery. This is a real issue for commuters in Phoenix and other hot climates who must drive home during the hottest part of the day.

Re: Questions before I buy

Posted: Thu May 09, 2013 9:02 am
by iDriver
cwerdna wrote:OP, can you update your location info via User Control Panel (near top) > Profile (left side)? That way, we don't need to ask in future posts/threads or do sleuthing to deduce it.
Sure. All done. Sacramento California. :D

So the lack of a cooling system for the battery has me a bit worried... You guys don't feel this is a problem?

Re: Questions before I buy

Posted: Thu May 09, 2013 9:58 am
by LEAFer
iDriver wrote:
cwerdna wrote:OP, can you update your location info via User Control Panel (near top) > Profile (left side)? That way, we don't need to ask in future posts/threads or do sleuthing to deduce it.
Sure. All done. Sacramento California. :D

So the lack of a cooling system for the battery has me a bit worried... You guys don't feel this is a problem?
Sacramento here too ... with about 33k miles, 2.3 years, have not yet lost the first capacity bar (CB), but it's close, and the loss of range is quite apparent, although not critical at this point. It's the summer heat here in the area that's doing it, but we are nowhere near as bad as AZ and some other southern/southwest inland areas (TX, NM, etc) since the heat spells over a few summer months are usually shorter and it cools off at night. Yes, the lack of cooling is a bit concerning in the long run, but luckily we leased.

Re: Questions before I buy

Posted: Thu May 09, 2013 10:40 am
by iDriver
LEAFer wrote:Sacramento here too ...
Greetings neighbor! :D That's great info. My i-MiEV has cooling, on a hot day, sitting at a stoplight, you can hear/feel the cooling fans kick in and blast air through the battery container. I guess the leaf battery is more tolerant? Does the car ever alert you in some manner if the battery is getting hot?

I'm taking a test drive today... so some of this might be answered then I guess.

Re: Questions before I buy

Posted: Thu May 09, 2013 10:48 am
by johnqh
I donnt think iMiev has battery cooling. The liquid cooling is for the motor.

For hot weather, the liquid-cooling won't help much IMHO. Most of the day the car is parked. As long as it is not cooled when parked, the battery will degrade.

Re: Questions before I buy

Posted: Thu May 09, 2013 11:29 am
by iDriver
johnqh wrote:I donnt think iMiev has battery cooling. The liquid cooling is for the motor.

For hot weather, the liquid-cooling won't help much IMHO. Most of the day the car is parked. As long as it is not cooled when parked, the battery will degrade.
It does have cooling for the battery, trust me, I hear it kick in all the time, but you are correct: It's not liquid cooling, it's air cooled via a fan and vent port in the battery pack. The liquid cooling is indeed for the for the motor and inverter, just like the leaf. Furthermore, just like the leaf, this does nothing when the car is parked, unpowered in a hot parking lot.

For the most part, this is still a non-issue for me. I'll have the Leaf garaged both at home and at work 99% of the time. I'm really more concerned by the commute home on a hot day. Sitting in gridlock is a sad reality here in California and sometimes it's well over 95 degrees out. Would you recommend I leave the car at home? Or am I worrying about something that just really isn't worth worrying about?

Re: Questions before I buy

Posted: Thu May 09, 2013 12:00 pm
by LEAFer
iDriver wrote:I'll have the Leaf garaged both at home and at work 99% of the time. I'm really more concerned by the commute home on a hot day. Sitting in gridlock is a sad reality here in California and sometimes it's well over 95 degrees out. Would you recommend I leave the car at home? Or am I worrying about something that just really isn't worth worrying about?
The battery weighs around 660 lbs. Thermally speaking, that's a LARGE thermal mass. Its temperature is not affected over short periods of time from the ambient temperatures. However, large charging or discharging currents do indeed heat it quite quickly, as encountered during QC (Quick Charge, sometimes still called L3) or full-power acceleration, if endured for longer periods of time or at a high SOC (State-of-Charge).

The commute home won't have much impact. Garaging the LEAF on both ends is a good thing (if your garage at home is well insulated; I am assuming you are using cool city garages in Sac'to). Letting it sit parked the whole day in the sunshine on hot asphalt (or even concrete) during hot summer days is NOT good.

All in all, with keeping it in the shade and the commute you are describing is not detrimental. You will still experience some loss, similar to ours, but if you lease it for 3 years (to get the $2,500 from CVRP) or 2 years, this concern is also mitigated. The leasing rates are very favorable and almost too good to pass up.

As far as alert to high battery temp: yes, it's right there on the driver's instrument panel. However, because of the (thermal mass) lag time, it's not exactly responsive, Still, this is not really a problem, plus you really don't get a lot of choice, but at least it's there to warn you if you are excessively doing QC. Overall, as we here at MNL have found, even "safe zone" battery temps -- when experienced over long periods of time -- are not good for the battery (like continuous 6 Temperature Bars (TB) or higher). We are just now seeing TBs starting to creep from 5 to 6 in our area on a routine basis. Later in the summer it will be 6 consistently, then some peaks at 7. The red zone does not start until after the 10th TB.

Re: Questions before I buy

Posted: Thu May 09, 2013 12:09 pm
by johnqh
iDriver wrote:
johnqh wrote:I donnt think iMiev has battery cooling. The liquid cooling is for the motor.

For hot weather, the liquid-cooling won't help much IMHO. Most of the day the car is parked. As long as it is not cooled when parked, the battery will degrade.
It does have cooling for the battery, trust me, I hear it kick in all the time, but you are correct: It's not liquid cooling, it's air cooled via a fan and vent port in the battery pack. The liquid cooling is indeed for the for the motor and inverter, just like the leaf. Furthermore, just like the leaf, this does nothing when the car is parked, unpowered in a hot parking lot.

For the most part, this is still a non-issue for me. I'll have the Leaf garaged both at home and at work 99% of the time. I'm really more concerned by the commute home on a hot day. Sitting in gridlock is a sad reality here in California and sometimes it's well over 95 degrees out. Would you recommend I leave the car at home? Or am I worrying about something that just really isn't worth worrying about?
Yes, I meant liquid cooling for batteries.

I was just pointing out that TMS, unless also on when the car is off, won't help much with the battery degrading in hot weather.

Re: Questions before I buy

Posted: Thu May 09, 2013 12:33 pm
by redLEAF
iDriver wrote:I've been lurking the forum for a while now. I own an i-MiEV and might buy a Leaf as well.

I was hoping someone could answer a few lingering questions for me:

[*]Traction Battery heating and cooling: Does the leaf have any of this? I keep finding mixed info on the forum.
[*]Regenerative Braking: does pressing the brake increase regen? Or is it like the Tesla, where the brakes are just plain old brakes and the regen comes from lifting your foot off the accelerator?
Back to OP -- both the Ford Focus EV and smart electric drive have liquid battery cooling tech but I think the air cooled system in the LEAF is fine for the 'moderate' climate states --- if I lived in AZ or other hot desert climate I'd be concerned but not where you live -- here in the 4 season midwest we're fine. I do notice the battery temp bars go up and down with changes in ambient temps but even on the hottest days (which don't typically last for weeks on end around here) its been fine. It's kind of fun to watch the regen work down hills and you'll notice what it does on the displays in the car as well as 'adding' capacity

Re: Questions before I buy

Posted: Thu May 09, 2013 12:50 pm
by TimLee
RegGuheert wrote:When the car is driven, it will conduct heat to the air which is moving across the bottom of the battery.

Of course if it is hot outside, this will *heat* the battery. This is a real issue for commuters in Phoenix and other hot climates who must drive home during the hottest part of the day.
The battery is covered by two under body plastic covers, so I didn't realize there was air flow past the battery.
But I took a closer look at the pictures of them at:
http://www.mynissanleaf.com/viewtopic.p ... 896#p91575" onclick="window.open(this.href);return false; and http://www.mynissanleaf.com/viewtopic.p ... 896#p91576" onclick="window.open(this.href);return false;
and they both do have indentions with small openings.
Are these designed and arranged to catch air at the front openings and flow it past the bottom of the battery pack with the air exiting through the holes at the back?
If so that is a good thing a lot of the time when ambient temperatures are in the good range for the battery.
But a real bad thing on a 120F day in Phoenix, and also not too good on a -30F day in Wisconsin.
Seems like the openings should have had electric damper doors to close them under conditions bad for the battery?
The photographs are from an early 2011 LEAF that did not have the cold weather package.
What do the panels look like on the later 2011s with the optional cold weather package or on the 2012 and 2013 LEAFs?