Battery Heat -- How are you prepping for summer 2013?

[Randy3]

First, if any of the mods think this needs to be moved into another thread, please do so...

Like many, my LEAF lost it's first battery capacity bar at the end of last summer. Since then, I've been reading about options to keep my garage cooler during the summer. From memory, some of the options appear to be:

1. Keep garage door partially open to let cooler outside air in,
2. Run a fan in the garage under the car battery area,
3. Install garage insulation,
4. Install a hybrid electric heat pump water heater, (with solar installed, I'm thinking of ditching my gas water heater, anyway...)
5. Install a ductless air conditioner in the garage,
6. Do nothing.

We're producing enough power on our solar that I don't think it would add much cost to run a fan all night or run an AC set a a 80 degrees or so for a few hours. We already own a portable AC that could be used for this.

To those who are leaving the garage door partially open, is it possible for thieves to open the door the rest of the way (assuming we're using an automatic garage door opener)?

What do you plan to do this summer, if anything?

 

[TomT]

I plan to do nothing. Leaving the garage door partial open is a recipe for disaster. Most automatic garage doors can be forced open fairly easily if they are not all the way shut due to the way that the mechanics work and lock... I have a small roof fan in the garage (it's been there for a long time - I didn't add it for the Leaf) and a couple of wall vents down low to let in air (also always there), so it is what it is...

 

[GregH]

To those who are leaving the garage door partially open, is it possible for thieves to open the door the rest of the way (assuming we're using an automatic garage door opener)?

I was getting sloppy with this technique a few years back (pre-Leaf) trying to keep the garage under my bedroom cool and one night left the door about 9 inches open.. Much to my surprise and anger, somebody (likely a teenager) did sneak under the door and stole a few items from my unlocked Prius (Sirius receiver (promptly deactivated), custom harness for ipod in Prius, iPod with my phone # engraved on the back). Now on occasion I do leave the door slightly ajar but not more than 4 inches. The motor on our door doesn't seem an easy thing to force so I'm not too concerned.

All this being said, now that I can see the exact battery temperatures of my Leaf I can safely say that cooling the garage by leaving the door a few inches open can make a few degrees difference in the temperature overnight... Often more than enough to compensate for the few degrees rise due to charging. I am considering a small fan for the summer to blow cool air from the 4 inch garage door gap under the car. I have noted the battery temp going DOWN during morning commute despite 30-50 amps being drawn from the pack.. likely due to the cold morning airflow under the car. I've also been surprised at how little the temp increases as the cabin might warm for a few hours in the sun in the afternoon. Ie, the insulation between interior and battery is good enough that a warm cabin doesn't dramatically warm the pack whereas cool air running under the car can draw away heat.. so perhaps not as much insulation under the car...?

 

[smkettner]

Box fan in the garage window set on a timer to run 11p to 6a.

Might change to 80% charging during the hottest days.

 

[TomT]

Frankly, I doubt that will make enough difference to barely even measure... The battery pack has so much thermal mass that its temperature changes very slowly...

Box fan in the garage window set on a timer to run 11p to 6a.

 

[Stoaty]

I am going to prep in a little different manner, since my main concern is heat during weekdays my Leaf is in the hot San Fernando Valley. My plan is to make sure that the SOC is down to about 50% when I get to work in the morning, as SOC is also a factor in capacity loss and I can't do anything about the battery temperature (except that I won't drive the Leaf to work when the predicted high is greater than 95 degrees).

 

[WetEV]

It is somewhat pointless to make modifications when you can't measure the thing you want to change.

Is there any "LeafScan" or similar instrument available that will output the measured battery pack temperature?

 

[gsleaf]

I put two ceiling fans in my unfinished garage that I turn on when needed. I crack the garage door about an inch if needed. It cools the garage off pretty rapidly and creates a small, but noticeable draft.

 

[GregH]

Is there any "LeafScan" or similar instrument available that will output the measured battery pack temperature?

*ANY* device that has a display and connects to the EV-CAN bus on the OBD2 connector *COULD* display exact battery temperature with the correct software. I describe how here:
http://www.mynissanleaf.com/viewtopic.php?f=44&t=11676

 

[mikeEmike]

I put a radiant barrier on my garage door since it gets direct sunlight in the afternoon. The total cost of materials was about $100. I already had passive venting on my garage, with several vents near the floor and a dormer vent near the ridge of the garage. If your garage door gets direct sunlight in the summer, I would recommend the radiant barrier if you don't have one already (or some kind of insulation). It's light enough where you probably won't need to adjust your garage door for the added weight. I was also thinking of swapping the dormer vent for an attic fan but don't know if it will make much difference.

 

[Stanton]

I'm #2 on your list: small 'shop fan' blowing from front to back aimed underneath the battery pack. I only do this on 7TB days (typically 100+ degrees) and the air movement is enough that I get 6TB (after charging) when I leave in the morning; the overall garage temp falls from 90's to 80's (the thermometer is NOT near my Leaf or the fan). I also started parking on the shaded side of the building I work in on those same 100+ degree days; it seems to delay/prevent those 7TB readings.

 

[abasile]

We had ice on the LEAF this morning, but summer will be here before we know it. Like Stoaty, I live in a cool area and work in a hot area. I'll avoid parking the LEAF at work on the hottest days, either by driving the Prius instead or by riding my bicycle for the majority of the commute. (My body can generally take the heat.) When I do drive the LEAF to work during the summer, I look for maximum shade. My goal has been to keep the battery at five temperature bars for most of the day, ideally until I drive home.

While the LEAF generally cools plenty at night in our driveway, I'll be more careful when the humidity rises due to the North American Monsoon. Humidity itself isn't a problem, but it does significantly reduce nighttime cooling.

On off days, we try to keep the SOC as low as possible, down to 30%, to the extent it doesn't interfere with drives that we do.

Driving more conservatively, with lower power levels, can also help.