Passive cooling ?

Keeping in mind that climate control also seems to reduce range, has anyone thought of wetting the cabin filter with water to see if the evaporation of the liquid would provide any additional cooling ?

If yes, then one can imagine some manual pump to avoid taking it out everytime.

Of course this would only work in dry climates.

I would be very wary of wetting the filter. First, if I remember correctly, the fan is very close to the filter. If water gets into the fan, there could be some serious problems. Second, the efficiency of the filter will drop significantly. The additional cooling from evaporation might be overwhelmed by trying to push air through a wet filter.

Here in Dallas, many outdoor restaurants use fine mist sprayers, so I understand the theory you have. I'm just wondering if there is a better implementation.

The fan being below the filter is definitely an issue.

I have oredered two of these cabin air filters. Will give a try to see which amount of water will not cause any dripping, nor excessive obstacle for the air. But I am not convinced if evaporating say 100 cc of water would change anything in the cabin temperature. Adding 5% alcohol would further increase the evaporation. Assuming it does not get absorbed by the driver through inhalation :twisted:

I guess one's range needs would determine interest in this sort of thing, but in general I just don't see much value in not running the A/C. It doesn't have a big impact on range once out of MAX mode, and it's worth keeping in mind that cabin air is circulated through the battery pack (unlike the Leaf), so the warmer you let the cabin get, the less cooling the battery gets.

In summary: Minor impact on range, improved battery life, greater comfort. Yeah, that's a win for me.

I agree. When you get to the point where using the fan to blow outside air isn't cutting it, an evaporative cooling system isn't going to help you too much. Wait until you park it in the sun and let that big solar collector we call a windshield heat up the interior . . . . you'll find out what 'MAX A/C' is for!

We ran the A/C nearly every day for the first 6 or 7 months after we bought the car a year ago this week and it's affect on the range was never an issue. They advertised 62 miles (100Km) and we always got more than that, even when running the A/C. I only wish the heater worked half as well and had the same negligible affect on the range

Save your time and money for the Webasto heater install and you'll be fine - The cooling system works just fine as is

Don

The re circulation of cabin heat to battery pack is indeed an important point in summer and winter.

Good to hear that AC does not affect range that much. Unfortunately my model does not have one

Definitely the Webasto seems a much better investment not just for passenger comfort but assuming the cabin air really can heat the battery pack even a little, then the benefits double up.

Thank you for feedbacks.

I'm not sure if you can manually direct warm air from the heater through the battery pack or not. Even in the North American cars which came with the optional battery warming package (most Canada cars did vs few USA cars) I think it's operation was automatic and didn't kick in until it was VERY cold out . . . . probably because it eats up battery power. How you would manually direct the heat from your Webasto through the battery . . . . I'm not sure. As I understand it, it's just not needed unless the battery pack is really cold, and even then, the only real advantage seems to be to warm it while charging - When underway and discharging, the battery generates it's own heat

Don

Don said:

I'm not sure if you can manually direct warm air from the heater through the battery pack or not. Even in the North American cars which came with the optional battery warming package (most Canada cars did vs few USA cars) I think it's operation was automatic and didn't kick in until it was VERY cold out . . . .

Click to expand...

I suspect the battery is not insulated to allow for easier heat dissipation in Summer. Therefore, running warm air through the pack in Winter would result in great heat loss and consequently no or little range extension. I think Webasto would provide enough heat to compensate for the heat losses and result in range boost.
Btw, which fan is used to circulate air through the pack? Is it the cabin fan or battery's own fan?
Stan

jaraczs said:

Btw, which fan is used to circulate air through the pack? Is it the cabin fan or battery's own fan?

Click to expand...

Stan, in case you missed it, we've been having quite a discussion on this very topic on this thread: My second IMIEV does not make the normal fan noise.

My Czero does not have AC but it does have the battery fan. Would you think that charging at high amperage like 14A would harm more the battery pack of a car without AC ? Of course not in winter but in a mid-European summer never reaching extreme temperatures more than a few days a year.

I have a I-miev with the battery warming option. I thought it was pretty useless in Florida but I found a good use for it. It works by directing air from the heater floor vents into the battery when the temperature is very cold. However, on my car I removed the actuator (one connector and two screws) which you can see from the drivers side, under the dash just above the console extension. Once removed, you can move the white plastic lever that will divert air that would normally flow from the floor vents into the battery. Putting the HVAC mode selector knob in the floor/face position you can direct cooled air from the A/C to both the cabin and the battery. Now you have "active" cooling!

Thank you for the info. Combined with a Webasto diesel heater, this could become a passive warmer for winter driving in order to improve battery performance.

I could not find the connector, would you kindly post a picture ?

Thanks

You must have either the quick charge option or the cold weather package to have this part in the car. As I am new to this forum, I don't think I can post pictures yet (there is no "advanced" option available). However, if you get your head into the drivers footwell and look in the opening above the console under the dash, you will see the actuator mounted to the heater floor duct (this is on a left hand drive car). There is a three wire connector plugged into it. It really works well as it is dropping the temperature quite a bit in the battery enclosure. I don't want to get it too cold as you don't want condensation to form inside. Condensation is a Florida problem, not a Phoenix problem and the temperature is easily adjusted with the A/C mode selector. I am getting another I-Miev tomorrow without either package and am going to see what is takes to change a standard car, parts wise, to one with this ability. Yes, in cold weather it would heat the enclosure. The I-miev draws air from the passenger compartment from a duct located under the passenger seat. This system just adds an additional duct to connect the heater and A/C floor vents to that existing duct. The actuator allows selection of the air from the system to blow on the floor or into the battery enclosure. If you want electric actuation, a switch will need to be added to supply power to select which position you want the door inside the floor outlet housing to be in.

Llecentaur said:

I could not find the connector, would you kindly post a picture ?

Click to expand...

I am posting pictures taken in October 2012 during some exploration of my base model iMiEV with winter package. I have not done any modifications regarding passive/active thermal management.
To siai47: Everyone can post pictures, it is just not simple process.
JoeS: Do we have instructions somewhere in this forum?
All: Please feel free to suggest/improve/correct part's description in pictures.
Picture 1 is taken from the footwell of the driver, aiming to the center:

Picture #2 is the Center panel with one cover removed (driver's underdash cover is removed, too):

Pictures #3 and #4 represent two stages of uncovering the center panel showing the battery duct inlet:


Picture #5 is some control unit:

Picture #6 is taken from the passenger footwell showing control unit 1 and also pipes to/from heater core. Interesting to note that these pipes can be located without any disassembling, even while driving to check onset of heater function. It takes little practice:

Many thanks !

I will check to see which parts I have.

Yes, the picture marked "actuator" is the actuator in question. The quick and easy way to get instant cooling is to remove the connector and take the two screws out that hold the assembly to the heater duct. Manually move the linkage until the lower arm faces forward and you are done. When you want additional cooling to the battery, just select the face/floor position with the A/C unit running. Works the same way for winter if you want to add heat. I would also think it works best in the non-recirculation mode as it would push the most air out through the battery enclosure. In the winter, if you want floor heat, you need to reach down and move the linkage back until the lower arm is pointing up. One thing that is puzzling to me is how the battery internal fan cooling works with this system as supplied by the factory. When the actuator is in the normal position (floor vent open) the opening to the battery enclosure is blocked. When the battery fan comes on for it's self test when you plug in the charging cord, the actuator doesn't move to an open position. I am assuming in cold temps, or while quick charging the actuator is operated by the same signal that starts the A/C or heat depending on what is required. I still don't know what would cause it to move if just the battery fan was called for.

Further to this topic, I came up with a proposal to upgrade thermal management of the battery with rather simple modification. The idea is built on the assumption that we know how to open the battery compartment inlet and if we run cool/warm air into the battery compartment, it is a good idea to return the air into the cabin to recover the residual cool/heat. Now we need to identify a suitable opening in the floor or make a hole in the frame. Inspection of the floor behind front seats and under the rear seats shows that there is a rectangular hole in the floor behind the central panel (see pics). The hole is plugged with a piece of rubber (5 x 4.5 cm) with cable for parking brake running through. It sits firmly and I have not been able to remove it without tools. When the lid above the rear engine was removed, the parking brake cable could be located as coming from the above the battery pack. In addition, the air outlet from the battery compartment is located in the back of the pack, near-center and it is facing front. The proposal would be to attach a suitable duct (perhaps 2-3 inch wide) from the battery compartment air outlet and connect it to the hole for the parking brake cable. The estimated length is 1 foot. The hole in the floor would have to be modified to allow the cable to go through without air leakage for the air return. The carpet inside of the vehicle would need to have openings as well. The metal shield on the floor (see pic) may need to be cut or lifted a little to increase the clearance so that the air can flow into the cabin. It is imperative, that in order to perform this modification, the battery compartment would have to be dropped, which renders the realisation difficult. This is a reason I cannot do it.


Things to further consider:
1) We may want to be able to control whether the air goes inside or out (damper?).
2) We may need to run the battery fan to improve the air circulation.
3) We may need to consider adding insulation between the battery compartment and the plastic shield under the vehicle.
4) If we install Webasto heater, such modification may become obsolete as the heat from combustion is rather cheap and the warm air can be vented out.

Llecentaur said:

My Czero does not have AC but it does have the battery fan. Would you think that charging at high amperage like 14A would harm more the battery pack of a car without AC

Click to expand...

You'll never charge at 'high amperage' unless you have and use the L3 Quick Charge feature. The built in charger is only 3300 watts and since it's a 330 volt battery pack, that means it can't supply more than 10 amps to the battery pack. Since it's a 50 AH pack, you're only charging at about 1/5th C (C is 'Capacity' of the battery). For Lithium batteries, 1/5th C is a quite slow charge so you have little to worry about overheating the battery during normal charging

Don

siai47 said:

Yes, the picture marked "actuator" is the actuator in question. The quick and easy way to get instant cooling is to remove the connector and take the two screws out that hold the assembly to the heater duct. Manually move the linkage until the lower arm faces forward and you are done. When you want additional cooling to the battery, just select the face/floor position with the A/C unit running. Works the same way for winter if you want to add heat. I would also think it works best in the non-recirculation mode as it would push the most air out through the battery enclosure. In the winter, if you want floor heat, you need to reach down and move the linkage back until the lower arm is pointing up. One thing that is puzzling to me is how the battery internal fan cooling works with this system as supplied by the factory. When the actuator is in the normal position (floor vent open) the opening to the battery enclosure is blocked. When the battery fan comes on for it's self test when you plug in the charging cord, the actuator doesn't move to an open position. I am assuming in cold temps, or while quick charging the actuator is operated by the same signal that starts the A/C or heat depending on what is required. I still don't know what would cause it to move if just the battery fan was called for.

Click to expand...

Can you measure, with canion, how much this process can cool the battery? Thank you for chairing this with us. In Portugal summers, we have some hot days and this should help to keep them cool.