How much power does the A/C and heater use?

Just out of curiosity. If you had a 40 mile round-trip commute and you were driving home from work and got stuck in a traffic jam for 3 hours on a really hot day, would the battery be able to run the air conditioner for that long?

Good question. I know there will be a 12volt battery in the car to run the accessories. I'm not sure what the interconnection is between that battery and the main battery. When charging, I'm assuming that some sort of converter will also charge the 12volt battery.

I'm assuming that the heater and AC will run from the 12volt battery, so the big question is what happens when that battery gets low?

I'd love to learn more...

The high-voltage "traction" battery will have to supply the energy to maintain the 12v (13v) system (and battery) while not connected to "shore power" (charging power supply).
It will most likely use a DC-to-DC converter, capable of supplying perhaps 120 amps (at 13v), like the Prius does.

The 12v battery is primarily there to power the electronics that must be "always on", like the RF door-unlock sensors, and to power the electronics used as the car is "booting" (powering up), before the relays are closed that allow the traction battery to be used.

In the Prius, this includes a motor that pressurizes the brake system whenever the driver door is opened, and things like the Nav system and listening to the radio when in "accessory" mode.

I expect the Leaf to be similar.

In the Media section, I watched the series of four videos under "Comprehensive video of the Leaf". Mark Perry, Nissan Director of Product Planning, spoke about the air conditioner. He said the air conditioner will lower your range by "about 10%". The heater, which is like a space heater, will take more power. Good videos.

I would like to know if the solar panel will charge the accessories battery while you are driving and if that battery runs the air conditioner?????

I guess the solar panel should be able to power the accessory battery all the time (including while driving).

The 12 V battery will not power the AC. AC needs more power - so that would have to come from the main battery.

I know for sure (I have the service manuals, plans, and/or personal experience) that the Chevy S10 EV, the Ford Ranger EV, the US Electricar/Hughes EVs, the Doran plans built car, the Riley XR3, and others use DC-DC converters to maintain the 12V battery directly from the high voltage traction pack - automagically.

The real beauty of a modern EV is there is very little to do or to think about in terms of maintenance. With the Leaf, we're probably down to periodic inspection (make sure everything works), flush brake fluid every two years, and replace the aux battery every 3-5 years (maybe less since it doesn't have to run a starter motor a couple times a day). It's enough to force us shade-tree mechanics to find another hobby.

AndyH,
That is a really long list of actual EV driving experience! Have you used any Lithium Ion type cells and what has been your impression?

The new "profession" or skill, the battery "doctor": history gathering, measurement, testing, diagnosis, health checkup, and ... transplant surgery.

sjfotos said:

AndyH,
Have you used any Lithium Ion type cells and what has been your impression?

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My 'retirement business' imports LiFePO4 cells, builds battery packs, assembles battery management systems (BMS), and consults with conversions. My daily driver is a lithium motorcycle and I use it as my 'BMS testbed' and 'data logging victim' as much as for transportation.

Lithium is absolutely the way to go!

Andy

Thank you Andy. Very interesting. I realize that comparisons between known things (your current and past batteries) and unknown things (the AESC batteries) are not reliable, but what do you think of the potential for more than 20% erosion of the power storing capacity after 5 years or so of use? My needs are minimal on a daily basis for mileage, but I am curious about the potential for, say, a 50% erosion in capacity. Have you seen this occur ?
Thanks !
Steve

I wonder if it's a resistive heater or a heat pump. If it's a heat pump (ie. the A/C run in reverse) it would be much more efficient, but it seems unlikely they did that as it would cost more to manufacture.

Over-charging and Over-discharging, which are presumably avoided by the Leaf's battery management system (BMS), can drastically shorten a battery's lifetime.

This "lifetime" is often estimated as the number of "full" (usable capacity, often 90% to 10%) discharge-and-charge cycles for the battery capacity to decrease to 80% of original.

Figures of 500, 1000, and 2000 are not uncommon, depending upon usage.

Using down to 20% and then charging to 80% would have even better lifetime figures.

Nine 10% charges, with no over-charging, might be roughly equivalent to one "full" charge.

As the capacity lessens, the battery eventually replaced, but that would be at different points for different usage-needs.

johnr said:

I wonder if it's a resistive heater or a heat pump. If it's a heat pump (ie. the A/C run in reverse) it would be much more efficient, but it seems unlikely they did that as it would cost more to manufacture.

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It's a resistive heater. Heat pumps don't work when it gets really cold out. You can preheat the car using utility power if it's connected to the EVSE. Also, the seats are heated.

They do work, but their output drops in conjunction with their COP. Of course, if you used the battery pack and motor as a heat source, that'd lower the temperature differential. Plus, nobody says you can't use both.

KarenRei said:

They do work, but their output drops in conjunction with their COP. Of course, if you used the battery pack and motor as a heat source, that'd lower the temperature differential. Plus, nobody says you can't use both.

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That's true, but hasn't Nissan gone on record saying the heater in the Leaf is resistive?

KarenRei said:

They do work, but their output drops in conjunction with their COP. Of course, if you used the battery pack and motor as a heat source, that'd lower the temperature differential. Plus, nobody says you can't use both.

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Karen...


My hot tub manufacturer touted the fact that 96% (or whatever number they used) of the heat generated by the blower motors was returned to the water and as such saved on your heating bill.

Seems like am easy concept for Nissan to use. (I almost said 'no brainer')

Bicster said:

KarenRei said:

They do work, but their output drops in conjunction with their COP. Of course, if you used the battery pack and motor as a heat source, that'd lower the temperature differential. Plus, nobody says you can't use both.

Click to expand...

That's true, but hasn't Nissan gone on record saying the heater in the Leaf is resistive?

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Yep.

Well here the solar power needs to accessory the battery all the time when you are driving and 12volt-13 volt battery will not power the AC whereas the AC need more power and this should come from the main battery it is only then going to work better.

Maybe in your Leaf, but definitely not in mine!

Bicster said:

Also, the seats are heated.

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I've built a dozen or so "BackCoolers" for my VW's and a couple primitive EV's. I'll make a nice one for the LEAF, it cools a driver a lot faster than an AC system and it uses less than an amp of 12v power.
http://www.instructables.com/id/Too-Hot-Remove-heat-from-your-body-with-the-Back-/

I can supply the fittings and pump for these if you want to put one together before the summer heat.

-HH