Winter Ahr Loss Method in SoCal

[Gorge]

Hey MNL!

I bought my 2012 Leaf used and I've been losing about 0.3 Ahr/mo since April, but the past month it has been stagnant. I still have 13 months until my warranty is up, but I have a few factors working against me. 51,000 miles on odometer, have a 13 mile round trip commute, park my car outside (we have a 1 car garage where my wife parks her car), and I use an extension cable for my trickle charger. The worst part, I live in Southern California, so we don't get hot weather. How would you recommend that I drop more AHrs in the winter and be mindful of the miles?

Here are my specs:

• 2012 Leaf
  Warranty till Fall 17
  51,000 miles
  AHr: 46.26 (3 Bar)
  SOH: 72%
  Live in SoCal (no hot weather)
  13 mile round trip commute
  Partial Garage use (wife parks her Prius Plug In in the 1-car garage. I could swap spaces in the evening)
  Extension cord to outside for my trickle charge
  Park car outside at work and at home (Charge outside at home)
  Can install a level 2 charger in the garage if necessary

What should I do to drop AHrs? The past month it hasn't moved at all and I'm a bit worried as the cold months are ahead.

Should I install a level 2 charger in the garage, run the heater non-stop in the evening and level 2 charge it to get battery temps up? My commute is so short that I don't have an opportunity to heat up the batteries.

I don't want to find myself in the last month of warranty and find that I'm, just short of losing the 4th bar. I'd rather be proactive in the winter and drop as much AHrs as possible.

Thanks so much!

 

[Gorge]

Bump! Hoping for some good responses.

 

[arnis]

There are two main factors that degrade battery fast. Very deep discharges (1 bar or less)
and high temperature. Especially while charging/discharging.

Three acceptable ways:
a) very low mileage, long time:
Charge the vehicle to 100% and keep it in hot room. Start searching for companies that have heat sources:
like powder painting production line, bakery, technical basement with heating system etc.
100F should be enough for a month.. Take it for a ride once in a while.
b) very high mileage, long time:
charge to 100% and don't charge before running down to turtle. Also possible to keep at Turtle for
longer periods, like few days.
c) low mileage, very short time but hard work:
find QC station or two with highway nearby. You must travel at high speed, above 75mph. Run down to 1 bar or less.
Charge until charge rate falls below. Very hard accelerations and hard regen (if even possible) constantly. Without
friction brakes. One forum user did that and lost something like 1% per day.


Keeping battery at 5 bars or below will not degrade enough. You need to have it at 6-7 bars for months. Hard to do if you
constantly need the vehicle and don't have a garage with heat source.
If you can heat it up to 10-11 bars you only need few days of hard work. It's easier if it is warm outside, 70F should be enough.

If you have a towing hitch tow something heavy.

You can cycle battery without mileage if you keep it on with heater and AC running in a garage. Run it down to empty and keep it
that way for a day. Fully charge it. Keep it that way for few days. Drive it (optional). Do not charge until nearly empty. Deplete
in garage.

Whatever you do do not keep battery level between 2 and 11 bars and temperature below 6 bars. Easy, isn't it
There are some requirements for warranty. Obey those too.

PS. You could put thin oil radiator under the vehicle in the garage (500-1500W). Cover the ground with thin insulation. Build small skirt around
the perimeter of the vehicle so air does not escape. Have 2-3 thermometers in the air pocket. Fine tune oil radiator thermostat
so it keeps your battery ambient air around 90-100F. Use LeafSpy to monitor temperature readings inside the pack.
You can use the vehicle in the meantime. Keep battery 100% charged during baking.
This will simulate something like Arizona summer. Should be fast enough. Also very safe as oil radiators are safe to touch.
The better the air pocket insulation the less electricity you will waste.
It is ok to use styrofoam(ground only), insulation wool, foiled insulation foam (almost like bubble wrap).
it is possible to use appropriate thickness insulation wool sheet as it can easily be driven over and it can act as a curtain.
Expect a dollar per day for extra electricity

Try to get to 4th bar average losing capacity 3-4k miles and 3-4 months before warranty runs out to be on the safe side.

 

[Gorge]

Wow! Amazing response! So thorough and thoughtful. Thanks!

One question though, what's the point of turtling it and keeping it that way for a few days? Wouldn't that be counteracting the fact of trying to keep the battery warm?

Also, does leaving the heater on at 90F at full speed in the garage generate enough heat for the battery? Should I be doing hard freeway pulls with the heater on too?

 

[arnis]

Leaf heater element is capable of heating air. But that air will rise up and not even touch the battery case.
If you route the air below the vehicle then yes, it is possible.
Oil radiator costs like 30-50€, pretty cheap and can be used in other situations too.


Keeping battery heavily discharged is worse than keeping it 100% charged.
Warranty does not allow keeping it discharged for more than 2 weeks but what about 5 days, doesn't mention.

I would say oil radiator is the best and most convenient way. As you can always use the vehicle if needed.
Discharged Leaf is not going anywhere. Especially if you only have 120V EVSE for charging.

Hard freeway pulls do heat up the battery but not much as air passing the pack will not let it get very hot.
If it is winter outside it is hard to get to 8 bars.
Heater during driving isn't helping as it only takes a fraction compared to motor.

1-6 bars, you need many months
8-9 bars you need few months
10 bars you need few weeks
11 bars you need days
12 bars you need few days
There is a limit for temperature you are allowed to use for warranty replacement.
But that is something like 11 bars.

 

[Gorge]

Wow. Lots of great info. Is the back near the front or rear of the car? I need to talk to my wife about this some more and need to pick up an oil heater. We do have a portable electric heater which I could use for now to heat up the garage.

Also, what are the temperature ranges for each bar? Is it the min, max, or avg temp per Leaf Spy?

 

[cwerdna]

Wow. Lots of great info. Is the back near the front or rear of the car? I need to talk to my wife about this some more and need to pick up an oil heater. We do have a portable electric heater which I could use for now to heat up the garage.

Also, what are the temperature ranges for each bar? Is it the min, max, or avg temp per Leaf Spy?

http://www.mynissanleaf.com/viewtopic.php?f=38&t=3896
http://www.evsafetytraining.org/~/media/electric%20vehicle/files/pdfs/nissan%202012%20leaf%20first%20responders%20guide%20%20version%2012.pdf

The battery temp gauge sucks with huge overlapping ranges and a black box adjustment algorithm: http://www.electricvehiclewiki.com/Battery#Battery_Temperature_Gauge.

 

[arnis]

It appears that on 2014 EU Leaf temp bars are representing specific temperature limits.
For example 5th bar on 2014 always appears if any sensor in the battery measures 15.0C or above.
6th bar appears when 25.0C is measured or above.
4th bar appears as soon as 5.0C is measured on any sensor.
If I remember correctly 3rd bar appears when any sensor detects at least -5.0C, or maybe 0.0C.

It doesn't drop a bar immediately. Bars are definitely measured in Celsius as they are rounded to 5C increments
in the average zone and half of that at the borders.

But that might not be the case for older Leaf. Just use LeafSpy.

Don't use heater that blows air. It is not efficient as it will heat the air in the whole garage. You can get maybe 10C/20F above
outside temperature. Expensive

Wall mounted oil radiators are slim. Ground mounted have legs. If they are screwed on then it doesn't matter, buy whatever you find cheap.
1000W minimum, 500W might be too weak if you don't insulate around the car perimeter well enough.

 

[Gorge]

Thanks. I live in a rental and my garage is partitioned with my neighbors garage. It's poorly partitioned with cardboard and some wood. I might buy some sheetrock to partition it better, but I don't think I can go all the way to the top. Plus, my garage door closes crooked and has a gap whenever I close it. I'll need to look into getting that realigned.

Is it ok if I place the oil radiator heater on its side and slide it under the car?

 

[DaveEV]

Keeping battery heavily discharged is worse than keeping it 100% charged.

I'd love to see some data backing this up, as I highly doubt that this is true. Nissan limits how far you can discharge the pack to avoid these types of issues by keeping cell voltages above 3.0V.

Hard freeway pulls do heat up the battery but not much as air passing the pack will not let it get very hot.

Hard freeway pulls do a great job of heating up the battery, especially on 8-9 bar batteries because the internal resistance of the pack is significantly higher than when new. Unfortunately, hard freeway pulls are not that easy to do unless one is willing to break the law. If you can find a long steep grade to drive up, that helps.

If it is winter outside it is hard to get to 8 bars.

This is true, but a QC or two while driving on the freeway will make this easy. But in Southern California, it's not all that cold here most of the winter.

It appears that on 2014 EU Leaf temp bars are representing specific temperature limits.

These limits also change depending on how much capacity the battery has lost. The limits to change temp bars move up as the battery loses capacity. But

 

[arnis]

Keeping battery heavily discharged is worse than keeping it 100% charged.

I'd love to see some data backing this up, as I highly doubt that this is true. Nissan limits how far you can discharge the pack to avoid these types of issues by keeping cell voltages above 3.0V.

It appears that on 2014 EU Leaf temp bars are representing specific temperature limits.

These limits also change depending on how much capacity the battery has lost. The limits to change temp bars move up as the battery loses capacity. But

Warranty does not allow Leaf to be discharged for long periods. Nothing about keeping it charged 100% for long periods. There is a risk that one of the cells might go below minimal safe voltage to recharge and will not allow charging any more. As voltage goes down even while not in use. I've seen voltages way below 3.0V in colder weather. My Leaf dies at around 2.6V weakest cell (pack around 260V).

I definitely know that 5th bar appears exactly at 15.0C. This was true when Leaf had more capacity left. This is true now, it has 90% left.
This 15.0C has never changed. Also in another topic others also mention 15.0C many times. They most definitely have other capacity values.

Is it ok if I place the oil radiator heater on its side and slide it under the car?

Yes. Oil radiator has a heating element submerged in oil. This oil will circulate (worse than if it is standing, but not much, whole radiator should turn hot but not burning to touch).
If you don't cover the sides of the vehicle, cold air will blow heated air away from the belly and radiator has to do more and more.
You should notice with LeafSpy that battery will get warmer within hours if air is trapped there.

It's best to find radiator that is not superslim to help oil circulate in horizontal position. I would say more than an inch should be good enough.
You should be able to leave the radiator on the ground and EASILY drive over it. Have somebody looking for the first time to be sure. It should be exactly in the middle between the tires. Power cord should be positioned so it is not being driven over multiple times (or use a shell).

 

[Gorge]

On LeafSpy, does a particular temperature bar represent a location of the car battery?

 

[arnis]

Jap. Old Leaf has 4, new has 3. It was not necessary to have so many so they removed one.
Old has one on the right, one on the left, two in the back.
But that isn't really noteworthy to know as the hottest sensor is the most important one