Optimal Portion of Battery to Use for Longest Battery Life?

[JPWhite]

43.68 angels can dance on the head of a pin

Is it OK (for the sake of argument) if I round that up to 44 angels dancing on a pin?

 

[JPWhite]

I hear what sounds like a fan kick in when I first plug up after a drive. I wouldn't be surprised if the LEAF keeps the battery ventilated during charging as required.

There is not active cooling on the batteries... no liquid, no air.

There is an electric liquid coolant pump to cool the charger, and fans for the radiators up front.

Is that right?

t all comes down to the Leaf's power pack lacking an active thermal management system, relying instead on a passive cooling set-up which, essentially, relies on a single fan to distribute heat evenly throughout the interior of the pack.

Source: http://green.autoblog.com/2010/01/25/is-the-nissan-leaf-battery-pack-under-engineered/

 

[Herm]

Is that right?

Thats right.. I even believe the pack has insulation, with more added for the cold package in 2012.. but it does not show up in pictures of a cutaway battery pack.

There were some rumors that there is an internal fan to equalize temps, but that does not show up in pictures either.

 

[JPWhite]

Is that right?

That's right..

OK I'm willing to be corrected. What's your source of info on the lack of fan assisted cooling for the pack? All I have is media reports, what info do you have?

 

[EVDRIVER]

Is that right?

That's right..

OK I'm willing to be corrected. What's your source of info on the lack of fan assisted cooling for the pack? All I have is media reports, what info do you have?

The service manual shows all components. The internet is full of old bogus info and rumor.

 

[Herm]

The service manual shows all components. The internet is full of old bogus info and rumor.

Does insulation show up in the service manual?

 

[Volusiano]

If they have an insulated version of the battery pack for cold weather, how are they going to uninsulate it for the hot summer? Wouldn't the insulation make the internal temperature hotter longer than the ambient temperature in the summer?

 

[davewill]

If they have an insulated version of the battery pack for cold weather, how are they going to uninsulate it for the hot summer? Wouldn't the insulation make the internal temperature hotter longer than the ambient temperature in the summer?

Insulation works both ways, keeping out the heat as well as the cold...but you knew that. Since the unit is sealed, my guess is that the pack itself doesn't generate enough waste heat to worry about, even with insulation.

 

[Volusiano]

If they have an insulated version of the battery pack for cold weather, how are they going to uninsulate it for the hot summer? Wouldn't the insulation make the internal temperature hotter longer than the ambient temperature in the summer?

Insulation works both ways, keeping out the heat as well as the cold...but you knew that. Since the unit is sealed, my guess is that the pack itself doesn't generate enough waste heat to worry about, even with insulation.

We always hear that heat is the enemy to the battery and people want to wait until the battery pack cools down enough after a drive before charging and all. Yet now we're guessing that the pack doesn't generate enough wasted heat to worry about, and that the insulation is useful to keep the ambient heat out because the trapped wasted heat will not exceed the ambient heat. Those are 2 contradicting guesses.

If I had to guess, I'd say the battery pack's wasted heat, if trapped by insulation, can easily exceed the ambient summer temperature quickly, and therefore needs to be vented off. So the insulation is not keeping out the ambient summer heat, but it's trapping in the internal wasted heat.

 

[davewill]

We always hear that heat is the enemy to the battery and people want to wait until the battery pack cools down enough after a drive before charging and all. Yet now we're guessing that the pack doesn't generate enough wasted heat to worry about, and that the insulation is useful to keep the ambient heat out because the trapped wasted heat will not exceed the ambient heat. Those are 2 contradicting guesses.

If I had to guess, I'd say the battery pack's wasted heat, if trapped by insulation, can easily exceed the ambient summer temperature quickly, and therefore needs to be vented off. So the insulation is not keeping out the ambient summer heat, but it's trapping in the internal wasted heat.

The first one wasn't my guess, and I never bought it. The fact remains that Nissan feels comfortable adding insulation. Until someone discovers that they also added some sort of active (temperature dependent) cooling/venting, I have to assume trapped heat around the pack isn't a problem.

 

[JPWhite]

We always hear that heat is the enemy to the battery and people want to wait until the battery pack cools down enough after a drive before charging and all.

I had wondered about this. But had the following dialog today with Nissan Chat Support.

Eric W: Thank you for contacting Nissan LEAF Consumer Affairs. How may I assist you?

JP White: Hi I've been reading the Owners Manual and have a question regarding some advice it gives......

Eric W: Go ahead.

JP White: ..... On page EV-22 it says to let the batery cool after use prior to charging. Does that apply even if the battery temp is in the normal range?

Eric W: The intention is not to attempt to charge the battery if the temperature of the battery is above a certain point at which charging could be detrimental to the battery.

JP White: Normally it maintains 'six bars' on the temperature gauge. Is that an acceptable temp to begin charging or should one wait anyway?

Eric W: Just a moment please.

JP White: k

Eric W: It should be acceptable to charge the vehicle if the battery temperature gauge shows that the battery is within normal range (between the blue and red gauge squares.

JP White: OK Thanks. That answers my question

Eric W: Is there anything else I can assist you with today?

JP White: No Thanks. I appreciate your help today.

Eric W: Thank you for contacting Nissan LEAF and have a good day.

I had this question because I saw a potential conflict in the user manual.

EV-20

NISSAN recommends that you connect
the normal charge cable when getting
out of the vehicle, even if it is not going
to be used. By doing this, you can get
the most out of the remote climate
control and Climate Ctrl. Timer functions
the next time you use the vehicle

EV-22

Allow the vehicle and Li-ion battery to cool
down after use before charging.

No wonder contradictions occur here, the message from Nissan is somewhat confusing.

 

[Herm]

Eventually the can-bus people will figure out how to read battery temperature.. Lithium-ion batteries are about 99% efficient within an 80% SOC window, if you are drawing 15kw in your normal runabouts then about 150 watts will be turned into heat.. its not a lot.

 

[surfingslovak]

LOL. I am sure NASA has a paper about that too.

Speaking of which, one of the two rovers, Opportunity, is still going strong eight years after landing. How is that for battery life?

 

[TickTock]

EV-20

NISSAN recommends that you connect
the normal charge cable when getting
out of the vehicle, even if it is not going
to be used. By doing this, you can get
the most out of the remote climate
control and Climate Ctrl. Timer functions
the next time you use the vehicle

EV-22

Allow the vehicle and Li-ion battery to cool
down after use before charging.

No wonder contradictions occur here, the message from Nissan is somewhat confusing.

I don't think this is a contradiction since they provide timers to control when to start charging, but they definitely could have provided some more information.

 

[TonyWilliams]

There is not active cooling on the batteries... no liquid, no air.

There is an electric liquid coolant pump to cool the charger, and fans for the radiators up front.

Is that right?

The protection for the batteries, temperature wise, are four temperature sensors on the battery assembly. When it detects an overtemp, the Lithium-Ion Battery Controller (LBC) enters Fail Safe Pattern A: No driving and charge stop. None of the individual temperature sensors have a fail safe mode, nor will there be an "EV system warning lamp".

The max sensor temperature is 55C/131F.

DTC message P33E2, "BATT PACK OVER TEMP" and the "EV system warning lamp" will illuminate.


Source: LEAF SERVICE AND REPAIR MANUAL, April 2011 update, page: EVB-37, 134, 223


While there are not any cooling devices, there are now 8 heaters and one heater controller (number 7 in the diagram):

 

[JPWhite]

The protection for the batteries, temperature wise, are four temperature sensors on the battery assembly. When it detects an overtemp, the Lithium-Ion Battery Controller (LBC) enters Fail Safe Pattern A: No driving and charge stop. None of the individual temperature sensors have a fail safe mode, nor will there be an "EV system warning lamp".

The max sensor temperature is 55C/131F.

Is there any mention of what the temperature bars represent in terms of actually temperature. Is the scale linear per bar or not?

Last night I noticed the temp gauge had one more bar than normal, still well within the gauges normal zone, but it would be good to know how much extra heat that bar represents. Yesterday was a hot one here in Tennessee.

 

[DurkaDurka]

Tony, the service manual if you have, is it in PDF format? Is if 2011 or 2012? And can you post it?

 

[hill]

Glad I didn't follow this thread until now. Wow - 8 pages and several days - and as I suspected, the difinitive answer about what portion of the battery to use the most is ? . . . . . . . . . . . . . . .

drum roll - - - - - - - -

 

[surfingslovak]

drum roll - - - - - - - -

OK, then. How about 40 to 80% SOC or 2 to 10 bars? That should be pretty conservative.

 

[Stoaty]

OK, then. How about 40 to 80% SOC or 2 to 10 bars? That should be pretty conservative.

But 40% is about 5 bars (assuming only 12 bars). If you count two "hidden bars" then 40% would about 6 bars (6/14 = 42%).