Battery Discharge Level?

My Nissan dealer told me that with my LEAF battery it is a good idea to totally discharge the battery occasionally in order to extend battery life. This in addition to the normal Nissan guidance to only charge the battery to 80%, also to extend battery life.

My confusion is that I am pretty sure that GM has their Volt Lithium Ion battery charging software set to never charge it beyond 80% AND to never discharge it to below 30% - all supposedly to extend the Volt battery life. My understanding is that GM deliberately put an over sized battery in the Volt in order to allow this 80/30 thing and still provide a roughly 40 mile electric driving range.

Does anyone understand this apparent contradiction between Nissan and GM? Is one Company wrong, or are we talking about different battery chemistries?

Don't believe the dealer!

The more technically knowledgeable on this forum will answer in detail. However, Nissan does keep the user from damaging the battery by shutting the car off after "Turtle" and by not allowing you to overcharge the battery. The consensus seems to be keeping the battery in the middle range of charge is best for longevity but then you won't have much range.

iamchemist said:

My Nissan dealer told me that with my LEAF battery it is a good idea to totally discharge the battery occasionally in order to extend battery life. This in addition to the normal Nissan guidance to only charge the battery to 80%, also to extend battery life.

My confusion is that I am pretty sure that GM has their Volt Lithium Ion battery charging software set to never charge it beyond 80% AND to never discharge it to below 30% - all supposedly to extend the Volt battery life. My understanding is that GM deliberately put an over sized battery in the Volt in order to allow this 80/30 thing and still provide a roughly 40 mile electric driving range.

Does anyone understand this apparent contradiction between Nissan and GM? Is one Company wrong, or are we talking about different battery chemistries?

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I don't think there is a contradiction here, Nissan has set a window for there charge/discharge of the batteries in the software just like everyone else, so what is left is a 0% to 100% window of customer usability. So in this customer charge window they call 80% a gentle or kind charge. Batteries are like your pet dog, you don't want to overfeed them or starve them, you don't want to get them too hot or too cold, and older dogs don't do as much and young dogs. Be kind to your batteries (pet) and they will be kind to you.

iamchemist said:

My Nissan dealer told me that with my LEAF battery it is a good idea to totally discharge the battery occasionally in order to extend battery life.

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Total BS.

This has been discussed often and quite thoroughly on the forum. The consensus seems to be that Nissan takes care of the car and the owner cannot damage it easily, even when being careless. The cells used in the Leaf seem to be pretty robust, and while we certainly can come up with a conservative set of guidelines for battery care, a few question marks will remain. We don't know how much better a well-informed and careful owner will do relative to someone who just drives the car without much regard to the battery. Personally, I like to err on the side of caution, and I don't mind getting acquainted with this technology, and follow a few rules if they don't inconvenience me too much or prevent me from reaching my destination safely.

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As a general rule of thumb, I would not hesitate to drive the car to turtle if I had to. However, I would not recommend to drive beyond the very low battery warning (three flashing dashes) on a regular basis. If you keep the battery between 2 and 10 bars on the battery gauge, you will be very close to what GM is doing with the Volt. One thing to remember is that lithium ion batteries don't have memory, and they don't need to be cycled deeply, quite the opposite. For example, satellites cycle their batteries often and in a very shallow cycle. Arguably, these batteries cannot be easily exchanged or maintained and they should last the life of the satellite. Yes, these are special lithium-ion batteries, but it's a good showcase for the potential of this technology. Dont' believe everything the dealer says, they are learning with us. We are the lab rats, so to speak

Just drive it.

TonyWilliams said:

iamchemist said:

My Nissan dealer told me that with my LEAF battery it is a good idea to totally discharge the battery occasionally in order to extend battery life.

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Total BS.

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+1.

Occasional total discharge of nickel based cells is recommended, but not lithium.

Bill

+1

surfingslovak said:

As a general rule of thumb, I would not hesitate to drive the car to turtle if I had to. However, I would not recommend to drive beyond the very low battery warning (three flashing dashes) on a regular basis. If you keep the battery between 2 and 10 bars on the battery gauge, you will be very close to what GM is doing with the Volt.

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I agree with your recommendations, but I would adjust your Volt comparison a bit. Originally GM planned on 30% to 80%, using only 8 kWh out of the 16 kWh total capacity. As they tried to justify their 40 mile boast, though, they had to extend to use 10.5 kWh out of the 16 kWh. That is actually quite comparable to using nearly 16 kWh out the LEAF total capacity, or about 75% of the capacity Nissan makes available to us. So the LEAF equivalent to the Volt allowable battery usage would be running from 92% (11 full bars) down to 17% (Low Battery Warning at perhaps half of 1 bar) of available capacity.

Ray

Wow! Thanks to everyone for the information about charge/discharge level! It had not occurred to me that Nissan wasn't actually giving me the straight story about Li-Ion Battery charge level. I am slowly learning, with a lot of help from the people in this Forum.

Ron

It is a "straight story":

1. Total Capacity - is officially Undisclosed

2. Charging to "max-allowed" (a 100% charge) is to the top of the User-Capacity range, and

3. Driving to "min-allowed" (Turtle-Stop) is to the bottom of the User-Capacity Range.

4. Staying under User-Max and above User-Min is "better" for battery life.

SmokeMaker said:

Batteries are like your pet dog, you don't want to overfeed them or starve them, you don't want to get them too hot or too cold, and older dogs don't do as much as young dogs.

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I hope my battery doesn't take a crap on the lawn :lol:

garygid said:

It is a "straight story":

1. Total Capacity - is officially Undisclosed

2. Charging to "max-allowed" (a 100% charge) is to the top of the User-Capacity range, and

3. Driving to "min-allowed" (Turtle-Stop) is to the bottom of the User-Capacity Range.

4. Staying under User-Max and above User-Min is "better" for battery life.

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Well said, Thank You

planet4ever said:

I agree with your recommendations, but I would adjust your Volt comparison a bit. Originally GM planned on 30% to 80%, using only 8 kWh out of the 16 kWh total capacity. As they tried to justify their 40 mile boast, though, they had to extend to use 10.5 kWh out of the 16 kWh. That is actually quite comparable to using nearly 16 kWh out the LEAF total capacity, or about 75% of the capacity Nissan makes available to us. So the LEAF equivalent to the Volt allowable battery usage would be running from 92% (11 full bars) down to 17% (Low Battery Warning at perhaps half of 1 bar) of available capacity.

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Ray, thank you for correcting that mistake. Obviously, you are correct. When you think about it, a 65% DOD corresponds to something spanning between 10 to 11 bars on the gauge, which is nearly the entire visible capacity range. Most owners will likely try to avoid the bottom bars. This means that the Leaf will likely be kept in a fairly conservative range, especially if it's only charged to 80%, as recommended by Nissan.