Charge and "top off" every day?

[stevon]

My commute to work is 8 miles each way so there is enough juice to make it there and home twice on one charge. Charge at work and wonder if it is better to run the car battery down and charge every other day than to "top off" battery every single day. 178 deep charges vs 356 light charges a year. Thoughts?

 

[NORTON]

Well there is that spec that Li-ion batteries have the longest shelf life if NOT stored at full charge.
That is why consumer items come charged only part of the way.
I say charge it only as needed, not topped up daily.

 

[stevon]

Norton,

Thanks, that is what I thought and have been doing. Hoping a GM or Nissan electrical engineer would "pipe in" with a comment. I've read posts about the Leaf loosing capacity in high heat environments like Phoenix AZ. also not to store battery at 100% charge for longer pack life. Found this article: http://insideevs.com/understanding-battery-capacity-loss-from-a-four-year-bmw-electric-trial-veteran/

Well there is that spec that Li-ion batteries have the longest shelf life if NOT stored at full charge.
That is why consumer items come charged only part of the way.
I say charge it only as needed, not topped up daily.

 

[Zoomit]

Well there is that spec that Li-ion batteries have the longest shelf life if NOT stored at full charge.

I wonder if that's why the only "charge later" option in the Spark EV is to have it complete by the planned departure time, instead of start at a specified time and sit fully charged for some number of hours per night.

 

[Homer]

I've wondered this too, because I don't even have a daily commute. I decided the owners manual recommends keeping it plugged in, and I think I am unlikely to see a major difference over the term of my 3 year lease either way, so I just leave it plugged in (esp. as it's summer and I don't want to decide whether today is hot or really hot).

I think I saw an article somewhere that recommended not keeping it topped up unless the manual said to do so, which raises the question of whether GM is recommending you keep it plugged in all the time so it will be plugged in for the very hot/cold days, or whether there is another reason.

 

[Jedi2155]

As an electrical engineer who works on batteries for a living, if you want to maximize the life of the battery, avoid storing the Spark battery at a full charge. What I'm saying below applies primarily to Lithium Ion chemistries so do not use this advice on Lead Acid or NiMH batteries.

LiIon Batteries age based on temperature, and how much charge is in the battery (State of Charge or SOC). The hotter it is and the higher the SOC, the faster it will degrade.

If I were you who only drives 8 miles a day, I would avoid regularly charging the battery to full. I would just run the car down to 20 miles range remaining before charging it back to full. Keeping it at a full charge is the fastest way to wear out a battery.

It is important for people to realize though that a full charge (100%) as reported by the car is not actually 100% of the battery manufacturer's rated capacity. Its usually only 80-90% of its rated capacity so its not "horrible" to keep the car fully charge, it is just better in general to not have it at higher SOCs.

If you'd like a better understanding Battery University has great write ups on the subject:
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

 

[Homer]

LiIon Batteries age based on temperature, and how much charge is in the battery (State of Charge or SOC). The hotter it is and the higher the SOC, the faster it will degrade.

Thanks for chiming in. I guess my question(s) would be, does leaving the car unplugged affect the use of the battery conditioning technology (which I assume adjusts the temp of the battery to better preserve it) and how much degradation are we talking about? (I think I saw an estimate somewhere of 10% over 10 years?)

 

[mczajka]

So, if I have the car sitting in a hot garage, I like to have it plugged in per the manual (for temps over 90 deg. - today in the DC area is a good example). I would then have to use delayed charging to prevent it from charging to full, yet to keep the battery temperature in check (fans, pumps, whatever should run if things get too hot?).

 

[NORTON]

So, if I have the car sitting in a hot garage, I like to have it plugged in per the manual (for temps over 90 deg. - today in the DC area is a good example). I would then have to use delayed charging to prevent it from charging to full, yet to keep the battery temperature in check (fans, pumps, whatever should run if things get too hot?).

This sounds like a good plan. You can set the 'finish by time' and then stop the charge early as you leave for work.

With the Volt it is known a TMS, Thermal Management System. For some reason the Spark EV is using the term 'Battery Conditioning'.
(Then there's 'Preconditioning' which makes the cabin comfy in hot or cold weather.)
Either way, it is to keep the battery in a happy temp range.

I'm in a situation where I never have to charge at home. Even on weekends I can use DCFC for free.
Only with really hot,,, dang, and even colder, weather on the way I should plug in at home for TMS to do its job.
Will I be able to set 'charge by' times such that I get TMS but don't actually suck up 3.3kW from my home L2?

 

[Zoomit]

It is important for people to realize though that a full charge (100%) as reported by the car is not actually 100% of the battery manufacturer's rated capacity. Its usually only 80-90% of its rated capacity so its not "horrible" to keep the car fully charge, it is just better in general to not have it at higher SOCs.

Is this really true for the Spark EV? It certainly appears, given the data available, that I can extract ~19kW from the battery, which matches the advertised capacity of the 2015 battery. Do you think the battery is capable of more but Chevy/LG Chem derate it for longevity?

 

[stevon]

Jedi215,
Thanks for the great info, questions partially answered. I have 28 miles left after driving to work today. returning home is down hill and increases range by 2 miles. So I can safely get home and make it back tomorrow. Question: is it better to deep discharge down to 10 miles left and charge every 3rd day or would it be best to top off battery every 2 days with a lighter discharge (more left in the battery). Any thoughts?
Article: http://arstechnica.com/gadgets/2011/02/ask-ars-what-is-the-best-way-to-use-an-li-ion-battery/

As an electrical engineer who works on batteries for a living, if you want to maximize the life of the battery, avoid storing the Spark battery at a full charge. What I'm saying below applies primarily to Lithium Ion chemistries so do not use this advice on Lead Acid or NiMH batteries.

LiIon Batteries age based on temperature, and how much charge is in the battery (State of Charge or SOC). The hotter it is and the higher the SOC, the faster it will degrade.

If I were you who only drives 8 miles a day, I would avoid regularly charging the battery to full. I would just run the car down to 20 miles range remaining before charging it back to full. Keeping it at a full charge is the fastest way to wear out a battery.

It is important for people to realize though that a full charge (100%) as reported by the car is not actually 100% of the battery manufacturer's rated capacity. Its usually only 80-90% of its rated capacity so its not "horrible" to keep the car fully charge, it is just better in general to not have it at higher SOCs.

If you'd like a better understanding Battery University has great write ups on the subject:
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

 

[Homer]

I'm in a situation where I never have to charge at home. Even on weekends I can use DCFC for free.
Only with really hot,,, dang, and even colder, weather on the way I should plug in at home for TMS to do its job.
Will I be able to set 'charge by' times such that I get TMS but don't actually suck up 3.3kW from my home L2?

You probably know this, but I think using DCFC exclusively will also degrade the battery long-term.

 

[NORTON]

... using DCFC exclusively will also degrade the battery long-term.

Some new reports show it is not a big deal. There is this article, you have to go to the links to get details:
http://www.autoblog.com/2014/03/17/dc-fast-charging-not-as-damaging-to-ev-batteries-as-expected/

And I thought there was something even more current but can't find it now.

With the 8yr/100k mile warranty this car is covered for a long time.
I had a Volt and I was blasting thru the warranty on miles due to road trips on vacations. That won't happen with the Spark EV.

 

[nozferatu]

As an electrical engineer who works on batteries for a living, if you want to maximize the life of the battery, avoid storing the Spark battery at a full charge. What I'm saying below applies primarily to Lithium Ion chemistries so do not use this advice on Lead Acid or NiMH batteries.

LiIon Batteries age based on temperature, and how much charge is in the battery (State of Charge or SOC). The hotter it is and the higher the SOC, the faster it will degrade.

If I were you who only drives 8 miles a day, I would avoid regularly charging the battery to full. I would just run the car down to 20 miles range remaining before charging it back to full. Keeping it at a full charge is the fastest way to wear out a battery.

It is important for people to realize though that a full charge (100%) as reported by the car is not actually 100% of the battery manufacturer's rated capacity. Its usually only 80-90% of its rated capacity so its not "horrible" to keep the car fully charge, it is just better in general to not have it at higher SOCs.

If you'd like a better understanding Battery University has great write ups on the subject:
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

What's more damaging? Full charge or high temperatures? My car is in a hot garage daily during the summer. I would assume leaving it plugged in will allow the battery pack to use cooling to keep the temperature in a safe range for storage throughout the day?

 

[mvly]

Jedi215,
Thanks for the great info, questions partially answered. I have 28 miles left after driving to work today. returning home is down hill and increases range by 2 miles. So I can safely get home and make it back tomorrow. Question: is it better to deep discharge down to 10 miles left and charge every 3rd day or would it be best to top off battery every 2 days with a lighter discharge (more left in the battery). Any thoughts?
Article: http://arstechnica.com/gadgets/2011/02/ask-ars-what-is-the-best-way-to-use-an-li-ion-battery/

As an electrical engineer who works on batteries for a living, if you want to maximize the life of the battery, avoid storing the Spark battery at a full charge. What I'm saying below applies primarily to Lithium Ion chemistries so do not use this advice on Lead Acid or NiMH batteries.

LiIon Batteries age based on temperature, and how much charge is in the battery (State of Charge or SOC). The hotter it is and the higher the SOC, the faster it will degrade.

If I were you who only drives 8 miles a day, I would avoid regularly charging the battery to full. I would just run the car down to 20 miles range remaining before charging it back to full. Keeping it at a full charge is the fastest way to wear out a battery.

It is important for people to realize though that a full charge (100%) as reported by the car is not actually 100% of the battery manufacturer's rated capacity. Its usually only 80-90% of its rated capacity so its not "horrible" to keep the car fully charge, it is just better in general to not have it at higher SOCs.

If you'd like a better understanding Battery University has great write ups on the subject:
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

It is not recommended to deep discharge. Li-ion battery likes to be around 40-70% typically. Anything lower or higher will increase the degradation of the battery.

 

[mvly]

As an electrical engineer who works on batteries for a living, if you want to maximize the life of the battery, avoid storing the Spark battery at a full charge. What I'm saying below applies primarily to Lithium Ion chemistries so do not use this advice on Lead Acid or NiMH batteries.

LiIon Batteries age based on temperature, and how much charge is in the battery (State of Charge or SOC). The hotter it is and the higher the SOC, the faster it will degrade.

If I were you who only drives 8 miles a day, I would avoid regularly charging the battery to full. I would just run the car down to 20 miles range remaining before charging it back to full. Keeping it at a full charge is the fastest way to wear out a battery.

It is important for people to realize though that a full charge (100%) as reported by the car is not actually 100% of the battery manufacturer's rated capacity. Its usually only 80-90% of its rated capacity so its not "horrible" to keep the car fully charge, it is just better in general to not have it at higher SOCs.

If you'd like a better understanding Battery University has great write ups on the subject:
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

What's more damaging? Full charge or high temperatures? My car is in a hot garage daily during the summer. I would assume leaving it plugged in will allow the battery pack to use cooling to keep the temperature in a safe range for storage throughout the day?

If your garage is hot, I recommend keeping the plug in. The car occasionally does turn on the coolant and pump things around to cool the battery. To answer your first question, I would say high temperature will degrade the battery faster.

I wouldn't worry too much about the full charge thing because:

1) If you needed the full charge range and didn't have full charge range just because you wanted to prolong the battery, then that is a much more inconvenience than having the car at 100% for 1 day.

2) If you are leasing the car, then why would you care?

3) The car probably already charges to less than 100% anyways. I suspect chevy probably sets it to 90% max even though you see 100%. This is typically what car manufacture do to prolong battery life. I remember somewhere the sonata hybrid is programmed to only stay between 40-70% SOC.

 

[Zoomit]

It is important for people to realize though that a full charge (100%) as reported by the car is not actually 100% of the battery manufacturer's rated capacity. Its usually only 80-90% of its rated capacity so its not "horrible" to keep the car fully charge, it is just better in general to not have it at higher SOCs.

and then

3) The car probably already charges to less than 100% anyways. I suspect chevy probably sets it to 90% max even though you see 100%. This is typically what car manufacture do to prolong battery life. I remember somewhere the sonata hybrid is programmed to only stay between 40-70% SOC.

Is this really true for the Spark EV? It certainly appears, given the data available, that I can extract ~19kW from the battery, which matches the advertised capacity of the 2015 battery. Do you think the battery is capable of more but Chevy and LG Chem derates it for longevity?

 

[oregonsparky]

Well I am an electrical engineer as well and I add one plus one differently. .

The battery has a certain capacity. But in order to extend life it will quit charging prior to reaching 100% state of charge (SOC) to avoid all the issues described here. Where It will also shut off before hitting zero SOC....

Me. I would leave it plugged in at every opportunity while at home. If I could always get away with L1 "gentle charging", then I would feel mighty good. Using this method you will also have battery at an optimal temp when you leave home. This will definitely increase battery life...

Jeff

 

[mvly]

It is important for people to realize though that a full charge (100%) as reported by the car is not actually 100% of the battery manufacturer's rated capacity. Its usually only 80-90% of its rated capacity so its not "horrible" to keep the car fully charge, it is just better in general to not have it at higher SOCs.

and then

3) The car probably already charges to less than 100% anyways. I suspect chevy probably sets it to 90% max even though you see 100%. This is typically what car manufacture do to prolong battery life. I remember somewhere the sonata hybrid is programmed to only stay between 40-70% SOC.

Is this really true for the Spark EV? It certainly appears, given the data available, that I can extract ~19kW from the battery, which matches the advertised capacity of the 2015 battery. Do you think the battery is capable of more but Chevy and LG Chem derates it for longevity?

Until we get hard conclusive data, there is really not way of telling if they really have 19KWh or slightly more. I would bet on the latter. Chevy and probably LG also are rating their batteries more conservatively to avoid lawsuit about capacity and to increase longevity of the battery. Moreover, when I did get close to using up 19KWh, my range was essentially showing 0 miles at that point. SO I would say it's safe to say when you get to 0 miles, there is still probably 5-10% left in the battery for maybe 5 more miles at reduced speeds.

 

[Zoomit]

Moreover, when I did get close to using up 19KWh, my range was essentially showing 0 miles at that point. SO I would say it's safe to say when you get to 0 miles, there is still probably 5-10% left in the battery for maybe 5 more miles at reduced speeds.

A friend with a '14 Spark EV confirmed this weekend that there is only about 1/4 to 1/2 mile range left when the indication is 0 miles. (He was close to home and pushed it the remainder of the way.)

Don't assume the car will let you go any further after the gauge reads zero.

Whether the battery is really at 0 or has some margin remaining is a different subject.