Which is better: 10bars to 2bars or 12bars to 4bars?

If your commute consumes 8 SOC bars every day, it it better to

(a) charge to 12 bars (100%) and then run down to 4 bars, or
(b) charge to 10 bars (83%) and run down to 2 bars?

What if the commute consumes 9 bars? Is the answer any different?

(a) charge to 12 bars (100%) and then run down to 3 bars, or
(b) charge to 10 bars (83%) and run down to 1 bar?

I would say A on both.

I'd use 12 to 4. Just to have that much buffer.

My sense is that 100% vs 80% will make less than 5% difference in capacity after 8 years. That is just not worth the effort.

b,a

"A" on both.

DarkStar said:

"A" on both.

Click to expand...

+1

I'd call 3 or 4 bars the lower limit for a normal day's use. If you can't come home with that much on a normal day's use, charging to 80%, you should be charging to 100%. Running it down is as bad as charging to 100%, plus the added inconvenience of riding the line all the time...

My commute takes 9 bars (with the 9th comming off about a mile from my house), and I'm doing "A". You never know when you have to run an extra side trip before, during or after work. I'm not letting the 80/100 debate keep me from having the extra piece of mind of having some extra miles left when I get home.

davewill said:

Running it down is as bad as charging to 100%, plus the added inconvenience of riding the line all the time...

Click to expand...

That's exactly why I asked the question. From the responses, it looks like I need to re-think the charging percentage.

So everyone's acceptable lower range is 3 bars to maximize battery life? With 80% charging, I used to return home with 4 bars -- until the service update and I am now returning home with 3 bars most of the time.

In a few more days, the L2 at my company will be up and I can easily charge if I have any unexpected trips.

greenleaf said:

In a few more days, the L2 at my company will be up and I can easily charge if I have any unexpected trips.

Click to expand...

That will almost certainly flip the equation back to 80%, if you can top up at work. BTW, in your shoes I would top it back up to 80% at work every day, not just when I thought I needed to. My understanding is that there's no downside to doing so. You'll just be cycling between 60% and 80% instead of 40%-80% (or whatever the bars precisely mean these days...)

davewill said:

My understanding is that there's no downside to doing so. You'll just be cycling between 60% and 80% instead of 40%-80% (or whatever the bars precisely mean these days...)

Click to expand...

Is not the number of cycles a factor? In our case, my wife can charge both at work and home and I was under the impression that we were better off just charging once a day between 10 and 2 or 3 bars (i.e. start day at 10 end day at 2/3, then charge back up to 10) rather than charging twice a day between 10 and 6/7 (ie. charge up to 80% both at home and work, use approximately 3.5 bars on 1 way of commute, then plug-in to refill to 10 bars).

Beachcliffs said:

davewill said:

My understanding is that there's no downside to doing so. You'll just be cycling between 60% and 80% instead of 40%-80% (or whatever the bars precisely mean these days...)

Click to expand...

Is not the number of cycles a factor? In our case, my wife can charge both at work and home and I was under the impression that we were better off just charging once a day between 10 and 2 or 3 bars (i.e. start day at 10 end day at 2/3, then charge back up to 10) rather than charging twice a day between 10 and 6/7 (ie. charge up to 80% both at home and work, use approximately 3.5 bars on 1 way of commute, then plug-in to refill to 10 bars).

Click to expand...

My understanding* is that two short charge sessions to 80% isn't any different than one long charge session to 80%...and the long session is worse if you're running the battery way down so that you only charge "once".

*and you can be sure that someone will correct me if I'm wrong...maybe even if I'm right.

My opinion is that it is probably ideal to keep the pack between roughly 30% and 80% SOC most of the time, if that fits with your driving patterns. Also, I believe that you don't want to leave the pack sitting at 100% longer than necessary. So, if you need to charge to 100%, do so (if you can) shortly before you need to start driving. However, as evnow mentioned, it is unclear that any of this will actually make a big difference over the space of several years. Some of us would rather just err on the side of being conservative where feasible. I personally would like to be able to keep the original battery pack for 10+ years if possible. Then one of my sons will be ready to start driving, we can give him our 2011 LEAF, and buy something with more range for ourselves.

You described my commute.

Here is what I do:

Set to charge to 80% overnight.
In the morning as I am getting ready to go, I push the override button and start charging again, then have breakfast, then hop in the car when it is at about 90% (11 bars). Do my daily drive and get back home with about 3 bars. So I split the difference.
I wish they would offer a 90% goal on the charge timer so I don't have to do the extra manual step.

Also, my feeling is that leaving that car at 100% for long periods is the real thing to avoid. Topping off to 100% if I am going to immediately get in and start driving is, IMHO, probably not as bad.

TEG said:

You described my commute.

Click to expand...

Same here - to the T...and I have _exactly_ the same question. Any battery experts wanna weigh in? (or have you already?)

So are you guys saying that running the battery down to 2 bars is a bad idea? I did not think about that at all. My drive daily is about 50 miles. I charge to 80% and come back home with 2 bars left and estimate miles of about 24 miles. I did not think that going down to 2 bars was a bad idea. If going down to 2 bars is just as bad as charging to 100% then I will just do 100% and have the peace of mind like others suggested.


I guess the ideal would be 11 bars to 3 bars..

The only guidance Nissan gives is that it is better to charge to 80%. No where do they say you shouldn't go below 20%. (unless some one can tell me where Nissan says that) Hence I my answer is b on both.

My other reasoning is that with the new software update, (we think) that the moved half a bar of power off of the scale on the low side, meaning zero bars means half a bar now.

-Matt

I'm with Matt, except that I'd go somewhat further. Before the update there was something variable around half a bar below zero. Now I think there is a more reliable 1½ bars worth of usable energy after the last bar disappears, and that the 12th bar is really more like half a bar. Those are not battery 0% and 100%, but are the limits beyond which Nissan engineers won't let us go, because they would have a serious effect on battery life.

I would cut those back by another 1½ bars on each side to give a range within which we can expect maximum battery life. That means don't charge above 10 bars and don't go below zero bars.

So, like Matt, I'd say b) on both cases if you are only considering battery life. But, as others have said, if you consider the exigencies of human life, you won't want to go down to zero bars on a daily basis. How far above zero bars you want to plan for depends on how much your daily usage might vary.

Ray

Nissan automatically takes care of the low end of the battery SOC, they wont let you go down far enough to do damage (when the pack is low recharge promptly to promote long life, leaving it low is not good, same as when its at 100%.. drive it soon to bring it down).. one thing you can do is to minimize charging to 100%, the other thing you can do is drive slow to minimize heating up the battery.. and move out of Death Valley.

Assuming a 100% charge is charging to 4.2V or 4.15V per cell.. no one has actually measured a pack behavior with an actual volt and amp meter, yet.

Best bet is to charge to 80% if that will allow you to get back home at night, slow down until you can do it with a bar or two left.

Its not really the number of cycles but the total numbers of coulombs (wh) that go thru the pack, but you do get a lot more coulombs if you limit the SOC to 65%, less at 80% and a lot less at 100% SOC.

Lopton said:

The only guidance Nissan gives is that it is better to charge to 80%. No where do they say you shouldn't go below 20%. (unless some one can tell me where Nissan says that) Hence I my answer is b on both.

My other reasoning is that with the new software update, (we think) that the moved half a bar of power off of the scale on the low side, meaning zero bars means half a bar now.

-Matt

Click to expand...

There are many flat out assertions that A is better cause you dont want to go to two bars.
But these appear to be JUST opinions, and exclusively based on issues having to do with whether you MIGHT leave the house again.
I am interested in the actual impact on the battery, I can make my own judgment about what additional driving I might do outside of the commute.

Lopton and CS45 also assert opinions but cite Nissan manual to support that.

I dont get WHY 80% down to two bars is a bad thing as opposed to 100% down to 4.
Can we have folks make clear that there view is based on science here and not just supposition or personal preference about after-commute range????