Does your charging time make sense?

[gbarry42]

I have had my LEAF for only a week, so I may discover some "newbie factors" to help understand my problem. As a Prius driver, though, I'm not exactly new to the energy game. The range of my LEAF seems awfully limited. If I start out with a full charge (and something like 88 mi range) and drive 17 miles to work, it's showing around 50 miles remaining. After returning home, it will show around 20. The terrain is S. California up-a-hill, across a mesa, down-a-hill, rinse, repeat. The miles per kWh reads around 3.3. And most of the calculations I do seem to make sense, if I believe all these numbers it is showing me. That's kind of hard to do, since SOC is highly quantized, the driving range is a guess based on a mystery algorithm, and I'm supposed to ignore anything that Carwings tells me.

The kicker (as advertised in the title) is, that when I plug it in at night, if it tells me it will take 3 hours to go to 80%, but it might charge 1.5-2 hours. If I want to top it off in the morning (go from 80 to 100 percent), it says it will take 1.5 hours, but will do it in 1. Last night it said the 80% charge would be 4-5 hours, but it took 3.

Knowing nothing, I would wonder if the capacity of the battery is 24 kWh or more like 18. I had fanciful visions of some of the packs not actually connected, but I just read AndyH's thorough explanation of the battery configuration and the only paralleling of cells is a pair inside each of the 48 modules. Everything is in series otherwise. And I would think any large scale problem like that would be picked up by whatever sensors they've planted in there.

So my questions are, how long does your charge take, and how does it compare to the predicted?

I will try to keep better numbers in the future, 'cause I know y'all will be asking some good questions.

Barry

 

[jcesare]

My predicted time is always longer than actual. It seems to be off by as much as 20%.

BTW 3.3 miles/kWh is pretty low. Im driving the same So Cal canyons and mesas and am getting over 4. I'm almost always in eco, monitor the meter, and squeeze every bit I can out of the regen. I make sure I never pin the needle.

 

[gbarry42]

I know it's low. I'm working on that, but so far it's by "giving up" things like cruise and climate. And freeway driving. I don't plan to live the rest of my life that way, though. It was worse, now it's better, but 3.3 makes for easy approximations, so I'm sticking to that for now.

I don't think regen is the save-all of efficient driving, but that's a whole nuther thread someday. I am using ECO though, if only because I don't yet know all the tricks it brings into play.

But, as a long-time electronics hacker, I know that a battery that charges up amazingly fast is usually the sign of a bad battery.

 

[gbarry42]

Did some Sunday driving yesterday. Started from 80% and ended up with 3 bars remaining. So, 7 bars. That got us 38.2 miles.

The predicted charge time was 5 hours. But I have discovered that Carwings always assumes 100% charge, despite the timer being set to 80%. That's my first useful discovery, revealed by actually paying attention.

So, 3.5 predicted hours, to put back in approximately 60% of the charge. Actual charge time was 2.5 hours. evnow suggests I read the kWh figure off the Blink, so I'll start tracking that. [edit] This turned out to be 9.9 kWhr.

This all seems closer to reasonable behavior. Better than the 2:1 I thought I was seeing.

 

[Mx5racer]

My charge time makes sense.
I drive 22 miles (3 bars down) and it takes about 5 hours to charge at 120v.

What makes no sense is carwings, it says that the same commute takes the battery from
83 to 44%

 

[gbarry42]

Looking at the energy needed to charge back up has kind of focused my research.

I did my 32.5 mile commute yesterday. I'm going to eliminate everything except the SOC and the recharge input from my observations.

I used 7 bars to go the distance, and the recharge used 10.3 kWh. This would suggest that whatever the gauges tell me, I'm using around half the capacity of the pack, which is either 21 or 24 kWh. I should be able to scale that up for when I try the far reaches--charging to 100%, and/or running it down to no bars.

It's 24.
No, it's 21.
Don't you know anything? It's 24.
Can't you read?? It's 21!
Only a fool believes we get 21. We get 24.
Get a life! Everyone knows you only get 21!
I don't know what you're on, but I want some! 21, indeed.
How can you possibly get 24 from your data?
Does a Blink tell lies?
Did you misspell "Carwings"?
Duck season!
Rabbit season!
:roll:

 

[davewill]

Looking at the energy needed to charge back up has kind of focused my research...
Duck season!
Rabbit season!
:roll:

We need to admit that there's just no way to find out with the tools at our disposal. We don't trust the car or Carwings. We can measure wall power to fully recharge, but we then are forced to make assumptions about charging efficiency, so that won't give us the answer. Unless someone has better tools available, we're not going to crack this.

As far as the original poster's dilemma goes, if someone REALLY thinks their LEAF is underperforming, all they can do is ask for warranty service.

 

[gbarry42]

Oh, thanks for the reminder. I have read enough from AndyH, ingineer, and so forth to convince me that anything serious enough to significantly affect the pack capacity would be picked up by the monitoring systems and throw a fault code. So unless I can produce any hard evidence to the contrary, I'm keepin' my mouth shut.

 

[mckemie]

At over 9,000 miles, my charge time has always seemed too low. Last night, I paid closer attention. My timer is set do 80% starting at 2am. By 4am, the charge was complete and it said 1.5 hours to go to 100%. I restarted it. By 5:30 am it was complete. Start state of charge was low, less than 10 miles on the SMRD (silly miles remaining display). So, less than 3.5 hours for a full charge on a nearly depleted battery. How can that be? We seem to be getting about 25 miles per hour of charging while we have been expecting about 15 miles.

BTW, after charging to 100% for the first several months, we started trying to reduce the time that it sits fully charged. First, set the time to mid-night and found that was too early. Now we use 2am and charge only to 80% which covers most of our days, up to 65 miles. If we anticipate needing to go more than 65 miles, we turn the charger back on for up to 1.5 hours before our departure.

 

[vegastar]

Do you have a energy meter for the LEAF EVSE? If not, I noticed that in my case for each hour I use 3,7kWh, or a power of 3,7kW. So for your 3,5 hours would give roughly 13 kW.h at the wall.

10 remaining miles seems like a low SOC, but it depends a lot on last driving conditions and Climate Control. How many bars did you have? Any low battery warning (I usally receive LBW at 15km / 10 miles).

In my case from LBW to full I use about 19,5 kW.h from the wall.

 

[Nekota]

One way to get an idea of the KWHr used at the wall is to use a set start time for charging, charge to 80% and turn on charge status notifications to your email. Charging to 80% starts the charging system at full power (3.8KW from the wall) and then stops at the 10 bar position (approximately 80%) sending an email with the time with minute resolution. So you can get "Wall to Wheels" KWHr charging input with time resolution of 1 minute with out any additional hardware. When you ask for 100% charging then this doesn't apply since the charging system tapers the charging rate and draws less than 3.8KW during the approach to 100% charge.

So if you stay with 80% charging with email notification, you have a means to accurately determine your energy input to the LEAF. And since you are running the charging system at it's max power during the charging time it's ratio of output to input (% efficiency) is constant. What I am seeing is I need 4 minutes of charging for each mile of travel or 15 miles of range for each hour of 3.8KWHr charging. As long as you stay with 80% charging, have a known charge start time and use the email notification, you have a simple way to collect charge energy input to your LEAF to correlate to your driving range and driving style. It also provides a means to determine the cost of the energy you supply to the LEAF.

 

[mckemie]

Do you have a energy meter for the LEAF EVSE? If not, I noticed that in my case for each hour I use 3,7kWh, or a power of 3,7kW. So for your 3,5 hours would give roughly 13 kW.h at the wall.

I don't measure energy/power from the wall. And, of course, the Leaf won't tell me anything about battery energy.

10 remaining miles seems like a low SOC, but it depends a lot on last driving conditions and Climate Control. How many bars did you have? Any low battery warning (I usally receive LBW at 15km / 10 miles).

"less than 10 miles" I said. The first low battery warning comes at 10 miles on the SMRD. After that, I have 15-20 miles to turtle. So, it wasn't alarmingly low; we do not become alarmed when the SMRD gets down to "---", we just know we have to charge "pretty soon". Since there is 8% of uncertainty, I rarely pay much attention to bars. I would guess we had zero bars, though. I estimate that ~10 miles on the SMRD should be about 15% of battery capacity remaining.

In my case from LBW to full I use about 19,5 kW.h from the wall.

Good information, thanks. I, then, seem to be charging at 19.5 kwh (or more) in 3.5 hours. Or, 5.7kw!
I need to check my timer and see if 2am somehow got translated to 1am at daylight savings or somesuch. Even 19.5kwh in 4.5 hours would be 4.3kw, well over the advertised capacity of the charger.

Let me correct that. 19.5kwh from the wall would probably be about 17.5kwh in the battery with a supposed charger efficiency of 90%. Implied charger rates would be 5kw for 3.5 hours or 3.9kw for 4.5 hours.

We did seem to be fully charged this morning. We traveled about 75 miles and came home with 18 miles on the SMRD.

All this illustrates the idiocy of the Leaf's instrumentation. What in hell was Nissan thinking when they foisted the current configuration off on us?

I recognize that battery charge current is proportional to ac voltage input. Chargers running off of one leg of three phase may see only 208vac and charge slower than at 240vac. My EVSE sees right at 240vac, plus or minus only a volt or so.

 

[gbarry42]

Definitely check to see if you were "an hour off" somewhere on the start time. While the stated kw-hours on the Blink EVSE has turned out to be the most informative, I've also kept a spreadsheet, recording the length of charge, and it tracks pretty well. With the LEAF set to 80% charge, the dash tells me the estimate to 80%. It is almost always just shy of an hour in the pessimistic direction. But also, it goes in half-hour increments. So it will either say 3:00 or 3:30 depending on if I've use just a little bit more. But as an example, if it claims 3:30 my actual charge time might be 2:38. I've rarely gotten down to 0 or 1 bar, but it's never taken longer than 5 hours to get back to 80%. And more like 4 hours if I've got 1 bar and about 8 miles on the SMRD (what we call the GOM or Guess-O-Meter around here).

My advice would have been to "recalibrate" the gauges or balance the battery, by running it down as far as you dare (which you have), and charging it to 100% (which you have also). So I guess we're left with calibrating your watch, and watching the time to get to 80%, and keep good notes. And if you get 65 miles from 80% everything is probably working as expected.

 

[vegastar]

I think it is VERY unlikely that you are using more than 3.7-3.8 kW.h from the wall. The maximum current draw is 16A so even at 240V it gives 3840W.

Is there any possibility that the hour the charge starts and the hour in the e.mails you receive for charge completed are wrong (like wrong time zone)? 3.5 hours is indeed very low from almost LBW to full.

My charging time is always between 1h and 1h30m lower than predicted by the car.

 

[mckemie]

Egg on my face!

For this morning, my timer was set to mid-night. So, it probably took 5.5 hours to fully charge, not 3.5. Sorry for the confusion.

 

[gbarry42]

Well, it goes to show that there's always a logical explanation!

 

[mark13]

At the 10 mile mark,I normally charge to 100% in 4 hours ..

 

[electricvw]

I have started to only check the bars instead of the mileage posted. I have been getting consistent 4.2 miles for the first bar then about 5 miles per bar after that. In the hot weather it is more but in the cool weather I am getting about 4 miles per bar. My miles per kWh has now dropped to about 3.3. I have been in the summer in the 3.8 to 4.2 miles per kWh. The actual distances in the Leaf are far from the advertised rate but then again I always drive at 55 to 65 mph during my daily commute of 44 miles. I think that Nissan should have put in a 42kwh battery pack for a real 100 mile range at freeway speed and at least an 80 mile true range in cold weather.

 

[LTLFTcomposite]

If I have a few days in a row where I only expect to be driving 10-15 miles per day should I refrain from "topping off" every night and wait until the battery is further depleted before charging?

 

[gbarry42]

If you are concerned about the battery, there will be no discernible difference in longevity between charging back up or not. This assumes an 80% charge, which is already reduced from 100%, which in turn is less than actually full. There are a number of other lifestyle and convenience reasons to do the top off, but I think you were asking about the battery specifically. And, of course, it's what I do, so that makes it right