How Do I Charge To 95%

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gmcjetpilot

Well-known member
Joined
Oct 30, 2017
Messages
130
I know my 2015 has newer battery design. Nissan says it's OK to charge to 100% every time. However some experts still recommend you don't, limit charge to 95% (and they give technical facts to back it up). The advice to not leave battery at 100% for extended time is still valid I assume.

Does anybody have any clever idea on how to do charge to 95%. I know you can use the charge timer to limit the amount of time you charge, but calculating the exact time to shut it off is kind of tricky. I've tried it a couple times to reduce charging time. Apparently not enough, it ends up at 100% anyway. Is there some way to set shut off at 95%? Is there a time to charge chart based on temperature and starting charge to get to 95%?
 
There is no way to set the car to charge to 95%. If it makes you feel any better, 100% indicated charge is likely more like 96% actual charge. You can get a charging station with a timer or even a remote start-stop feature, and estimate when you want it to stop.

Yes, it does suck.
 
I've mentioned it a few times now in these forums but haven't seen any posts by anyone who owns one. For $200, I think it's a little pricey, but the JuicePlug will do the trick, based on the sales copy:

https://emotorwerks.com/products/charging-stations/juiceplug
 
When you come home you take a few moments to plug in your vehicle. Just make it a habit to set the timer so you get around 95% or whatever percent you want.

How do you do this? Simply. First do a one hour charge and note the change in battery state of charge. If the battery State of charge changed about 20%, then you have a multiplier for how many hours to charge based on your starting point.

The last 5 or 10% to 100% takes a little longer than when Charging from a state of charge in the middle (say 30 of 40%), but you can do a few trail Charging to find something your happy with.

Yes, it’s an extra step. Only you can decide how much you really want to do this. But once you develope the habit, it is not that hard.

Note: once a year or so you may want to reconfirm the % Change in state of Charge for one hour charging as this may change slightly over time if the battery degrades. Also, be aware of how temperature may affect this.
 
If you are driving the car after every charging session, there is no valid reason to not charge to 100%. Trying to calculate when it will hit a specific % during the charging process is almost impossible, especially above 80%. The charging rate is varied based on pack temperature and resistance, and slows down as it gets closer to full. The final part of the process is balancing the cells, and that varies in time based on cell state. The resistance of the pack increases with age and degradation, but there is no chart to spell it out as it is different for every pack. Charging to around 80% should be fairly easy to estimate, based on the SOC and EVSE Charge Rate. Above that is a guessing game.

Charge it and drive it and don't worry about it. There is no hard evidence that regularly charging to less than 100% significantly extends the life of the battery pack. Just don't let it sit at 100% for extended periods, especially in high heat. That is known to speed up degradation, as experienced by those living in hot climates, and is a method used by those with marginal packs to help ensure the necessary drop to get a warranty replacement. If the car is going to be sitting idle for extended periods, it is best to keep the charge state between 20% and 80%.

I live in a hot climate, and just recently had the battery pack replaced under warranty. I have the 80% charge option, and use that with the timer to delay the start of charging until 2:00am. I do that because I don't drive the car every day. On the days that I know I will drive enough to get below 80%, I charge to 100% to balance the cells. Since I have a separate work vehicle, the Leaf can sometimes sit idle for a week. Not letting it go above 80% will help keep degradation in check (along with the dirt parking space under the trees). If I did not have the 80% option, I would have to get a much more expensive EVSE with the ability to control charging.
 
If you have LeafSpy (LSpy), this is pretty easy to figure out:

1. Read from LSpy your battery capacity at 100%
2. Let us know your EVSE volt and amp specs

Then we can tell you the battery % charging increase per time.

As an example,
My EVSE charges up the car 1% every two minutes (an L2 240 volt, 30 Amp device that sends ~ 6 kWh per hour to the battery)
If I return home at a SoC of 30% and want to leave the car at 80%, I set the timer to charge 100 minutes.

---
If you do not like arithmetic, then do this:
Note the starting and ending SoC after an hour charge.
The difference is the percent increase per hour.
NOTE that different EVSEs may have different charging rates, so the results may not be transferable.
 
powersurge said:
There is no reason to make extra effort to charge to 95%, or even to 90%. Charge up to 100% and be done with it..
Bad advice, if the battery is going to sit at 100% charge at higher temperatures
 
I recorded charge time to between 90-95% from different starting charge states. I notice charge rate starts to slow down above 91%.

jy0GnpV.jpg
 
SageBrush said:
If you have LeafSpy (LSpy), this is pretty easy to figure out:

1. Read from LSpy your battery capacity at 100%
2. Let us know your EVSE volt and amp specs

Then we can tell you the battery % charging increase per time.

As an example,
My EVSE charges up the car 1% every two minutes (an L2 240 volt, 30 Amp device that sends ~ 6 kWh per hour to the battery)
If I return home at a SoC of 30% and want to leave the car at 80%, I set the timer to charge 100 minutes.

---
If you do not like arithmetic, then do this:
Note the starting and ending SoC after an hour charge.
The difference is the percent increase per hour.
NOTE that different EVSEs may have different charging rates, so the results may not be transferable.
Thanks I don't have LeafSpy (LSpy) yet. I guess it is just a Bluetooth on OBSII Dongle and a free App?

My Clipper Creek Charger is 20 AMP or 220 x 20 = 4.4 KWh (estimate). I have the 6.6 KWh charger.

I can see from my two charges charge time (typical will be 3:30 hours to 2: hours (or less).
 
The 20 Amp Clipper Creek will run at 16 Amp continuous for safety reasons, so your throughput is about
16A*240V = 3840 watt. About 12% is lost to heat, so about 3840*0.88 = 3379 watts into the battery.

The missing information for now in your case is that you do not know the battery capacity so it is simpler to just learn through experiment how many percent the battery takes up in an hour. Since your end goal is to reach a specific percent anyway, you might as well leave everything in percent units.
 
gmcjetpilot said:
I know my 2015 has newer battery design. Nissan says it's OK to charge to 100% every time. However some experts still recommend you don't, limit charge to 95% (and they give technical facts to back it up). The advice to not leave battery at 100% for extended time is still valid I assume.

Does anybody have any clever idea on how to do charge to 95%. I know you can use the charge timer to limit the amount of time you charge, but calculating the exact time to shut it off is kind of tricky. I've tried it a couple times to reduce charging time. Apparently not enough, it ends up at 100% anyway. Is there some way to set shut off at 95%? Is there a time to charge chart based on temperature and starting charge to get to 95%?


You can do this but it will take some work on your part due to differences in home EVSEs.


First;

*check SOC

*Check estimated charge time for your EVSE (you will have both slow and fast L2 times listed)

*set end timer to 3 hours AFTER you plan to be up the next day.

*next day (or whenever) get up check SOC.

record all this data over a few days.

Analyze data. You will likely find that it becomes easy to hit your target SOC within a 5-10% delta. (charge times jump in 15 min increments at times)

what you need to look for;

Making sure you check your charge before it gets to balancing stage. This is why I recommend 3 hours. I would be specific but cannot because your EVSE is different than mine.

Yes, this requires setting end time for charging EVERY NIGHT.

Finally; why 95%. The general consensus is 90% based on Bolt, Tesla, etc.

FYI; your best bet is running your car at lowest SOC that covers your needs. This grows in importance with the Mercury. When cold (if it gets cold for you) the issue is pretty small and range is reduced in Winter so charging to full is a not the "best" option but also not significantly bad either. Its better to play it safe than be stranded in life threatening weather
 
DaveinOlyWA said:
gmcjetpilot said:
I know my 2015 has newer battery design. Nissan says it's OK to charge to 100% every time. However some experts still recommend you don't, limit charge to 95% (and they give technical facts to back it up). The advice to not leave battery at 100% for extended time is still valid I assume.

Does anybody have any clever idea on how to do charge to 95%. I know you can use the charge timer to limit the amount of time you charge, but calculating the exact time to shut it off is kind of tricky. I've tried it a couple times to reduce charging time. Apparently not enough, it ends up at 100% anyway. Is there some way to set shut off at 95%? Is there a time to charge chart based on temperature and starting charge to get to 95%?


You can do this but it will take some work on your part due to differences in home EVSEs.


First;
You win the Rube Goldberg medal for complicating something trivial.

Step 1a: Charge for about an hour and note the SoC change per minute

Step 1: Arrive home and decide how much you want to charge in percent
Step 2: Divide Step #1a into Step #2. You now know minutes to charge
Step 3: Set start charging time (Step #2) minutes before the end charging time

Example, using my car and my EVSE:
It takes 2 minutes to gain one percent

I arrive home with a SoC of 25% and want to charge to 80%
I set the start timer 130 minutes before the end charge time.

---
That is for the OCD amongst us.
Everybody else can just set the start timer to match their typical drive routine and only calculate the unusual days.
 
SageBrush said:
The 20 Amp Clipper Creek will run at 16 Amp continuous for safety reasons, so your throughput is about
16A*240V = 3840 watt. About 12% is lost to heat, so about 3840*0.88 = 3379 watts into the battery.

The missing information for now in your case is that you do not know the battery capacity so it is simpler to just learn through experiment how many percent the battery takes up in an hour. Since your end goal is to reach a specific percent anyway, you might as well leave everything in percent units.

My charger is a LCS 25 (not a LCS 20), and it runs at 20 amps continuously (needs a 25 amp breaker). The .88 efficiency factor is a good tip. Also my line voltage is a little under 240 volts. What I see is there is little difference in LEVEL 2 charging from 16 Amp to 30 Amp... The quantum jump is going from LEVEL 1 to LEVEL 2.
 
SageBrush said:
You win the Rube Goldberg medal for complicating something trivial.
Step 1a: Charge for about an hour and note the SoC change per minute
Step 1: Arrive home and decide how much you want to charge in percent
Step 2: Divide Step #1a into Step #2. You now know minutes to charge
Step 3: Set start charging time (Step #2) minutes before the end charging time
---
That is for the OCD amongst us.
Everybody else can just set the start timer to match their typical drive routine and only calculate the unusual days.

There are variations or differences in rate of charge, due to temperature and other factors, including starting SoC. The charge rate is not linear. Yes your rule of thumb is a good ball park, and for your typical charge can come up with a time. From my two monitored charges my typical charge will be about 2-3 hours. My charge rate varied from 3.9% to 4.75% every 10 minutes.
 
DaveinOlyWA said:
Finally; why 95%. The general consensus is 90% based on Bolt, Tesla, etc.

FYI; your best bet is running your car at lowest SOC that covers your needs. This grows in importance with the Mercury. When cold (if it gets cold for you) the issue is pretty small and range is reduced in Winter so charging to full is a not the "best" option but also not significantly bad either. Its better to play it safe than be stranded in life threatening weather
[/quote]

I got the 95% from the YouTube Video
Title: Fast Five: How To Keep Your Electric Car Battery Healthy
Channel: Transport Evolved
Date Aug 30, 2017
https://www.youtube.com/watch?v=AoYmSLBQYDc
 
Ignore the "experts" who created that video.

Just charge and drive the car as needed. Don't worry about 95%.
 
LeftieBiker said:
You might also want to ignore this expert. Limiting charge in hot weather is reasonable and prudent.
I'm no expect, nor do I pretend to be one on the Internet.

I agree that limiting charging in hot weather is reasonable and prudent. That video makes overbroad statements that it attempts to apply to all EV batteries equally. That's not useful.
 
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