Tag Archives: leaf

How to limit charging to 80% on a later model year (2014+) Nissan Leaf

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Early (2011-2013) United States Nissan Leaf’s had a “limit charging to 80%” feature in the dash.  Nissan removed this feature from US cars after the EPA ruled that if the feature remained, they had to report a lower battery range because on average the car would not be fully charged when it left. [This ruling was incorrect in my opinion…but Nissan removed the feature so that they could advertise the EPA range based upon a 100% charge of the battery.]

I, and many other people, still like to limit charging to only 80% of the battery total capacity in an effort to extend the life of our EV batteries. [This extra effort may or may not be worth the trouble, and many people advise to just charge to 100% and not worry about your battery health, especially for 2016+ vehicles which have a longer battery warranty. But I like to limit charging of Lithium Ion batteries to 80% if I don’t need the extra range.]

If you wanted to only charge your Nissan Leaf to 80% (unless you need extra range for longer trips) on a regular basis, how can you do it on later model year vehicles?

There are three options that I know of:

1. The only way to get a similar effect (keeping the car below 80% SOC most of the time) using only  inbuilt features (i.e. without spending extra money) is to set up the charging timer to charge your vehicle right before you leave. This only works well if you have a regular departure time each day (e.g. for a static work schedule). Then, when you plug in the car, it will not charge until a few hours before your scheduled departure time, aiming to reach 100% about 30 minutes before you depart. This means that the time the battery sits at 100% is minimized. [If you are clever, you can lie about your departure time so that it is reaching 80% about the time you actually leave…]

The downside is that your vehicle is not “ready to go” if you need to leave for an unplanned trip before your regularly schedule departure time, and if you want to charge any other time you have to remember to disable the charging timer so that it will actually charge when you plug in. [My 2015 leaf has an easy to use button for disabling the charge timer…]
Nissan Leaf charging timer disable / off button

So this can be made to work if you have a regular schedule, but it can also be annoying.

2. You can “mimic” the “charge only to 80%” feature by using a Smart / connected EVSE that has a charge limiter built in. For example, I have a JuiceBox, and when I plug in my 2015 leaf, I use the phone app to set the “plugged in percentage” and “stop percentage” (which I just leave at 80%) and it estimates the amount of power needed and will shut off charging after that amount is used. This requires that you pay money for a smart EVSE…but if you haven’t already purchased an EVSE, getting a “smart” or “connected” one with a similar feature will probably only add 1-2 hundred dollars to the purchase price.

Juice Box Pro 40 front faceplate, original silver model from e-motor-works

3. There is also a 3rd party add-on box you can install in your vehicle called Open Vehicle Monitoring System (hardware device) that would allow you to set a charge % limit and also do things like pre-heat in the winter remotely, and has a lot of other logging features…. but it costs $260 (and if you want to be able to use it on a cellular network away from your home/work WiFi networks or the bluetooth range of your phone, you need to include a SIM card with data capabilities which will also probably have a monthly fee)

Open Vehicle Management System Screenshots

Because I already had a JuiceBox, I use method 2…but if I already had a non-smart EVSE, I would probably go with the OVMS route, as it adds other features to the car.
[Especially since the Nissan Connect system in my 2015 leaf no longer works as it used an older 2G cellular service that has since been retired.]  If you have a brand new Nissan Leaf, it probably includes the Nissan Connect service, at least for the first three year of car ownership.

Salvage 2013 Nissan Leaf Modules – 8 year age capacity test: 75-80%

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six nissan leaf modules with capacity test values written on the sides
Back in 2015 I bought a wrecked 2013 Nissan leaf and salvaged it’s 48 battery modules to use in my s-10 electric pickup truck. At the time, the batteries had 18,921 miles from the Leaf on them, (10 quick charges and 775 Level 1/ Level 2 charges) and the leaf BMS reported a capacity of 64 amp hours (98% state of health). [The modules are rated at a minimum of 60 AH new, but most exceed the minimum specifications a bit.]
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Salvage 2013 Nissan Leaf modules – 7 year old range update

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Back in January of 2016 I put a set of battery modules harvested from a salvage 2013 Nissan Leaf into my S-10 conversion electric pickup. In march of 2016 I drove the truck for a while to see what its range was. [More than 46 miles, as I got tried of driving. The pack had a capacity of at least 15 kWh at that point in time.]

37.4 miles on trip meter.

Today I drove the truck for 35.8 miles before the low cell warning beeper from the BMS started to alert. After I got home [37.4 miles total], the average cell voltage of the pack was 3.75, while my (one) lowest cell was down at 3.3 volts. As it turned out, that cell must have started the trip out at a lower state of charge / voltage from the other cells, as it was still low when charging finished and I had to manually add charge to it individually. [My BMS does a good job of alerting at high/low voltage conditions, but does not do much for balancing the pack.]

According to my JuiceBox, the pack required 14.74 kWh to recharge, which is a good estimate on the battery pack’s current capacity. [This is almost exactly the same amount of power that I used in the trip in 2016, but I didn’t go as far due to different driving conditions. And I also hit the bottom of (at least one cell’s) state of charge.

The 2016 trip averaged 322 watt-hr/mile. This trip consisted of a lot of stop & go city driving as well as a few lengthier stretches of 49 mph arterial streets, and I wasn’t light on the accelerator. My measured watt-hour / mile (from the wall, including charger losses) was: 394 watt-hr/mile

Assuming that the pack has a 15 kWh capacity, this is 63% of the brand new 24 kWh capacity, which means I lost 37 % of the capacity over 7 years. (Some of that was in the original Nissan Leaf, but most of it was in my s-10 conversion.)

I’ll repeat the test after balancing my cells a bit better and see how things go.

Update: I drove the truck until the low cell beeper came on again. I went a total of 38.5 miles, and recharged the pack with 16.69 kWh (16690 watt-hours). The relatively higher   433 watt/hours per mile number is a result of the weather being a lot cooler so I was running the heater in the truck and more 45 mph roads. Balancing the cells got the usable pack capacity (measured from the wall with charging inefficiencies) to 16.69 kWh (which could have theoretically gotten me to 42 miles at 394 watt-hour/mi or 51 miles at 322 watt-hr/mile)

The main take-away is that at 16.5 kWh, I still have access to 68% of the brand new 24 kWh capacity Leaf pack, which isn’t too shabby for a 7 year old battery.

 

 

 

Nissan Leaf 12 volt accessory battery replacement

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My wife came home one night and told me that when she had started up her Leaf for the drive home it “acted wonky” with lots of warning lights on the dash, and the brake pedal went to the floor without actually keeping the leaf from inching out of the parking space she was in.   This sounded like the 12 volt accessory battery was no longer holding a charge and was in a low voltage state (which the electronics in the car really don’t like!). This happens when the battery ages, and Nissan Leaf’s are notorious for going through 12 volt accessory batteries quickly.   (Even though the batteries don’t need to provide a lot of cold cranking amps to turn over an engine, the car electronics draw a lot of power, and the main power distribution unit will re-charge the battery at a high amp rate when the car is on. They are also a relatively small sub-compact size (Group Size 51R).   The car is 4 years old, so I figured it was about time for the OEM battery to be replaced.

When I went to examine the battery under the hood, I realized that it needed to be replaced sooner rather than later. It’s never a good sign when the special blue power crystals escape from the positive terminal lug, or battery acid eats the paint off of your battery hold down bar…

So, after spraying foaming battery acid neutralizer all over the place, I re-painted the battery hold down strap and bought a Duralast Platinum 51R AGM (Absorbent Glass Mat) battery at AutoZone that comes with a 3 year replacement warranty.   (It was   cheaper than the yellow top Optima AGM battery that is widely recommended for the Leaf, and the warranty period was the same.)

People online have said that AGM’s work better with the high current charge rate provided by the leaf’s power distribution center, and I figure that being sealed they would be less likely to vent acid over other parts of the car. I could have gone with the $70 battery that came with a 3 month warranty, but I figured that the Leaf is hard enough on it’s accessory battery that I’d better pay for the good one.

So far the maintenance needs of the Leaf have been relatively small, and this is the first major item that needed to be replaced. (New tires are coming up soon.) Other than this   battery replacement, I’ve bought new wiper blades, replaced the cabin air filter, refilled the wiper fluid and rotated the tires.

How far can it go?

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Summary: I drove my truck 46 miles on one charge (and had some juice left over).
Instant-1457835710687

When you have an electric vehicle, everybody wants to know how far it can go.
I typically tell them “19,800 miles so far.”

But then you have to answer their real question, which is “What’s your range on a single charge?”. If you have a commercial EV like the Leaf or a Tesla, you can just refer to the EPA range figure for a nice apples to apples comparison. But when you have a conversion EV, the number is unique to your particular vehicle, motor, controller, battery pack and testing methodology. (And changes as the pack ages…)

I used to know the answer to that question for my truck with a (new) lead acid battery pack (“25-30 miles without killing the pack”), but I haven’t fully characterized the trucks’ power usage and range with the new (lighter weight, more powerful) pack made up of Nissan Leaf cell modules. My truck is heavier and has more air resistance than a stock Nissan leaf,   the motor/controller is slightly less efficient, and the (big fat!) tires have quite a bit more rolling resistance. I figured “half the range of a Leaf” would be a good ballpark estimate.

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Nissan Leaf Modules powering my S-10 Pickup conversion

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I have successfully driven my S-10 Electric Pickup conversion powered by 48 modules from a salvaged Nissan Leaf battery pack. I have them wired in series, 16 sets of 3 parallel modules, providing 128 volts with 180Ah capacity (23 kWh).

LeafPackInBack

It took me a full three days of work to make the swap and get the truck to a barely drivable condition. I have the cells hooked up with a warning buzzer on the BMS low voltage loop signal, but I do not yet have the charger fully connected. I anticipate another 8 hours of work to get the charger and pakTrakr system fully set up.

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16 volt Nissan Leaf Battery Management System (BMS) information

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In a previous post I have shown how to physically mount six Nissan Leaf battery modules in two series groups of 3 parallel modules to build a 180 Ah by 16 volt Lithium (LiNMC) battery.

The batteries are covered by these very cool laser cut acrylic protective covers (which obscure the BMS wiring).
cover_with_bms_topview

Anthony Felix asked for more information about the BMS units I’m using on my batteries, so here it is! (Jump down to the last picture if you just want to see where the BMS units are attached….all of the text between here and there is an explanation of WHY they are attached there…)
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Economies of harvesting Nissan Leaf battery modules

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rear_of_car_smushed

I purchased a 2013 salvage (wrecked) Nissan Leaf from the CoPart auto auction house for $4081 (including delivery and fees). I consider this to be a very good price for a wrecked Leaf, but if you stalk a lot of auctions and bid on Leafs that have the most damage you can probably get a similar deal with enough patience.

Then I spent 439$ on the following tools that I needed to move the car around and extract the battery (the largest amount was for jacks and wheel dollies…)

Car Cover (Keep the neighbors happy) 37.1
Wheel dollies & Jacks 243
Bluetooth OBD II scanner 9.98
Leaf Spy Pro android app (to check battery) 14.99
500V gloves   (Safety first!) 21
2 Jackstands (already had 2) 25
Air Impact Wrench & Sockets 46.5
18mm wrench 12.4
13mm deep socket 8.99
21 mm combination wrench 20.69

This puts my total costs at 4520.75 ($94.18 per module) for a 24 kWh battery pack, which is less expensive than if I bought large format prismatic cells.

Of course, with a lot of time and effort, you can sell all of the other parts from the car. Over the course of six months I made back $3180.46 (including the sale of the smallest of the three jacks I had purchased and 0.46 in change I found in the car.) I’m posting this after selling the main body of the car, leaving me with just a few small items listed on ebay. I may earn a few hundred extra dollars over the course of the next several months, but the overall cost recovery is finished.
final_sale

My current total out of pocket expenses (not including lots of labor!) is 1340.29 (or $27.92 per module) which is quite a significant savings over other options for purchasing large format Lithium Ion batteries.

I’ve seen Nissan Leaf modules selling on Ebay for around $130 each with shipping (in larger quantities), so my ~ $30 per module cost is around 21% of the cost of purchasing them on the used market.

To put this cost savings in perspective, purchasing 20 lead acid golf cart batteries to replace my current pack would probably cost me around $2000-$2200, so the Lithium Ion Nissan leaf battery pack was actually less expensive than a replacement lead acid pack!

However, the process of parting out the wrecked car takes a lot of time and effort. If you are just after the battery and can find one for sale at a salvage/junk yard for less than $2500 it would probably be easier to buy the battery alone without the rest of the car. The one advantage of purchasing the whole car is that you can (sometimes) find out how many miles are on the battery pack. In my case, I was able to use an OBDII scanner with the Leaf Spy Pro application to find out that my battery pack health was still at 98% before I removed it from the car.

If I were to buy a whole car again, I would try much harder to sell the entire car (minus battery) in the $2000-2500 range before parting it out and trade some money for my time.

The Nissan Leaf pack weighs about 650 lbs less than the lead acid batteries currently in my truck. They are capable of providing more amps with less voltage sag due to lower internal resistance, and more of the pack capacity is usable as they don’t suffer from the Peukert effect as much as lead acid batteries.

The overall performance of the truck should be much improved. Also the battery life should be much longer than 2 years. (Cycle life for lithium ion batteries is measured in thousands of charge cycles, instead of hundreds of charge cycles for lead acid batteries.)

However, because I am changing battery chemistries, I am also upgrading my trucks’ charging system (and home EVSE) and those costs are actually more than the battery pack, so the total upgrade cost will be more than just getting another lead acid battery pack. (I will talk more about charger upgrade costs in a later post).