Dala's Leaf buildthread (2015 Nissan Leaf)

Omien autoprojektien esittely.
Post Reply
Dala
NORMAL USER
NORMAL USER
Posts: 76
Joined: 14. Oct 2014 19:39
Location: Vaasa

Dala's Leaf buildthread (2015 Nissan Leaf)

Post by Dala » 05. Nov 2018 10:10

So I thought I might start a project thread on this car, that wasn’t supposed to be a project.
I recently picked up a commuter, 2015 ZE0 24kWh Nissan Leaf, with 5k km on it. It has extremely low range, the guess-o-meter(GOM) on the dash says 160km, but as soon as you start driving it you are lucky if you manage 20km. Pretty shite for 15 000€ :D

Due to this being an USA model imported to Europe, so I apparently don’t have any battery warranties in place. I also wasn’t fully aware that the battery was this bad, so if I could go back in time I would have never bought this car.
But nevertheless, let’s stay positive and start fixing this car up.
Here’s a picture of the bog standard car. Not much to say really. Was a wet day.
Image

The car seems to deplete about 3-4kWh of battery, and then promptly report it as empty. This is strange, since it’s supposed to be a 24kWh battery! Charging it back up also goes suspiciously fast, so something is indicating that one or more cells are dragging the whole pack down.

It also goes into turtle mode from time to time, and with a handful of dash warnings and load reductions.
Image

So next order of business is to start diagnosing the battery. The CAN communication needs to be forwarded to a phone running the LeasSpy Pro app. This is achieved with a bog standard v1.5 ELM327 Bluetooth OBD2 dongle. Note that it has to be v1.5, the cut down v2.1 won’t work.
So here are some screenshots from an almost fully charged battery. Notice anything suspicious? :D
Image

So as you can see, the cellpair 57&58 are down 150mV from the rest of the cells. The Nissan battery management system utilizes passive balancing of the lithium cells using shunt resistors. Unfortunately, these are not very beefy, and can only bypass a few mA when charging. So if any cells have drifted far enough, and ESPECIALLY when replacing cells, you need to pre-balance them before you insert them into the pack.

So a manual rebalance of 57&58 seems like the best way forward. Later down the line I can always replace them, but let’s start with a rebalance.

First thing to do is disconnect the 12V battery in the front, or else the control system will freak out when I start disconnecting HW stuff
Image

Next thing to disconnect is the fuse from the HVDC pack. The fuse is located under the floor, and can be accessed via a panel in the backseat floor.
Image

After pulling the fuse, it is now safer to work under the car, and next step is to disconnect the high voltage cabling from the pack. Notice that I’m wearing Class 0 high voltage gloves each time I’m near anything labelled orange.
Image

Started propping up the car high with multiple failsafes.
Image

Removed splash plates. There are three of them.
Image

Here are the battery high voltage connections and CAN cabling, disconnected them. They were quite hard to figure out how to open.
Image

I then put pressure on battery with some wood and four jacks, started loosening bolts. There were 18mm, 8 in total.
Image

Built a dolly to be able to slide the pack around. The battery weighs circa 280kg!
Image

Lowered battery onto dolly
Image

Then it was very easy to slide the battery out
Image

For some reason they don’t want you to be able to open it easily. It was glued shut, but with the help of some prying and cutting tools, it eventually came apart
Image

Here is the battery exposed. Several stacks of modules, totaling at about 400V DC. Safety first, so gloves on at all times now!
Image

I then started to charging. Decided to take it slow due to not knowing much about the Li-MnO2 cells (I'm more of an 18650 guy :D) Since the cellpair 57&58 was at the absolute bottom of the stack, they will be extremely hard to get to. I don't want to disassemble the pack, so I improvised some sticky leads with hard drive magnets inside alligator clips. That way I can just lower them down into the pack, and they will stick to the terminals.
Image

I then hooked up a bench supply, set it to 8.4V and connected it to the outer terminals of the 2S cell. I am lucky that the rest of the pack is at 4.00V cell average, so I won’t have to worry about CC/CV switchover, just CC charging up to 4V (8V effective due to 2S). As charge current limiter, I set it to 0.3Amps, to keep temps and everything nice and smooth.
Image

I also disconnected some of the BMS leads, don't know if this was necessary, and hope I don't break the BMS by piggyback charging this way.

After 18h of charging, the cells are up from 3.60V -> 3.95V, so just a few more mV to go!

User avatar
Sammyboi
SUPPORTER
SUPPORTER
Posts: 108
Joined: 01. Aug 2015 01:49
Location: Oulu

Re: Dala's Leaf buildthread (2015 Nissan Leaf)

Post by Sammyboi » 05. Nov 2018 18:46

Wow. So soon with the techy stuff. Keep us posted.

Hopefully you will sort it out, any other plans for the Leaf? It is a bit of an "meh" looking car. Maybe modifying the exterior would help it? :D

Dala
NORMAL USER
NORMAL USER
Posts: 76
Joined: 14. Oct 2014 19:39
Location: Vaasa

Re: Dala's Leaf buildthread (2015 Nissan Leaf)

Post by Dala » 06. Nov 2018 10:28

After charging the cell up and letting it sit for 16h, it unfortunately drooped back a few mV, indicating high internal resistance. It will have to be replaced in the future, but the car should be usable now, so I spritzed some bathroom silicone around the battery, and popped it back in to the car.

I then plugged the charger back in, and tadaa, the blue dash charge leds lit up! :D What a relief, I didn't break anything!
Image

The leafspy now reports a 46mV diff, heck of a lot less than 150-225mV delta before!
Image

The GOM happily reports a total 177km range now, but I need to just drive it and see what the actual range is.
Image

Now I will start the process to try and get my hands on a good low-mileage Gen2 cell from another 24kWh leaf...
Sammyboi wrote:
05. Nov 2018 18:46
Wow. So soon with the techy stuff. Keep us posted.

Hopefully you will sort it out, any other plans for the Leaf? It is a bit of an "meh" looking car. Maybe modifying the exterior would help it? :D
Yeah it looks like shit :D But I bought it to save money long term, not having to spend 1X00€+ every year on fuel, and instead charge it for free at work, so I guess that frees up some cash for a few mods :)

Dala
NORMAL USER
NORMAL USER
Posts: 76
Joined: 14. Oct 2014 19:39
Location: Vaasa

Re: Dala's Leaf buildthread (2015 Nissan Leaf)

Post by Dala » 09. Nov 2018 21:45

While waiting for emails on potential cells,

I decided to do my first mod! It's quite common in Finland to do grille blocks during winter, this allows the engine to heat up more rapidly and improve efficiency. But wait a minute, this is not an internal combustion car (ICE), so why do it to an EV?
-It improves aerodynamics, no air will be forced into the engine bay. Leaf owners swear by this mod, claiming 1-2% more efficient km/kWh at highway speeds

So here it is;
Image
I cut out some plexi, 70cm x 7cm, and attached it with zipties. I need all the extra range I can right now in this limited state :D

Post Reply

Who is online

Users browsing this forum: Majestic-12 [Bot] and 3 guests