Thread Rating:
  • 1 Vote(s) - 5 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Dala's Leaf buildthread (2015 Nissan Leaf)
#1
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€ Big Grin (Yes these cars are extremely expensive in Finland!)

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.

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.

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 a fully charged battery. Notice anything suspicious? Big Grin

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 HV stuff


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.


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.


Started propping up the car high with multiple failsafes.


Removed splash plates. There are three of them.


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


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


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


Lowered battery onto dolly


Then it was very easy to slide the battery out


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


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


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 Big Grin) 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.


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.


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 3.80V -> 3.95V, so just a few more mV to go to 4.00V
Reply
#2
Where is the leafspy screenshot showing per cell voltages when it's in limited power mode ?

Nissan would have resolved this issue for you, given it's age, despite you being slightly remote and despite wthe vehicles history - but you've obviously voided that warrenty now.

I've done the same as you a number of time, if you need a source of gen 2 cells let me know.

I'm assuming you've left it plugged in on the home charger for at least 48 hours ?, when there is such an imbalance the process does take a while - but, seeing as you have allready done most of the work required to get access to what is potentially a very weak cell, why not just replace it now ?
Reply
#3
(11-05-2018, 09:46 AM)Sean Wrote: Where is the leafspy screenshot showing per cell voltages when it's in limited power mode ?

Nissan would have resolved this issue for you, given it's age, despite you being slightly remote and despite wthe vehicles history - but you've obviously voided that warrenty now.

I've done the same as you a number of time, if you need a source of gen 2 cells let me know.

I'm assuming you've left it plugged in on the home charger for at least 48 hours ?, when there is such an imbalance the process does take a while - but, seeing as you have allready done most of the work required to get access to what is potentially a very weak cell, why not just replace it now ?

-When in limited mode and lower battery voltage, the mV diff is 220mV

-Nissan wont resolve this, USA->EU means no warranty at all.
"Vehicles that have been sold in Europe have Pan-European warranty, this vehicle doesn't. Unfortunately we can't help you in this matter and offer goodwill."

- I might take you up on that, if I need a 2nd gen cell replacement if this balancing wont do

- Yeah, been charging it 6 times now, no visible change. The bypass shunts are minimal in the BMS, the nissaneleafforums said the process for solving imbalance can take 3-9months. I simply cannot wait for that long, especially since the cell might be bad! Let's see how it performs tonight and re-assess Smile
Reply
#4
The easy way to cut through the battery housing sealant is to use an oscillating saw, using both the half round, and straight blades - with one of these the two halves can be separated (thus giving full access to the cells) in about 20 minutes, which no damage or deformation to the casing. It's just RTV silicone, but use a good quality one when resealing.



(11-05-2018, 10:08 AM)Dala Wrote: -Nissan wont resolve this, USA->EU means no warranty at all.
"Vehicles that have been sold in Europe have Pan-European warranty, this vehicle doesn't. Unfortunately we can't help you in this matter and offer goodwill."

It'll not have the battery warming plates either ? You might want to try retrofitting them if you can find any, your climate will not be kind on the battery.

Are you intending to capacity check the cell before you reassemble ?
Reply
#5
(11-05-2018, 10:12 AM)Sean Wrote: The easy way to cut through the battery housing sealant is to use an oscillating saw, using both the half round, and straight blades - with one of these the two halves can be separated (thus giving full access to the cells) in about 20 minutes, which no damage or deformation to the casing. It's just RTV silicone, but use a good quality one when resealing.


It'll not have the battery warming plates either ? You might want to try retrofitting them if you can find any, your climate will not be kind on the battery.

Are you intending to capacity check the cell before you reassemble ?

Yeah thanks for the tip Smile I unfortunately don't have any oscillating saws at my disposal, so basic knifes had to do the job. RTV silicone is just what I had in mind, since anything stronger like sikaflex would probably result in a practically welded shut case.

Also the warming plates, I thought about that, from what I've gathered, it's a 300W heating element for the batteries. I already have somethings that could be used as battery heaters, but I'm gonna focus on getting it running now first, and asses later on in winter how the range behaves.

No capacity check, if it sucks I'll replace it.
Reply
#6
Out of interest, all of the packs I've disassembled have had some really badly applied seem sealant within the battery case, I assume Nissan are not confident that the case is fully weather proof - does yours have the same ?



Reply
#7
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! Big Grin


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


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


I took it for a test drive, and got 35km with loosing only two bars. That trip would have been impossible pre-surgery!

Now I will start the process to try and get my hands on a good low-mileage Gen2 cell from another 24kWh leaf... (Thanks Sean for pointing me in the right direction!)

(11-05-2018, 12:37 PM)Sean Wrote: Out of interest, all of the packs I've disassembled have had some really badly applied seem sealant within the battery case, I assume Nissan are not confident that the case is fully weather proof - does yours have the same ?

Yes, it had tons of goo all over the bottom and inside the case!
Sean likes this post
Reply
#8
If you buy an entire pack, you'll have enough cells for a wall, and to repair your EV.
Dala likes this post
Reply
#9
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;

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 Big Grin
Korishan and Glubux like this post
Reply
#10
After completing the rough balancing, the car can now go 85km instead of 25km. Still really bad, should be closer to 150km. So the troubleshooting continues.

I contacted a company that specializes in EVs, (EVs Enhanced), and they suggested doing a bottom balance instead of middle balance. This makes sense, since a balance in the middle of the State Of Charge(SOC) can be very imprecise. Making the cells bottom balanced will also help me in the future when I decide to swap the cell.

So here are the instructions for how to do a bottom balance:

1) Discharge the pack to a lowish point - the two cells will limit how far you can discharge of course
2) Remove the pack again and re-open it
3) Charge the two cells to significantly higher voltage than the rest of the cells in the pack
4) Temporarily, reinstall the pack into the car and continue to discharge (lights/heater/etc on) until all the cells in the pack (except the two higher ones) are in the 3.0-3.3V range. This time the two cells wont be limiting your ability to discharge the pack
5) Remove the pack and this time discharge the two cells to match the voltage of the rest of the cells - so they are all bottom-end balanced. Leave the cells to settle for a day after discharging to re-check the voltage and discharge further if required.
6) Reinstall the back and fully charge it - if the two cells hit 4.12V while charging before the rest of the other cells then they are certainly lower capacity so replacing them would increase range to some extent. If other cells in the pack hit 4.12V before the two cells, then this replacement module has equal or better capacity compared to the rest in the pack - replacing it would give you no benefit.

Let's get cracking!

Assume the service position after draining the battery.


Remove the pack again. Charging 57&58 up to 3.8V, when the rest of the cells are at 3.7V


Start discharging again with the unbalanced ones at top


Interestingly, when the SOC number dissapears from the dash, the car still runs the heater for over an hour! The heater pulls ca 3kW


After completing the true discharge, the diffs are growing rapidly at close to 0% SOC


While waiting for all this charging and discharging, I started cleaning the car properly for the first time.
First thing to remove was the dealership stickers


Much better


Also waxed it for the first time


I had also read threads about common issues. One of these was a faulty design in the shock absorber top mount, allowing water to pool on top of the bolt. This also affected this car and corrosion had started


Dried it out and smeared some silicone sealant over it to make it waterproof. Very worthwile, some people even had reported failures here!


So now I'm waiting for the pack to settle, and will continue with step 5&6 tomorrow.
netmonk, Korishan, Redpacket like this post
Reply


Who read this thread?
56 User(s) read this thread:
slsbatt (12-10-2018, 10:29 PM), Wolf (Yesterday, 01:38 PM), Ronald Hyde (11-11-2018, 03:53 PM), hermitdave (11-22-2018, 02:22 PM), emuland-metroman (11-09-2018, 07:07 AM), Electronic Matrix (12-01-2018, 11:11 AM), chuckp (11-20-2018, 12:01 AM), Buzz0515 (11-13-2018, 05:55 PM), Dragora (11-17-2018, 06:33 AM), Sholphin02 (11-26-2018, 11:20 PM), JDish (11-29-2018, 10:44 AM), micsa84 (11-06-2018, 04:45 PM), Zvonko000 (11-19-2018, 08:46 PM), Bastler_Ro (11-22-2018, 09:04 PM), collinkoolen999 (11-21-2018, 08:18 AM), asamnc (11-28-2018, 01:43 PM), newone972 (11-26-2018, 09:30 AM), jfosdicknmu (11-25-2018, 06:20 AM), ajw22 (12-09-2018, 09:53 AM), eric.peton@laposte.net (11-09-2018, 11:30 AM), marc (11-07-2018, 04:06 PM), BigDav (11-18-2018, 03:35 PM), Bdaearth (11-09-2018, 10:50 AM), stevelectric (11-23-2018, 07:27 PM), Speicher (11-06-2018, 07:06 PM), Melan (12-02-2018, 12:46 PM), camthecam (11-22-2018, 11:14 PM), Redpacket (11-21-2018, 10:22 PM), Dala (Yesterday, 08:04 AM), mr_hypno (11-09-2018, 10:34 PM), Geek (Today, 03:11 AM), ivnz (11-07-2018, 08:15 PM), netmonk (11-20-2018, 03:39 PM), Stefaan De Ridder (Yesterday, 09:57 AM), Hanssing (11-06-2018, 05:35 AM), watts-on (Yesterday, 11:24 AM), jdeadman (Yesterday, 11:41 AM), PAF (Yesterday, 11:18 AM), Korishan (Yesterday, 12:55 PM), Glubux (12-15-2018, 04:33 PM), mike (11-22-2018, 09:36 PM), floydR (11-23-2018, 02:33 AM), slimf (11-21-2018, 01:05 PM), Paul (11-23-2018, 05:34 PM), Jimbob01 (11-27-2018, 11:13 PM), gpn (11-06-2018, 06:21 AM), EGOksy (11-16-2018, 09:17 PM), gregoinc (11-10-2018, 08:26 AM), brwainer (11-08-2018, 05:07 AM), Jason Morris (11-09-2018, 09:23 PM), spinningmagnets (Yesterday, 11:23 PM), BaronVonChickenPants (11-05-2018, 08:16 AM), Charly144 (Yesterday, 08:18 AM), bigblue (11-19-2018, 04:45 PM), CarelHassink (11-10-2018, 07:04 AM), Sean (Yesterday, 08:21 AM)

Forum Jump:


Users browsing this thread: 1 Guest(s)