LeftieBiker
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Re: Timecapsule 2015, dodgy battery troubleshooting

Thu Nov 01, 2018 2:42 pm

I too think it's more than the cells not having been pre-charged. I'd expect them to be closer to being charged by now - maybe 60% - and slowly improving.
Scarlet Ember 2018 Leaf SL W/ Pro Pilot
2009 Vectrix VX-1 W/18 Leaf modules, & 3 EZIP E-bicycles.
PLEASE don't PM me with Leaf questions. Just post in the topic that seems most appropriate.

WetEV
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Re: Timecapsule 2015, dodgy battery troubleshooting

Thu Nov 01, 2018 10:32 pm

Dala wrote:So it seems like the monkeys who replaced the cell in the car did not pre-balance it. Guess the next step is to open up the pack, and charge it manually up to 4.1V like the rest of them with a LI-ion CC/CV charger. Wow the Leafspy Pro is a great tool!


No. Charge the car to full, and get a LeafSpy screenshot. Then drive the car and use climate controls right by the charging station to get down to near turtle again, and get another LeafSpy screenshot. Then charge the car to full again, get a third LeafSpy screenshot. Then with the car at or near full charge, wait a few days, get another LeafSpy screenshot.


Is it because the BMS or something else is always discharging these cells (57 and 58)? If so, then it might improve during a charge discharge cycle, but will get worse with time.

Or will it improve over a charge discharge cycle and stay that way (aka a "pre-balance" issue)? If so, then it might be fixable by just cycling.

Opening up the pack is something to approach with a lot of caution. Find out as much as you can first. Then make sure you have the correct tools and do things the correct way.
WetEV
#49
Most everything around here is wet during the rainy season. And the rainy season is long.
2012 Leaf SL Red (Totaled)
2014 Leaf SL Red

Dala
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Joined: Sun Oct 28, 2018 11:24 am
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Leaf Number: 316851

Re: Timecapsule 2015, dodgy battery troubleshooting

Fri Nov 02, 2018 12:20 am

The guy I bought it from seemed to somehow think 25km range was acceptable for an EV. He had been using it in this state for a few months. Only with slowcharger, constantly topping it up to 100%. So I doubt it will get better with more cycles.

I have now personally racked up 6 charges, with range staying the same on each run.

There are some things I still wonder;
-When I picked up, he had the supposedly broken cell in a box. (no clue who replaced it)
-What if the replaced cells were preLizard? (or just not replaced at all)

I mostly lean on that the cell was replaced, but someone did a poor job of pre-balancing it. I also googled around, and it seems like hoping for it to balance out over time is a pipedream, taking several months due to the balancing circuits in this pack is just heaters, that barely pass any mA thru them

So I've decided to open the pack up. That way I can visually confirm that the cell is a lizard cell, and also try to bump it up manually. With no warranty I have nothing to loose. One of the reasons I sprung for a leaf is that it seems to be one of the few EVs that you can actually tinker with.

Stay tuned for pictures.

GerryAZ
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Re: Timecapsule 2015, dodgy battery troubleshooting

Fri Nov 02, 2018 6:38 am

Another possibility if charging/discharging is not improving those cell pairs: Something is wrong with the BMS (such as defective A/D converters) causing it to think the cells are low.
Gerry
Silver LEAF 2011 SL rear ended (totaled) by in-attentive driver 1/4/2015 at 50,422 miles
Silver LEAF 2015 SL purchased 2/7/2015

Dala
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Joined: Sun Oct 28, 2018 11:24 am
Delivery Date: 01 Jan 2015
Leaf Number: 316851

Re: Timecapsule 2015, dodgy battery troubleshooting

Fri Nov 02, 2018 6:48 am

Question,
If someone actually installed one pre-lizard battery cell, would that mess up the charging?

I think I've seen some data that pre-lizard charged to 3.9V, and lizard batteries charged to 4.1xV Can anyone confirm this?

powersurge
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Re: Timecapsule 2015, dodgy battery troubleshooting

Fri Nov 02, 2018 7:01 am

Lesson to learn... If a car has unusually low mileage it probably is because it was not drivable. I recently saw a several year old Leaf on ebay with only 100 miles on the clock... I would never touch that...

Also, Cars are sold AS-IS, this is the poster's burden, unfortunately.

Lothsahn
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Re: Timecapsule 2015, dodgy battery troubleshooting

Fri Nov 02, 2018 11:17 am

Dala wrote:Question,
If someone actually installed one pre-lizard battery cell, would that mess up the charging?

I think I've seen some data that pre-lizard charged to 3.9V, and lizard batteries charged to 4.1xV Can anyone confirm this?


The Gen1 (Canary, pre-lizard) cells charged to 4.0V. See here:
https://qnovo.com/inside-the-battery-of-a-nissan-leaf/

The maximum voltage at the pack is 2×4.2×48 = 403V, though it is widely known that the Leaf only uses about 80% of the pack’s capacity (20 kWh out of the 24 kWh to preserve cycle life) making the maximum cell voltage closer to 4.0V

I'm pretty sure that the voltage characteristics remain unchanged for ALL 24kWh battery packs. However, the voltage characteristics DID change for 30 & 40 kWh battery packs:
https://pushevs.com/2018/01/29/2018-nis ... eal-specs/

The maximum voltage remains roughly the same, but the discharge curve changes dramatically. A 30/40 kWh cell charged to 50% SOC will be at 3.6v, where 3.6v is nearly dead on an original 24kWh cell. This is one of the primary reasons you cannot install a higher capacity cells into a 24kWh pack--the old BMS will believe that it is nearly out of capacity when the pack is below 50% SOC.

So I'm pretty sure it should be theoretically possible to mix pre-lizard and lizard cells together in a single pack, but don't do it. This is because there are likely to be subtle differences between the discharge curve that would cause significant BMS shunting and lower range. It'll also become a big issue as the pack ages because the pre-lizard cells will likely age more quickly and thus you'll end up with an unbalanced pack.

Who did the cell replacement? Was it Nissan or a 3rd party? If it was Nissan, I'd take it back to them and tell them it's covered under warranty and should be fixed. The pack has both a 60k mile, 5 year capacity warranty, and an 8 year failure warranty. I would get them to fix the car. if you (or a 3rd party) open it up and start messing with it, they'll rightly claim that it's no longer warrantied. Note: If the battery was stored at zero or near zero SOC for more than 14 days, it may not be warrantied anyway:
https://www.greencarreports.com/news/10 ... p-it-valid
2011 Silver SV, purchased 2018, lives in Missouri (previously in CA)
LeafSpy Pro + BAFX Products OBDII dongle
Battery swap 2019/04/24 (87% SOH, 12 bar)

LeftieBiker
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Re: Timecapsule 2015, dodgy battery troubleshooting

Fri Nov 02, 2018 12:01 pm

Nissan voided the battery warranty when the car was shipped to another continent.
Scarlet Ember 2018 Leaf SL W/ Pro Pilot
2009 Vectrix VX-1 W/18 Leaf modules, & 3 EZIP E-bicycles.
PLEASE don't PM me with Leaf questions. Just post in the topic that seems most appropriate.

Dala
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Joined: Sun Oct 28, 2018 11:24 am
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Re: Timecapsule 2015, dodgy battery troubleshooting

Sat Nov 03, 2018 7:50 am

So I started taking it apart.

Got it into the garage, was a wet day
Image

Disconnected the 12V battery
Image

Found the fuse
Image

Disconnected the fuse, gonna stick to HV gloves each time i'm remotely near orange cabling
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Started propping up the car high
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Removed splash plates
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Found the battery connections and CAN cabling, disconnected them
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Put pressure on battery, started loosening bolts
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Built a dolly to be able to slide the pack around
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Lowered battery onto dolly
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Battery out
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Started to pry the glue apart
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Cover off
Image

Dala
Posts: 67
Joined: Sun Oct 28, 2018 11:24 am
Delivery Date: 01 Jan 2015
Leaf Number: 316851

Re: Timecapsule 2015, dodgy battery troubleshooting

Sun Nov 04, 2018 8:56 am

So yesterday I started the charging process. Decided to take it slow due to not knowing much about the Li-MnO2 cells (I'm more of an 18650 guy)

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 dissassemble the pack, so I improvised some sticky leads with harddrive 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 wont 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, 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!

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