Battery Upgrades are very possible

[Lothsahn]

Added pictures of the covers here: https://photos.app.goo.gl/tcVLm3SHCtozeLSa6

Wow, really impressed with the work you did! That's top notch stuff. When we first talked, my thought was "I'm not sure he knows what he's getting himself into", but you clearly did and are.

Congrats on your 200+ mile car. Looks awesome!

What did you use to modify the CAN messages?

 

[Daklein]

Added pictures of the covers here: https://photos.app.goo.gl/tcVLm3SHCtozeLSa6

Wow, really impressed with the work you did! That's top notch stuff. When we first talked, my thought was "I'm not sure he knows what he's getting himself into", but you clearly did and are.

Congrats on your 200+ mile car. Looks awesome!

What did you use to modify the CAN messages?

Well, I tend to get into things and then figure out the rest of it eventually.

mux's Muxsan CAN bridge makes it work! I had another old CAN interface and s/w that I used initially to get my old battery's data so the bridge would have the correct data programmed on it. In the future, there will be a way to use the bridge (before removing the original battery) to read and record the data (and spit it out if needed for reference). The USB port will allow input of some configuration commands to make it happen.

I just came back from a drive where I tested down to the bottom SOC, near end of range. The GOM, low battery light/message, and the very low (flatline GOM) all work appropriately still.

 

[knightmb]

I just came back from a drive where I tested down to the bottom SOC, near end of range. The GOM, low battery light/message, and the very low (flatline GOM) all work appropriately still.

With your experience, can you override those flat bars to continue battery & range estimates. I always thought Nissan did this to avoid lawsuits where someone was trying to drive the last bit miles but only got 2 miles when the GOM said 3, :lol:

 

[Daklein]

can you override those flat bars to continue battery & range estimates. I always thought Nissan did this to avoid lawsuits where someone was trying to drive the last bit miles but only got 2 miles when the GOM said 3, :lol:

Other vehicle manufacturers do the same idea, switch over to 'hey, you better stop as soon as you can, unless you're Kramer on a test drive.' https://www.youtube.com/watch?v=TuEdU_lrtZk

I guess anything is possible. It might take getting into the dash display controller though, to still show a number instead of dashes. I suspect it does a certain thing to the display (blinking for the LBW & turning on the yellow light, or dashes at VLBW), as a function of the remaining energy. Those energy thresholds might be set and fixed in the VCM or the dash display. The miles estimate value is from that remaining energy * recent miles/kwhr consumption.

The segments of the SOC display can be changed directly. So, what if those were used to show, theoretically, what portion of the remaining energy is left since the VLBW triggered. It would still be showing blinking dashes, so it's clear you'd better stop. But it could immediately pop back up to full SOC, then drop those soc segment bars as you consume the remaining energy. It might require having a CAN bridge just for the dash display, to not goof up other things.

Neat feature idea, let's keep thinking. But I think I would skip it for now. I mean, we can look on Leaf Spy instead. And watch that there are no individual cell voltages going too low. Having LeafSpy working of course..

 

[Oils4AsphaultOnly]

I just came back from a drive where I tested down to the bottom SOC, near end of range. The GOM, low battery light/message, and the very low (flatline GOM) all work appropriately still.

With your experience, can you override those flat bars to continue battery & range estimates. I always thought Nissan did this to avoid lawsuits where someone was trying to drive the last bit miles but only got 2 miles when the GOM said 3, :lol:

The last bit of energy isn't like gas and is completely dependent on the power drawn. If you can coast at 5mph (drawing less than 1 kw) versus 30mph (drawing 20kw), you will be able to draw more energy from the chemical state of the batteries. So the flat bars display is accurate, because how much is left is completely dependent on how much current your motor is drawing and NOT on how much energy is in the cells.

 

[mux]

That, and the imbalance tends to be quite chaotic at low SOC, so it is very hard for the BMS to accurately estimate the remaining energy anyway. Even for relatively healthy battery packs this is an issue.

VLBW is actually quite 'low' in EV terms, they tried their best to allow the user to extract as much energy from the battery as possible. Same goes for turtle/cutoff - they were quite generous in letting the user go below 300V on an LMO pack. Those last 2 kWh are really unreliable and the pack has a really high internal resistance at that point, making extracting that energy that much more difficult.

They upped VLBW to 4kWh on the 40kWh packs, but that is really also still too low, as the IR skyrockets below ~25% SOC. I've got an upcoming article about that by the way, a customer of ours experienced the car shutting down unexpectedly at about 25% SOC because of what we believe to be a gross design mistake (although rare and hard to trigger) in the Leaf's BMS.

 

[knightmb]

I've suspected that too, I always wanted turtle mode to trigger when the battery charge hits the flatlines (5% or less) since even in turtle mode you can still drive a safe traffic speed. I've driven miles in turtle before when I had LeafSpy to help.

 

[mux]

With a completely healthy, as-new battery, 5 GIDs (one of the turtle modes) gets hit at like 3.2V/cell, yet the battery will happily discharge all the way to 2.75V/cell before the car will actually stop. Yeah, that can be a few miles. But as the car ages, the imbalance will often already stop the car at or barely beyond turtle mode kicks in.

By the way, what we call turtle mode isn't one thing, it is just the symbol the car displays when something isn't right. This can be low state of charge but also various DTCs. I feel like I've encountered them all by now, and it's a lot of different triggers. So for that reason too, never rely on turtle mode being 'just' low SoC. It may be something more serious.

(one thing in particular that a customer had was the insulation resistance changing drastically from empty to full - causing turtle mode near empty, but still above LBW)

 

[knightmb]

By the way, what we call turtle mode isn't one thing, it is just the symbol the car displays when something isn't right. This can be low state of charge but also various DTCs. I feel like I've encountered them all by now, and it's a lot of different triggers. So for that reason too, never rely on turtle mode being 'just' low SoC. It may be something more serious.

Interesting, so something not even related to the battery SOC can trigger this. I suspected that after reading some other topics here where really cold temperatures trigger turtle mode on high SOC. Does the Leaf not have something like the generic "check engine" light that the ICE vehicles use? Thanks for all info Mux, your experience and wisdom sharing is greatly appreciated.

 

[Dala]

Does the Leaf not have something like the generic "check engine" light that the ICE vehicles use?

Yes it has, that's the "Check EV system" light

 

[DougWantsALeaf]

Maybe Nissan should get out of the battery business and just open source the platform for 3rd party. It can then focus on the rest of the car. It’s kind of happening already.
Just sell that as a feature. Use it as a way for the dealers to sell some upgrades.

 

[webeleafowners]

Maybe Nissan should get out of the battery business and just open source the platform for 3rd party. It can then focus on the rest of the car. It’s kind of happening already.
Just sell that as a feature. Use it as a way for the dealers to sell some upgrades.

I thought they sold off their battery division. Did that fall thru?

 

[knightmb]

Yes it has, that's the "Check EV system" light

You are right, I've been lucky to not encountered it. So it's like having a "check engine 1" and "check engine 2" on an ICE, yeah that wouldn't be confusing. :lol:

 

[mux]

Maybe Nissan should get out of the battery business and just open source the platform for 3rd party. It can then focus on the rest of the car. It’s kind of happening already.
Just sell that as a feature. Use it as a way for the dealers to sell some upgrades.

They tried to sell off AESC, nobody wanted to buy it. They've set it up specifically to deal with the dearth of battery manufacture at the time, which was a really good move, but they made some critical mistakes in both the battery chemistry and assembly, decisions which you can't really overturn easily once you optimize a factory for throughput. And now everybody knows they produce **** batteries, so nobody is going to buy that factory, especially as it's becoming ever more profitable to just start your own gigafactory.

So they're stuck with essentially a stranded asset.

That being said, they could have fixed a LOT of issues by just making their Leaf batteries like the e-NV200 batteries. Those batteries have the minimum of thermal management and last literally 5x longer than Leaf batteries. We've recently serviced an e-NV200 EVALIA taxi that had around 1300 QC sessions (and just 1000ish slow charge sessions), something like 120.000km and the battery was still at 90%. Same exact chemistry, same cells even, just different module layout and a heat exchanger in the pack.

 

[Oilpan4]

Maybe Nissan should get out of the battery business and just open source the platform for 3rd party. It can then focus on the rest of the car. It’s kind of happening already.
Just sell that as a feature. Use it as a way for the dealers to sell some upgrades.

They tried to sell off AESC, nobody wanted to buy it. They've set it up specifically to deal with the dearth of battery manufacture at the time, which was a really good move, but they made some critical mistakes in both the battery chemistry and assembly, decisions which you can't really overturn easily once you optimize a factory for throughput. And now everybody knows they produce **** batteries, so nobody is going to buy that factory, especially as it's becoming ever more profitable to just start your own gigafactory.

So they're stuck with essentially a stranded asset.

That being said, they could have fixed a LOT of issues by just making their Leaf batteries like the e-NV200 batteries. Those batteries have the minimum of thermal management and last literally 5x longer than Leaf batteries. We've recently serviced an e-NV200 EVALIA taxi that had around 1300 QC sessions (and just 1000ish slow charge sessions), something like 120.000km and the battery was still at 90%. Same exact chemistry, same cells even, just different module layout and a heat exchanger in the pack.

Can you tell us a little more about this factory heat exchanger if you have had the pleasure of taking one apart?
We don't have many nv-200 in the US.

 

[mux]

I just found out I don't have the right service manual, actually. This is page EVB-221 from the e-NV200 service manual and shows the internals of the e-NV200 battery. Pointed out in the figure is a cover that around here is used for a coolant in/outlet. In that void space behind the cover, there's a big radiator type arrangement with a fan. The radiator is connected to the air con/heater loop and can be activated during charging and driving. Its control is a bit dumb, but even then it does an amazing job at keeping temperatures throughout the pack even, lack of which is the biggest cause of accelerated degradation in Leaf batteries.

 

[Oilpan4]

Very cool, thank you.
I was just going to use a bilge blower to suck ambient air through a filter force it into the battery, then use another bilge blower to help suck the air out. My slightly better than nothing solution.
Then add 300w worth of 120v stick on warmers and about 100w worth of 12v stick on to the under side of the pack then coat it with spray foam.

Someone might want to show fenix that nv200 pack :lol:

 

[mux]

I would HIGHLY DISCOURAGE blowing ambient air into the pack. Condensation will cause massive issues over time.

These battery packs are purged with super-dry air, often even just nitrogen/co2/argon to make sure that if temperatures drop, no moisture will condense inside the pack in inconvenient locations. This is an issue any time the battery comes close to the dew point, which can be any temperature under roughly 17C, depending on how much moisture is in the air inside the battery pack.

Once condensation forms, you can get rust on the compression frames, cause shorts or low resistance paths on contacts, etc. It's a major cause of battery fires in early EVs (although much less prevalent recently).

And you don't need to either. It's already a big help if you just mount a (fairly strong, it has to move air through tiny spaces) fan inside the battery enclosure, then reseal it and flush it with nitrogen or co2 and a bunch of silica gel packets. Circulating air inside the pack will even out temperature differences, which will even out the internal resistance of different cells and alleviate a lot of weak cell behavior.

We've been thinking about how to do a 'proper' thermal management system for the battery. Considering the battery already has heaters in most areas where the Leaf is sold, that part is easy. Cooling it is harder. It's probably inevitable that you would need to cut a large hole into the battery enclosure and weld/glue/bolt on a big extension piece that houses a heat exchanger and fan to cool the battery. Then add a separate controller for the heater pads inside the battery that doesn't suck balls. Not an easy mod to do, but the only way to do it properly.

 

[Andrey]

...Pointed out in the figure is a cover that around here is used for a coolant in/outlet. In that void space behind the cover, there's a big radiator type arrangement with a fan. The radiator is connected to the air con/heater loop and can be activated during charging and driving.

And this heat can be used at cold times to warm up air in the car, not using battery for that!

 

[nlspace]

And this heat can be used at cold times to warm up air in the car, not using battery for that!

Sounds like BS to me, where did you come up with this idea?

Where would the heat come from--a stack of cold cells sitting all night?