Large electric motors, batteries and vehicles

Funkworks

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Is your battery gauge designed by Apple? Always 100% until dead......
For home batteries, that is typical and often a good thing.

Alkaline-vs-Lithium-AA-battery-Graph.jpg

But all cars have different battery management systems (BMS) to "manage" the shape of the curve. Real-life data for cars is something I'd like to see.
 

FredA

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For home batteries, that is typical and often a good thing.

View attachment 539644

But all cars have different battery management systems (BMS) to "manage" the shape of the curve. Real-life data for cars is something I'd like to see.
But what about that steep drop right at the start?
The green line is down ~9% almost immediately.
Batteries almost NEVER have 100% capacity, nor do you want to charge/discharge them 100% unless you really need to.

BTW - really posted in jest.
 

Funkworks

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But what about that steep drop right at the start?
The green line is down ~9% almost immediately.
Batteries almost NEVER have 100% capacity, nor do you want to charge/discharge them 100% unless you really need to.

BTW - really posted in jest.
On one hand, I think you're joking again and that's fine, but on the other, there's a really interesting scientific/engineering question in there. There's many ways I could answer this and I might later.
 
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FredA

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The "Apple" post was a joke - but with a dose of reality behind it.
Batteries have significant ageing right out of the chute.
Lithium-based cells do flatten out nicely, but not at the capacity printed on the cell unless they over-provisioned to account for the loss.

Also - notice the new Rivian - set points for charging to 80%, 90% or 100% with the later only really recommended when going far off grid. An unvarnished attempt to teach users how to be nice to their battery which I applaud.
 

dhbarr

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The "Apple" post was a joke - but with a dose of reality behind it.
Batteries have significant ageing right out of the chute.
Lithium-based cells do flatten out nicely, but not at the capacity printed on the cell unless they over-provisioned to account for the loss.

Also - notice the new Rivian - set points for charging to 80%, 90% or 100% with the later only really recommended when going far off grid.
No too different from the RPMs and MPH on my truck. Sure I -could- redline it all the time, but that has trip-and-part limiting side effects.
 

Funkworks

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The "Apple" post was a joke - but with a dose of reality behind it.
Batteries have significant ageing right out of the chute.
Lithium-based cells do flatten out nicely, but not at the capacity printed on the cell unless they over-provisioned to account for the loss.

Also - notice the new Rivian - set points for charging to 80%, 90% or 100% with the later only really recommended when going far off grid. An unvarnished attempt to teach users how to be nice to their battery which I applaud.
Yeah so you could call it a matter of printing the right thing. But then, I can't blame those who print the number because they have to go with a number that can be compared to historical cells (alkalines, etc.). What I think people really want is a long flat part. Those making the cell just have to make sure it beats a comparable alkaline cell and I doubt anyone cares very much about the very short initial drop. The 100% point could be at the very very beginning, or at a short time later once the flat curve begins. It's hard to say what they actually do unless you test the cell.
 
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Funkworks

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As for this:
Is your battery gauge designed by Apple? Always 100% until dead......
After more thought, I don't see why I should hold back here:

"Always 100% until dead" is exactly what happens to an ICE.

So I actually don't quite get where's the funny part. 🤔

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A few features of the Rivian R1S.

 

Greg Furtman

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An American company, Shoals Technologies Group has come up with a way to run cabling for EV chargers stations above ground and has received UL Certification for their system. This should greatly reduce the installation cost of a charger.

 

BEC

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An American company, Shoals Technologies Group has come up with a way to run cabling for EV chargers stations above ground and has received UL Certification for their system. This should greatly reduce the installation cost of a charger.

That does look interesting. I hadn’t really thought that just trenching for cables would be such an impediment to putting in charging…but now I can see both how it could be and how this approach could help.
 

jderimig

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An American company, Shoals Technologies Group has come up with a way to run cabling for EV chargers stations above ground and has received UL Certification for their system. This should greatly reduce the installation cost of a charger.

Running electric power above ground is not robust against the coming climate catastrophe.
 

Funkworks

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An American company, Shoals Technologies Group has come up with a way to run cabling for EV chargers stations above ground and has received UL Certification for their system. This should greatly reduce the installation cost of a charger.
I didn't even realize that was missing. I wonder why no one started doing this earlier.

Running electric power above ground is not robust against the coming climate catastrophe.
I wouldn't know what catastrophe you have in mind, but I'd be glad to discuss climate in another thread. That's quite a different topic than batteries and motors.

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Here's another company making grid storage solutions:
 
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jderimig

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I would know what catastrophe you have in mind, but I'd be glad to discuss climate in another thread. That's quite a different topic than batteries and motors.
I was commenting on power lines above ground. They are susceptible to storm damage. It is well accepted that burying power cables results in a much more robust electrical grid and lower cost in the long run.
 

Funkworks

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I found this very entertaining. They all look like so much fun.

 

Funkworks

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"In the second half of 2022, almost a million EVs a month will be added to the global fleet, BNEF said. That’s about one every three seconds. Vehicles eventually get retired from the fleet due to age, wear-and-tear, crashes and battery degradation.

But that’s not a big part of the EV story so far, mostly because the majority of EVs in the global fleet were sold in the past 18 months. By the end of 2022, BNEF is expecting more than 26 million plug-in vehicles on the road."


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A shop specializing in Tesla vehicles, including the 14-year-old, original Roadster:
(14 years is very good news by the way :))

"The Tesla Roadster started the Electric Vehicle rEVolution. And now, 14+ years later, the main batteries may finally be starting to die. The original Tesla main battery design engineers were targeting a 10 year service life, and we are all pleasantly surprised to find the majority of Roadsters still driving and functioning. In today's video, we delve into a trend we are beginning to see in the type of Roadster main battery repairs we've performed for years, a recent uptick in battery packs with accelerated range loss, the result of single cells going resistive. Although repairable, we believe this may be early indications of an end of life failure mode, and a predictor of similar main battery demise in the next generation Teslas, the Model S."

 

Greg Furtman

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⚡ ⚡ ⚡ ⚡ ⚡ ⚡ ⚡ ⚡ ⚡ ⚡

A shop specializing in Tesla vehicles, including the 14-year-old, original Roadster:
(14 years is very good news by the way :))

"The Tesla Roadster started the Electric Vehicle rEVolution. And now, 14+ years later, the main batteries may finally be starting to die. The original Tesla main battery design engineers were targeting a 10 year service life, and we are all pleasantly surprised to find the majority of Roadsters still driving and functioning. In today's video, we delve into a trend we are beginning to see in the type of Roadster main battery repairs we've performed for years, a recent uptick in battery packs with accelerated range loss, the result of single cells going resistive. Although repairable, we believe this may be early indications of an end of life failure mode, and a predictor of similar main battery demise in the next generation Teslas, the Model S."


It's interesting that they have the diagnostic software & tools to find a single bad cell in the 6000+ cells that make up the battery pack.
 

FredA

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It's interesting that they have the diagnostic software & tools to find a single bad cell in the 6000+ cells that make up the battery pack.
Since you need to balance the cells, the system will see a bad one pretty quickly.
This is how the cells fail - they go "resistive" which is a euphemism for they are shorted or nearly so.
Going resistive will surely hurt range and performance, but the next step is swelling which could get exciting.

Cutting out a bad cell and replacement is probably too labor intensive to be worthwhile.
 

boatgeek

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Since you need to balance the cells, the system will see a bad one pretty quickly.
This is how the cells fail - they go "resistive" which is a euphemism for they are shorted or nearly so.
Going resistive will surely hurt range and performance, but the next step is swelling which could get exciting.

Cutting out a bad cell and replacement is probably too labor intensive to be worthwhile.
This is where having a smaller number of larger cells can be helpful. The ship-based system I mentioned a while back has racks of cells. Each rack has 24 individually replaceable cells that total up to around 8.8 kWh. The racks are then ganged together into strings. Looking at how they were built, I'd guess it would be a matter of about a day's work or less to replace a single cell.

IIRC, when Teslas were first introduced, larger LiPo cells were more or less in their infancy, so they had to stack lots and lots of small cells.
 

KC3KNM

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This is where having a smaller number of larger cells can be helpful. The ship-based system I mentioned a while back has racks of cells. Each rack has 24 individually replaceable cells that total up to around 8.8 kWh. The racks are then ganged together into strings. Looking at how they were built, I'd guess it would be a matter of about a day's work or less to replace a single cell.

IIRC, when Teslas were first introduced, larger LiPo cells were more or less in their infancy, so they had to stack lots and lots of small cells.
Yeah, my Golf has 264 cells and I’m able to view each individual cell voltage using VCDS. While it’s nice for maintenance and manufacturing to have a small cell count, I think there’s more to it than just smaller cells available. Having two smaller capacity cells in parallel vs one larger cell of the same type would have reduced power dissipation. Less heat is always better.
 

Funkworks

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Since you need to balance the cells, the system will see a bad one pretty quickly.
This is how the cells fail - they go "resistive" which is a euphemism for they are shorted or nearly so.
Going resistive will surely hurt range and performance, but the next step is swelling which could get exciting.

Cutting out a bad cell and replacement is probably too labor intensive to be worthwhile.

🤔 🤨🧐

I also don't watch every video, but I did watch this one and here's how the expert explains a typical sequence of events:

1. Owner notices a range loss and goes to mechanic.
2. Mechanic finds a cell that has gone resistive (exactly the opposite of "shorted").
3. Mechanic replaces cell.

Whether or not it's worth replacing a cell depends on mileage, model, costs, etc.
 

Greg Furtman

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Yeah, my Golf has 264 cells and I’m able to view each individual cell voltage using VCDS. While it’s nice for maintenance and manufacturing to have a small cell count, I think there’s more to it than just smaller cells available. Having two smaller capacity cells in parallel vs one larger cell of the same type would have reduced power dissipation. Less heat is always better.
VCDS has this ability? Cool. I've owned & used VCDS for years. Bought it after I had a check engine light come on and the nearest VW Dealership wanted almost $100 just to do a quick scan & tell me what the problem is.
 

KC3KNM

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VCDS has this ability? Cool. I've owned & used VCDS for years. Bought it after I had a check engine light come on and the nearest VW Dealership wanted almost $100 just to do a quick scan & tell me what the problem is.
Yup! I’m glad I went with the HEX-V2 tool over a standard OBDII reader. I haven’t had too much time to play with it, but being able to plot the sensor outputs and CAN bus data is really neat. Only bummer is you can only connect to one controller at a time through the ODB port, but it’s still pretty handy being able to see real time current draw vs battery voltage, etc.11DC5DA2-6D96-4AE9-981E-BC63917C6DBD.jpeg 918DE103-2851-4B3F-AA2C-919D188CFAE6.jpeg
 
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FredA

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3. Mechanic replaces cell.
Yep - just three simple words that represent a lot of effort and risk.

Many cars have their cells buried inside water jackets; have welded contacts; and the pack is always hot [at the cell level] and not for the faint-of-heart when it comes to high-power electronics.
 

boatgeek

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Yep - just three simple words that represent a lot of effort and risk.

Many cars have their cells buried inside water jackets; have welded contacts; and the pack is always hot [at the cell level] and not for the faint-of-heart when it comes to high-power electronics.
That's where it really helps to have your cells designed for replacement. As noted above, the big marine battery units do a really nice job of that. I'm pretty sure the Leaf battery packs are a stack of more easily replaced cells. They're air-cooled-only, which makes that easier.
 

Funkworks

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Yep - just three simple words that represent a lot of effort and risk.

Many cars have their cells buried inside water jackets; have welded contacts; and the pack is always hot [at the cell level] and not for the faint-of-heart when it comes to high-power electronics.
High-voltage people have been around for more than a century. If you want to know more about how cells are packed, here again are some of the links I posted:






Here's a nice one:


And a very short video:

 
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KC3KNM

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That's where it really helps to have your cells designed for replacement. As noted above, the big marine battery units do a really nice job of that. I'm pretty sure the Leaf battery packs are a stack of more easily replaced cells. They're air-cooled-only, which makes that easier.
The older Leafs had cell modules that were 2s2p. It’s easier to just swap a module. I haven’t heard of many people tearing a pack down to swap a cell within a module, but I do know there’s plenty of companies looking for failed modules that will swap bad cells and resell the module for use.
 

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