For the trolls

Doesn't matter if you clicked the link I sent. Given that you embedded the same video (with your suggestion that other people "will learn something or maybe not"!), it's fair to presume you've watched the video you chose to embed.

Whether to have a single BMS unit or a distributed one is a simple choice in the packaging design.

It's not the number of sense wires that dictates your choice of a single or distributed BMS. It's the other way around: the choice determines how many wires you need.

Toyota likes a single BMS, and Toyota understands what that choice means: when they are building an NiMH battery, they can get away with one sense wire for every twelfth cell, and when they're not, they need per-individual-cell sense wires. That's why their non-NiMH BMS needs so many more sense wires.

Had they wanted their non-NiMH version not to have so many wires all running to a single BMS, they could have gone distributed, and moved some of the BMS functionality into each module. One way or another, the BMS needs to respond to every single cell's condition, and it doesn't matter which way they do it. What matters is Toyota knows they need to do it, and they do it.

Nexcell's lithium pack chose a module packaging of ten Li cells (5s2p) per module and fourteen modules. That would be ok if there were also five sense wires coming out of each module and there was a replacement BMS with 70 sense inputs to go in place of Toyota's NiMH one.

If that seemed like too many wires, there was the alternative of moving some BMS functionality into each module to use fewer wires. One way or another, the BMS needs to respond to every single cell's condition, and it doesn't matter which way that's done. What matters is needing to do it and not doing it.

The V3 (non-GT) seems to be two big modules of 35 cells each. 35 sense wires out of each module would do the trick, again replacing Toyota's NiMH BMS with a 70-input sodium one. Or, again, five sense wires out of each V3 GT module (if those are 5s, I haven't seen one's insides).

Or, again as an alternative, move some of the BMS logic into each module to avoid all those wires out. The choice of how to do it doesn't matter. What matters is needing to do it and not doing it.

 

What ChapmanF describes in post number 22 on this thread really is key.

And he summed it up quite well.

As far as Azusa Price's idea about coming up with a pack that works better...

I don't imagine anyone is going to come up with their own cells for a replacement.

It's more likely it would use some sort of off the shelf automotive cell.

Once the cell has been chosen then if required by the chemistry, some sort of hardware software battery management system would also need to be created.

(This is the part ChapmanF and others have noted)

For the Honda Insight world there is a n aftermarket drop in lithium replacement packs that use OEM Honda modules repurposed from other vehicle's modules.

In conjunction with those modules is a separate hardware / software packages that does the battery monitoring and management.

The battery monitoring and management package is open source. And likely could be adapted in some way to be used for the prius.

Heck, nextcell battery designers could take a look at that and use it to add the additional battery monitoring and management function to any or all of their products.

 

So, whom shall we learn from here? Toyota, for having designed and built cars, and knowing when a battery chemistry calls for per-cell monitoring, and doing it?

Or Azusa, for having "worked on the Prius system for 10 years and knowing its limits and needs."? (And for so adroitly changing the subject once shown that Toyota knows to do per-cell monitoring with framedrops from the exact video he pretends to school others with?)

 

Is it legal to completely change the batteries without going through government safety approvals? Maybe even crash testing? Not sure. If it doesn’t meet standards it shouldn’t get a license plate.

 

Take a look at the 14:04 mark of the video that you linked. He explains that each 3.6 volt lithium-ion cell has a voltage sensing wire connected to it. Why do you think that Toyota did this for the litium-ion chemistry (Gen 4 Prius) and Toyota only used one sensing wire for every 12 cells for the NiMH chemistry (Gen 2 and Gen 3 Prius)? The answer is that it is needed to safely control the battery (keep the cells balanced to each other).

Why were there problems with the V1 and V2 LiFePo4 batteries that Jack sold? It was not the chemistry of the battery, it was that each cell did not have a sensing wire to keep all the cells in the pack balanced to each other. Jack was trying to use the Toyota one sensing wire for every 12 cells, which did not work out too well because the cells became unbalanced with each other over time

Jack is doing the same thing for the V3 sodium-ion battery. He is using the same Toyota supplied one sensing wire for every 12 cells. The results will be the same as the V1 and V2 batteries. The cells will become unbalanced with each other, and then you will have battery failures. Again, it is not sodium-ion chemistry of the battery that is the problem, it is that each cell does not have a sensing wire.

The key point is that you need to keep all the cells in the battery pack balance to each other no matter what the chemistry of the battery.

It is like Jack is putting his head in the sand and does not want to face the fact that every cell needs to have a sensing wire for the LiFePo4 and sodium-ion chemistries. I think that the V3 will be the death of NexPower Engery. It may take a few years to get to that point, but I predict that it will happen. It is a real same, because I was rooting for Jack to succeed.

 

Before you get called needlessly on a quibble, Jack did include a rudimentary balancing circuit in each of those modules. The 5s2p cell pairs are wired to a small board inside the module capable of (slowly) bringing overcharged cells back within range (though it hasn't got any way of comparing those cells' voltages to cells in other modules).

What he didn't do was bring individual cell voltages out to a BMS interfaced with the car, so the car could change its behavior if there's a cell in trouble. There's just one wire per module, being monitored by the car's original firmware tuned for NiMH, and so the car has no way to know it should back off or signal an error unless the overall voltage of a whole 5s2p cell group happened to look like twelve NiMH cells in trouble.

He could have tried to find a way to get adequate information to the car, by putting a separate stud on each module for the sense wire, and driving that stud from an internal circuit, so that if any internal cell was in trouble, an 'out of range for 12 NiMH cells' reading would be put on the sense wire. Kludgey, but at least the car would know there was an issue. (If I remember right, mudder suggested an idea like that at some point.)

But instead of doing something like that to give the car's BMS more-usable information, the V2.5 business with the signal soother went the opposite way: with that, instead of even seeing the voltage from a single 5s2p group of cells, the car's BMS would be shown the average of that group and the next group over—thus making the car strictly less able to recognize and head off battery trouble.

The sodium batteries have at least dropped that idea, but are still stuck with the car having no sense data for individual cells.

 

I think one big sticking point we have is differing paradigms as to whether or not per cell monitoring is needed for the chemistries being implemented in the Nexcell products.

Mudder has the world view that per cell monitoring is needed.

Nexcell has the world view that per cell monitoring is not needed.

I am definitely not a battery expert so can't definitely say which view is correct.

Mudder is trying to objectively show that there isn't enough monitoring in the Nexcell products.

Nexcell is staying that there is enough monitoring in the Nexcell products.

Is one side 100% right, while the other side is 100% wrong?

Or is there some truth in each viewpoint?

I guess I feel that I don't know for sure.

 

@2k1Toaster tried to point out this would cause problems when Project Lithium first came out on the forum. He was ripped up and down by the same culprits. History and hindsight sure make it look like he knew what he was talking about. History repeating itself? I personally would say there's been so much hidden stuff going on, trust level is in the sewer. It's shame such knowledgeable people decide to wrap it up due to being overwhelmed by ridiculousness.

 

Given the above previous statements, I feel the following statement is on topic and relevant to the discussion:
Today I received a Cease and Desist Notice alleging business defamation.
Here are the three claims Jack asserts are defamation:
1: "At minutes 10:34-11:30, you claimed that the cells are moving around and even touching each other," and;
2: "At minute 28:26, you claim NexPower's product is unsafe due to a lack of supervisory control," and;
3: "At minutes 31:34-32:28, you mention there is not enough space and air can't get through the blade."

Further, the C&D suggests that I somehow unlawfully obtained the V3 prototype I reviewed, and 'respectfully' asks that I immediately ship the prototype back to NexPower.

The C&D ends with the following demands:
5: "Refrain from making future false statements about NexPower...", and;
6: "Remove all YouTube videos making reference to the same".

In response to this letter:
7: I have removed all NexPower content from my YouTube channel wherein I knowingly made false statements. Specifically, I have removed zero videos.
8: I will continue testing the V3 prototype unit, and then when I am satisfied with my results I will return it to its rightful owner. I would advise Jack's legal team to better research the "state and federal trade secret laws" they allege I am violating.
9: I intend to post a YouTube video wherein I discuss my findings.

 

Apparently, via a cease and desist.

Yes, this is legal if you meet the criteria laid out in 40 CFR 85.502.
In short, crash testing isn't required if the replacement alternative energy device doesn't appreciably alter the vehicle's OEM weight or handling, etc. Also, alternative energy modifications are exempt from the EPA's emissions defeat device laws that would normally apply when modifying an OEM emissions component.

 

Given the video in post 1 gives us a view of NexPower Jack’s personality, perhaps a video of John Sullivan (mudder) being interviewed about his products would give us perspective.

The link below has Sullivan discussing his Honda hybrid battery upgrades (up to 80mpg) and his Honda conversion kits to create plug-in hybrids.

While this video has no direct application to Prius battery upgrades, it does demonstrate John Sullivan’s humble and confident personality along with input from a satisfied customer.

I sense integrity and professional skills in John which makes him a person I would trust to provide expert consultations of a product demanding safety and reliability.

 

Only courts and government agencies can issue binding C&D "orders".

A C&D "letter," from a private entity, does not prohibit anything, so claiming a "violation" of it is a bit pretentious.

 

But it isn't a legal action in itself.

Maybe because, it has no legal standing? At this point, it is just a negotiating tactic.

"A cease and desist letter can be an inexpensive and efficient alternative to costly litigation."
Cease and Desist Letter: Definition, What It Does, and Examples

 

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