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My apologies for the belated reply, I've been busy this past week!

I just read Marios post and realized that he basically found every thing that I have (and more) at least I know I'm not out in left field with what I have so far.
The only thing I'm confused about is that he mentions the batery voltage being 8 bit (FF) but I am seeing the voltage for a single cell move 12 bits (FFF) am I doing something wrong?
As an example with a tap voltage of 2.318v I see a hex value of 619 and with 2.411v I see 6AF.
I don't think I said that, did I? The battery voltages are 12 bits each, spread over 3 CAN frames, so you get all 12 cell voltages. You take the 12-bit value and multiply it by 1.5 and that's your voltage in mV. Be sure to check this link, it explains the CAN frame format well and tells you how to distinguish and order the three packets that hold all the cell data. https://www.endless-sphere.com/forums/viewtopic.php?f=7&t=90621#p1473988

The taps did not move around (change position) in the data stream as voltage changed so my research shows they are fixed which makes sense.

Your result in this area don't correlate with mine, perhaps your cells are just in voltage order naturally?
Yes, the cell voltages are transmitted in the same order every time, would be a bit silly if they changed around. :) If you look at my diagrams you'll see my cell numbering, cell 1 is always transmitted first and 12 is last.

Mario.

I'm confused by this. Is it reversed ;)

Looking at the logic data Serial_TX, it's full of info and quite long messages, and would seem to be encoded cell voltages, and other stuff, but you say it is going in the other direction from the CAN to the BMS chip?
Or am I misreading what you have put?

Ditto Serial_RX that is a short message, and because we aren't putting anything (commands) into the CAN end is basically zeros that are being sent over the isolation to the BMS chip.. We aren't telling it to do anything, but you say it's going the other way BMS > to > CAN?
As there isn't anything in these messages it can't possibly generate the cell voltages on the CAN side from these.
Edit: Ah, my mistake, I did reverse the TX and RX in my description. In the analyzer data, the line labeled SERIAL_TX is from the BMS side to the CAN side, and SERIAL_RX is from the CAN side to the BMS side.

I've re-attached the logic analyzer capture so everybody can take a look at it if you want. You need to change the extension from .txt to .logicdata. You'll need Saleae's Logic program to open it (https://www.saleae.com/downloads/). This has the serial communication going both ways as well as the CAN messages.

Here's how the can/serial communication works, as far as I can tell.
There's two isolated halves on the board, one that handles CAN communication ( the "CAN side"), and one that does all the battery management (the "BMS side"). They communicate via serial over an optoisolator. In my logic analyzer capture, SERIAL_TX is from the CAN side to the BMS side, and the SERIAL_RX pin is from the BMS side to the CAN side. The serial is 625,000bps with odd parity.
It looks like when the board boots, the CAN side sends a short message to the BMS side. The BMS side responds with a lot of data, and the CAN side sends out a CAN message based on that data. As soon as it finishes sending the CAN message, it asks the BMS side for data again and the cycle repeats.
As you noted, the CAN side sends packets that start with 0x80, 0x81, 0x82, and 0x83 (then repeats). The BMS side responds with the same beginning byte.
Since the cell voltages are transmitted in groups of three CAN frames, I figured the different serial packets would be for the different cells. This doesn't make a lot of sense though, since there's an exchange of serial packets for every CAN packet sent out, but there are four of these serial packet IDs and only three CAN frames for complete cell data, so they get "out of sync". So it's not like 0x80 corresponds to the first 4 cells, 0x81 the next 4, etc since it keeps changing.
It might just be some sort of "heartbeat" to make sure both halves are functioning properly and there aren't duplicate serial messages or something. Perhaps the serial packets are also grouped in threes and the first byte doesn't correspond to which cells' voltage is being sent.
I haven't yet figured out how the serial data corresponds to the CAN data.

I assume the small serial packet that the CAN side sends to the BMS side commands the BMS side to balance the cells or not, as you noted. We could send custom serial packets and see what happens. However, this still won't tell us the magic message to send over CAN to enable cell balancing, so it's probably not useful. The best way would be to observe the cells in a real car, but of course that's a bit hard if nobody has one.

This is an interesting list of available BMS chips.
If we can identify which one the LTO is based on we might get some more clues about the comms protocols from a data sheet.
Have a look see if we can spot anything..

These boards don't use any sort of specialized BMS chip, both the CAN side and BMS side use the same microcontroller. You can read the numbers off the top-side one, it's the R5F2136. Oddly enough, it doesn't seem to have a CAN peripheral.
The BMS side incorporates a multi-channel differential ADC to read all the cell voltages, as well as a whole lot of MOSFETs/transistors presumably for balancing. If you look at my pictures of the underside you can count 12 groups of everything.

The lower id board seems to take priority in the stream.
Yes, that's how CAN arbitration works. The ID is both an identifier so you know what data is being sent or what device it's coming from, as well as determining which device gets to continue transmitting if they both start to transmit at the same time. The first device to transmit a recessive (1) bit loses the arbitration, so lower-value IDs have higher priority.

The BMS board is connected to some sort of car harness by a short multiwire pigtail. Though only 6 conductors are used by the board, an additional 2 wires are hooked to a temp sensor on some packs and these 2 wires are wired to pins in the car harness end. Though off subject a bit for the current discussion, the sensors might figure somehow into some future thermal plan.

Unfortunately, my limited sample indicates the temperature sensors are on only about 1 in 6 to 1 in10.
Interesting, when I was looking at the CAN data I was trying to decipher if it included any sort of temperature data, but I eventually concluded it didn't have any, which was very surprising to me. It's super important to be able to monitor the temperature of the batteries in a pack like this, so I was shocked there wasn't any sort of module-level temperature, even just like a temperature sensor on each BMS board. Interesting to know that there are indeed temperature sensors, they're just not included in the modules themselves.


Also, for everybody following along, be sure you don't miss the info that Ian quoted from me in a PM (it's hidden behind a "click to expand" to I wanted to make sure people didn't miss it):
 

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Sorry about that Mario I think that this line is what confused me, I was skimming and I think I saw bit instead of byte.

The CAN ID always stays the same, and the voltage info is sent in sets of three CAN frames, 8 bytes each.
I also found out that my setup doesn't always start on the first frame or ID, my code must be screwed up I need to look at that if i'm going to be any help at all.


Yes, that's how CAN arbitration works. The ID is both an identifier so you know what data is being sent or what device it's coming from, as well as determining which device gets to continue transmitting if they both start to transmit at the same time. The first device to transmit a recessive (1) bit loses the arbitration, so lower-value IDs have higher priority.
Thanks for the info , I'm a newbie with can data.
 

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So doing some googling it looks like the mcu's are from Renesas, this link appears to be the one on the top of the board.


and this one on the bottom

 

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So doing some googling it looks like the mcu's are from Renesas, this link appears to be the one on the top of the board.


and this one on the bottom

Oh, they are different? My mistake! I guess I didn't look closely enough, I thought the part numbers were the same. Makes sense, the one you say is the top one does have a CAN peripheral, whereas the bottom one (the BMS one) doesn't.
 

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Honda would be seen as "socially responsible", "environmentally responsible", participating in "a green initiative", etc. etc. were Honda engineering to divulge the CAN information needed to balance these LTO cells. Thus allowing for the proper repurposing / recycling of these batteries.

If someone (me?) were to approach Honda marketing from the right angle, I wonder if this information could be obtained with much luck and persistence. It really is the right thing for them to do. I'm probably being idealistic. I recall reading that a few people on the forum have made successful contact with Honda representatives in the past - regarding what, I do not remember.
 

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Honda would be seen as "socially responsible", "environmentally responsible", participating in "a green initiative", etc. etc. were Honda engineering to divulge the CAN information needed to balance these LTO cells. Thus allowing for the proper repurposing / recycling of these batteries.

If someone (me?) were to approach Honda marketing from the right angle, I wonder if this information could be obtained with much luck and persistence. It really is the right thing for them to do. I'm probably being idealistic. I recall reading that a few people on the forum have made successful contact with Honda representatives in the past - regarding what, I do not remember.
I'm not going to discourage you from trying if you want to, but I highly, HIGHLY doubt you'll get anything at all from Honda. Companies don't divulge that sort of information.


I've actually been thinking about picking up a Honda Fit Hybrid with these batteries so I could sniff the CAN communication and see if we can figure out how to use these modules. Using these modules greatly simplifies replacement pack design since they do the balancing and have actual good battery management!
I think LTO is the way to go for homemade (read: non-professional) Insight battery conversions because it's a much, much less volatile chemistry and doesn't catch fire or explode when crushed, punctured, or overcharged.
It can also take far more charge-discharge cycles than li-ion without losing capacity. I want a replacement pack that lasts me the next 10 years.
Personally, I'd prefer not to run a li-ion pack in my car using a battery management system developed by hobbyists... not to put down anybody's engineering capabilities here. But there's not nearly as much rigor, testing, verification, oversight, etc. as a large company would have.

Does anybody know exactly what year/model car(s) use these batteries? I want to see if I can find a cheap trashed-but-working one.
 

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Does anybody know exactly what year/model car(s) use these batteries? I want to see if I can find a cheap trashed-but-working one.
as far as I know

Honda Fit BEV
Global total of 1,100 vehicles made.
Of which 1,040 were leased (not sold) in the U.S.

Deliveries began July 2012 .. completed manufacture of the 1100th vehicle and ended production July 2014.
~20kwh (~432 cells) per vehicle

I don't know how many of those leases are still out in the wild.
The Fit BEV forum is still active .. I don't know if any of those still with one , would be open to having someone scope things in the car .. Although not confirmed I suspect the youngest lease is already about ~4 years old.


Every 1 Fit BEV could yield between 5 to 7 Insight Conversions.
60 to 84 cells used per Insight Li Conversion.
 

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Originally the Fit electric was available only on lease, or that is my information. They called them back and refused to extend the leases or sell the cars, iirc.

HOWEVER, Carguru.com returns one hit in Corona, CA at an unlisted price. It is supposedly at Corona Honda,
(562) 501-4766. Corona, iirc, is a suburb of San Diago.

I'm doing more research. Just looked at the carguru pictures. The car appears to be in beautiful condition.

I'm clearly confused. Maybe Honda allowed for lease conversion in CA. They did not in MD.

I saw in passing that was some reference to 5 yr. leases, so that would put some into 2019. If you could find a friendly owner, maybe through their forum, you could do some probing ;)
 

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Deliveries began July 2012 .. completed manufacture of the 1100th vehicle and ended production July 2014.
~20kwh (~432 cells) per vehicle

I don't know how many of those leases are still out in the wild.
The Fit BEV forum is still active .. I don't know if any of those still with one , would be open to having someone scope things in the car .. Although not confirmed I suspect the youngest lease is already about ~4 years old.
I did some reading on the Fit forum. I found one ref to having a 6 year lease, so there may still be some left in the wild, IF these production dates are correct.

Also, this is an interesting link, though the writer's conclusion may be in error.

 

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Leased only, and only 1100 made? That doesn't give me a lot of confidence about getting my hands on one.
My second concern is then that there won't be a good supply of these modules to use in Insight conversions.

How do second-hand places get the modules to sell? (like this: https://greentecauto.com/hybrid-battery/repurposed-batteries/honda-fit/20ah-lto-titanate-li-ion-scib)
Are these taken out of those Fits or are there other cars that use them?

Edit: Apparently Honda is set to release a new version of this car in 2020, so perhaps those could become a good source of likely similar modules.
 

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from the Honda Fit EV forum: Rensselaer Polytechnic Institute in Troy, NY. They have two of them and they are being used in the new "Safe Ride" program.

Does anyone live nearby who has interest, knowledge of CAN bus and resources to help with 'testing' the BMS capability?
 

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How do second-hand places get the modules to sell? (like this: https://greentecauto.com/hybrid-battery/repurposed-batteries/honda-fit/20ah-lto-titanate-li-ion-scib)
Are these taken out of those Fits or are there other cars that use them?
As far as I know ... AFAIK

Only others are listed here:

Most consumers and OEMs seem to feel as though :
Other batteries with fewer cycle/years are still good enough
Other batteries with slower charge rates are still good enough
Other batteries that are less safe are still safe enough
And by giving up all those above, those other batteries get them higher wh/kg energy density.

I think it has the battery chemistry has the potential to fit very well into stationary applications like solar, and grid back up systems .. but that is a long way off .. and even if it did .. those don't tend to come available 2nd hand like HEV/PHEV/BEV car batteries do.

Existence of the used cells for sale .. AFAIK ... It's an artifact of chain of different companies in the recycle/disposal path .. Honda gives up ownership when it goes to that recycle/disposal company path .. because Honda does not itself own and opperate their own recycle / disposal facilties .. and sometimes someone is in the right place at the right time .. with a large amount of cash in hand .. buys a whole pallet or trailer load off the recyceler .. the recycler gets more $ than the Li and such inside the batteries are worth , so it's good for them .. and the one buying it takes on the risk as he has to pay up front , and just hope he might later be able to sell them for enough profit to be worth it .. just guessing , but given the numerous pallets worth GreenTec has posted / sold / etc , I'd not be at all surprised if they bought up around 50-100 cars worth in their original bulk buy from recycler.
 

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Either Greentecauto was the recycler or they purchased the packs from who ever had the recycling contract. IMO

Greentec suffered some political pushpack when they advertised the original application in some of their early eBay sales. There was a rush to remove certain labels, etc.

It is interesting that the Mazda 3 "mild" hybrid is using some variation of the SCiB packs. That might be another source, since those cars aren't held closely by the manufacturer ifaik. Near as I can tell, it isn't available in U.S. yet, but is available in Europe. Wrecks might be a source of some worthwhile LTO batteries on the other side of the pond. Loaner cars might serve as "intelligence" sources on their BMS.

"Mild" might mean availability in used market of the 2.9Ahr cells, but that is speculative of course. Those cells are physically smaller and might make a great roughly equivalent replacement for the NiMH Insight packs. I haven't been able to find confirmation of battery capacity.
 

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"Mild" might mean availability in used market of the 2.9Ahr cells, but that is speculative of course. Those cells are physically smaller and might make a great roughly equivalent replacement for the NiMH Insight packs. I haven't been able to find confirmation of battery capacity.
"confirmation of battery capacity" for the Mazda 3 'mild' hybrid, right?... Possible they use the 2.9Ah cells... But, one thing to keep in mind, particularly in the context of this thread topic, is that buying the Fit modules already built saves a lot of work. What's more, if you get the BMS and 'we' figure out how to make it do some things, then that's another major bonus.

I bought a bunch of the 2.9Ah cells, unused, thinking I'd make a go of it. To make a long story short, I bought ones that were pre-tapped and the taps suck, almost unworkable. I've just now cobbled together a 12V battery out of the worst ones and I'm testing that, trying to figure out if/how to make it work. I also got a batch of untapped ones. But either way - sucky tapped terminals or untapped terminals needing some kind of connections - both options pose big difficulties in getting a pack together. For instance, the smallness of the 2.9Ah cells leaves little real estate for the terminals - they're just big enough to make the right connection for high power -- IF you have nearly perfect connections. That's a lot of connections with little room for error, a high bar for the DIY'er...
 
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