Is there a way to find the date that a Prius Hybrid battery was manufactured?

I am sure there is a lot of data in the serial number if we could decode the whole thing, but so far, this is as much as we have been able to know for sure.

 

This is interesting enough for me to comment on, so here goes...

1. Are you guys trying both Li-ION or Li-PO?
1a. Cost of Lithium batteries are usually pretty high, is that the reason for fewer "packs" in this series?
2a. Cost of Lithium may or may not be high due to demand for other uses (medicinal for mental issues) or is that some other form of Lithium? It brings to mind, you can defray the cost if you get somebody from big pharma to sign off on it

Lastly, I can't quote directly from another posting in this thread, but my main worry (as is anybody's) is when will Toyota stop manufacturing of the 1st Generation batteries. It is disconcerting to know that 08 is the most recent verified date of manufacture for any battery of the first generation. So, Re-involt should be commended for their efforts not only on the lithium front but also on the rebuilding of the battery front as well.:rockon:

I know, I just said lastly, but I'll part with with this: I actually like the body style of the Gen1 Prius over all current subsequent generations. Is there a possibility with the new models that Toyota has on offer, that a sensible, not as much in-your-face body style will again carry the Prius badge? It probably should be another thread in a different forum, or even a poll. What do you guys think?

 

That has not been confirmed. Unless Toyota discloses the coding of their serial numbers, there is no way of knowing whether or not any claims as to the meaning of those numbers is accurate.

 

I think they exist already but under a different badge. The Ford Fusion and Camry hybrid are examples but I think the Nissan Altima also uses the same drive system.

Personally, I think it makes sense to keep an open mind. Yes, the compact, sedan style (very similar to Ford Focus) body works fine. But I also offer that the ZVW30 and NHW20 have a coefficient of drag ~0.25-0.26 and the NHW11 is at 0.29. The impact is greatest at higher speeds but other characteristics of the NHW11 drive limit high-speed performance.

Bob Wilson

 

Nice! I recently came into a large amount of A123 26650's. I am going to make a 7.2kwh Lithium-Ion PHEV pack with custom BMS that replaces Toyota's as well. It isn't going to be lighter or smaller, but PHEV is the goal here.

I'd love to talk to you some time about this, maybe we can be of assistance to one another?

 

I want folks to understand a little more about how difficult (NOT impossible) it is to bring in a different battery chemistry. The easiest thicket is dealing with the charge/discharge limits (easy as in walking a tight rope with untied, loose shoes!) The really hard problem is thermal management.

When I read GM was going with LiON batteries, I knew the hardest problem was keeping them within the battery healthy temperature range. Then I read that GM encased the batteries in a thermal controlled case. By going 'plug-in' as well as tapping battery (or system) energy, they keep the traction batteries 'in a happy place' regardless of Arctic cold or Mohave heat. Some have gone with a liquid bath although that increases weight. This is a seriously hard problem.

I mention this because a LiON traction battery pack running in a moderate climate could go "poof" (and the car) in temperature extremes that most cars go through. I'm not trying to discourage experimentation but suggesting "there be dragons there!"

Bob Wilson

 

Thanks Bob,

Yes, you are absolutely right. The A123 26650's are probably some of the toughest cells out there though. 1 cell has an 8 milliohm ESR, and can handle 70A of continuous discharge (obviously with thermal management.

I am likely going to be putting them in cell-blocks of 12 parallel cells to make a 3.3v @ 27ah building block, (.67mOhm) then using those in series (with a custom-derived BMS board per block) to get my operating voltage. I am intending on totally removing Toyota's system (including BMS) from the car and replacing it with my own design using a Silicon Labs C8051F500 CAN 2.0 micro for the new BMS.

~100 amps in/out is nothing for this kind of configuration, as this pack would be able to effortlessly handle 5 times the Prius amperage even with no real thermal management.

If we are driving @ 100A that's only a loss (heat) of 6.7 watts per block, so that puts my pack total at around 400 watts of waste heat. Conversely the best figures I've seen for the stock pack puts it no less than 20 watts per cell or 3.3kw for the whole pack! (8 times more heat!) Of course, we rarely sustain 100A of Regen/Motoring for any significant time as well.

They also have a 120 amp fast-charge capability, which would permit charging the entire pack from 100% DoD to 80% DoC in mere minutes. (okay, less than 10 anyway ;-)

The trick would be trying to shoehorn some other chemistry into the Prius and keep the OEM BMS. You'd likely have to do all kinds of spoofing and other tricks (as many have) to get it to work half-way decently. After careful thought I decided this isn't really the proper way to do it.

 

I think some basic misunderstandings are at play here. There is nothing that makes lithium-polymer batteries inherently more dangerous than conventional lithium-ion batteries. Both the Chevrolet Volt and the Nissan Leaf utilize lithium-polymer cells. I'm guessing that their designers know a little about battery safety. Indeed, some of the fastest Level 3 fast-charge battery packs use Li-Po cells.

At the cell level, the relative stability of a particular Li-ion or Li-Po type is dependent on many factors, such as the type of anode, cathode, and/or electrolyte used. At the pack level, both Li-ion and Li-Po battery packs can of course be quite dangerous if they are controlled with a sloppy battery management system. Most folks in the field, however, have significant experience and expertise.

If after reading this, you remain convinced that Li-Po represents a unique risk, you may want to check your cell phone as well as your laptop. At least one of them is likely to use a Li-Po battery.

However, if you'd like to learn about the technology, a variety of guides to Li-ion and Li-Po batteries are available online. Such an introduction, of course, only scratches the surface, and is not nearly enough education for someone who wants to start experimenting, but it's a start. Good luck.

Out of curiosity, how did you determine that your interpretation of the serial numbers is correct?

 

I suspect when you build your BMS, the specific configuration of the modules becomes more flexible. One advantage is you can build-in more charge balance than we're aware of in the Toyota battery controller. One observation, the HV ECU has a number of private communication wires to different ECUs including the battery. In fact the battery ECU does not directly connect to the OBD connector but appears to pass via the HV ECU. There appears to be a tight coupling but I've not read anything about the protocol(s) being used.

For what it is worth, the maximum discharge and discharge seen with the Graham scanner recording has been ~70 A and ~50 A.

You might want to check some of the Dept. of Energy reports from Battelle Labs. I remember one paper that discusses cooling.

This approach may offer some advantages:

• 19 series resistor network to spoof the sense lines
• Hall effect sensor for current
• block 273 V. pack assembly
  • 80 A. peak charge/discharge rate
• four temperature sensors

All of the interfaces are well known and don't require reverse engineering of the private data bus between the HV and battery ECU. The sense line resistor network voltage does not have to follow the actual traction battery voltages but rather go up or down as needed to put the car in various charge/discharge modes. This assumes no independent traction battery voltage sensor other than the 19 sense lines.

Still, if you can get a good read of the private HV and battery communications, an independent controller would work. I would be interested in your specifications, how you're expecting the new battery controller to work. As a suggestion, the Prius Technical Stuff group would be a good group to share and get a good critique of the technical details.

Bob Wilson

 

Yes, for more precise voltage control, and to effect monitoring/control for my BMS I need a dedicated microcontroller in any event, and I'd also need to spoof Toyota's system; either by intercepting/generating CAN messages, or manipulating what the Battery ECU "sees". My conclusion would be that it's less hardware (and thus more reliable) to go my route, also with less unknowns. However, the trade-off is lots more software development time, But I gain absolute control of what's going on, both in my battery, and how I tell the Hybrid ECU to Regen/Motor. Plus, I get the ability to store my own DTC's, broadcast CAN messages elsewhere and for other purposes, logging, etc. Keep in mind I'm working with a 2008, so the system is different than on the NHW11. It's all CAN based, and the CAN bus actually starts at the ECM and ends at the Battery ECU, going right though the DLC (OBD2) connector on the way. There is no other communications except what take place on the CAN bus, and it's been pretty well documented already.

Attached below is a diagram showing the NHW20's Battery Management System and how it connects with Notations by me showing what the non-obvious connections are.

I've seen all kinds of reports on this for the NHW20. The Oak Ridge Labs report claims the system itself was built to handle up to 125A in/out, but they only saw 105A in practice for peak motoring current. The CAN messages that allow the Battery ECU to stipulate maximum current in or out (CCL/DCL) will accept up to 125A in either direction, even though typically the stock ECU usually keeps the CCL at 115A. However, it's been observed to be as high as 125A at times. Most research indicates the max charge current never gets over 100A in any event, so this is not really relevant.

Thanks Bob, I don't think I've seen this one. I've read many DOE reports on the Prius. A wealth of information is available just by searching for "Prius" in the DOE document library. I'll see if I can find it, You wouldn't happen to have a link would you?

Yes, this method has much prior art, though I would be spoofing the nominal voltage of 201.6v rather than 273v, and only 14 resistors needed instead of 19. The aversion to this method is that the algorithms the battery ECU uses to make it's decisions are not known, so a lot of trial and error or needed to accomplish anything. Plus, i'd need extra hardware to spoof high voltages and it just seems "clunky" to me. Also, for my method if I have any trouble while performing my experiments, I can just reconnect the OEM pack and BMS and the car is back to baseline. I will not be modifying anything OEM in the car, as I still am under warranty.

The SiLabs C8051F500 Microcontroller will be the heart of the system. It has built-in hardware to make the CAN bus interface simple and will allow a quick development to get us talking to the car properly. Basically I tell the Hybrid ECU the Max Charge and Discharge currents I will allow (CCL/DCL), and the SOC. Manipulating the reported SOC will also enable me to influence the decisions of the Hybrid ECU about when to charge/discharge and by how much. I will set these parameters to allow the greatest use of my new pack, while protecting it thermally and electrically just as Toyota did with the OEM pack. The difference is that the A123's are superior in most every way, so I will not have to "coddle" the pack as much as Toyota does with theirs. I will likely add a UI that will allow the driver to influence the system to allow decisions based on drive cycle, terrain, etc. For instance, on a long downhill, you set the reported SOC lower, so you get maximum regen and stockpile energy for the approaching hill. Then you set the SOC high at the bottom and enjoy maximum use of the stored energy up the hill. Also, these parameters are going to be affected by the PHEV specifics, so they will manipulated to achieve the best PHEV range. There will be lots to learn and lots of tuning to get the system to ideal performance.

Yes I am on PTS, and will definitely share my learnings with the group when I have solid information. I am just beginning on this project!

Thanks for your insight!

 

Sorry, I didn't realize this was an NHW20 project. There are a lot of resources available for the NHW20 . . . the NHW11, not so many.

GOOD LUCK!
Bob Wilson

 

You can email me direct at [email protected]

 

D

Dear Patrick. Where have you being all this while? You've not being up here as you used to.
Hope all is well with you though?

Dxta

 

Thanks for the concern, I check in to the G2 and G3 forums periodically. Not so much Classic.