G1 traction battery shelf life?

Discussion in 'Generation 1 Prius Discussion' started by klodhopper, May 13, 2008.

  1. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Hi Chap,

    I've studied photos of the busbar construction and have not noticed any resistors in the sense lines. My wiring diagram also does not show any resistors between the busbar connections and the battery ECU.

    Hi Roy,

    The minimum SOC is supposed to be 40%. The battery ECU is supposed to maintain SOC from 40% to 80%, with 60% being the normal SOC. However this does not mean that the battery voltage is prorata according to SOC. When SOC is 60%, the battery voltage will be around 320V. If the battery voltage is the nominal 274V, it is probably around 40% SOC.

    Congratulations on locating a salvage battery assembly. As you know, there are 38 modules in the assembly. The issue with just charging 4 modules at a time is ensuring that you keep all 38 modules at the same relative SOC when you are done. If the battery ECU detects that module voltage from the lowest to the highest module pair is off by more than a nominal amount, it will trigger an error code.

    Also note that the modules will have a tendency to expand when they are charged; hence you must keep them under compression at all times when current is applied, or risk an explosion.

    I know of a 2G owner who used ~0.7A for a few hours to charge his battery pack and ended up destroying it. So I suggest that you set your power supply to 0.2 or 0.3A and keep a careful eye on the battery pack while it is charging.

    Since the battery modules are rated at 6AH, I suggest that you charge 0.3A for no more than 8 hours, checking periodically to ensure that the modules are not overheating or showing signs of distress. At that point there should be enough charge to start the Prius. If your starting voltage is pretty high, then less charging would be needed.

    Regarding your idea to tow the car in an effort to force charge it, I think that has a lower probability of success than charging 4 modules at a time.

    Instead of charging 4 modules at a time, I have seen a setup where a Variac is used to generate variable AC voltage, then diodes are used to create DC that is then filtered by electrolytic capacitors. A light bulb can be put in series with the Variac input to limit current. The benefit of this approach is that you can charge all 38 modules at once; however you have to be very careful to monitor charging current or risk a large explosion.
     
  2. ChapmanF

    ChapmanF Senior Member

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    Thanks, Patrick, that's good to know; I don't think I had seen any photos that close. I /had/ noticed the wiring diagram didn't show any resistors there, but then it doesn't show the one in the SMR either (or even any of the internal SMR details, like the current transformer or its own sense lines) - it's just a blue box with some wires going to it from the ECUs. And I guess it would be possible to build integral resistances into the busbar modules, that wouldn't look like discrete resistors in a photo.

    I guess the real way to find out would be to measure the resistance between the ECU end of one of the sense lines, and the corresponding (!!!) busbar terminal pair. It just happens at the moment that my trunk and back seat are all buttoned up like a normal car for some odd reason, so I was hoping maybe somebody else has a battery apart and could easily make the measurement, or maybe even already has it.

    -Chap
     
  3. rapidroy

    rapidroy New Member

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    Thanks for the info Mr. wong as it is very helpful. I was wondering at what rate to charge the battery if needed. Looks like about 7.2VDC and about .05 amps per module. Dose aney body know what the minimun voltage is that will still start the ICE? This is what I really need to know to know if I need to charge the battery or not. I think the best thing to do is let the car system charge the battery if it will start. Thanks for everybodys help. Roy
     
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Hi Roy,

    My belief is that the traction battery needs to produce at least the nominal voltage, or 274V or better, to have a reasonable chance that the battery will start the car. However you'll have a great opportunity to add new knowledge when you receive your salvage battery, determine its current voltage, and see if it will start your car.

    Each module has a nominal voltage of 7.2V. However when charging you will need to apply somewhat greater voltage to reach the desired charging current. The critical issue is the current applied, and I previously suggested 0.2A to 0.3A max. Assuming that you are charging multiple modules in series, the current will be the same for each module. You cannot charge multiple modules in parallel because one module will tend to hog the charging current.

    I assume that you have a lab power supply where you can either set maximum voltage or maximum current. If true, then set the current so that it is limited to 0.2A or 0.3A, then allow the voltage to vary as needed to continue delivering that current over the charging period.

    As I previously mentioned, it is really important to monitor module temp and if you see that they are overheating or showing any signs of distress, then stop the charging process. It is also important to keep the modules compressed. Finally, it is important to charge the modules equally so that you don't end up with an unbalanced situation where some modules have a greater SOC compared to others.
     
  5. rapidroy

    rapidroy New Member

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    Thanks Patric, I read on yahoo on a battery info report that to put the G1 Prius in ready mode, as I understand it is what is required to start the ICE the drive battery needs to be between 150 to 300 Volts. So I will check my battery when I get it to make sure I have at least 150 Volts, If so I will try it, if not I will charge it.
     
  6. ChapmanF

    ChapmanF Senior Member

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    Here's what I found out.

    There are no limiting resistors, fuses, or anything else, in the wires from the sensing busbar back to the connector that plugs onto the Battery ECU inside the battery enclosure. That connector (which is not identified in the Electrical Wiring Diagram
    because it's internal to the battery assembly) does have AMP 11422 and its pin numbers stamped on it. In the attached image, lower left is pin 1, upper left is pin 13, lower right is 14, upper right is 26. For a size reference, it's scanned at 300dpi. The wiring's as follows:

    Code:
     NiMH      wire         AMP
    module     color       11422
    ------    -----------  -----
     1        GY-BK         14
     2  3     V-Y            2
     4  5     GY            15
     6  7     O              3
     8  9     GN-BK         16
    10 11     BU-O           4
    12 13     GN            17
    14 15     PK             5
    16 17     Y-BK          18
    18 19     BU-W           6
    
    20 21     BU             7
    22 23     GN-R          20
    24 25     Y              8
    26 27     PK-BU         21
    28 29     GN (dark)      9
    30 31     BU-R          22
    32 33     GN (dark)-W   10
    34 35     R             23
    36 37     W             11
    38:       BU-BK         24
    
    This connector might be a useful interface for somebody wanting to build something that could use a low voltage charger to top off pairs of modules one pair at a time - though it would be important to remember that there's up to about 300V between some of the pins here, very skinny wires, and nothing to limit current.

    -Chap
     

    Attached Files:

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  7. bwilson4web

    bwilson4web BMW i3 and Model 3

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    WONDERFUL!!!

    You have solved a problem that has been bothering me. Can you post a photo of the space where these connectors are located?

    Is this a standard connector? Can I get both the male and female?

    My problem is I 've wanted a way to instrument and monitor the individual cells. Yes, I do plan to put together my own battery minder. This solves the problem very nicely!

    Thank!!!
    Bob Wilson
     
  8. ChapmanF

    ChapmanF Senior Member

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    Now Bob, I can scarcely believe you haven't seen it, given that you've been taking G1 batteries apart - this connector hangs off the driver's-side end of the forward busbar module and plugs into the forward (concealed) end of the battery ECU, near the system main relay and all under the battery cover of course. Probably there's no getting to it without lifting the cover.

    I don't have photos in its natural habitat because I haven't opened my battery; I just examined a new busbar module in captivity.

    I have no idea how gettable it is. Seeing an AMP number stamped on it is an encouraging sign, but whether it's anything your neighborhood AMP distributor can obtain or you need to be the size of Panasonic and order it by container load, I do not know.

    -Chap
     
  9. bwilson4web

    bwilson4web BMW i3 and Model 3

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    The used battery pack I bought was just that, the used batteries. I do have a complete salvage pack but want to finish my current module experiments before cracking that one open. I want to rebuild that one just once with my planned 'gadgets.'

    On the connectors, I'll check the 'usual suspects'.

    Thanks,
    Bob Wilson
     
  10. ChapmanF

    ChapmanF Senior Member

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    Aha. I was (obviously) sure that you'd had more open than just that one.

    The diagram on page 10 of the SSC 40G sealing-modification instructions sets out the lay of the land pretty well. (Oddly, one thing I can't deduce with confidence from the diagrams in SSC 40G is actually which end of the module stack is the overall + and which the overall -. There are diagrams on pp. 24 and 30 that would make module 1 (driver's end) the most + and module 38 the most -, but then there's a diagram on p. 29 that's obviously mirrored - it shows the service plug cabling running toward the passenger side - so I don't know how far I can trust them. Hmm, if I had written down the orientation of any one of the modules in your battery enclosure before unbolting them all, I would know this ... I guess the cops threw me off my game.)

    If you do find a source, let me know. If you need to make up a minimum order you might be able to count me in (for one pair, which probably won't help much, but we'll see).

    I was sort of surprised to find AMP on the connector and not, maybe, Yazaki. (Yazaki has an office near Detroit and while I lived there I once walked in and managed to talk someone into sampling me a couple of connectors that would mate with the harness in my Mazda; I'd have been happy to pay but they would never have talked to me about an actual order.)

    -Chap
     
  11. TonyDeru

    TonyDeru Junior Member

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    Hi Bob, did you ever get the connectors? I need a set also! Plz let me know, as I'm thinking to just solder the sensor wires to the back side of the male.
    Thank you
    Tony
     
  12. TonyDeru

    TonyDeru Junior Member

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    Chap, thanks so much for posting this Info!
     
  13. Prodigyplace

    Prodigyplace Senior Member

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    You are responding to a 9 year old thread but @bwilson4web is still here. I tagged him to alert him to your query.
     
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