Gen 1 Battery Rehydrating Experiment Results

Discussion in 'Generation 1 Prius Discussion' started by jeffkay, Mar 23, 2010.

  1. jeffkay

    jeffkay Junior Member

    Joined:
    Feb 21, 2010
    20
    17
    0
    Location:
    burbank, ca
    Vehicle:
    2001 Prius
    Model:
    I
    Hi Forumites! Recently I acquired a 2001 Prius for $1200. I own a 2008 and a couple of EV's so I figured I could bring this Prius back to being a usable daily driver. I was told by the previous owner that the car got a new battery not long ago. Be that as it may, I was soon finding out through codes that I had a few HV battery issues. First, there was one block giving code 3028. This means they are weak or some such. Armed with info from here, I tore into the pack.

    I found it to be a 2007 replacement! I got a couple "good" modules from the Bay of E and installed them. The symptoms of fan blower coming on, brake light and racing engine occasionally went away and I was happy. But still the error lights came up! So I had the car scanned by a competent individual. The pack showed low capacity and to make matters worse, the block of two modules I replaced were WORSE than mine! But now I was really mad.

    Why would the pack from 2007 (well after all the leaking KOH nonsense was sorted out) still fail in just a few years? My theory was heat because the car lived near Death Valley! What more brutal test of a battery, huh? So basically the moisture in the cells simply dries up. It happens in many battery chemistries.

    Now I should say not only am I cheap--I am creative. I thought about putting in Gen 2 modules but thought matching the two from different cars would be a pain. I certainly did not want to spend actual money on a new pack or even a Re-Involt. My mileage was telling the story. The car could barely do 29MPG in the city!

    I decided with nothing to lose, I would try reviving my pack. I looked over Bob and other's great info here and other places on the web and came up with my own approach which I now share here...

    Because each module has 6 cells, I wanted to be able to attack them individually and not have to take the modules out or be baking them and stuff like that. Here is the basic method:

    Small holes are drilled above each well. Boiling distilled water is injected via syringe--30ml each. The boiling water makes the grids or plates more likely to wick up some water. Panasonic used a gel originally but "re-gelling" them would be impossible...

    Stainless steel screws are "self-threaded" right into the case after the water is insjected. I wanted to use some o-rings but got lazy. The screws can be opened in the future should you go to Death Valley once more. As Bob notes, The dissimilar plastic screw interface may leak vapors. But between the main vent opening and the fact that these batteries should not vent under normal conditions, I did not make any big deal over it. I did test melting chunks of a junk case into the holes with a simple soldering iron and it works great but is time consuming. May be the way to go if you are worried about leaks.

    Now the real-world data: I have a battery analyzer and used it to come up with the water amount and test a few loose modules. As Bob notes, you need to do several charge discharge cycles to get capacity back. I started by seeing 2.5AH and in the end around 6AH before I decided things were going well and I started drilling holes in the modules of the car.
    After the pack was rehydrated and I had been driving it around a bunch I found the mileage going back up to the normal Prius expected range. Today, I drove it about 10 miles city driving and it stayed at about 42.5MPG. I will update here with the ongoing results...

    I invited the competent individual to scan the car again and repeat the battery tests. The HV battery now tests within usable range as far as capacity. ...For how long? That I don't know but things look great so far for my $4 screw investment and the gobs of time drilling and filling. Sadly, I still have an HV leak (not in the battery) that may be the dreaded MG2. I am resolved to grinning and driving with much better mileage and not looking at the error lights. I doubt I can stand that very long and soon will be drilling holes in the MG 2!

    Jeff K.
     

    Attached Files:

  2. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
    18,178
    6,260
    0
    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    Thanks for the update. Glad to hear your confirmation that the dead battery module resulted from water loss.

    (BTW, when the 12V AGM battery dies, a temporary rejuvenation may sometimes be obtained by adding an ounce or two of distilled water into the cells.)

    DTC P3009 might also be caused by the traction battery ECU, the battery cable, the inverter, or the transaxle (MG1 or MG2). I recall that Art's Automotive posted good info regarding how to identify the component with the high voltage leak.
     
  3. bwilson4web

    bwilson4web BMW i3 and Model 3

    Joined:
    Nov 25, 2005
    24,281
    13,809
    0
    Location:
    Huntsville AL
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    I'm impressed! GREAT JOB!!

    I wished I'd thought of the self-threaded screws and plastic melt. The only change I would make would be to put the battery pack 'on end' and use only two holes per module. There is an alternative, one hole solution but that means the syringe has to inject water and remove the gas. The water can flow via the vent interconnect from cell-to-cell. Still, impressive job!

    The main point is we're all at the 'bleeding edge' of Prius battery recycling and this is a good place to be.

    You might want to get a megger tester to see if you can fault isolate the likely, high resistance bridge to ground. My only concern is the KOH is an excellent conductor, which is why we have to pay particular attention to sealing the case. (Gosh I wished I thought of self-tapping, stainless steel screws and plastic melt sealing.)

    Bob Wilson
     
    flxcon likes this.
  4. adric22

    adric22 Ev and Hybrid Enthusiast

    Joined:
    Apr 6, 2009
    641
    143
    2
    Location:
    Fort Worth, TX
    Vehicle:
    Other Hybrid
    Model:
    N/A
    I'm still surprised that a 2007 battery pack would have failed under any condition. Makes me wonder if another scenario took place:

    • The car sat unused for a long period of time
    • the battery was drained too low by driving the car without gas.
    • there is some other problem causing the cells to drain themselves inside the car (possibly the high voltage leak?)
     
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
    18,178
    6,260
    0
    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    Could be. In order for the cells to drain themselves, there would need to be at least two electrolyte leaks allowing a current path via the battery case.

    Regarding the OP's discussion of very hot weather and its negative impact on the Prius battery:

    The very first Prius problem I experienced was driving the 2001 in Palm Springs during the summer of 2006 (115 degrees F ambient temps), where the car had a no-start problem (DTC P3191). The Cathedral City Toyota service advisor told me that this was a common problem in hot weather and that if it happened again, I should get the engine ECU replaced. (They did not have the ECU in stock and we were just traveling through.)

    The problem happened twice and my local dealer at the time, Rancho Santa Margarita Toyota, replaced the engine ECU at 59K miles under TSB EG011-03. That was the incident that prompted me to start learning about Prius and what could go wrong with this very complex machine...

    Two months later the traction battery died at 61K miles, and was replaced by RSM Toyota under warranty.
     
  6. jeffkay

    jeffkay Junior Member

    Joined:
    Feb 21, 2010
    20
    17
    0
    Location:
    burbank, ca
    Vehicle:
    2001 Prius
    Model:
    I
    Bob, On the bench I tested many times and ways of filling with only one or two holes. It is a no-go in my opinion. First, If the wells of the module are filling so much with water as to "bucket-brigade" along to the next cell, then you are using valuable gas expansion volume in the module. When the module is sealed, bulging will occur earlier and to a greater degree. Not good. Perhaps if you had a magic orthoscope-like device you could go in and deposit water from one hole, dropping it in each well using the communal upper gas area.

    Here is an idea that could work: Make two holes--one at each end. Then inject steam. The steam would condense and flow around inside alright but I have no clue how you would know the volume you are putting in. The steam would also help with the "wicking" effect. Maybe if you could deliver steam in a known flow and then time it for each module, you could find the right combo for therapy...

    My HV code (3009) is proved not to come from the battery. Since the car shudders on take-offs, I am pretty sure we are dealing with the MG2 coils breaking down. I can do further tests. I am pretty sure that Toyota did not provide enough cooling (or it becomes poorly cooled with bad transmission maintenance).

    Regarding heat and the '07 battery drying. The reader that comented how could this be is quite possibly right... There could have been an event like overcharging, etc. that allowed venting. We can never know. A Toyota specialist tells me that in the summer the dealers see many packs come in after the weather gets hot. I do not believe enough vapor escapes through the "KOH leaking" scenario.
     
  7. TexomaEV

    TexomaEV Member

    Joined:
    May 19, 2010
    154
    18
    0
    Location:
    Bonham, Texas
    Vehicle:
    2001 Prius
    Model:
    N/A
    Do you have any photos of a single module outside of a pack, where I could see easily where to drill holes for the boiling water injection? This is really interesting stuff. Might get some students into doing this on some bad cells, to see if they can recover them.
     
    flxcon likes this.
  8. jeffkay

    jeffkay Junior Member

    Joined:
    Feb 21, 2010
    20
    17
    0
    Location:
    burbank, ca
    Vehicle:
    2001 Prius
    Model:
    I
    The holes are drilled in the top and easily seen in the photos earlier in the thread. By the way, I have about a thousand miles on them with no issues or codes (DTC)... Jeff
     
    KaJuNMan1969 and TexomaEV like this.
  9. TexomaEV

    TexomaEV Member

    Joined:
    May 19, 2010
    154
    18
    0
    Location:
    Bonham, Texas
    Vehicle:
    2001 Prius
    Model:
    N/A
    Thanks, I looked at them again, and finally found/counted all "6" screws.

    Can't wait to do some experiments in NiMh Battery recovery. By the way, our EV Truck uses NiCd batteries, flooded with KOH, We use deionized water in them. Would there be any reason to use deionized over distilled or vice versa?
     
    flxcon likes this.
  10. tochatihu

    tochatihu Senior Member

    Joined:
    Apr 10, 2004
    7,968
    3,086
    0
    Location:
    Kunming Yunnan China
    Vehicle:
    2001 Prius
    Good work, Jeff, with the 'drill baby drill'.

    Texoma, if the deionized and distilled waters are both correctly labelled, there should be no difference. If you have a college handy, someone in the chemistry or biology departments should able to measure conductivity. The lower the better. Actually they could probably donate some very pure water to your effort with only a little coaxing.
     
    1 person likes this.
  11. TexomaEV

    TexomaEV Member

    Joined:
    May 19, 2010
    154
    18
    0
    Location:
    Bonham, Texas
    Vehicle:
    2001 Prius
    Model:
    N/A
    Started experimenting with a dead module, the 5 cells measured less than 1mv when the experiment began. Note the 6th cell was destroyed in an earlier visual inspection:
     

    Attached Files:

    flxcon likes this.
  12. bwilson4web

    bwilson4web BMW i3 and Model 3

    Joined:
    Nov 25, 2005
    24,281
    13,809
    0
    Location:
    Huntsville AL
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    Hi Mike,
    The voltage is a little high for 5 cells. Have you measure the discharge, Ahr?

    Thanks,
    Bob Wilson
     
  13. TexomaEV

    TexomaEV Member

    Joined:
    May 19, 2010
    154
    18
    0
    Location:
    Bonham, Texas
    Vehicle:
    2001 Prius
    Model:
    N/A
    That was the voltage at the very beginning of the initial charge. I think the cell might need to be compressed, it was bulging on the sides when I originally cut into the first cell quite awhile ago. The module has been sitting outside for 4 to 5 months and was completely dry in all the cells. I suspect this would be a pretty good worse case example of a dried out module. If it's cells recover, with any capacity, I'll be surprised.
     
  14. bwilson4web

    bwilson4web BMW i3 and Model 3

    Joined:
    Nov 25, 2005
    24,281
    13,809
    0
    Location:
    Huntsville AL
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    Ok, that is something I recently saw with a module I've been trying to rehydrate. I'm seeing:

    • high back EMF - charging voltages are insanely high
    • low capacity - we're talking 10s of mAhr ... milliamp hour!
    I'm about to try some truely abusive things to see if I can get more normal battery function . . . discharge a cap into the battery.

    Bob Wilson
     
  15. TexomaEV

    TexomaEV Member

    Joined:
    May 19, 2010
    154
    18
    0
    Location:
    Bonham, Texas
    Vehicle:
    2001 Prius
    Model:
    N/A
    Capacitor idea is interesting. Therefore, for grins, We connected a Pb/Acid battery desulphator (one of those magic, snake oil devices) to the 5 cells in the module under test. I believe it charges a capacitor to a high voltage, and then does a rapid discharge into the battery.

    NOTE: I noticed you can dip your voltmeter leads (use old ones) into the electrolyte between the cells and measure the voltage of each cell. So far I'm seeing that the individual cells in the module are dramatically out of balance. Therefore, I'm going to use a battery maintainer, and the desulphator (even though NiMh doesn't have sulphation issues) to keep a constant flow of current through the module, hoping they'll eventually balance out.
     
  16. jeffkay

    jeffkay Junior Member

    Joined:
    Feb 21, 2010
    20
    17
    0
    Location:
    burbank, ca
    Vehicle:
    2001 Prius
    Model:
    I
    I am the one that started this thread describing my procedure. Update: As of 9/11/2010, I have now used the rehydrated pack for over 2500 miles with no codes or issues. Jeff K.
     
    flxcon, zsc100 and bwilson4web like this.
  17. zsc100

    zsc100 New Member

    Joined:
    Jul 24, 2011
    1
    1
    0
    Location:
    Tulsa, Ok
    Vehicle:
    2001 Prius
    Model:
    I
    So, can you tell me what the amount you ended up adding to each cell was,, and what is the current status of this project? Is your battery still up and running or did it die out again?

    Thanks,
    Zach
     
    flxcon likes this.
  18. jeffkay

    jeffkay Junior Member

    Joined:
    Feb 21, 2010
    20
    17
    0
    Location:
    burbank, ca
    Vehicle:
    2001 Prius
    Model:
    I
    Re: Gen 1 Battery Rehydrating: UPDATE 2012

    Thought someone would want to know... Car is still working fine, no codes, no issues (other than people like to crash into it!). Approximately 20,000 miles on rehydrated pack as of today! I'd say it worked. Jeff
     
  19. Rob Thomas

    Rob Thomas Junior Member

    Joined:
    Nov 18, 2012
    11
    4
    0
    Vehicle:
    2001 Prius
    Model:
    I
    I know this is an old past, but thought I would give it a little bump. Jeffkay hope your rehydrated battery is still working. Any updates?
    I recently replaced a couple bad packs in my 2001. I got about 800 mile out of the repair. Then the codes came back. It was another bad pack.
    I tore the battery back apart. Your post gave me an idea. I weighed the packs. My packs all weighed in at 36.2-36.4 ounces. The three packs that were bad weighed 36.2, 36.2, and 36.3.
    The three replacement packs that I bought on THE BAY weighed 36.7, 36.7 and 36.8. I realize that there may be factors that effect the weight other than drying. I also do not know the density of the original gel. If drying is the problem, .5 ounce difference in weight would translate to about 15ml of water.
    I fear that the extreme temperatures here in WI may have played havoc with my battery. I am thinking about using your method it rehydrate my packs. I think I would start by just adding 3ml per cell. Any thoughts?
     
    flxcon likes this.
  20. bwilson4web

    bwilson4web BMW i3 and Model 3

    Joined:
    Nov 25, 2005
    24,281
    13,809
    0
    Location:
    Huntsville AL
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus

    The problems I ran into:
    1. sealing the hole used to inject the water - the Toyota/Panasonic patent mentions using 'plastic welding' and I even got the part and tool. But then I realized there was another problem I could not resolve.
    2. dealing with a melted or compromised terminal "O" ring - there is a black plastic-rubber "O" ring, the path the gas escapes. Many times you can find the smear where they have effectively melted due to excess heat. I could never figure out how to 'refurbish' the "O" ring and achieve a pressure-tight, gas seal. Technical challenges include rates of thermal expansion and the small space. Perhaps if a new ring could be fashioned and embedded in a larger, plastic washer . . . maybe.
    In the end, I decided it was easier to get NHW20 modules that have lower internal resistance (aka., less heat) and improved terminals rather than spend time trying to refurbish the old-style NHW11 modules. It just depends upon how you value your time and the quality of repair.

    GOOD LUCK!
    Bob Wilson
     
    flxcon likes this.
Loading...