Re-hydrating the battery modules.

Hello Brad

Yes, they sitting out of car, unused for the last two months since last charge cycles, and after two months they still holding at about 7.75 volts!

 

Hi John - Alex posted 2 graphs that were made by Bob Wilson a long time ago that showed the efficiency after many cycles to approach 95 %. ?????? Very interesting

Roy

 

Hi John,Alex and Brad

There may be hope for your low performing cells, my concern is the change in capacity as the cell is cycled in the car, as I am doing, will cause the code 3006 ( unusual module voltages to occur) as the modules are cycled by the cars charge/discharge system.

Looks like re-hydrating 38 modules simultaneously in the car may be possible but constant codes will appear as the battery modules gain capacity. All my original dry batteries tested around 5500 mahr discharge and did not bring up 3006 codes before re-hydrating as they were running the car OK, with no codes, dry for about a month before the start of the re-hydration process. I would not use re-hydrated batteries in the car till they became stable with their discharge capacity if you need the vehicle for regular transportation (the codes will drive most drivers crazy).

 

Still no results after many cycles, i read few documents where described different problems of NiMH and i suspect in my case is electrode corrosion or electrode deterioration, so the restore in my case looks like impossible

 

Hi Gents,
I contributed questions back awhile on this thread and have followed the conversations closely....Good discussion. and great advice. I had 2 sets of codes indicating 2 banks becoming weak and rehydrated per John's recipe and instructions....All went well. Today, the triangle appeared again....DTC 3009...leak detected....I am assuming this is from the possibility of overfilling one of cells/modules with John's Juice. I did note that upon filling 10 ml per cell, that the level of electrolyte in in SOME cells came clear to the top....near the drilled hole. I corrected by adjusting the hypodermic needle with a 3/8 in stop to keep from touching the top of the cell, and withdrawing all juice in that cell so there was at least a 3/8 inch air space in each cell. My intuition ( works occasionally) leads me to assume that not all the cells were dry, and that some must have some electrolyte in them prior to rehydrating. Here's the question. Can I ignore the leak and hope that the liquid evaporates and the code may no longer appear, OR, must I open the blasted thing up again and withdraw additional juice from each cell? I am hopeful that ignoring it, and hoping that it simply goes away is a viable option.....Oh, Gen I with 131k. last 4 k averaged 49.4 mpg....all cmodules appear to be balance and within a gnats hair of similar voltage.

 

The ground fault is not going to disappear via magic. Once the electrolyte path to ground has been established, voltage will continue to leak along that path until the dried electrolyte is cleaned off the module case.

You can ignore the fault since you have found that the Classic Prius can continue to be driven with DTC P3009. From a safety perspective, it is not wise to allow this fault to persist. If a second ground fault develops, that could result in a fire within the traction battery case - depending upon the location of the two ground faults and their severity.

With newer generation Prius, a ground fault results in the hybrid vehicle ECU prohibiting a restart because of this safety concern.

 

Hi Dave - Roy from Canada here -

I have been re-hydrating a 38 module pack in the car and p3009 code has come up because of cells leaking and causing the battery to go to ground. Finding the proper way to seal the holes made for filling was my problem.
Did you re-hydrate Gen 1 or 2 modules. I am re-hydrating Gen 2 cells to put in a Gen 1 battery as I only have experience with re-hydrating Gen 2 modules I may not be of much help.

First - I found the the battery will discharge itself with a ground, how fast depends on the severity of the ground.
Second - the leaked fluid eats the paint off the battery housing, I had to clean it with soapy water and then clean water let it dry and painted over the area with silver spray paint.

This information has been added as of July 17, 2015 ------

Clean the batteries with a solution of borax - it will do a better job of cleaning the modules as it neutalizes the KOH in the battery solution - soapy water does not always do the job. Do not leave the module immersed in the borax solution - a chemical reaction occurs that removes the nickle plating from the positive terminal. Keep the positive terminal out of the solution if possible while cleaning.


Third - I have tried various sealing processes and the best one I have found is using a product called "liquid electrical tape" (most hardware stores sell it) - it comes in red or black. It is messy to work with and does not look great on the battery but it works.
Here is what I did after a leak.

1) remove the battery and remove the top, all connector bars and all the screws holding the modules to the housing. Remove the modules from the housing for cleaning - do not try to clean while in the battery housing.
2) Clean and paint the battery housing where the acid has ate into it.
3) Wash all the tops bottoms and sides of the batteries with hot soapy water and then rinse with clean water, dry the modules well before testing and re-assembly - test each module when clean and dry by using a dc voltmeter - install a bolt in the bottom of the battery that normally grounds and holds the module to the battery housing - measure the dc voltage from the positive terminal to that bolt - any reading higher then 0.01 volts dc can cause p3009 code to occur.
4) Remove the filling screws from each module
5) Take the can of liquid electrical tape and using the brush in the can apply a dab of the sealant over the hole
6) Put the screw back in the hole, repeat for all screws. Put a dab of sealant over the top of each screw head so the sealant below the head congeals with the top covering the head - I did this to give electrical isolation as the metal screw is touching the fluid.
7) Put the modules back in the battery housing ( I did not put the bottom screws into the modules, I only clamped them. I also did not put on the top of the battery and left off the fan housing so I could see what was happening . Also left back seat out so battery was exposed. Replaced the 4 bolts that hold the case to the car to hold down to secure the battery. Connected up the electrical connections, replaced the connection to the 12 volt battery ( I had it disconnected so it would not run down from having the trunk lid open) , replaced the orange hv safety connector and started the car up. Ran the car for a few days watching for leaks.

This method allowed me to replace any a poor performing or leaking module without removing the whole battery from the car.

 

Hi Dave, in post #195 you can see i re-measured the depth and found that it's about 17.5mm, so you can make your needle longer and go about 5mm further, i don't know if the Gen.I modules have different dimensions inside but you can measure in seconds like i did

I wonder what screws you used that you have leaks?

Alex.

 

Hi Alex - I think that any screw will leak regardless ot the number of threads etc. - the mating area between the threads and the screw is so low that any heating or cooling of the module repeatedly will cause a leak. The rates of expansion between the two materials is likely the cause - my sealant may not be the final answer and a more rubbery one that will allow for expansion and contraction may be needed

Roy

 

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Hi Alex

If your modules are leaking when installed in the battery then you have to find a way to stop the leak. Sealing the screws may not be needed,however, if the modules leak fluid when installed and running in the car then a good method of sealing the holes has to be found.

In your car it may be difficult to leave the battery modules open for inspection and possibly the removal of a module but it may be worth your while to try this approach. I found removing the battery and replacing it hard on my back and time consuming - if you can not see the battery when operating the car then it is difficult to see problems with the modules.

Roy

Dave - do not remove any solution from the cells, find a way to seal the area of the leak - my method using "liquid electrical tape" appears at this time to stop leaks. If their has been a lot of leaking it will show up on the bottom of the module( the metal where the module is fastened to) as corrosion. The leak may be because you had an overflow during the filling process and cleaning the modules is all that is required. If the leaking is from the screws not sealing properly you have to reseal as I have done. I did not use a fine machine screw as john recommended, I used a self taping sheet metal screw that has a course thread and a larger body then the ones he was using, because the heads on my screws are large the sealant I used went under the heads. The metal screws are sitting in the cells chemical solution and are able to conduct current from the cell = that is why I covered the tops of the screws with the sealant that is an insulator. I used "liquid electrcal tape" color black to make my seals.

 

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I run the car without the cooling fan and its ducts connected to the battery - I also have the top removed so I can see the tops of the cells. I only do short trips and I have found the battery does not heat up very much so fan is not required for this testing.

 

I used SS screws( Machine bolts actually) ....find thread, 1/8 in. by 3/8 long, and i tapped each hole with threads. I lathered each bolt with silicone before putting it into the threaded hole...It seemed to seat tightly.....I havent run the beast since this morning... I may go for a spin and see if Mr 3009 DTC comes to visit again...If so, I will pull the cover and do a close visual, clean and use liquid electrical as suggested. I was pretty cautious about drips and spills given the caustic nature of the juice. I cleaned up any dribbles, but there was no "overflows" or spills. Any comment on there being any electrolyte already in the modules? Also, I only rehydrated the 4 modules that caused the Weak bank DTC to show.... I did not do all 38 modules.

 

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My p3009 would not go away until I cleaned all of my modules, sounds like you may only have to do the 4 you re-hydrated.

Note ----Be sure to remove the modules from the battery for cleaning and drying. This note was put in after for clarity for others who may assume you can clean the modules in place. Sorry Dave for not being clear. Roy

Best of luck

Roy

Re fluid in the modules - no if these are the original modules all fluid would be gone long ago,(I think). Sealing with silicone sounds OK as long as the fluid in the cells does not attack it. If you get the 4 batteries out, measure with a voltmeter from the positive terminal to the bottom mounting screw or the battery case if the module is still in the case - should be close to zero volts - some of mine showed readings up to 5 volts - after cleaning they were close to zero.

 

Hello. Toymo here. After a successful rebalance and equalization procedure on my heavily DTC'd "triangle of death" GenII on my first try (yay! thanks PRIUSChat), I got into the exciting new realm of re-hydration. Taking all posts from start to finish into account, JeffK's approach on his GenI was most attractive so I replicated the procedure with two of my extra GenII modules (1 good capacity 7.7v~8.2v module and 1 bad reversed cell module 6.4v) by drilling 6 small holes as shown in the photos and syringe injecting each cell with 5ml/g/cc of boiling water. Once 30 minutes elapsed, they were plugged into the hobby charger for 3 slow cycles of DSCH>CHG initially down to 6.0v at 2A then up to 9000mAH at 0.7A.

Results came back with flying colors. Both the good and bad module increased significantly in capacity but the bad module could not shake off nor undo the reversed cell reading the same low 6.4v even though it output a whooping 6650mAH. See below data.

My good dry module (prior to re-hydration) had measured caps with these results.

3467 6736 4689 7250 5083 7250 4559 7250 5235 7250 5179 7250 [on a regular cycle down to mid ~5v]
4204 7214 5235 7702 4998 7483 4987 8000 6211 8000 [on a slow deep cycle down to 4.0v(ouch!) ]

After re-hydration, here are the stunning results on just 3 slow cycles down to the recommended 6.0v then up to 9000mAH! We could only imagine how high it would go if deep cycled down to 4.0v instead...

3203 9000 5552 9000 5457 9000 6116

It works! As for hermetically sealing and plugging of holes, I will try different types of self-tapping screw sizes with liquid electric tape, etc.

Thanks all for so much fun!

Kevin

 

Hi Kevin - your testing shows good results - however I have found if you mix strong modules with non-re-hydrated weaker modules, in the battery, the code p3006 comes up ( unusual voltages on module pairs). However cancelling the code and driving the car gently the modules came closer in voltage when under load and the code eventually stayed away. Best of luck and glad you shared your experience. Please continue to give results when you place the modules in the battery.

Roy from Canada

 

Roy and others,
I just spent half of my Saturday digging into this 3009 leak detected issue. There is absolutely no indication of any electrolyte leak anywhere, including the 4 modules that I rehydrated. I pulled the wiring harness and cleaned and dried all the connections, the module terminals, the harness, the module case surface, everywhere i thought there could possibly be an electrical leak......I recoated the SS machine bolts used to close the holes in the rehydrated modules with liquid tape. ( the silicone appeared to be sufficient, none the less, I re coated all the SS machine bolts_). All the codes cleared when I had the 12 V battery disconnected. I put all back together again, started her up and within 5 minutes, the triangle was back. DTC3009! While the ICE was running, and when it was off but in READY position with fuil battery, with code showing, I carefully inspected every module, looking for some, any, indication of a leak..(bubble, spark, hiss, smoke, )..I might mention that while i had the harness off, I checked the voltage of all the modules...Still within a tenth of a volt for each one individually, and for each pair. I am looking for suggestions for how to isolate this leak. It does not appear to be related to the modules rehydrated, but I did not have this DTC until I rehydrated.....Suggestions gents? I have not heard or seen anything from Britprius...John, where art thou?

 

Roy here - did you clean the modules while they were bolted down or did you remove then to clean them? If you did not remove them and tried to clean them in place they could still have a conductive coating that the computer is picking up.

Did you check with a dc voltmeter from the positive terminal of the re-hydrated modules to the case before you put the bus bar connections back on. If you have a voltage from the module to the ground of the case and not zero (even any voltage above ,01 volt) the computer will pick it up and give you the code. Be sure the module you are testing is not connected to other modules on this test.

Did you let everything get real dry after the cleaning? If you checked just after the cleaning the moisture around the modules could still be conductive and give the code. Leave overnight and try again in the morning.

The voltage difference between module pairs is not an indication of a ground, it only indicates that p3006 ( voltage differences between module pairs) should not appear.