Re-hydrating the battery modules.

Good thinking - The steel syringe needle could go too deep and cause a problem.I have edited my post to include your suggestion.
Alex - did you find any other posts as interesting as this one is? I am going to re-hydrate modules (that are located out of the battery on a bench) with the testing procedure recommended by John later in the week and I will report the results to John. I have enough spare gen 2 batteries to do other tests that may be recommended.

Roy

Thanks Brad - excellent post

Roy

 

Maybe even easier and faster will be if you cut the needle and make it length 10mm, so it will never touch the plates and you will not have to look at mark all the time with that way also you don't have to look how much is water you injecting, you can fill it too much and then take the water back to syringe since your needle will reach only 3.5mm above of plates

10mm is just example i don't have idea how much is better to cover with water the plates, i think John can you tell better

I'm also going to re-hydrate 40 modules battery pack(from Lexus) i'll start soon as will receive everything that i bought from eBay, in my modules i will use M1.6x5mm steel grade 12.9 screws, i wanted M1.4x5 but did not found them with machine thread and non stainless steel as John said in post #48 that stainless steel that contains nickel may can be react with electrolyte, also got 480 grams of KOH this i think will be enough at least to do half of my pack, after i will get more.

Alex.
Thanks.

 

Fascinating....but dangerous.

Having hung around Prius Chat for so many years, I realize that there are a percentage of Prius Owners that are far more involved and focused on the specifics of their Prius as machines than a lot of people are with either their Prius or any vehicle.

But where do you draw the line?
From Toyota's perspective the hybrid battery is pretty much presented as being a non-user maintenance item. This doesn't stop some Prius owners from a wide variety of rebuilding, rebalancing, recharging....and now re-hydrating.

I'm NOT against this. Well not exactly.....

But I think there is a danger, in presenting some actions, that are very technical, nearly if not fully experimental- in a public forum. This has already in this thread been referred to as a new step in battery maintenance. The way the batteries are built? I think to perceive of this procedure as anything like common approved battery maintenance is a dangerous approach.

My fear is for the young kid, or person just not really experienced or qualified who may read "portions" of this thread and be enticed to try to do something that if done wrong can create a very dangerous situation.

I think for the vast majority of Prius Owners, myself included, attempting to re-hydrate the batteries on any level is simply NOT a good idea. There is a reason Toyota as an automaker and builder presents the Hybrid Battery as a non-user maintenance item. Outside of perhaps keeping the Hybrid Battery fan clean...Toyota would like you to simply use your battery....until if fails, then let them handle it.

I don't mean to upset those interested in this procedure. The attempt, the knowledge, is fascinating. But I do think it should be underlined, that this ISN'T a good idea for 99.9% of the Prius owning public. It's a very dangerous procedure, and I think one that should be avoided.

 

Here is another link, this is for the patent on the re-hydrating process.

Patent US6936371 - Method for recycling battery pack - Google Patents

The patent refers to the batteries as "electrolyte starved". It also mentions a weight loss of 9 grams and that amount of electrolyte should be divided among the six cells. That is a very different amount than the 22ml per cell being proposed here. It is also claimed that pulling a vacuum on the module will help pull the electrolyte deep into the cell plates. I do not understand why this would be so. I just weighed 20 Gen I modules. One set of ten have a capacity of 4000 to 5000 mAh. They weighed from 1012 grams to 1048 grams for a total of 10,307 grams. The strongest modules are also the lightest. The second set of ten are real duds with 400 to 500 mAh capacity. They weighed from 1033 to 1055 grams with a total of 10,439. That shows a small negative correlation between weight loss and capacity loss. 22 ml per cell would add 132 grams of weight. 22ml per cell will also use 2/3 of the free air space in the module. That should increase the pressure build up by a factor of three.

Lots of testing needs to be done. Proceed with caution.

Brad

 

Micro or milli?

If the community NHW11 PID database is to be believed, the values read from the ECU represent milliohms.

-Chap

 

Thanks Chap - I should have said my cars readings were usually 18 ot 19 milliohms (not micro). that would make each module around 8.5 to 9 milliohms( .0085 ohms to .0090 ohms ).

Roy

Roy from Canada here ---

Many people on this site have very little electrical knowledge yet the site is filled with public posts about removing the battery and its modules and testing them electrically - an inexperienced person can get killed by using information from these posts. Public information about re-hydrating the cells is no more or less dangerous.

Your post should be taken to heart by anyone who has doubts as to their ability to safely do this procedure but excluding the posts from being public would (in my opinion) not be a good idea. Working around a car (even changing a tire can be dangerous) and is avoided by most of the general population anyway.

Roy

The article did not make much sense to me, it really did not say how to re-hydrate the battery in layman's terms I could understand.

I suppose the term "electrolyte starved" means a battery that has little to no free fluid in its makeup. Examples would be the AA and AAA alkaline batteries we use everyday to power toys, clocks etc. If one of these is cut open it appears dry or electrolyte starved. The cells that most of us are talking about re-hydrating are truly starved because they are very dry when opened up but the original design was wet ( fluid leaked from the Gen 1 cells and a messy sealing process was completed by Toyota ) so they seem to be a wet battery that is completely sealed.

That being said --- the fact that all these older batteries are actually still working and probably all of them are dried out (after a few years ) qualifies them as "electrolyte starved" .

A lead acid wet cell battery will not work for long when dried out, so manufacturers installed water caps to re-hydrate the cells as they were meant to work in a wet solution..I see our attempt to re-hydrate the cells in a safe manner as being a logical move to correct the loss of moisture and thus give a longer life to the cells. From a disposal point of view this would cut down on thousands of batteries g being destroyed.
If the manufacturers could come up with a way to manufacture them with a cap or valve on each cell to allow re-hydration it could give the battery( the same life as the car).

 

Ok, I guess I could have looked at p. 52 myself, which does spell them out:

• polyphenylene ether
• polypropylene
• hydrogenated styrene butadiene block copolymer
• hydrogenated styrene isoprene block copolymer

Kind of overwhelming, how much materials engineering goes into all the stuff I look at and call "plastic".

Hmm, everything I can find about any of these resins says they're thermoplastic ... which I'm guessing is what you meant, since the reports of successful remelting would be odd if they were thermoset. Do you remember if any reports included the temperature for successful remelting?

-Chap

 

Glue a short piece of very thin tube (vacuum tube, or?) over the needle, so that just enough of the needle protrudes. Easier?

Yup. I keep thinking that: little caps with O-rings. And that's about all I can think, lol. Just happy to read this discussion.

OTOH: Caps might not be practical, or only marginally practical, or too expensive, or (bad thought): they purposely omit them, engineering obsolescence.

 

John I have bad news about the amount of water to fill the cells, I was using measuing spoons and must have not filled the spoons to the top each time thus giving me overstated readings. I purchased a syringe to day that is used that dispenses the water very accurately and I trust the readings.

The new readings are ( taken as a average over the 6 cells) is

1) 7.5 ml fills the cell to a point where the fluid just starts to cover the top of the battery.
2) 3 ml more puts water up to the 9.50 mm level (the top of my cut).

I am going to go back and change my original post.

Roy

 

I would not be concerned about using real 316 stainless screws for sealing purposes. That material is used as the plates in KOH based electrolysers with no problem. It may not be possible to know what grade of stainless screws one finds on the peg board at the hardware store, however.

In the U.S. KOH in small quantities can be had from suppliers of soap making materials. The smallest bottles can be mailed without problem, even to Hawaii. Larger amounts are more trouble due to the oxidizer hazard.

Also, it should be possible to check the fill level with just one insulated wire, cut off flush at the end, and a DVM. One DVM lead goes to the wire and the other goes to either terminal of the module. As soon as the end of the wire hits the electrolyte there will be a sudden jump in voltage seen at the meter. A high resistance, say 1 Meg across the leads would make a more definite reading.

I have been helping a neighbor recharge his genII battery, and swapping cells. There are some rejects to play with, so I will try this out soon. Just the sort of game that retired EE's can play.

 

What are you using to clamp the module?

 

Hi John - I will measure the pads tomorrow and report.

I had drained all the fluid out of the one cell I used to give my original ml readings - the module then sat open to the air for a few days.
My second set of ml readings were taken using all 6 cells - all were very close to each other except the fill over the cells was a little different because when I cut the top off the battery it left some cells with a higher wall to fill the water up to the top (crooked cut).Since I emptied the water out immediately after the measurements there was very little time for absorbtion (maybe 10 minutes) . I did not have distilled water to put in the cell so I used tap water so I did not want to leave it in the cell.

Roy

 

View attachment 79505

John, have you tested the normal maximum operating pressure of a non re-hydrated module? We know that modules rarely vent. So it would follow that the pressure stays below the 80 psi limit of the valve. Let's assume a normal unadulterated module has a maximum pressure of 40 psi. This is just a guess that should be confirmed with testing. Such a module would swell under pressure but not vent. Now take the same module and fill 2/3 of the free air space with electrolyte. The amount of gas that can be produced from overcharge will not change. But the gas now has 1/3 of the space to fill. You are correct that the pressure will now build quicker. But now there is a potential for 120 psi to build. Maybe the vent will work. Maybe the module will break. Maybe the module will hold.

Much testing to be done. Be careful.

Brad

 

It was a Gen 1 John

 

Hi John, here is a bit of usefull info the stuff in this link Thaumaturgy Clear A Drain 1L | Travis Perkins is a mixture of 10-30% KOH and 10-30% NaOH making a maximum of 60% right? So typical me I wanna know what the other 40% is so i rang the manufacturer basically it is water but not distilled or demin, the advantage of it if it could be used is its liquid?? what do you think??