P3009 battery Frankenstein project

OK, the old battery has been tested as much as I can think of. The buss bars and holders are clean. The modules have been washed in vinegar, rinsed and dried. The good modules are back in parallel on a trickle charge.

The newER battery with the P3009 is on the garage floor, and the cover is off. Here's a picture of the obvious place where it's leaking. Note from the buss bar cover, this is on the side opposite the sense wires, just to the left of the cables that effectively split the battery in two halves. This is module 18, part of module pair 9.

Pardon me while I get back to disassembly.

 

Module voltages in attachment.

Particularly bothered by modules 24 and 25.

There's much more evidence of leakage in this battery, not too surprising, but less obvious from the marks on the pan. Photos later.

 

Looks like I may need a set of voltage sense leads. I noticed that one broke in taking them off this battery, and went and looked at the leads from the old battery. They're so thin that a little corrosion makes them very fragile. I may be able to reuse the ones from the old battery, but they're making me very nervous.

I went to this page, but they aren't showing the buss bars or the voltage leads:

Toyota Parts Cheap.com

Does anyone have a part number or source for the voltage sense leads?

 

Great! thanks!

Ok I got the results from the first charge cycle on module 19 (from block 10, which I judged as a representative of the worst block based on Scangauge data). Discharge is 1216, charge is 3112. That's beginning with the ECU reporting a SOC of 68. I'm still waiting on the cycle from module 38, which should be one of the best modules.

I only did a single discharge/charge cycle because I was impatient for data, and you can't see the results until the entire cycle is done. But I think the next one will be module 24 because of the low voltage. I'll let it cycle 3 times as I did for the other battery, so the final cycle should be directly comparable.

 

Module 38: discharge 2062 charge 4018

 

From Module 24, three cycles:

	Column 1	Column 2	Column 3
0	Cycle	Discharge	Charge
1	1	1439	2543
2	2	2584	3062
3	3	2942	3917

This is better than the best of the modules from the other battery, and yet this has the lowest voltage in the stack and comes from a block that is relatively weak and from the middle of the stack.

I'm going back to do a complete cycle on module 18 (because it's next to block 10 and had the most significant leakage) and two more cycles on block 19 to finish the three cycles I normally run. Given that the first discharge was 1216, and that was only one module in the block, maybe one of these modules may be weaker than the best module from the old battery, but I'm not counting on it. So it looks like I'll be washing and reusing these modules with block 1 and 19 in the center.

Boy, what I wouldn't do for 38 MRC's!

Currently modules 24 and 38 have been through a full charge cycle, and where the rest of the battery read 7.98 - 8.03 volts, these two read 8.16 and 8.18. The same will be true with 18 and 19 when I'm done with them. I think it's fairly easy to bring all the voltages together by paralleling them all, and it will probably take a little while before the ECU notices a difference in State of Charge, but this may cause problems with overcharging down the road.

So I'm thinking that the first step may be to discharge these modules with 1.3 volt per cell setting, and then put the pack together in parallel. Then manually do a series of shallow charges and discharges, maybe down to 8 volts and up to 8.2 volts or so . I can probably do a fair number of cycles pretty fast if I set the MRC to 5 or 10 amps. Hopefully the parallel arrangement will allow the modules to equilibrate the charge as well as the voltage. Does this make sense?

Also of concern is whether to attempt to seal these terminals. From what I'm seeing, I don't really think the sealant does a hell of a lot, other than to divert the electrolyte from the absorbent pad below the positive terminal and possibly give it a straighter run down to the pan. Also, the leakage is pretty consistently on the positive terminal, which goes along with the theory that the electrolyte ions are following the charge as they do in carbonate fuel cells. Note that individual ions can pass through apparently solid materials, so there may be no way to "seal" them per se. In any case, I don't know what material they were using. Any thoughts?

 

Unless these last two modules come up worse off than the best of the modules from the other pack, I will be discarding the whole "documented" thing. This pack is not as well documented as your battery, merely because I got limited data from the scangauge.

You think the O-ring is part of the original assembly? Or added with the gooey sealant? I don't notice the black rubbery material on most of the modules, just the severely corroded ones.

I could imagine sealing the terminals by setting O-rings around the terminal boss and then squishing them down with the bus bar. There are some ceramics that don't seem to create a trail for the ions to follow, I could see making a crushable plastic gasket that would fit around the terminal boss, coated with a thin layer of said ceramic, that would deform as it's crushed by the buss bar and forms a seal. That would be a helluva lot more elegant than this goop. But I don't have the resources to engineer such a fix.

 

Yeah, that's why I switched mid paragraph from talking about o-rings to plastic gaskets. The gasket can be made to the exact profile of the terminal boss. Also plastic deformation tends to extrude into gaps, whereas elastic deformation is more likely to bridge over them.

Of course I'm talking about this as if I actually intended to do something about it, but I don't work for Toyota. Hmmm, so what am I going to do with these things?

I didn't realize that the absorbent pads were part of the sealant recall. It seems like it's the only part that might actually work. Certainly the way the sealant was slathered on makes the pads less effective.

 

Not as much evidence of corrosion on the pan.

Lots more corrosion on the bussbars, and you can see growth of corrosion coming up through the bussbar covers in several places.

Quality Toyota service broke off the end of this locking clip on the cover to the power cable attachment points.

 

Data so far on this pack. Looks like maybe I will use a couple of the modules from the other pack after all.

I'm continuing to cycle the modules from the weakest blocks, to see which ones are the best candidates for replacement. Note module 14 only went through 2 cycles instead of the normal 3 (somehow I changed the setting), it may come up a little further on a third cycle. I'm leaving it to do 3 more cycles while I sleep tonight.

Also, I did a parallel charge on the other battery. So far I had only done a trickle charge on it, but I set it to 10 amps and watched. I was curious to see if the charger would decide that it was fully charged, when the 6 "cells" were actually a bunch of modules in parallel.

First off, the MRC can do 10 amps, but the fan ran full blast, so I decided that it might not handle 10 amps at 100% duty cycle. So I backed it down to 5 amps and the fan cycled on and off happily. It got up to 8.35 volts and then decided it was done, and went to trickle charge. So I guess the charger decided the pack was "charged."

 

Here's today's data.

The red data indicates that I'm planning on cycling those modules to see if they are weaker than modules from the other pack. This is based on the Delta SOC, or just low SOC, or because I saw a lot of electrolyte leakage, so it's kind of random. But I simply don't have time to cycle every module, so I have to prioritize.

The second page is me attempting to draw a correlation between the amount the module can discharge vs. the ratio of discharge/charge. There's no definitive decision making here, yet, but I was struck by module 19's 94% discharge/charge. That's pretty amazing efficiency.

The big surprise here is that modules 19 and 20 are from block 10, which was consistently one of the Vlo blocks, along with 13 and 14 from block 7. Of these, only 13 is a clear loser, although 14 is borderline. But 19 and 20 are among the top performers. I don't know what to make of that, but I must bear in mind that what I'm comparing is the worst of the new modules to the best of the old modules.

 

I'm cycling the last two modules right now. I'll post the data tonight when I get home from work. My plan is to build the parallel stack tonight and start trying to get the modules charged evenly by Sunday, then I'll be reassembling the battery and reinstalling it on Sunday.

If anyone has any input as to how which modules to use, or how to pair them up, now's the time to speak up.

 

Yes, from now on everyone should rotate their modules at regular intervals!

 

As I see it, the problem with strong-strong is that it implies that other blocks be weak-weak.

I've been considering the effect of charging the modules in parallel, and one of my thoughts is that even though an equal voltage is applied across all the modules, certain modules will take more charge than others. This compared with charging the battery in series, in which case all the modules, indeed all the cells have the same amount of current pass through them.

Of course, in my case, the parallel charging is unavoidable, since I don't have a 300+ volt charger. (At home, anyway, I do at work, but...)

And I think from the standpoint of equalizing the voltage to present a balanced charge to the ECU, parallel charging is perfectly good. It's pretty clear that part of the reason the blocks in this battery weren't showing a more uneven state of charge is that weaker ones were (sometimes) paired with stronger ones, which masked the voltage difference. I don't have any way of knowing if weaker modules cause a parasitic effect with adjacent modules though. (with fuel cells they do)

So I'm planning on using the data I have from the voltage decay over time to pair weak modules with stronger ones, in an attempt to create blocks with matched voltages.

I'm heading out to get the last of the data from these two modules. Be back shortly with the data.

 

Here's today's data (note there are two worksheets, the module selection worksheet is what I'm currently working with). I'm pretty much just using the discharge data to decide which modules from the new pack to replace with which modules from the old pack.

The lower section is me attempting to figure out how to pair modules to have the voltages balance, based on the tendency of different modules to find different voltages as they settle.