2007 TCH w/182k miles throwing VSC and Hybrid codes
 

My TCH is trowing the P0A80 code but none of the P30xx codes indicating which block(s) is(are) bad. This is the 2nd inning in this particular ballgame. I'm looking for advice on the best way to proceed given a few constraints (S Keith's input especially desired):

• Replacing the full pack with new, though ideal, isn't on the cashflow table for me right now (kid in college, etc, etc). Not sure it will be for this car given the other improvements I should do if I was looking for 10 more years + another 120,000 miles. (~$2k worth of this and that including recovering the driver's seat and fixing the garage dings on the corners from kid learning to drive*)
• I'd rather go another round or two with the battery before caving in and replacing with a rebuild ... see cashflow above.
• I'm OK doing load testing / battery refurbishing over a few days, but I'm not in a position where I can let the car sit for 7+ days between steps. I have built my own load discharger, but can purchase a Schumacher BT-100 or similar if that's really better given I don't have the 7+ days to let the car sit.

The back story

• Japanese built 2007, put in service new in August 2006.
• Has been garaged in the DC Metro area its entire life.
• Fairly consistent 14-15k miles per year

In October 2018 it threw the dreaded P0A80 code. Included were a couple P30xx codes pointing me to specific blocks. Upon removal and disassembly of the pack, the level of corrosion on the copper connectors near those blocks was ... like very, very old pennies. Others were corroded, too, but not as bad. Cleaned everything up to a nice shine, then load tested with my home-brew load tester (used a headlight bulb) for about 15 seconds. (Not nearly enough time, I have since learned by reading more here.) Replaced the one battery cell that was very low compared to the rest. 33 others all performed the same in that very limited test. Figured corrosion was the major culprit for the rest. Reassembled the pack, re-installed in car, and was good for the next 5 months (but only ~4k miles). Last week, P0A80 appeared again, but since then no P30xx codes to give me a hint as to which block might be the trouble-maker this time.

My Prolong charger arrived this week ... and I'm ready to run the charge/discharge cycle (home built bulb discharger using S Keith's discharge routine). Willing to take a few more whacks at the moles but want to be efficient at it given my time constraints, if possible. The BIG Q I have is: Would it be valuable enough to take data via the Techstream software / cable / laptop to order and wait a few more days before starting ???

TIA

Re: 2007 TCH w/182k miles throwing VSC and Hybrid codes
 

Climate?

Re: 2007 TCH w/182k miles throwing VSC and Hybrid codes
 

Mid Atlantic ... warm/hot (high 80'-90's) humid summers, cold'ish (low30's-mid40's) winters, beautiful spring/fall. Too cold for Mrs 07Blue ('Nawlins girl) to go farther north ... too hot in summer for me (NE Penna boy) to want to live farther south.

Re: 2007 TCH w/182k miles throwing VSC and Hybrid codes
 

Trying to gauge how much damage your battery has sustained. Camrys are very hard on them. Cooler climates tend to fare a bit better.

The issue with a Techstream evaluation up front is that you're assessing an old deteriorated pack, which won't tell you a lot beyond maybe helping identify the culprit. The idea with the following is to recondition everything to ensure everything is as good as it can be. That's the big issue with module replacement... you have (34 - # replaced) other modules that have deteriorated to a small fraction of their rated capacity and are more prone to failure.

I've made a lot of recommendations, so I'm not sure which you're using. Assuming two light bulbs in series.

Charge for 24 hours
Discharge to 224V at max wattage.
Discharge to 163V at 40W max (may take a VERY long time)
Charge for 24 hours
Discharge to 224V at max wattage.
Discharge to 102V at 40W max
Charge for 24 hours

Note that the above cycles can be run non-consecutively, i.e., as long as you precede any discharge with a 24 hour charge, you're good. Do the first one over a weekend, drive the following week, do the second one over the 2nd weekend. You may opt for a 3rd discharge. If so, repeat it to 102V, don't go lower. If you don't have enough time to do the 2nd 24 hour charge during the weekend, do as much as you can, 12 hr minimum.

Additional goodness: if you're inclined to remove the cover during the discharge and capture the module voltages at various target voltages, that can be diagnostically useful. Consistency is key. You'll want readings at 245V, 224V and 204V on both discharges (±1V).

Techstream assessment:
Connect to car, HV Control computer and select the dropdown that focuses on the battery
It may help to create a custom data set that has only, SoC, current and the 17 block voltages.
Start recording
Discharge in Neutral using as many electrical accessories as possible (lights, interior lights, rear defroster, A/C or Defrost setting). Continue discharge until the car squawks that you should put it in "D" or "P"
Note that A/C is the best, but your climate may not permit it. If that's the case, use defrost. The engine will have to run to produce the heat, but in "N" it can't charge. Defrost can work nicely too because the 12V system is running the spark plugs, and the HV battery has to charge the 12V system.

That should show you how the blocks are behaving under a decent load.

There may be one or more turds that prevent a meaningful test, but you'll know to replace them when you see the block voltage drop off a cliff. You'll KNOW to replace that one.

If you get lucky, you'll only crack the pack once, but it may take two forays into the pack to get it sorted... Small chance of 3+; HOWEVER, once complete, your repair should be much more long-lived, particularly with occasional techstream assessments and one charge/discharge cycle per year.

Re: 2007 TCH w/182k miles throwing VSC and Hybrid codes
 

Thanks for the quick reply.

I replaced 1 module back in Oct. ... 33 originals. That replacement was dated 2011, IIRC. I've learned a lot about the battery module life/behavior since then and if I need to replace modules want to evaluate them all as best as possible (sans letting the pack sit for 7 days between actions ... would love to, but life attm won't permit it ... summer or next fall, maybe).

Follow-up questions - apologies in advance if they seem more educational rather than practical in nature. I do respect and appreciate your time.

• For planning purposes, how long do you anticipate the discharge from
• Max wattage ... 2 x 200W still OK? (your most recent rec, from what I could find)
• Skip the 2 x 100W step and go straight to 2x40W? Works for me ... just curious about the logic of skipping the 2x100W step. Is a longer, slower drain more beneficial?
• You probably explained someplace that I missed ... but why the higher end-voltage on the first discharge cycle?
• You mention the 3rd discharge/charge cycle is optional. I've had good results with 3 cycles on 1.2V NiMH AA and AAA cells in a Maha charger using the "soft" charge (lower amperage, less heating) cycle. Honestly never compared 2 vs 3 ... but you have me wondering about diminishing returns. Nevertheless, I'm likely to do all 3 if it helps, taking data at each step. Engineering nerd ... gathering data is a hobby. Someplace I have the voltages from the testing in October ... will post when I find them.
• Sounds like the techstream is really good to have for later testing, but not needed/strongly recommended to get started. (Yay!) Looks like the techstream s/w is Windows only, true? Suggestion for best source for cable?

Again, thanks in advance.

Re: 2007 TCH w/182k miles throwing VSC and Hybrid codes
 

Initial discharge may take a very long time. I wouldn't be surprised if you're looking at 12-15 hours.
2X200W still okay if you can find them.
You can still do 100W x2, but I usually omit it for simplicity. May help shave a little time off the process.
Not sure I understand "higher end-voltage"
Depending on the severity, it's not uncommon for the 3 cycles to improve 30-50%, 10-15%, 0-5%, respectively. IMHO, diminishing returns on the 3rd.

I was under the impression you already had Techstream. If you're going to take module voltages at stages, you can probably get away with not using it.

If you're truly an enginerd, wire a cheap harbor freight multimeter in series with the load in 10A ammeter mode and measure the actual current being discharged. log periodic time, volts and amps readings, 1 min, 5 min, 30 min, 60 min and each hour thereafter as well as the target voltage points (where you're measuring the 34 modules). You'll be able to calculate your actual capacity.

Re: 2007 TCH w/182k miles throwing VSC and Hybrid codes
 

Charging is underway ... I'll post the data I've taken so far later tonight.

"higher end-voltage"
On discharge number 1 you suggest stopping at 163V, as opposed to the 102V used for subsequent discharges. (0.8V per cell vs. 0.5V per cell)
... Curious about why the difference? Is it not to over-stress potentially weak cells before that first big re-charge?

I assume it's ok just to unscrew one of the 200W bulbs rather than swap out to 2 x 100W bulbs - don't have to pause the discharge that way. I have 2 x 40W "appliance" bulbs for the last part of the discharge. Let me know if I'm off-base here.

Speaking of charging - Why is the charge target/limit at 24 hrs as opposed to some preferred voltage level or charging current parameter? Since the Prolong displays both ...
Is it a time/heat thing? (Something you don't worry so much about with lead-acid batteries, within limits of course. Equalization charge is done at a slightly higher voltage than the nominal cell voltage, e.g. 2.45V/cell for a typical LA/SLA/VRLA batt, until charging current drops under 1% Ah capacity). I do realize that perfect modules with their 6500 mAH should only take ~11 hours to charge from 40%-100% if the charge rate was steady-state. But after bulk charging I'm assuming the current drops off during the equalization phase. (True for any good LA/SLA/VRLA charger.)

If all goes well I should be done the 3x cycles by Sunday. My inner nerd now wishes I had the time-luxury of getting the 7-day self-discharge data ... but I am looking around for my old/cheap multimeter to wire in during discharge per your suggestion. (That was a particularly creative idea - thx!)

Re: 2007 TCH w/182k miles throwing VSC and Hybrid codes
 

The level of voltage depression in each of the modules will vary wildly. You won't have 204 cells at 0.8V per cell. You may have some CELLS (not modules) at -0.5V (yes, negative) and some at 1.1V. Running the cells for too long in reversed polarity will damage them.

Use the safety plug to terminate the discharge and replace the bulbs.

24*350 = 8400mAh. The ANSI spec for NiMH capacity testing calls for 0.1C charge for 15 or 16 hours (can't remember which), so 50-60% MORE input than rated capacity. This is to address charge inefficiencies (charging efficiency goes way down above 80% SoC) and imbalance.

It's highly unlikely your battery is anywhere near its 6500mAh capacity after reconditioning. Possible, but unlikely. NOT getting all 204 cells to 100% SoC is way worse than if you have to overcharge the snot out of some. 24 hours is somewhat arbitrary for conservative reasons to ensure all CELLS are at 100% SoC.

Alternative means of termination are:
Peak voltage held for 8 hours OR
Voltage drop that comes back up to peak OR
Voltage drop that keeps dropping OR
Warm air exiting out of the pack

Different because NiMH charging and Pb charging aren't anything alike. Bulk, absorption, float and equalization have no literal analogy. The closest one is equalization, but it's not about voltage, it's about input. NiMH cell voltage DROPS when it gets full unlike Pb, which will keep going up until things get really ugly. Cells in different conditions have different peak voltages, so LITERALLY, every single pack is unique and even though you can get kinda close, there's no one-size-fits-all.

Re: 2007 TCH w/182k miles throwing VSC and Hybrid codes
 

I didn't realize what you were saying here until just now. You are WAY off-base. First, the bulbs need to be in SERIES, not parallel. If you wire them in parallel, they will blow almost immediately (110V bulbs subjected to > 250V). When they are in series, if you unscrew one bulb, you open the circuit and the other bulb goes out.

Re: 2007 TCH w/182k miles throwing VSC and Hybrid codes
 

If it makes you feel any better, here's my (continuing) story. I got the battery dead code some time ago. I cleaned the terminals, re-assembled, and started driving again.

Maybe 10,000 miles later I got the code again. Using my tablet, Torque, and a $20 dongle, I reset the code and drove another couple thousand miles before the code reappeared. Long story short, I have reset the code no fewer than 30 times since then and it's still running some 30,000 miles later (maybe 40k). (Note that I also get the VSC code and it just goes away)

The car has so many miles (over 300k) that I have no intention of investing in a battery but it's amazing how it just runs and runs and......