Gen III Hybrid Batt. Recon

Greetings all,

About 18 months ago, I purchased a 2011 Gen III Prius (base model, about 201k miles) from my stepson. It was flying the Triangle of Death at the time. After driving it around on the ICE since then (short & local trips only, low mileage), I finally felt I had adequate knowledge & available time to open up the hybrid battery, this message board helped a lot with that. The bus bars and some associated wiring was showing some extreme corrosion in places, I cleaned the bars and connective wiring to the best of my ability and reassembled with a very light coating of dielectric grease.

I assembled a DIY grid charger with APC 35-350 modules and a discharge device with an old porch light and a couple 100 watt incandescent bulbs, per instructions elsewhere on this site. I went through some charge/discharge cycles. Full charge first, then down to about 150 volts on first discharge, down to about 60 volts on second discharge, down to about 20 volts on third discharge. Charged it up again and this is what I'm seeing when I test each cell pair (below). My question is, is there anything here I should be concerned about? Or is it time to take the batt. off the bench and slap this bad boy back together for in-vehicle testing?

 

Correction: modules 9-10 pre-load should be 16.05 - not 16.5
That's a typo, my bad.

How does that change things? I'll see if I can update the graphic.

 

Well, if there's a way to update the image I'm not finding it. Here's an update with the 9-10 module voltage corrected.

 

My understanding of dielectric grease is, it exists to protect surfaces and impede corrosion w/out interfering with the flow of electricity. I did consult an electrician friend who consulted someone else and the received answer, why not use some dielectric on parts that are prone to corrode and develop questionable electrical connections as a result of corrosion.

It's a very light coating anyway, doesn't seem to interfere with charge/discharge cycles or voltage tests. Not enough there to drip or run if things get warmish.

 

Yay, sounds like I can start putting things back together. And thank you for the tip on that Dr. Prius app, I'll check that out.

 

What I have was purchased from NAPA many years ago. It didn't seem to interfere with charge/discharge cycles or with voltage measurement tests. And as I said earlier, it's a very light coat. If it causes problems days, weeks, or months from now it won't be too difficult to pop things apart and clean everything up with some lacquer thinner now that I have a better idea of how all of that goes & works together.

 

I was just about to confess that I seem to've misplaced my OBDII reader, thank you.

 

SitRep:

Hybrid batt. is in the car, all electricals connected but not much else re-assembled yet. I still need to finish some cooling fan op tests but initial indicators (Dr. Prius app) are that the 1034 bulb wasn't a heavy-enough draw, the app is reporting a .34 volt diff across the hybrid battery and there is a P0A84 error code IIRC, it may be an old code though. Still need to reset and retest that.

Assuming the .34 volt differential is correct, can any addition life be gained by rearranging the individual modules to balance things out a bit better? Or is that a wasted effort or worse, recipe for destruction? How about replacing the most problematic modules? Is there anyone selling decent-quality used modules at a reasonable price?

 

I found the secret answer elsewhere:

Looks like yes, after replacing the 2, 3 or 4 bad modules the new assembly can have all the modules re-ordered to balance things out better on the "book" voltage measurement front. I'm still looking for the best seller of suitable used modules though.