Finally past the covid but some residual fatigue is still there for me. But I did do a home made reconditioning. In the photo you can see I breadboarded the whole thing and used alligator clip jumpers to make connections. I am an experienced audio designer working with vacuum tubes so I didn't bother to package this and 360 volts doesn't scare me. Also you pull the disconnect plug on the side of the pack and it breaks the battery pack into 2. Since it floats, i.e. not grounded to the chassis, that makes it relatively safe to work on.
Also I didn't plan to keep doing this so breadboarding was enough packaging for now.
I used the directions from Prolong to hook up the high voltage. I had to research on my own how to get the fans to run. I bought a 3 amp 12 volt power supply and hooked the fans up with 5 ohm resistors in series with each. I had to ground the speed control pin in the connectors to enable them to spin. The fans draws 2.5 amps at full speed and around 1amp with the 5 ohm resistor. However the power supply would run 5 seconds shut down for 1 and turn back on as the overload protection kicked in and out. No harm to the power supply and the fans ran fast enough to do the job.
Also note that I had a larger fan blowing on the whole battery pack but it wasn't enough to keep it cool until the I had built in fans running during a sunny day.
My initial charged reached 339.4 volts and would not go higher. So I did a discharge as per the Prolong directions. I had to use 3 200W bulbs in series to start then dropped to 2 60 W bulbs when the voltage was low enough for them. I went through the whole procedure 3 times and the last charge got up to 344 volts max.
When I did a deep discharge the 3rd time I took some voltage readings on the battery modules in the HiHY. There 2 blades in each one 15 modules total, i.e. 30 blades. I found at least 7 modules that drained down to a few volts or less and some others held up to around 15 volts. So knowing that I dialed back my expectations for a revival of the battery. Although it did improve.
While I did this I used Dr. Prius app to obtain readings. It has a nice recording feature of the parameters so I was able to dump them into spreadsheets.
Attached are photos of the charger and the whole mess at work.
Rough schematic. I used a 1 ohm resistor in the ground leg to monitor current, which allowed me to also switch to voltage easily. However I didn't include switches or or the fan circuits. I hooked up the fans with alligator jumpers. Also it shows 2 ways to build fan control modules for a Toyota fan but doesn't show the 5 ohm resistors or a necessary 555 pulse width modulator to control fan speed fi you don't want to do the 5 ohm resistor.
I could not find the connectors online to hook to the fans or I would have built a more complete circuit. If anyone knows where to get them let me know, though I know this isn't a Toyota forum.
Here are some Dr Prius screen shots.
Before, heavy discharge, and after.
Again, thanks for all the help and inspiration. I will be looking for some decent blades to rebuild the pack or I may just spring for a rebuilt battery with a warranty with gas is at $5/ gal.
All in all, I have a much deeper picture of the health of this battery however this just took a lot of time.