The fact that you have 19 sticks ranging 7.9-8.1 is a very bad sign. They should be within 0.05V of each other. You likely have a bunch of bad sticks.

All of them are likely in need of the prescribed discharge. Replacing a single stick will likely throw things way off.

If you recorded the 20 voltages, please list them.

 

Here are the voltages. The first set is from last month; the second set I just took. When I get the pack back in the car today, I'll commence the charge-discharge cycles and see what happens.
First readings:
1- 7.85
2- 7.85
3- 7.83
4- 7.81
5- 7.82
6- 7.82
7- 7.84
8- 7.86
9- 7.83
10- 7.83
11- 7.80
12- 7.79
13- 7.80
14- 7.83 <--normal then, but then changed at second reading.
15- 7.85
16- 7.82
17- 7.81
18- 7.80
19- 7.81
20- 7.82


Second readings;
1- 7.88
2- 7.85
3- 7.86
4- 7.84
5- 7.80
6- 7.83
7- 7.85
8- 7.88
9- 7.87
10- 7.84
11- 7.80
12- 7.82
13- 7.80
14- 6.97 <--when taking a reading, this number fluctuates wildly before settling on 6.97
15- 7.88
16- 7.86
17- 7.83
18- 7.83
19- 7.83
20- 7.79

 

Wild fluctuation typically indicates measurement error.

For the two groups of readings, please estimate:
1) time since last grid charge
2) # of drives since last grid charge
3) miles driven since last grid charge
4) time sat without driving/charging before readings were taken.

#14 is very likely bad, may be what's preventing successful grid charging, and may need to be replace, BUT the fact that your other 19 sticks range from 7.79 to 7.88 indicates they are at substantially different states of charge in the operating range.

 

For the first reading, the grid charge was Oct. 7, before a trip to the mountains. This is when the IMA and CE lights first came on. That trip was roughly 200 miles through winding mountain roads, and the pack was filled and emptied with multiple ascents/descents several times.

To be honest, I never wrote down when I did grid charges, but of course I should have. It's roughly every two months, as I don't drive it daily as I should.

It sat for 2 days before I pulled the pack for testing. I then placed it back in the car and hooked it up for a grid charge. The lights came back after 77 miles.

Since then, it's been driven about 100 miles before I pulled the pack again this week, Nov 7. It's been driven maybe 40 times before the second set of readings.

Estimate for the first set of readings:
1. 2 months
2. 30
3. 400-ish
4. 2 days

Second set of readings:
1. 1 month
2. 40
3. 250-ish
4. 3 days


I have the pack reassembled and started a grid charge last night, Nov 9. The first reading was 158 volts.

Tonight, after the 30 hours are up, I'll unhook it and start the discharge with a 60 watt bulb.

 

3 day sit before voltage readings is helpful.

I expect you'll be able to restore the 19 sticks to a much higher level of function with the discharge. The < 7.0V stick likely needs to be replaced, but on rare occasions the charge/discharge/charge can restore a weak cell to acceptable function.

 

Are these optimal discharge settings (from Hybrid Automotive discharge guide) for the HCH1?
First Discharge 96V
Second Discharge 72V
Third Discharge 60V
I'd like to do everything by the book, so I'd like to be sure these are the best ones.

 

Stepping isn't necessary, but you may certainly do so. Note that you MUST do a full 30 hour charge between discharges, so a 3 step process may take more than a week.

As I mentioned, discharge with two 40-60W bulbs in series may take close to two days.

 

A curious turn. I started the discharge process last night with one 60 watt bulb, after the grid charge settled on I think 168 volts.
I checked at noon today and the bulb was off, after 14 hours. I used the multimeter on the battery where the grid charger connects, and the reading was 135 volts.
As I understand, the bulb should still be on when I reach the desired voltage, and off when the battery was discharged.
The bulb and discharger are good; I plugged it into a wall outlet to verify.
Am I doing something wrong?

 

You have a connection problem somewhere.

Very good chance of blowing a single 120V bulb in this process. That's why I indicate using two in series. Running a 120V bulb at > 120V forces more current through the filament, and they don't last.

 

Luckily, I found a splitter at home that lets me run two bulbs from one socket.
Weird thing is, when I thought that bulb had gone out, I plugged it into another socket and it works fine.