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Discussion Starter #1 (Edited)
I am seeing a lot of new commentary on Grid Charging that seems to counter methods used over the years. This makes for a very confusing mix.

It seems that the initial process stemmed from the R/C crowd's experiments and apparatus for small battery packs in radio controlled cars and planes.

Can we use this thread to work out what the most optimal current procedure should be for grid charging and discharging of Gen 1 Insights at this point in time?


Some suggested parameters & topics:

- Consideration for battery pack's age & condition
- Grid Charge Current
- Grid Charge Start Voltage
- Grid Charge End Voltage
- Grid Charge Duration
- Grid Charge Frequency (schedule)

- In-Car discharging pack (by driving) before grid charging
- Preparing pack for load discharging
- Discharge Load : Incandescent Bulbs vs. Resistors
- Discharge Current
- Discharge Start Voltage
- Discharge End Voltage
- Discharge Rate
- Discharge Frequency (schedule)

- Natural Discharge (unattended packs for weeks/months)

- Stepped Discharge/Recharge process

- Pack Cooling

- Compare & Contrast Stick Level charge/discharge vs. Pack charge/discharge

- Commentary on climate, ambient temperature and pack life

 

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Just my 0.02$...

Grid charge frequency: once a year ore more often when your battery is weak and gives IMA light or recals frequently.

Grid charge end voltage: does not matter. What matters is: when voltage has not changed for 1-2 hours while still charging or when it even drops a bit, keep it going for 2-4 hours or so.

About discharging pack (by driving) before grid charging: it is even better to let the car do auto stop with headlights on and fan on (A/C off). The only problem: when the HV battery is empty from the car's point of view, the 12 V battery feeds it all. I have not checked that exactly, but it was no longer than 1,5 hours of auto stop on my last (and first) discharge session.

This was followed by single bulb discharging. Stage 1: 100 W/230 V down to 135 V or so. Stage 2: 18 W/230 V down to 70 V.

YMMV, but I thing that this helped in keeping my battery healthy. Besides, my pack is in good condition. I have never seen IMA codes.
 

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Good luck with getting that list filled in,theres way too many personal options,the newest one going around is now after a 24 hour charge which is been the common theme,now suggesting that it takes closer to 36 hours to get a good charge,
 

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I think the big issue is there is no wiki or faq, so instead one must sift through 35 pages of opinions and discussion. It's hard to distill actual answers. Even if there were 3-4 differing opinions, it'd be nice to have them in one spot. I'm not knowledgable enough about them to compile it.
 

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I agree. Unfortunately there are multiple projects with huge amounts of discussion, i.e. OBDIIC&C with 247 pages or IMAC&C aka IMA Control with 47 pages. I don't know what to do about such threads because to distill them down to pertinent info and instructions takes a great deal of time. I'm going to IF to find out the answers.
 

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I know my answer was a little dickish... at least I felt that way when I typed it due to frustration at the idea that anyone can give definitive information on the vast majority of it. There are too many variables.

TL;DR
Buy a Hybrid Automotive grid charger and follow Jeff's directions

https://hybridautomotive.com/pages/recon

Long version:

Here's my asshole, erm... opinion (YMMV):

Charging:


  • The WHY of charging: Grid charging is the single most important aspect and essentially the ONLY way to actually "balance" a pack. By "balance", I'm referring to each and every single CELL in the pack being at the SAME state of charge (SoC). When you've fully balance charged your pack, all cells will be at or so very near 100% SoC.
  • Preventative maintenance on a healthy pack should only be done every 3 to 12 months depending on circumstances. If the car sits a lot or is highly cycled due to hilly terrain - 3 months. If the car is in a mild climate and driven normally without exceptional hardships - 12 months. Extreme environments (Phoenix): once in April to prepare for summer, once in October to recover from the summer.
  • Grid charging as a preventative maintenance item on a pack that has thrown codes or is regularly recalibrating should only be done frequently enough to restore acceptable performance, e.g., the first recal witnessed 30 days after the last grid charge, two recalls within a week, one recal per day, etc.
  • Force charging within the car's normal operational range is an acceptable option to reduce grid charge time.
  • On a pack in an operational state (presumed 60-80% SoC), charge to peak voltage for 2-4 hours, 10 hr max @ 500mA max.
  • On a healthy pack from a discharged state, 10,400mAh input limit at 500mA max (based on 0.1C charge for 16 hours)
  • On a deteriorated pack from a discharged state, 8,450 mAh input limit at 500mA max (based on 30% charge inefficiency on a deteriorated pack).
  • Periodically recording total voltage as well as tap voltages is a very useful tool in determining when the pack is full. Constant voltage for 2-4 hours has you close enough to 100% SoC.
  • NEVER EVER EVER NEVER EVER NEVER grid charge without cooling. With a 350mA charge and no cooling, I've seen pack temps at 130°F when ambient was 37°F. Note that if you can monitor temps, cooling is not necessary provided no cell exceeds 110°F.
  • Precaution: extended charging of NiMH at low currents induces voltage depression with subsequent capacity loss. The practice of grid charging eventually necessitates the need for a deep discharge.
Discharging:


  • The WHY of discharging: Is done to eliminate "memory" associated with voltage depression. Voltage depression: Every time a NiMH cell is charged without being FULLY discharged, the phase of the terminal is altered. This altered phase produces current at 0.8V (depressed) instead of the nominal 1.2V. Deep discharging "consumes" the capacity stored at 0.8V. When the cell is recharged following a deep discharge, the proper phase is restored at the terminal and that capacity is again available at 1.2V. It's not uncommon for a deep discharge to restore > 25% capacity.
  • Should be done only when grid charging does not produce the desired results.
  • Current should be monitored ($5 harbor freight multimeter in 10A current mode in series with the load).
  • Time, Voltage and Current should be periodically recorded during a discharge (every 5 minutes for the first 30 and every 30 minutes thereafter).
  • The above record of time and current can be used to compute actual capacity. This can be compared between discharges to assess pack deterioration.
  • Tap voltage snapshots at 144V and 120V while UNDER 25W load can give insight into stick health.
  • High current (>25W) discharging should be limited to >1.2V/cell.
    Below 1.2V/cell, discharging should be limited to about 200mA (25W).
  • Capacity extracted below 144V should be limited to 1000mAh (about 5 hours on a 25W bulb).
  • Initial discharge target voltage should be 0.8V/cell, but the 1000mAh limit is more important. When capacity is computed, one can actually see the improved capacity above 144V on subsequent discharges. If there is a 20-25% improvement after the first cycle, subsequent cycles are likely not needed. If a second cycle only produces <10% improvement, a 3rd is likely unnecessary. If the computed capacity of a discharge to 144V @ > 25W is > 80% of rated, subsequent discharges are unnecessary.
  • Bulbs or resistors may be used. It doesn't matter which provided the voltage and current limits are respected. Bulbs behave a little more like constant current loads and resistors taper current linearly with voltage drop. Resistors will take longer.
  • Discharging in-car within the car's normal operating range is an acceptable option for reducing discharge time; however without current monitoring, the ability to compute actual capacity is lost.
"natural" discharging:
This encompasses MANY months and even a year or more of sitting. NOTE: A truly healthy pack WILL NOT DISCHARGE much BELOW 144V OVER MANY MONTHS. Yes, for deteriorated cells, extended self-discharge is very effective at eliminating voltage depression and restoring the capacity of cells/sticks/packs to their full potential, but a pack that self-discharges below 1.2V/cell is an unhealthy pack. My personal experience with extended self-discharge was an HCH2 pack (in NH, 110K, IMA light) that sat for 2.5 years ending at 0.45V/cell. The sticks all tested at 90% rated capacity, and the pack performed well in-car for 10 months. Note there is evidence that extended self-discharge improves IR measurably.

See my sig for stick level reconditioning.

Tidbits:

  • ANSI standard for NiMH capacity testing: 0.1C charge for 16 hours, discharge at 0.2C.
  • Per Energizer, NiMH cells are polarity reversal tolerant up to 50% extracted capacity, i.e., if you have a battery pack and one cell reverses polarity after 2000mAh extracted, significant cell damage should not occur until an additional 1000mAh is extracted. This must be done at low current. High current can force electrolysis in the reversed cell and destroy it prior to the 50% limit being reached. Momentary reversals of cells for short durations do not cause measurable damage. I've done it at 20A for about 5 minutes, and there is no measurable decay over the next few test cycles. I would not deliberately repeat the reversal for any reason but data gathering on a stick that I would never put back in a car.
  • Tap variations at rest and under moderate load (13A or less) should be less than 0.2V from Max to Min. A truly healthy pack will be < 0.1V min/max variation at rest.
  • Tap variations under max load (>80A) are typically 0.4-0.6V.
  • Cell variations within a fully charged stick should be less than 0.03V, >10 hours after charging.
Steve
 

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Discussion Starter #10 (Edited)

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I'll bite:

Background:
The various design choices and methods are all the result of a horribly implemented IMA system that guesses as much as we do on the overall SoC. The result is an unhealthy pack by design:
-No per-cell measurement circuitry, so can't analytically determine good/bad cell status.
-No bypass circuit in parallel with each cell, so can't nondestructively charge less-full cells once first cell hits '100%'.
-Some newer packs (even from Honda) lack series thermistors on each cell, so the only real method the computer previously had to tell when at least one cell was full (due to overheating <horribly, shudder>) is no longer present.
-Relying on NiMH's "self-recovering" overcharge condition - recombining oxygen and hyrdrogen back into water inside the cell - to overcome the above design decisions, yet not effectively trickle charging the pack when full during normal use.

In short, Honda really dropped the ball on the battery management system.

Most people agree that constantly trickle charging the IMA pack at ~350 mA is the safest method to balance the pack. I don't think you'll find anyone that disagrees with the method. Some people charge at higher current; others perform multistage charging. The recipes vary, but the theory is solid. You can easily build your own grid charger and install it with all the connectors for under $100... others prefer spending many times that buying some other system and even more getting said system installed, and I can't knock that because while I know electronics very well, others do not. I wouldn't know the first thing about performing heart surgery (how difficult most people think installing a grid charger is), but I could probably draw someone's blood with a little instruction (the actual difficulty).

Most people are also in the 'deep discharging' camp. I've been skeptical about the effectiveness, so I recently gathered some data on my own failing pack, since I couldn't possibly care less about its longevity*. In general, 'Deep Dischargers' make two claims:
1) "Deep discharging pulls all cells to 0 volts." It doesn't. Instead, it horribly unbalances the cells, particularly the weakest ones. After a weaker cell reaches 0 volts (i.e. runs out of juice), it starts 'charging' in the opposite direction due to the current still flowing through it from better cells. At some point, the overall voltage across all cells sums to 0 volts, even though the strongest cells are still very much charged, whereas the empty ones might be several hundred mV NEGATIVE. Eventually, the sum of all cell voltages is zero, so no current flows through the pack.

Test:
0: Discharge pack with a programmable load set to 1 amp. A light bulb and/or resistor bank aren't going to cut it for this test. Get an electronic load with programmable current sinking, remote sense, and very low dropout (less than 100 mV @ 1 A).
1: After a few hours, the pack still hovers around 50 Volts. Then suddenly the pack can no longer deliver 1 A. The programmable load does what it can.
2: A few minutes later the load can no longer sink more than 10 mA because the battery no longer generates a cumulative voltage. When this occurs, place a DMM across the pack (or use the one built into the load if you're using remote sense). You'll measure 0.00 volts.
3: Unscrew the semi-transparent "YOU WILL DIE" cover from the side of the pack. Take your DMM and probe stick pairs 14S at a time. Note that even though you might expect to read 0V across all the sticks, you'll actually see that there's a voltage soup ranging from 0 volts all the way up to plinus 12 volts!

Conclusion:
-Deep discharging certainly doesn't bring all cells to 0 volts.
-In fact, is does the opposite: Cells that have more charge to begin with (the good ones) stay positive, whereas cells that have less charge to begin with (the bad ones) end up at a negative voltage.
-If there's a chemical benefit to pulling cells negative, the 'worst' cells get the best medicine.


2) "Deep discharging changes crystal/chemical structure." Not in my test data. Methodology:
0: I charged the entire pack at 1 A for 3 hours, fans blazing high and monitoring PTCs.
1: I charged the entire pack at 100 mA for 48 hours, fans blazing high and monitoring PTCs. Total accumulated Ampacity: 7.8 Ah.
2: I disassembled the pack to 20 sticks.
3: I discharged each stick @ 30 A until the voltage 'necked', indicating the weakest cell was empty. I recorded the Ah on the stick in black.
4: To perform A/B testing, I paired sticks that performed similarly into twin pairs.
5: To maintain a control group, I divided the twins into two groups:
GroupA ("charge only") and GroupB ("discharge & charge").
6A: I did nothing. Being a control is easy.
6B: I continued discharging at 1 A until each stick output 0 V @ 10 mA load.
7: I charged all sticks as per 1 & 2 (above).
8: I discharged all sticks as per 3, and recorded the Ah on the stick in red.

Conclusion:
-There was no distinguishable difference between GroupA & GroupB cells.
-Deep discharging doesn't appear to have any benefit based on my test data.
-The only benefit I see to discharging the pack is that it allows you to charge the pack more; I believe any potential chemical/crystalline benefit occurs while charging. To fully test this theory, each control 'twin' would need to be charged the same number of additional Ah that the test twin discharged to reach 0 volts, then discharged the same amount. This neglects charge/discharge inefficiencies, which are difficult to calculate and are also part of the value we're trying to measure, so there'd be room for foul data.


Overall conclusion:
Deep discharging with an external setup takes a ton more time and effort than simply going for a drive and accelerating hard until the pack is again empty, then charging more. It's possible that the added benefit people attribute to deep discharging is actually the result of additional low-level charging.

*Full disclosure: I'm working on a competing project right now - Linsight - that will replace the entire OEM battery system and solve these problems.
 

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Overall conclusion:
Deep discharging with an external setup takes a ton more time and effort than simply going for a drive and accelerating hard until the pack is again empty, then charging more. It's possible that the added benefit people attribute to deep discharging is actually the result of additional low-level charging.

*Full disclosure: I'm working on a competing project right now - Linsight - that will replace the entire OEM battery system and solve these problems.
You are a ridiculously smart guy, and you know your ****. Your position on this baffles me every time you express it.

The pack is NEVER empty in the car. Never. Every reference indicates capacity is lost when NiMH is charged before it's fully discharged. How do you explain the capacity improvements obtained from cycling that have been documented here likely hundreds of times? Deliberately running the battery as low as the car can get it doesn't do anything to increase available capacity. It simply increases the depth of discharge, which increases "wear."

Your termination criteria is a bit confusing. Why did you not just terminate the discharge at the prescribed 1V/cell? How consistent was your termination voltage? Did you also compute extracted energy in Wh to see if there was a difference?

I can't tell you how many times I've seen it happen either from cycling or deep discharge. My first deep-discharge of an HCH2 pack increased the usable capacity by 25%. I grid charged for 24 hours, discharged to 132V (1V/cell) in 48 minutes at an average current of 4.2A (500W Halogen). I continued the discharge to 106V w/60W bulbs. I then recharged it for 24 hours and repeated the 4.2A discharge to 132V - which took right at an hour. The extracted energy in Wh increased even more than the Ah as the average voltage was a little higher.

I currently have a Prius pack on my bench. I have conducted a 10400mAh input charge, discharged to 1.05V/cell, deep discharged at 0.2A. I still need to repeat the input charge. I will then repeat the discharge to 1.05V/cell. I will post the results of each of the 28 modules before and after capacities.
 

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I'm still relatively new here. Both mudder and S Keith are ahead of me in many ways.

mudder's approach of bringing the pack to 0 volts is not what I've seen recommended. Maybe its recommended somewhere but I haven't seen it.

Yesterday, I did a detailed read of Hybrid Automotive's (HA) user notes for their bulb-based dischargers. That's because I'll build my discharger this weekend; my charger build last spring went well.

HA's user process runs three discharge cycles of the pack. Each discharge cycle is preceded by grid charging fully, to cell saturation. Each discharge cycle uses a series of three bulbs in decreasing wattage, ending up with a 25W bulb as the load.

Bottom line is that they don't recommend going lower than 0.1V per cell, which they only do in the last of the three discharge cycles. That's 12V for the full pack. HA's first and second pack discharge cycles only go down to 0.8V and 0.5V per cell, respectively. After reaching those limits, their process is to end the discharge cycle and recharge the pack.

Personally, I don't want to take my packs down to 0.1V per cell, or 12V/pack. Since I'm doing the whole pack as a unit, I don't want to risk pulling individual cells down below zero, which could happen if the whole pack is down at 12V. I'll probably end my final discharge at about 40-60V (pack), which is 0.3-0.5V per cell, assuming incorrectly that all cells will be at equal voltages.

Note, that 12V pack target from HA is with a 25 watt bulb for a load. At about 100V (pack voltage) when first connecting the 25W bulb, that's only a 0.25A load. Much less than the 1 amp load mudder discussed using.

As mudder touched on, bubs (which I'll use) have oddities when used as load resistors - their resistance changes with current and temperature so it's pretty much impossible to say what the ohms and loads really are (though you can clearly see the voltage). That said, all the bulb based discharge schemes I've read, use lower wattage bulbs late in the process, to reduce amps load. That way they have slower voltage drop, so the user is able to stop the process long before voltage goes to zero.

Hybrid Automotive bulb discharger user guide
 

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I'm still relatively new here. Both mudder and S Keith are ahead of me in many ways.

mudder's approach of bringing the pack to 0 volts is not what I've seen recommended. Maybe its recommended somewhere but I haven't seen it.

Yesterday, I did a detailed read of Hybrid Automotive's (HA) user notes for their bulb-based dischargers. That's because I'll build my discharger this weekend; my charger build last spring went well.

HA's user process runs three discharge cycles of the pack. Each discharge cycle is preceded by grid charging fully, to cell saturation. Each discharge cycle uses a series of three bulbs in decreasing wattage, ending up with a 25W bulb as the load.

Bottom line is that they don't recommend going lower than 0.1V per cell, which they only do in the last of the three discharge cycles. That's 12V for the full pack. HA's first and second pack discharge cycles only go down to 0.8V and 0.5V per cell, respectively. After reaching those limits, their process is to end the discharge cycle and recharge the pack.

Personally, I don't want to take my packs down to 0.1V per cell, or 12V/pack. Since I'm doing the whole pack as a unit, I don't want to risk pulling individual cells down below zero, which could happen if the whole pack is down at 12V. I'll probably end my final discharge at about 40-60V (pack), which is 0.3-0.5V per cell, assuming incorrectly that all cells will be at equal voltages.
First, you need to understand that you will be pulling DOZENS of cells below zero before you get to 0.8V/cell. Reversals start happening between about 135V and 144V (nominal). The Genesis One grid charger has reversal detection as a termination criteria, and it's pretty common for it to trip in that range.

A good rule of thumb is (1 - volts/cell) *100% = the % of reversed cells, e.g., at 0.8V/cell, you've reversed 20% of your cells. This breaks down at about 0.5V/cell. When you start to get really deep, total voltage is reduced as much by reversed cells showing more negative voltage thus offsetting the non-reversed cells.

Again, you need to adjust your perspective. You will begin reversing cells very quickly between 1.1 and 1.2V/cell. You need to get past it. :)

Per my list above, the key is to keep the current low and limit the total extracted capacity by measuring current and computing capacity.

Note, that 12V pack target from HA is with a 25 watt bulb for a load. At about 100V (pack voltage) when first connecting the 25W bulb, that's only a 0.25A load. Much less than the 1 amp load mudder discussed using.

As mudder touched on, bubs (which I'll use) have oddities when used as load resistors - their resistance changes with current and temperature, so it's pretty much impossible to say what the ohms and loads really are (though you can clearly see the voltage). That said, all the bulb based discharge schemes I've read, use lower wattage bulbs late in the process, to reduce amps load. That way they have slower voltage drop, so the user is able to stop the process long before voltage goes to zero.

Hybrid Automotive bulb discharger user guide
Per my list above, they behave MORE like a constant current load. For a halving of the voltage, you'll see about a 30% drop in current. The $5 Harbor Freight multimeter in 10A ammeter mode provides invaluable current data that takes a LOT of the guesswork out of it... it enables you to CALCULATE your actual extracted capacity. It is surprisingly accurate.

Given that you're going DIY, there's no excuse for you to omit that $5 piece of hardware.

Your conclusions are incorrect. First, you'll almost never get a pack to zero volts. I've inadvertently been as low as 1.2V on a Prius pack (168 cells). It was with the equivalent of a single 12.5W bulb (2X 25W in series), and the current flow was around 50mA.

Second, the use of lower wattage bulbs has nothing to do with any desire to allow the user enough time to terminate before getting to zero. It has everything to do with keeping the current flow low to minimize damage potential to the dozens cells that are in polarity reversal.
 

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Keith: Your post is a good description of what is going on while discharging a series connected pack. As eq1 and others have also pointed out cell reversal can occur at quite high pack voltages.

Second, the use of lower wattage bulbs has nothing to do with any desire to allow the user enough time to terminate before getting to zero. It has everything to do with keeping the current flow low to minimize damage potential to the dozens cells that are in polarity reversal.
Exactly.

This chart I made and present on my website might help people to see generally how different wattage series connected light bulbs affect the discharge current vs pack voltage. The straight line is a 500 ohm, 100 watt resistor discharge "curve" to show the affect of a set resistance vs the varying load of light bulbs.

http://projekt.com/locouki/Website/insight/insight-images/RL-Light%20Blubs_500R.jpg

For the apprentice Electrical Engineers, the load at any particular voltage vs current using different combinations of bulbs or resistance is: R = E / I (Voltage divided by current [in amps]). Please note that the cold resistance of the bulbs is very different while in use and should NOT be used to guesstimate what the current will be while discharging the battery pack.
 

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Thanks for that link. At some point, I checked my charts and just remembered the 30% current drop for a 50% voltage drop relationship. I see the same on three of the wattages I checked on your charts. Confirmation is good.

The resistor takes all the guesswork out of it. The 500Ω resistor puts the current at 240mA @ 1V/cell and 290mA at 1.2V/cell. Those are pretty good numbers. The only downside is the extremely long discharge time. IIRC, Peter uses a 300Ω resistor, which would help expedite the trip to 144V.
 

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More thanks, to S Keith and olrowdy01. The more I thought I knew, the more I discovered I had yet to learn. I'd planned my procedure on Hybrid Automotive's writeup but I like Steve's attention to detail. So here's my plan, per SK as best I can absorb what you've written.

0) Start with a fully grid-charged pack (SOC display is meaningless here).
1) I can discharge with a 150W bulb (or for me, 2-75W bulbs in parallel), but only to a point. 144V, or 1.2V/cell, should be the cutoff for the 150W phase. Note the time to reach that point, for comparison later.
2) I think I'll modify Hybrid Automotive's intermediate stage of discharging with a 75W bulb. I'll use 2-25W bulbs instead, total 50W. I expect some cells will likely start going into reversal in this phase, so I want lower current to avoid causing damage while in reversal. Good idea? Terminate that phase at 110V, or maybe at 100V.
3) After the 50W phase, I will use 1-25W bulb. I expect initial voltage to be higher than the 100-110V termination of the 50W phase due to the reduced load. Following your recommendation, I'll terminate the 25W phase after 5 hours (1,000mA) or when it reaches 0.8V/cell or 96V/pack. Whichever comes first.
4) Recharge fully after discharge.
5) Discharge again with 150W bulb or equivalent. End at 144V and note the time to discharge. If time is +20% or more from the time in step (1), consider it all complete.
6) If time to full is increased by less than 20%, continue into another deep discharge phase using a 25W bulb. This time, continue discharge down to 60V/pack, but again, limit time to 5 hours/1,000 mA.

Hmmm. If I get into a step (6), it could take longer to reach 60V than it did to reach the 96V limit of the first cycle. I'll just have to see how that plays out.
 

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Modifications in bold based OMHO:

More thanks, to S Keith and olrowdy01. The more I thought I knew, the more I discovered I had yet to learn. I'd planned my procedure on Hybrid Automotive's writeup but I like Steve's attention to detail. So here's my plan, per SK as best I can absorb what you've written.

0) Start with a fully grid-charged pack (SOC display is meaningless here).
1) I can discharge with a 150W bulb (or for me, 2-75W bulbs in parallel), but only to a point. 144V, or 1.2V/cell, should be the cutoff for the 150W phase. Note the time to reach that point, for comparison later. Wire in an ammeter in series. Record time, voltage and amps at 1, 5, 10, 15, 20, 25 and 30 minute intervals and every 30 minutes thereafter.
2) Deleted
3) 1-25W bulb. Initial voltage WILL be higher than the 144V termination of the 150W phase due to the reduced load. Following your recommendation, I'll terminate the 25W phase the sooner of 5 hours (1,000mA) AFTER 144V is achieved under 25W load or when it reaches 0.8V/cell or 96V/pack. Whichever comes first. Record time, voltage and amps at 1, 5, 10, 15, 20, 25 and 30 minute intervals and every 30 minutes thereafter. Record tap voltages at 144V and end voltage under 25W load.
4) Recharge fully after discharge.
5) Discharge again with 150W bulb or equivalent. End at 144V and note the time to discharge. If time is +20% or more from the time in step (1), consider it all complete.
6) If time to full is increased by less than 20%, repeat step 3 except terminate at the sooner of 60V/pack or 5 hours/1,000 mA

Hmmm. If I get into a step (6), it could take longer to reach 60V than it did to reach the 96V limit of the first cycle. I'll just have to see how that plays out.
We're talking $5 and increased monitoring/data recording to give you actual numbers you can compare to in the future AND data to share with the group. Sure, time alone is valuable, but it's a special kind of chubby knowing where your pack stands (might just be me, though). :D

Steve
 

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I think the big issue is there is no wiki or faq, so instead one must sift through 35 pages of opinions and discussion. It's hard to distill actual answers. Even if there were 3-4 differing opinions, it'd be nice to have them in one spot. I'm not knowledgable enough about them to compile it.
Exact. So let's collect our opinions. Our experiences.

I have written down my experiences and my knowledge in terms of GC'ing. I think everyone should do so to have one place with all of our experiences.
 
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