I blabber about a lot of stuff on here and other forums. I frequently make claims that cycling is a waste of time. Here's some recent cycling I did on an HCH1 stick.

Superbrain 989 settings:

• 6 cells
• 120°F charge cutoff
• 15mV delta-V charge shut off (pumps as much into the battery as possible)
• 0.9V/cell discharge cutoff (squeezes a little extra juice out and can help eliminate voltage depression)
• Wait time between cycles: 1 minute (impatient, 20 min better, 60 min best)

Stick condition: from 2003 vintage pack, history unknown, brought to me as a "spare" to use in conjunction with the installed pack to build 1 good from 2 bad. This exercise failed. Between the two packs, only 8 sticks (out of 40) still possessed the ability to deliver 90A for 10 seconds at > 5.4V - the most important and first-to-fail criterion. Initial efforts included a deep discharge to eliminate voltage depression and 2-3 cycles. The deep discharge was done at the pack level, cycles at stick level.

The google sheet below shows the results of 10 cycles on the Superbrain 989 on one stick. They were done in two groups of 5; hence the bump in the chart at cycle 5. The 989 only cycles in discharge/charge order, so since I didn't charge the stick first, the first discharge was only 15mAh as the stick was nearly depleted when I started, so out of 2 sets of 5 cycle runs, I only have 9 meaningful discharge data points.

Please note that this is "impatient" data. The lack of "cool down" periods between cycles exacerbates the trend as the cells are kept at elevated (though well within spec) ranges. The rest period between cycles helps to normalize the data. I was too impatient to waste 400 minutes in this exercise. When this cool-down period is allowed, the trend is less abrupt, but it is still in the same direction.

Simply put, discharge cycles to 0.9V/cell, which is more apt to eliminate voltage depression than the traditional 1.0V/cell, does not improve capacity or internal resistance. These sticks were deep discharged in the pack before it was ever cycled, so I can confidently say that voltage depression is not present to any significant degree.

Google sheet and chart

 

BTW... I'm wrong on the above.

Kinda...

There is hope for single Insight/HCH1 sticks. They were made during a time where quality was higher and there was other demand for industrial grade "D" cells. For HCH2 and any of the 12 cell subpacks - don't even bother. It's a complete waste of time:

https://www.greenhybrid.com/forums/f...26/#post260567

3 failed packs in 4 months.

You MIGHT be able to build a good pack if you start with 5 core packs.


For Insight and HCH1, it is still very unlikely that you'll have a lasting repair. You'll be back in it again unless you actually identify and replace the bad sticks... because you will definitely have some bad ones that just won't recover... always. If you don't replace the bad sticks, the best option is periodic grid charging to maintain performance... if you're going to grid charge, you might as well deep discharge to recondition the pack... if you're going to do that, there is essentially no reason to do stick level reconditioning.


IMHO, the ONLY reason to do stick level is if you have at least 2 packs from which you plan to build one good pack and hopefully have a few good spares left over. Don't be surprised if you need 3 packs to make one good one.

The above test results fail to consider (even though I mention it) that the sticks have already been "reconditioned" to eliminate voltage depression and restore capacity.

The Capacity loss observed is due to my "impatience" and not providing cool downs. And the trend is NOT in the same direction.

Cycling DOES have value, and it needs to be done with REAL currents. Charge at 1C to a 4-5mV/cell deltaV cut-off and discharge at 10A or more. Following a 10A+ discharge, you should discharge at 0.2C to see if there's much left in the battery. If you have more than 10% of the total cap extracted during the 0.2C discharge, one or more cells have higher IR, and the stick is junk.

Lastly, the absolute most important thing is self-discharge. Charge that sucker up and let it sit for AT LEAST 7, 14 or 21 days (longer is better). When you're doing a pack's worth of these things, the 10-20A discharge capacity, the 0.2C follow-on discharge capacity and the capacity remaining after 7, 14 or 21 days will absolutely identify the outliers.

Those outliers need to be replaced, or you will need to incorporate grid charging into your normal operations.


Head over to 99mpg.com and review the reconditioning process he describes.


Lastly, if you have any outliers that go into the pack, hope isn't going to make it work. A pack with outliers is a pack that lasts weeks or months, not years.

 

Is this taking grid charging into account, or strictly for packs that do not ever grid charge?

It seems replacing really bad sticks with decent ones can be a worthwhile endeavor if you combine with grid charging. I'm hoping you have real life data and experience to back up my hypothesis.

 

Two lines above the one you quoted:

"Those outliers need to be replaced, or you will need to incorporate grid charging into your normal operations."

People who cycle sticks expect a fix, i.e., they get to drive trouble/maintenance free for years just like they did before. It doesn't work that way.

"If you don't replace the bad sticks, the best option is periodic grid charging to maintain performance... if you're going to grid charge, you might as well deep discharge to recondition the pack... if you're going to do that, there is essentially no reason to do stick level reconditioning."

Replacing the "bad" ones is the challenge. How do you find the bad ones? How do you know the "new" ones are good?

Many people nurse a recently failed pack for many months or years with periodic grid charging and discharging... without ever touching the individual sticks.

 

I've read people having packs that have deteriorated so badly they have to grid charge weekly or biweekly and still getting IMA lights. These pack should have sticks that are relatively easy to identify as bad, say by trickle grid changing and waiting a week for self-dishcharge, or with harbor fright 12V load tester and identify the lowest performing sticks. Then check tap voltages and replace the lowest value ones with better sticks. Next grid charge should extend IMA light trigger to say 3 months rather than a week or two. Keep doing this indefinitely, and maybe you need to cycle out some severely bad sticks every 6 months or so, maybe even every year or two with monthly or quarterly grid charging and fortune on your side. Does this usage pattern sound feasible?

New ones being good would be via the usual hobby charger->harbor freight 12V load tester->self discharge tests. Keep a couple good sticks on the ready for the next 6 month-2 year rotation.

 

Most are looking for a "fix" that means they don't have to worry about it again. That is extremely difficult.

If you're willing to crack back into it up to 2-4 times/year and diagnose as you describe, then you should be able to get lots of trouble-free operation with periodic grid charges in-between.

Where are you located?

 

Awesome, that's good news! I'm in bay area, CA. I'm the one with all the annoying questions about 9AH packs and what not as well. Don't mean to aggravate anyone with my questions and curiosity. New to the game, thinking out of the box and what not.

I did just get into the whole hybrid thing after my old school '94 civic manual was stolen a couple months back and I had to go shopping for a replacement vehicle, and getting a hybrid was a no-brainer. Last time I had to buy a car back in 2009, a decent hybrid was still more than I wanted to pay at the time.

My main replacement is a 2011 Prius that needs no tweaking, so decided to get a 2004 civic with IMA troubles to amuse myself.

You're in AZ somewhere right? I saw something about an Insightfest. Do you know what that's about, and where it's held? Sounds like it could be fun to attend.

 

LOL. It's just that you haven't read the site. There are hundreds of pages of that activity.

Simply put, if you want to buy a new battery, get a Bumblebee. He builds the best, and it doesn't matter whether it's 6.5Ah, 8Ah or 9Ah - it's the PRE-build testing that he does that adds all the value. The tests them down the the cell level.

Sorry to hear about the theft. That sucks. I didn't do the hybrid thing until 2010, HCH2.

You've definitely taken on a project. If you ever just want to fix it right, the BB battery is the way to go.

Phoenix. I can't remember where it was. Indiana? I think they do it every other year. Just happened a few months back.

 

Oh man, I've already spent dozens of hours reading the site ramping up as a newbie. You seem to read all the postings, so you must have spent hundreds at least if not thousands. I know what the easy way is, but hard to justify dropping more change on a battery than what I paid for the car and what the car is worth even with a new battery. Maybe if I end up really loving it and driving the heck out of it, I may eventually do so. For now, incremental improvement, testing, learning and see if my interest sticks.

Since I just got started on this, I'm not quite so jaded to write off any new claims of increased capacity. But yes, I am extremely skeptical already from what I've learned via my several dozen hours of reading. And the fact they claim 9AH, not 10AH just gets my curious george hat spinning even more, such an odd number to stake a claim in. I doubt the guy will even call me back, but if he does I'll post anything I learn from it for posterity.

 

Write it off. It's pretty much BS. The 8Ah sticks are pushing it.