Best discharge rates for new eneloops pre and post break-in?

Got a new C9000 and 12xAA/4xAAA new eneloops today.

Trouble is now I`ve got the freedom of setting the discharge rate indipendantly of the charge rate I`m not really sure what to set it too :thinking:

Before settling them into service I plan to run a discharge cycle, rest for 2 hours then a break-in.

What discharge rate do you recomend for the initial discharge and once their broke in should I use the same rate when doing a cycle?

Thanks all.

I normally use 500 mA discharge for the AA and 200 mA for AAA Eneloops.

I do a 100mA discharge before doing a break-in cycle on my AA eneloops. My reasoning behind this practice is, that if any crystalline formation has occurred during the time the cells have been on the shelf (in the case of eneloops, this can be quite long), this low rate will remove more of the structure than a higher rate.

The C-9000 really isn't the best charger/analyzer to do this with, as it uses PWM. It's actually discharging the cells at 1000mA no matter what you set it at. In the case of 100mA discharge rate, it is discharging the cells at 1000mA, 10% of the time. Just the same 100mA will achieve better breakup of the crystaline structure than a higher rate. I have verified this with a CBA II.

When I first used this method, I was getting about 100-150mAh higher capacitiy after the first break-in cycle, than others on the forum who used higher discharge rates, or didn't discharge the cells at all, before running the break-in cycle.

Dave

Black Rose, any particular reason?

Dave, Makes sense, I suppose it`s best to use the lower rate whenever discharging aswell.

45/70 said:

In the case of 100mA discharge rate, it is discharging the cells at 1000mA, 10% of the time.

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hmm, why does it use PWM if it`s not the best way?

Thanks for the input guys.

crofty said:

Black Rose, any particular reason?

Dave, Makes sense, I suppose it`s best to use the lower rate whenever discharging aswell.

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I don't believe it's necessary to use 100mA all the time. For one thing, it takes forever! I just use it before doing a forming charge (break-in) or when I actually suspect there is crystallization in the cell(s). For example a cell that's sat around unused for a long time.

As for

hmm, why does it use PWM if it`s not the best way?

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I'm not sure what you mean. I suppose Maha uses PWM because it's simple and makes the charger efficient etc. For most tasks the C-9000 is used for, the PWM is fine. As I pointed out, it still works, just not as well as a steady current, when breaking up crystalline formations.

Dave

crofty said:

Black Rose, any particular reason?

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No particular reason on the discharge rates.
Most likely related to something I read here in one of the numerous charging threads

Those rates are one quarter the capacity of the cells, so it wouldn't stress the cells very much, to a certain degree would address the crystalline formations Dave mentioned, but also wouldn't take forever to drain them.

45/70 said:

I'm not sure what you mean.

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You said it`s not the best method so I just asked why the best method isn`t used. Like you say it still does a good job though so I can live with it.

Black Rose, Yeah, there`s lots of info here, various rates are used by everyone. There doesn`t seem to be an ideal set rate, maybe because the ideal rate differs depending on what your doing, what info your after and how much time you`ve got.

I think I`ll use the lowest rate before a break-in, then pick the best rate for the given situation after that.


Thanks for the help guys.

The AAA`s have just finished the out of pack discharge, here`s the stats if your interested:

dated July 2006
Battery 1: 579 mAh, 381 min, 1.23v
Battery 2: 579 mAh, 381 min, 1.23v
Battery 3: 557 mAh, 368 min, 1.23v
Battery 4: 575 mAh, 384 min, 1.23v

Considering the factory don`t charge them to 100% and they`ve been siting for 2.5 years I`d say that is quite good. Consistency is good aswell, battery 1 and 2 are identical... spooky.

Looking good, crofty, and sounds like a good plan. :thumbsup:

Dave

crofty said:

Considering the factory don`t charge them to 100% and they`ve been siting for 2.5 years I`d say that is quite good.

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You sir are the master of understatement

Those capacity numbers are fantastic....that is why Eneloops are king when it comes to NiMh LSD batteries.

Black Rose said:

You sir are the master of understatement

Those capacity numbers are fantastic....that is why Eneloops are king when it comes to NiMh LSD batteries.

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Can we expect the same good performance from the Duralcells (supposedly made as well by Sanyo)

Thanks Dave.

Black Rose said:

You sir are the master of understatement

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Don`t let my cool words fool you, the numbers speak for themselves :thumbsup:

bp044, White topped made in Japan Duracell LSD`s are confirmed rebadged eneloops

This is a timely thread. I just got a C9000 (early Xmas gift, I guess. I enjoy living life on the edge).

I read through almost all the C9000 threads/FAQs and was overloaded with information. Had a hard time filtering through all the info to find the "best" charge and discharge rate, procedure out of the box (Discharge/Break-in, Discharge/Break-in/Refresh & Analyze), procedure when used, etc.

Information overlaod :duh2:

HunkaBurninLove said:

This is a timely thread. I just got a C9000 (early Xmas gift, I guess. I enjoy living life on the edge).

I read through almost all the C9000 threads/FAQs and was overloaded with information. Had a hard time filtering through all the info to find the "best" charge and discharge rate, procedure out of the box (Discharge/Break-in, Discharge/Break-in/Refresh & Analyze), procedure when used, etc.

Information overlaod :duh2:

Click to expand...

I too am confused as to the best procedure to use . Could I use my MaHa C800S do do a proper forming charge or is the c9000 the way to go ?

Hello Crofty, and others,

The proper break in charge is 16 hours at 0.1C. Since Eneloop cells are 2000 mAh, this means a 16 hour charge at 200 mA.

Once the cell is charged, industry uses a 0.2C discharge rate to determine capacity. This means discharging Eneloop cells at 400 mA.

As Dave indicated, you can obtain a more complete discharge by discharging at a lower rate.

I usually use a standard charge followed by a standard discharge and check the capacity. If I find that the capacity is not up to par, I will then go into cell recovery mode and use a lower discharge rate followed by a standard charge. It may take a few cycles of this to bring the cell back into vibrant life.

Tom

Thanks, Tom. That's a useful summary.

I got my C9000 after I have been using AA Eneloops and Duracell pre-charged a few times. The initial few charges on those batteries were on a Maha MH-C401FS.

I've been running a Refresh and Analyze (using the default 1000 charge/500 discharge) on the Eneloops and Duracells and logging the capacity and voltages. The differences compared to the rated capacity range from 3.4% to 6.10%. So I guess I may do a break-in if things don't improve :shrug:

HunkaBurninLove said:

I've been running a Refresh and Analyze (using the default 1000 charge/500 discharge) on the Eneloops and Duracells and logging the capacity and voltages. The differences compared to the rated capacity range from 3.4% to 6.10%. So I guess I may do a break-in if things don't improve :shrug:

Click to expand...

If you run a break-in with the C9000 on Eneloops the typical result is in the 1900-2000 mAh range. R&A tends to come in lower due to the conservative charging algorithm the C9000 uses -- maybe less than 1900. This is nothing much to worry about and is a normal result for those cells on the Maha.

I've noticed that if I use Cycle mode instead of Refresh and Analyze, the C9000 reports slightly higher capacities.

bp044 said:

Could I use my MaHa C800S do do a proper forming charge or is the c9000 the way to go ?

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The simple answer is, no. As Tom pointed out, there are specific criteria that must be met to perform a forming charge. Keep in mind though, that not everyone has a C-9000, or one of the more expensive programmable chargers, that will perform a forming charge.

Your C-800S is an excellent charger. While there are benefits being able to do a "standard" forming charge, it's not absolutely necessary. The advantages would be longer cell life and increased capacity. If you use your C-800S regularly however, it should keep your cells in good shape.

There are other ways you may be able to perform a forming charge. One possibility, is if you happen to have an older "dumb" charger (14-16hr) that just happens to charge (in the case of eneloop AA's, or other 2000mAh cells) at 200mA (0.1C). If you put the cells in, time it manually, and pull the cells out at 16 hrs, this will work. One point to note is that when using one of these type chargers for this, you want the charge rate to be no more than 0.1C, or 200mA in this example. You may get away with a slightly slower rate of charge and extending the charging time proportionately, but don't go over 0.1C.

I hope to add a Maha 80x series charger in the future. An 8 bay would be nice.

Dave