Rechargeable LSD NiMH Battery Maintenance [Archive] - Glock Talk

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Bolster
05-27-2012, 13:17
I've been on a "learning bender" the last week regards how to care for my LSD NiMH cells (= Eneloop, Duraloop, others), which are currently the "go-to" type of rechargeable AA and AAA cell on the market. I'm not the world's expert on this, but I have studied and learned the following:

- Stockpiling Eneloops (or other LSD NiMH) takes a little maintenance. Can't just throw them in the drawer and expect to recharge when needed. Neither can you expect the stock charger to keep them in good shape.

- Buy as many as you can use, but not more than that. Or you'll just have a maintenance task on your hands.

- The capacity of a seldom-used or stored Eneloop will be down to half capacity in a few years. Regular use keeps them healthy. But even regular use needs the occasional "Refresh & Analyze" cycle to redistribute electrolyte.

- You can (usually) get (most of) that capacity back with a smart charger.

- The two smart chargers most frequently recommended for NiMH AA and AAA (and maybe up to D? Not sure) are the Maha C-9000, and the La Crosse BC - 900. I purchased the former due to slightly more recommendations on CPF.

- Smart chargers have these "conditioning" cycles, "refresh & analyze" cycles, or a really thorough one called the "break in mode" (BIM). The BIM will trickle in an overcharge, then drain it out, then trickle it back in, over the course of two days. This process redistributes the electrolyte and gives most your capacity back. Oddly the overcharge does not harm the cell due to the very (agonizingly) slow rate it is trickled in.

- You should BIM lightly-used Eneloops every 12 months and BIM stored Eneloops every 6 months. (Oops. I'm now reviving cells I bought in '07!)

- Eneloops are best stored at 60% capacity or thereabouts. So if you're really neurotic, after you BIM, you run a discharge cycle till the cell's down to about 1100-1200 mAh, then store in a cool place. Opinions split on whether refrigerator is good idea or not. Not necessary.

That's the basics of what I learned, hope it's helpful to someone. Apologies to all of you who already knew this. And further apologies if any of it is incorrect, please chime in if so.

Carry16
05-27-2012, 20:33
This is a great topic - I've wondered about this myself. I periodically recharge all my AA-AAA rechargables, but don't have a routine established. I'm curious about storing the LSD batteries at 60% - did that come from the manufacturer? The whole reason I bought these is that they hold (maybe) 85% of the initial charge for close to a year. Storing them at 60% seems to be self defeating. Are they saying that at 60% they will last longer or hold that level charge longer?

Bolster
05-27-2012, 20:49
Since I'm not an engineer I just try to keep up. One of the moderators at CPF (and a good one, SilverFox, with lots of knowledgable posts) posted that 60% "rule." He further explained that when Eneloops came from the mfg at 80%, that was an ideal compromise between "ready to go" and "could be stored for awhile."

I've continued reading and wouldn't you know it, I've found another poster (bbb74) who stores his at full charge because he's "not found much evidence to say that any other charge rate is better or worse." (And he's a refrigerator storer.)

So at some point, if you rely on forum chatter, the way forward gets murky. SilverFox has the credibility of being a very high post moderator (11K), in a forum where you are cut to ribbons if you make a mistake. I asked SilverFox if he'd recommend after doing a BIM, that we discharge to 60% if we had storage planned and he said, "Probably not. Just use them." So I think I'm starting to get into the etherial academic realm with what charge to store at, but from what I've read so far I'd not store fully charged or discharged for NiMH (other chemistries have different preferences.)

WAY more important that what charge you store at, is the ability to do a Refresh or a BIM. Do you have the ability to do one of those every 6 months or so? If not, and you want to keep your LSDs healthy, best to get a smart charger. Because using the factory supplied charger won't help you redistribute electrolyte, as is needed every so often.

Regards "every so often," the Maha recommendation is R&A every 10 cycles and BIM every 30 cycles.

Oh, I forgot to add: the other reason I got the Maha-c9000 is because it can be run off 12v. So that fits into my off-grid plans.

And a third reason, if you need one, it makes a very bright night-light. That sucker lights up the room.

Bolster
05-27-2012, 21:09
One other odd piece I've learned about, is ideal charging rates. Eneloops are 1900 mAh capacity (when functioning well), and that implies it will do OK with charge rates from .5C (half capacity, 1000 mA, although some sources go as low as third capacity, or about 650 mA) up to 1C (1900 mA). It appears that 1/2C is the standard go-to rate (again, that's 1000 mA for an Eneloop). There's a "no go" zone between .1C and .3C; apparently charging too slowly is bad, because with a slow charge the charger can miss the end-of-charge voltage drop (which terminates the charge) and keeps going, thus an overcharge.

And yet...a .1C charge is not only good, it's the cornerstone of a BIM. Yes, the charger can't detect the end-of-charge voltage drop (in this mode it is timed), but at those very low rates, you can overcharge and the effect is to stir up the battery (a good thing). But if you overcharge at a higher rate than .1C, then...bad.

Here's where it gets odd: Sanyo's bundled Eneloop charger charges at 300mA, ie .15 C, putting it just in the "danger zone"! Not to mention that it is an exceedingly slow charger. Now I can hardly believe that the mfg is screwing their own batteries, but it is puzzling. Maybe they terminate by time and not voltage drop; I have no idea. At any rate, why not get your cells done much faster, and safely, with a smart charger.

ratf51
05-27-2012, 21:39
Look, I tried to resist this but I can't:

I thought LSD was an illegal substance; but "The Secret of NiMH" was a good movie and a good children's book (the book title was "Mrs. Frisby and the Rats of NIMH".) :rofl:

(Actually, I do know what NiMH is, but I am unfamiliar with LSD in this context. What does it stand for?) :wavey:

Carry16
05-27-2012, 21:49
I have a C-9000 - yes, it makes a great emergency light.

I have been very apprehensive about charging my NimH batteries at 50% of rated current. Probably because everything I've read about solar installs suggests charging your battery bank at 10% or slightly higher, but never at 50%. But you have researched this far more than I and I have a lot of faith in your posts here so I'm going to start doing the 50% on the LSD units, but stay at 10-20% on my standard NiMh batteries. I know the composition of lead acid deep discharge golf cart batteries is far different than NiMh, but it would just seem that a 50% charge rate would be stressful to most batteries. But then I'm an old man and times do change.

One other question, do you know of some way to instruct the C9000 to discharge to the 60% level and stop? I don't recall reading anything like that when I bought the unit. Fact is I never have used the discharge feature.

Deputydave
05-28-2012, 08:38
(Actually, I do know what NiMH is, but I am unfamiliar with LSD in this context. What does it stand for?) :wavey:

LSD = Low Self Discharge. These batteries don't lose much on their own normally. I looked at some recently and according to the info provided maintain something like 80% after 6 months and 60% after 1 year.

ratf51
05-28-2012, 09:58
LSD = Low Self Discharge. These batteries don't lose much on their own normally. I looked at some recently and according to the info provided maintain something like 80% after 6 months and 60% after 1 year.

Thanks for the answer, once again, I have learned something new! :wavey:

Bolster
05-28-2012, 11:52
I have been very apprehensive about charging my NimH batteries at 50% of rated current. Probably because everything I've read about solar installs suggests charging your battery bank at 10% or slightly higher, but never at 50%. But you have researched this far more than I and I have a lot of faith in your posts here so I'm going to start doing the 50% on the LSD units, but stay at 10-20% on my standard NiMh batteries. I know the composition of lead acid deep discharge golf cart batteries is far different than NiMh, but it would just seem that a 50% charge rate would be stressful to most batteries. But then I'm an old man and times do change. One other question, do you know of some way to instruct the C9000 to discharge to the 60% level and stop? I don't recall reading anything like that when I bought the unit. Fact is I never have used the discharge feature.

Yeah, I have to admit, I was of the same mind when I started researching this. It blew me away that people are charging their NiMH's at 1C without damage. 1C!! I'm way more comfortable with 1/2C myself, but I did not know that the .1C to .5C was a no-go zone. And I believe that's true also for regular NiMH, not just the LSDs, but verify that. The danger, again, is your charger not finding the termination voltage with a slower charge. Which would not be different for non-LSD cells. So research before you slow-charge your regular NiMH.

Now as you say, solar installs would be charging lead acid batteries and I don't know anything about that chemistry. I'll take your word on 10% there.

Finally, I do not know of a direct way to stop the charge at a certain amount. Although there are various ways you can "game" the charger and fool it, but it might just be easier to watch the display and terminate when you want to. Not sure you're gaining anything that way. If it were me I'd full charge and then DIScharge to the storage level.

At any rate, check your PM, Carry16. Thanks.

Babynine
05-29-2012, 20:29
1A is the default setting on your C9000 charger, as in if you just stick a AA battery in it and plug it in without touching a thing, it will go to the default charge setting of 1A. It works well:wavey:

If I remember correctly, the c9000 also moniters each cells tempature during the charge cycle. At the default 1A charge, I have read that the c9000 only charges at the 1A rate until the cell reaches approx 80% (off the top of my head) charge, then it trickle charges to top them off well.

When I first got mine I ran it non-stop for over three weeks breaking-in every cell I had, all while buying more and more cells. Now I just put the cells in and plug the charger in and let it go to the default 1A setting. I occasionaly do some discharge cycles to see where they are at.

The Eneloops in my SteriPen purifier after treating about 25 liters of drinking water only require about 30-40 minutes to top them up to a full charge at the 1A charge rate (the Eneloops are only about 40% discharged after 25l).

Also Bolster, you forgot to mention the reported "melting" of some of the LaCrosse chargers. Once I read that, and having already living though a fire in my last building, I chose the Maha c9000 unit over the LaCrosse. The 12vdc option is great too.

UneasyRider
05-29-2012, 20:52
Bolster a man with your OCD is truly a pleasure to read. Only a small percentage of people will throw themselves at a project like you do and I want to give you propper credit for it. By the way I think OCD is one of God's finest survival gifts.

Stevekozak
05-30-2012, 06:42
Bolster a man with your OCD is truly a pleasure to read. Only a small percentage of people will throw themselves at a project like you do and I want to give you propper credit for it. By the way I think OCD is one of God's finest survival gifts.
Yeah, can you imagine if Bolster and EMT ever got together on a project?! :wow: :rofl:

Bolster
05-30-2012, 10:03
Bolster a man with your OCD is truly a pleasure to read. Only a small percentage of people will throw themselves at a project like you do and I want to give you propper credit for it. By the way I think OCD is one of God's finest survival gifts.

LOL, so true! Well, as my momma always told me, "You gotta nut up or shut up." (Oh wait, no, that was Woody Harrelson.)

SFCSMITH(RET)
05-30-2012, 10:13
Yeah, can you imagine if Bolster and EMT ever got together on a project?! :wow: :rofl:

Would make for an epic thread, no matter the subject.

I use the Tenergy LSD's, in a LaCrosse bc-700. No complaints.

Still learning about the world of rcr123's... have a few.. ok, a dozen.. or two.

Bolster
05-31-2012, 21:32
Also Bolster, you forgot to mention the reported "melting" of some of the LaCrosse chargers. Once I read that, and having already living though a fire in my last building, I chose the Maha c9000 unit over the LaCrosse. The 12vdc option is great too.

Of which I was ignorant.

Like Baby9, I'm rolling through a stash of (too many) rechargeables and trying to BIM all of them. At two days for every set of four...it's a real project.

Good news is, most cells (even the old ones) are being restored to 1900 mAh ranges. So the Maha is working well.