# Eneloop C & D Cells Exposed



## Bones (Aug 13, 2010)

It's confirmed folks, the Eneloop C-cell is composed of 4 x AAA cells and the D-cell is composed of 3 x AA cells:




Source website linked via Google Translator:

http://translate.google.com ... ldblog.jp

Hmm, does this mean they must now be classified as batteries?


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## 45/70 (Aug 13, 2010)

Bones said:


> Hmm, does this mean they must now be classified as batteries?



Um yup!

I'm not too sure how these will workout. The cells composing the "battery" are going to be charged in parallel. As I understand it, that doesn't work too well with NiMH cells.:thinking: I just figured they came up with a couple versions of sub C's for these "batteries". Odd.

Dave


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## qandeel (Aug 13, 2010)

Bones

Good stuff. Does this mean that the D cell is 6000 mAH?

Thanks for sharing


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## Bones (Aug 13, 2010)

qandeel said:


> Bones
> 
> Good stuff. Does this mean that the D cell is 6000 mAH?
> 
> Thanks for sharing



Not quite gandeel. Sanyo decided to forego stating the typical capacity on the Eneloop C & D-cells, instead stating only their minimum capacity.

Accordingly, the C-cell was stated as having a minimum capacity of 3000mAh and the D-cell was stated as having a minimum capacity of 5700mAh.

When you consider that the Eneloop AAA-cell's minimum capacity is stated as 750mAh and the AA-cell's minimum capacity is stated as 1900mAh, the math works out very well.

Incidentally, if you've been following the relevant threads, you will note that Apple chose to follow Sanyo's exemplary lead by only stating the minimum, or guaranteed, capacity on their new NiMH AA cell.


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## Bones (Aug 13, 2010)

If memory serves, the kudos for being the first of us to surmise what has now been confirmed go to IMSabbel:

http://www.candlepowerforums.com ... post2591311
-


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## swxb12 (Aug 13, 2010)

Thanks for the info., Bones. I'll be interested to see the kind of charger they will sell to pair with these new formats.


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## Colorblinded (Aug 13, 2010)

45/70 said:


> Um yup!
> 
> I'm not too sure how these will workout. The cells composing the "battery" are going to be charged in parallel. As I understand it, that doesn't work too well with NiMH cells.:thinking: I just figured they came up with a couple versions of sub C's for these "batteries". Odd.
> 
> Dave


Would parallel be a bad thing if the individual cells are always being used in an identical fashion? One would hope that's how it'll work out inside one of these C or D cells.


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## Canuke (Aug 13, 2010)

Colorblinded said:


> Would parallel be a bad thing if the individual cells are always being used in an identical fashion? One would hope that's how it'll work out inside one of these C or D cells.



That helps, I daresay.

When Eneloops first came out, I was impressed with how consistent they were; all four cells in a AA pack would measure no-load voltage to within a millivolt of each other, fresh out of the pack. Sanyo must be pretty confident in their ability to build these within such tight tolerances that parallelism works.


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## 45/70 (Aug 13, 2010)

Colorblinded said:


> Would parallel be a bad thing if the individual cells are always being used in an identical fashion? One would hope that's how it'll work out inside one of these C or D cells.





Canuke said:


> That helps, I daresay.



You Guys may be right. The cells within each battery will all be from the same manufacturing lot, and used in exactly the same way, obviously. Maybe that will work, we'll see I guess.

Dave


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## jasonck08 (Aug 13, 2010)

Interesting, but kind of disapointing that Sanyo isn't going to develop actual D and C cells. I'm guessing that they think the quantity of cells sold will be very small, so rather then developing a whole new size cell, they'll just throw them in a little battery pack.

I wonder how Sanyo will price these...


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## Fulgeo (Aug 13, 2010)

Great thread. I had always wondered why their LSD C and D cells had such a low capacity, considering that other manufacturers *cough* Accupower *cough* have LSD D cells rated at 10,000 mAh. I thought it reflected somehow on their particular manufacturing technology of their cells, which didn't make sense to me considering how great their AA Eneloops cells are. I figured that an Eneloop D cell should have around 10,000 mAh capacity. Now it makes sense.


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## Battery Guy (Aug 13, 2010)

Fulgeo said:


> Great thread. I had always wondered why their LSD C and D cells had such a low capacity, considering that other manufacturers *cough* Accupower *cough* have LSD D cells rated at 10,000 mAh. I thought it reflected somehow on their particular manufacturing technology of their cells, which didn't make sense to me considering how great their AA Eneloops cells are. I figured that an Eneloop D cell should have around 10,000 mAh capacity. Now it makes sense.



C and D cells do not provide near the profit margin that AA and AAA cells do. Not only are manufacturing volumes for AA and AAA cells are much larger, but the amount of raw materials in C and D cells are obviously much higher as well. A 10Ah NiMH cell should cost 5X more than a 2Ah NiMH cell, but that is typically not the case. This is why most of the smaller battery companies only make AA and AAA, and don't even bother making C and D cells. Even the big battery companies put most of their R&D efforts and manufacturing/quality improvements into their AA and AAA products, while improvements to C and D sizes come slowly.

Bottom line is that most cell manufacturers would rather sell you three AA or four AAA cells than one D or C cell. And they would really rather sell you 2 AAA cells instead of one AA cell, since they have somehow convinced the customer to pay close to the same price per cell for both AA and AAA.

At least Sanyo didn't follow Energizer's lead with the one AA in a D size NiMH cell. :thumbsdow 

Cheers,
BG


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## rushnrockt (Aug 13, 2010)

Bones said:


> Incidentally, if you've been following the relevant threads, you will note that Apple chose to follow Sanyo's exemplary lead by only stating the minimum, or guaranteed, capacity on their new NiMH AA cell.



Probably because those are actually Sanyo's Eneloops they are selling.


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## Locoboy5150 (Aug 13, 2010)

Interesting - thanks for the heads up! I don't even know where to buy Eneloop C and D cells here in the US. All that the vendors I know of just sell the C and D sized spacers for the AA Eneloops.


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## Lynx_Arc (Aug 13, 2010)

Too bad they (eneloop) couldn't have just made some 3AAA>C and 3AA>D adapters and sold them instead of this. I would like to see the D cell version taken apart to see if you can remove the cells or if they are soldered/welded in place. I am guessing it is easier to retrofit AA/AAA into D/C cells instead of starting up another plant to make C/D cells and deal with designing and testing cells. C/D cells with greater capacity than these would either sell and cut into the AA/AAA profits or not sell because they cost too much. I am mostly interested in subC LSD cells myself for two battery soldering irons I use once every 6 months that are always dead (nicads).


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## MarioJP (Aug 13, 2010)

what's the problem of charging nimh cells in parallel?


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## ryanandty (Aug 13, 2010)

MarioJP said:


> what's the problem of charging nimh cells in parallel?



From what I understand, if there is a cell that does not take a charge as well as the others, it affects the charging performance of the others in parallel with it. This is why everyone seeks out chargers with individual channels.


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## Mr Happy (Aug 14, 2010)

Having parallel cells like this is not so peculiar when you think about it. A single cell is a rolled up sandwich of electrodes and insulator. In effect, the whole cell is "in parallel" throughout. If a D cell were made, it would just consist if a much fatter roll consisting of a longer strip of electrodes. What we have in the Eneloop D cell is the same long strip cut up into three pieces and made into three thinner rolls. Electrically it is much the same as one fat roll.

Charging in parallel for NiMH cells can be acceptable, as others have said, if all the cells are identical, from the same batch, connected with equivalent circuit paths, and treated the same way. Most importantly, all the cells should be in good thermal contact so they maintain an even temperature.

Problems can happen with parallel charging if the cells are allowed to attain different temperatures. In that case any cell that gets warmer than the others will drop in resistance and steal extra current from the charger, making it warmer still. The positive feedback of higher current and increasing temperature can lead to thermal runaway and cell damage. This is the main reason for recommending against the charging of NiMH cells in parallel.


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## KiwiMark (Aug 14, 2010)

MarioJP said:


> what's the problem of charging nimh cells in parallel?



If one cell has internal shorts it would have less resistance and less capacity - less resistance means that a greater amount of amps would flow through that cell than the others, but with less capacity it would need less rather than more amps.
In ideal condition all 3 cells would be the same and charge fine, so when new it probably isn't a problem. As the cells age charging in parallel becomes a worse idea.

Also:
Sanyo Eneloop D battery will have at least 5700mAh
Accupower D cell has 10,000mAh (I have test my 4, all 4 have over 10,000mAh)
My Mag4D with Malkoff LED drop-in can run for around 6 hours on Eneloop D or 10 hours on Accupower D.

I know which D cells I would rather buy!


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## MarioJP (Aug 14, 2010)

So does charging them in series makes the problem worst since current has to go through all of the cells in series. What's interesting is I underestimated my mobile usb charger. Not only does it provide portable power to mobile devices, but it also is a mini battery charger by simply connecting the charger to a usb port on a computer charging your cells.

I can see this being very useful when on the go. it charges in 2 or 4 in series and it is done from 4hr-6 hours (all depends the available power that computer can provide from the usb port)

no outlets needed for this charger pretty cool I guess

Although I do notice the cable gets warm and the end of the usb attach to the computer gets warm to almost hot. Did caused one computer to flip out guess that computer was too weak for my charger lol.


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## Colorblinded (Aug 14, 2010)

Mr Happy said:


> Having parallel cells like this is not so peculiar when you think about it. A single cell is a rolled up sandwich of electrodes and insulator. In effect, the whole cell is "in parallel" throughout. If a D cell were made, it would just consist if a much fatter roll consisting of a longer strip of electrodes. What we have in the Eneloop D cell is the same long strip cut up into three pieces and made into three thinner rolls. Electrically it is much the same as one fat roll.
> 
> Charging in parallel for NiMH cells can be acceptable, as others have said, if all the cells are identical, from the same batch, connected with equivalent circuit paths, and treated the same way. Most importantly, all the cells should be in good thermal contact so they maintain an even temperature.
> 
> Problems can happen with parallel charging if the cells are allowed to attain different temperatures. In that case any cell that gets warmer than the others will drop in resistance and steal extra current from the charger, making it warmer still. The positive feedback of higher current and increasing temperature can lead to thermal runaway and cell damage. This is the main reason for recommending against the charging of NiMH cells in parallel.


I feel like people are getting worked up over charging cells in parallel while having the mindset they would for cells that weren't used together in parallel. These cells won't see separate or different workloads in different devices where they might be in serial, parallel or working individually. Each D or C cell will always be the same set of batteries internally going through basically the same thing together.


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## Black Rose (Aug 14, 2010)

45/70 said:


> I just figured they came up with a couple versions of sub C's for these "batteries". Odd.


That would have been nice.

The Rayovac Hybrid/Platinum C & D cells have 3000 mAh LSD sub C cells in them.


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## Fulgeo (Aug 14, 2010)

Battery Guy said:


> Bottom line is that most cell manufacturers would rather sell you three AA or four AAA cells than one D or C cell. And they would really rather sell you 2 AAA cells instead of one AA cell, since they have somehow convinced the customer to pay close to the same price per cell for both AA and AAA.
> 
> At least Sanyo didn't follow Energizer's lead with the one AA in a D size NiMH cell. :thumbsdow
> 
> ...


 
I am just curious if Sanyo just went to the trouble of making a true one cell D what its properties would actually be. Do not get me wrong I love Eneloops. I have even been instrumental in replaced every AA and AAA used in my company with Eneloops. I would just like to see/experience this technology extended to its C and D brethren. Anyone know what the market price of Eneloops C and D batteries are? Comparatively speaking to their AA cells. I think the C and D cells are not available in the USA.


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## Mr Happy (Aug 15, 2010)

Fulgeo said:


> I am just curious if Sanyo just went to the trouble of making a true one cell D what its properties would actually be. Do not get me wrong I love Eneloops. I have even been instrumental in replaced every AA and AAA used in my company with Eneloops. I would just like to see/experience this technology extended to its C and D brethren. Anyone know what the market price of Eneloops C and D batteries are? Comparatively speaking to their AA cells. I think the C and D cells are not available in the USA.


The capacity of a cell is roughly proportional to its internal volume.

Therefore, we can estimate:

Volume(AA) = π/4 · 14.5² · 50 = 8300 mm³
Capacity(AA) = 1900 mAh

Volume(D) = π/4 · 34² · 61 = 55,000 mm³

Capacity(D) = 550/83 · 1900 = 13,000 mAh

We find D size NiMH cells with capacities up to 12,000 mAh, so this estimate stacks up.


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## Fulgeo (Aug 15, 2010)

Mr Happy said:


> The capacity of a cell is roughly proportional to its internal volume.
> 
> Therefore, we can estimate:
> 
> ...


 
Is the improved separator used in LSD batteries specifically Eneloops a thicker material than the separator material in non LSD NiMH batteries?


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## Robin24k (Aug 15, 2010)

I think I might as well just use AA's in an adapter instead of getting these cells...at least I will be able to use the same Duracell CEF23 for everything.


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## Lynx_Arc (Aug 15, 2010)

Robin24k said:


> I think I might as well just use AA's in an adapter instead of getting these cells...at least I will be able to use the same Duracell CEF23 for everything.



If you could only get those 3AA eneloop adapters for decent prices


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## Robin24k (Aug 15, 2010)

I got 2AA adapters for about $1 each from Hong Kong, 3AA would mean an odd number of batteries again, and that's not good...


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## Lynx_Arc (Aug 15, 2010)

Robin24k said:


> I got 2AA adapters for about $1 each from Hong Kong, 3AA would mean an odd number of batteries again, and that's not good...



Not if you had a 4 channel smart charger. Most D cell devices use 2 or 4 or 8 cells so with the 4 and 8 cells you have 12 or 24 AAs.. easily divided by 4


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## Robin24k (Aug 15, 2010)

I've got a CEF23, so the problem I have with odd number of batteries is that they always come in even numbers (and two sets of 9 is too many batteries).


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## Lynx_Arc (Aug 15, 2010)

Robin24k said:


> I've got a CEF23, so the problem I have with odd number of batteries is that they always come in even numbers (and two sets of 9 is too many batteries).



buy a single AA LED light to use the odd battery then :thumbsup:


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## Robin24k (Aug 15, 2010)

I think we usually buy batteries for lights, and not lights for batteries.


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## Mr Happy (Aug 15, 2010)

Robin24k said:


> I think we usually buy batteries for lights, and not lights for batteries.


No, quite wrong.

When buying a light, your first decision is how to power it. Do you want to use primaries or rechargeables? Will the light be used every day or infrequently? Might you want to switch between primaries and rechargeables in the same light? Do you consider yourself technically sophisticated, or do you just want your batteries to be "charge it and forget it"?

The power source is the thing that makes your light work. If you don't get the power source right you won't be happy with the light.


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## Robin24k (Aug 15, 2010)

True, but what I was referring to was buying a light just so that spare batteries could be used (because if that's the case, I need to find several lights that run on the bunch of 9V batteries I have...).


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## Lynx_Arc (Aug 15, 2010)

Robin24k said:


> True, but what I was referring to was buying a light just so that spare batteries could be used (because if that's the case, I need to find several lights that run on the bunch of 9V batteries I have...).



Apparently you are not a full fledged flashaholic yet 
There is dozens of threads of people here buy lights to use up batteries of all sorts that are partially used up in other things etc.


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## Robin24k (Aug 15, 2010)

Nope...*clasps wallet*


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## KiwiMark (Aug 16, 2010)

Robin24k said:


> I've got a CEF23, so the problem I have with odd number of batteries is that they always come in even numbers (and two sets of 9 is too many batteries).



Easy solution - take left over batteries and buy lights to use them in. Quark AA and/or Zebralight H501w would be good choices. Let's face it - could you ever have TOO many lights?



Robin24k said:


> *clasps wallet*



If you want to hang on to you money you may be on the wrong forum - we're here to help you SPEND it!


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## ryanandty (Aug 16, 2010)

KiwiMark said:


> Easy solution - take left over batteries and buy lights to use them in. Quark AA and/or Zebralight H501w would be good choices. Let's face it - could you ever have TOO many lights?
> 
> If you want to hang on to you money you may be on the wrong forum - we're here to help you SPEND it!



This post is psychically (is that a word?) charged!

Cruising this forum prompted me to go from a sole Bell bicycle headlight and rayovac alkalines (my only light for years) to a Zebralight h501w, a 6d ROP that is awaiting these eneloop D cells (it's on eneloop d adapters), and has me ready to pull the trigger on a Quark aa mini nw.

Oh yeah, I bought a maha c808m just to prepare for future lsd D cell goodness, it will charge my aa duraloops too  .

Gotta let the bank card cool off...


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## KiwiMark (Aug 16, 2010)

ryanandty said:


> awaiting these eneloop D cells



I like these D cells: http://www.thomasdistributing.com/s...html?SP_id=&osCsid=a98rm8a91donrsllit8gi3gna7
They work well and 10Ah of capacity should provide a decent run time (~2 hours on ROP high or ~4 hours on ROP low).


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## ryanandty (Aug 16, 2010)

KiwiMark said:


> I like these D cells: http://www.thomasdistributing.com/s...html?SP_id=&osCsid=a98rm8a91donrsllit8gi3gna7
> They work well and 10Ah of capacity should provide a decent run time (~2 hours on ROP high or ~4 hours on ROP low).



Thanks for the tip, but my wife would confiscate my wallet if I burned 60 more bucks on battery stuff! (I've even had to use the "paypal hide my money" shuffle.) I was planning to bide my time using the ROP as a 20 minute security "flasher" until I can find a lsd d cell solution for about $30. I wouldn't mind the 5700mah, the mh-c808m can charge 5700 in about three hours. But you probably knew that already .


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## gSPIN (Sep 26, 2010)

the danger with parallel charging NiMH or NiCd happens when u charge past the peak.
no matter how closely matched, one of the cells out of the parallel group will always reach peak first.
it's after peaking where its voltage drops that's the big problem which prevents the others from reaching their peak all the while continually diverting all the current that is supposed to be shared equally.
until it finally overheats & vents while endlessly waiting for the remaining cells to fill up.

to parallel charge safely one simple way is to charge reely, reely slo.
so slo that if one cell does hog the current meant for all of them it still doesn't exceed the max trickle charge of a single cell.
that would make for something like a 50 hour rate so for a fast charge u need to terminate well b4 any cell can reach its peak.

this means -dv/dt can't be used at all which is really what all the dire warnings against parallel charging NiMH/NiCd are targeting.
to allow for fast _and_ safe parallel charging it's likely Sanyo will opt for dT/dt (having them thermally equalized housed within the same small container certainly helps) altho dv²/dt might work too.
a slight reduction in capacity by not filling to the brim is the only trade-off for the improved reliability & longevity.
i think negative deltaV charging is generally damaging to NiMH cells anyways, parallel or not.




Mr Happy said:


> The capacity of a cell is roughly proportional to its internal volume.
> 
> Therefore, we can estimate:
> 
> ...




now plug in 2500 mAh for the Eneloop XX.
everyone raise their hand, who can use a 17 Ah LSD or 20 Ah super lattice D cell?
then try & tell me there's no market for hi cap D cells.
i hoping when the Chevron patents expire in a couple more years that prevent anyone from manufacturing large high density NiMH cells that Sanyo will still be interested in producing a true D size Eneloop.


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## LuxLuthor (Sep 26, 2010)

Looks familiar, except I put them in series.


​


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## niktu (Aug 11, 2011)

Hmm, lets look at problem scientifically ... *evil grin*

What really separates bigger cell from two smaller cells connected together in parallel?

What makes it work properly in single cell, even if end part of Nimh charging process seems to be tolerating any imbalance poorly?


1. All parts of single cell have same use history - parameters are similar at start and change in similar conditions.

2. single cell equalize all pressure changes during charge (and that pressure changes quite significantly, and gets to quite high levels at end of charge). Same goes for any little gas venting that happens when conditions are not ideal.

3. single cell equalizes temperature well - cylindrical metal electrodes wrapped in steel can, then wrapped in plastic wrap - temperature change will equalize internally much faster than any outside cooling asymmetry might try to tip it off

4. single cell equalizes electrolyte saturation over time (slower than pressure and temperature, but over time it still happens ... think concentration change after gas venting)

5. resistance between parts of electrodes inside single cell is probably much lower than you can connect whole cells together ... and for sure will be more consistant between those parts and external electrodes - less voltage and current fluctuation


So, why it might work in Sanyo case? 
1. and 3. are taken care of by mating cells during manufacturing (and they stay like that for their life), while their steel cans are pressed together, while whole assembly is wrapped in plastic case (working temp equalization, same service history), 
5. can be taken care of by properly engineered connections made at factory (so even if resistance might not be as low as in case of single cell, it will be reliably consistent across cells, during life of battery)

Lack of 2. and 4. might be mitigated by amazing consistency of eneloops (while other quality cells might keep their parameters close while cycled often, many of them will veer off wildly only after few months of storage and require few cycles to get them back in line between themselves)

Thats why I think that Sanyo execution might work well enough. 
And why putting off-the-shelf cells into off-the-shelf battery holder is doomed to fail during charging, sooner than later (no consistency of contact resistance, and no proper temperature equalization, and it would require vigilance on part of user to use same set of cells as set for their entire life).

Avid dyi'er might get some success by imitating Sanyo build:

get fresh cells from one batch, strip thir plastic casings leaving only steel cans, affix them together making sure there is very good thermal and electrical contact, wrap them together with something with giving partial themal isolation (so single cells equalize temperature between each other much, much faster than between surroundings)

Would that work? it should, if done well ... i doubt that Sanyo uses any additional tricks in their product. 



Ughh ... it turned out much lengtier than planned, my apologies 

I guess i will have to leave "everybody knows NiMHs can't be float charged!" and "with some caveats you CAN float charge even a parallel string of NiMHs!" rant for some other time then


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## Chrontius (Oct 7, 2011)

So far, one vote for Accupower Evolution 10 Ah cells. Anyone else used LSD Ds, or are they just that niche?


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## Wangstang (Nov 21, 2011)

So did these ever come to market in the US? If so where can you find them & how are they priced?

Thanks
Wes


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## Lynx_Arc (Nov 21, 2011)

Wangstang said:


> So did these ever come to market in the US? If so where can you find them & how are they priced?
> 
> Thanks
> Wes


I haven't heard of them being made anywhere on CF, I would expect a review of them if they were available.


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## Illum (Nov 21, 2011)

LuxLuthor said:


> Looks familiar, except I put them in series.
> 
> ​



   

I wonder if Sanyo arrived at the ability to test cell resistances and combined those with similar resistances to avoid unbalanced cells charged in parallel


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## Lynx_Arc (Nov 22, 2011)

Illum said:


> I wonder if Sanyo arrived at the ability to test cell resistances and combined those with similar resistances to avoid unbalanced cells charged in parallel


I don't think it is much of an issue with nimh cells in parallel, but rather in series. Once they reach voltage balance in parallel the weaker cell should be supported by the stronger one unless under severe loads that would require two cells to support the load.


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## bcscheps (Jan 8, 2013)

Lynx_Arc said:


> Too bad they (eneloop) couldn't have just made some 3AAA>C and 3AA>D adapters and sold them instead of this. I would like to see the D cell version taken apart to see if you can remove the cells or if they are soldered/welded in place. I am guessing it is easier to retrofit AA/AAA into D/C cells instead of starting up another plant to make C/D cells and deal with designing and testing cells. C/D cells with greater capacity than these would either sell and cut into the AA/AAA profits or not sell because they cost too much. I am mostly interested in subC LSD cells myself for two battery soldering irons I use once every 6 months that are always dead (nicads).



I purchase all my "LSD" batteries from "ALL-BATTERY.COM." Their "LSD"-Battery-line are called "CENTURA" and are VERY reasonably priced. (Their "C" and "D" "Centura" cells usually cost no more than $16.00 plus postage.


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## Shadowww (Jan 8, 2013)

Lynx_Arc said:


> I don't think it is much of an issue with nimh cells in parallel, but rather in series. Once they reach voltage balance in parallel the weaker cell should be supported by the stronger one unless under severe loads that would require two cells to support the load.


NiMH cell charging is terminated by delta -V signal, which can't be properly detected with multiple cells in parallel.


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## Lynx_Arc (Jan 8, 2013)

Shadowww said:


> NiMH cell charging is terminated by delta -V signal, which can't be properly detected with multiple cells in parallel.


I'm not so sure of that as eneloops tend to be high quality so the variance of cells is minimal and the internal resistance of the cells in parallel will actually be reduced vs one cell thus making it easier to detect a signal. What makes it harder is cells with high internal resistance which many chargers will even refuse to charge. I've not heard of a lower internal resistance cell being rejected by a charger even though it is possible.


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## alpg88 (Jan 8, 2013)

Shadowww said:


> NiMH cell charging is terminated by delta -V signal, which can't be properly detected with multiple cells in parallel.



yes. i agree.

i used parallel nimh cells in my packs, but i never used smart charger for it, low current timed "dumb" charger, and it works just fine.


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## VidPro (Jan 8, 2013)

Shadowww said:


> NiMH cell charging is terminated by delta -V signal, which can't be properly detected with multiple cells in parallel.



Agrees also Shadoww & Gspin. i would far prefer that the cells are put into a parellel adapter, and charged seperate. Dont matter how well matched (gspin) "it's after peaking where its voltage drops that's the big problem" 

Charging with a nice slow rate for the cells that are internal to it like say <C/5 for single AAA or AAs in it, or stopping at a voltage max (some maha chargers) would work just fine Trying to get a v-drop going for termination would not go well , reducing the life of the thing each charge.
I dont care how well they are tied together, or matched, there aint no special curcuitry in there to fix the parellel ni-?? thing (when used in v-drop terminating chargers) 

Some of the sanyos own chargers use "different methods" than relying on v-drop so they may have it covered in some of thier own stuff.
If you know about how parellel charging fails, and know the drop current (single cell) or control voltage high, on the internal cells then you can pull it off.

I would put these on my "must be a better way" list and forgedabout it. sanyo made some of the best D-cell rechargables available in ni-mh that were not LSD special, they worked wonderfull and for long and hard and had good capacity. These are an embarassment compared to them 

darn-it sanyo, I want a Real eneloop Dcell, saving money just for it, this aint it At All.

Side notes: "slow rates" would be actual slow rates, and not "averaged" slow rates that are higher current rates pulsed to average lower. So pummeling it with a high current with a "pulse averaged" low rate is not the same thing.


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## mccririck (Jan 8, 2013)

Battery Guy said:


> C and D cells do not provide near the profit margin that AA and AAA cells do. Not only are manufacturing volumes for AA and AAA cells are much larger, but the amount of raw materials in C and D cells are obviously much higher as well. A 10Ah NiMH cell should cost 5X more than a 2Ah NiMH cell, but that is typically not the case.



Eh, that's because there's only one casing. btw have you ever noticed how AA and AAA tend to cost the same even though AA uses about 2.5 times as much inside stuff?


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## sedstar (Apr 11, 2013)

someone mentioned up early in this thread... and skimming down thru i didnt see it mentioned again...

"would this mean its a battery and not a cell?"

=====================================

Humm. Actually, i dont THINK so.

we call a car BATTERY a "battery" because there are actually 6 individual CELLS built together in a series connection... to up the voltage.

i think all of us know that a 9v BATTERY is actually a battery, as there are several little AAA or AAAA sized cells inside in series...

...on this logic train, i *think* but am not sure... this is still a CELL as they are in parallel.


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## SilverFox (Apr 11, 2013)

Hello Sedstar,

Technically, a cell is a single unit and a battery is made up of 2 or more cells. In actual discussion both battery and cell are used interchangeably. A battery can be looked at as stored energy and a special case is the one cell battery.

Tom


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## mccririck (Apr 12, 2013)

In the UK people tend to just use the word battery for any type of cell/battery.


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## bobrip (Nov 25, 2013)

mccririck said:


> In the UK people tend to just use the word battery for any type of cell/battery.



I visited a Sanyo factory in Japan about 7 years ago. They showed us a Nimh D cell. It was used in the battery of a Hybrid car. If memory serves me right it was 10 ampere hour. Of course they will have improved them by now. Another comment made by them is that they grade cells into two groups. One was a lower capacity. They they build a battery out of the low or high capacity cell, not both. I worked with Sanyo for about 10 years and I developed a lot of respect for Sanyo's battery manufacturing. Of course the Eneloop helps justify that respect.


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## mojo-chan (Nov 26, 2013)

So can someone explain why they wouldn't just sell 3xAA or 4xAAA with an adapter? It seems like people could then use their existing chargers and all concerns about unequal charging would be taken care of.

The only thing I can think of is that consumers just want to buy D and C cells and can't understand this complex adapter thing.


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## Lynx_Arc (Nov 26, 2013)

mojo-chan said:


> So can someone explain why they wouldn't just sell 3xAA or 4xAAA with an adapter? It seems like people could then use their existing chargers and all concerns about unequal charging would be taken care of.
> 
> The only thing I can think of is that consumers just want to buy D and C cells and can't understand this complex adapter thing.


One problem with adapters is putting unbalanced cells in them imagine an almost dead cell with 2 full cells in parallel the dead cell could experience being charged at a higher rate than the adapter can handle melting your adapter or worse. Single cell adapters can be found at times along with series adapters but parallel ones are a rarity in the stores.


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## mojo-chan (Nov 27, 2013)

Lynx_Arc said:


> One problem with adapters is putting unbalanced cells in them imagine an almost dead cell with 2 full cells in parallel the dead cell could experience being charged at a higher rate than the adapter can handle melting your adapter or worse. Single cell adapters can be found at times along with series adapters but parallel ones are a rarity in the stores.



Ah, true dat. Sanyo must be very confident that their matches packs will age evenly, which is encouraging.


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## Lynx_Arc (Nov 27, 2013)

mojo-chan said:


> Ah, true dat. Sanyo must be very confident that their matches packs will age evenly, which is encouraging.



Actually once the batteries equalize in one of their C/D cells or whatever it doesn't matter how the cells age in it as long as none short out because there is no way they can be charged unevenly when always in parallel.


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## mojo-chan (Nov 28, 2013)

Lynx_Arc said:


> Actually once the batteries equalize in one of their C/D cells or whatever it doesn't matter how the cells age in it as long as none short out because there is no way they can be charged unevenly when always in parallel.



That's what I mean. They are fairly sure they will get a very low number of cells failing/degrading significantly before their rated number of recharge cycles. We have been through a lot of NiMH batteries at work and the number of manufacturers with high early failure rates or not able to come close to their rated capacity after a year is incredible. Ansman, Varta, Tekcell, Duracell, I'm looking at you.


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## N8N (Nov 28, 2013)

mojo-chan said:


> That's what I mean. They are fairly sure they will get a very low number of cells failing/degrading significantly before their rated number of recharge cycles. We have been through a lot of NiMH batteries at work and the number of manufacturers with high early failure rates or not able to come close to their rated capacity after a year is incredible. Ansman, Varta, Tekcell, Duracell, I'm looking at you.



Have you tried the new Duracell Ion Cores? Seems that a lot of people (self included) suspect that they are relabeled XXs but I'm not a heavy enough user to confirm.

Sent from my XT897 using Tapatalk


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## mojo-chan (Nov 28, 2013)

N8N said:


> Have you tried the new Duracell Ion Cores? Seems that a lot of people (self included) suspect that they are relabeled XXs but I'm not a heavy enough user to confirm.



I have not tried those, but it figures that the only good ones they make would be rebranded Eneloops.


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## kreisl (Nov 30, 2014)

Bones said:


> It's confirmed folks, the Eneloop C-cell is composed of 4 x AAA cells and the D-cell is composed of 3 x AA cells:



Interesting. Does the picture show a C-cell? I see.

So i could build my own Eneloop D battery and Eneloop C battery by buying a round 1s3p-AA and a round 1s4p-AAA battery holder?

Then i could test the 3 amps max charge rate of my new charger on them woot!! :devil:


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## MidnightDistortions (Nov 30, 2014)

It would be better if they just made these into adapters where you can change the batteries out if they didn't want to create a real C and D NiMH battery. They would sell more AA's and AAA's that way for those who have D and C cell rechargeables or even in general since it would take a 4AAA pack for C size and a 4AA pack (3 batteries) for the D size.


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## N8N (Dec 1, 2014)

You can do it yourself, see the post before yours. I got my adapters from a Chinese eBay seller but it appears that now they're available from Amazon.


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## conanthewarrior (Jun 11, 2015)

Does this mean I could buy a pack of C cells, and re wrap the AAA's to use individually?


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## Lynx_Arc (Jun 11, 2015)

conanthewarrior said:


> Does this mean I could buy a pack of C cells, and re wrap the AAA's to use individually?



possibly... but I'm guessing that you aren't going to save any money doing that and probably end up with weld marks on the ends of the batteries to boot.


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## WalkIntoTheLight (Jun 11, 2015)

Lynx_Arc said:


> possibly... but I'm guessing that you aren't going to save any money doing that and probably end up with weld marks on the ends of the batteries to boot.



It also looks like from the picture that the cell sides aren't wrapped. So, they'd be part of the negative contact point. You might have to be more careful about short circuits if you use them that way.


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