Eneloop C & D Cells Exposed

[Bones]

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?

 

[45/70]

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

 

[qandeel]

Bones

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

Thanks for sharing

 

[Bones]

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.

 

[Bones]

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
-

 

[swxb12]

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

 

[Colorblinded]

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.

 

[Canuke]

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.

 

[45/70]

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.

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

 

[jasonck08]

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...

 

[Fulgeo]

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.

 

[Battery Guy]

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

 

[rushnrockt]

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.

 

[Locoboy5150]

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.

 

[Lynx_Arc]

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).

 

[MarioJP]

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

 

[ryanandty]

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.

 

[Mr Happy]

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.

 

[KiwiMark]

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!

 

[MarioJP]

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.