Duracell 15 minute charger, need specs

Anyone have the AA and AAA charging current specs for the Duracell 15 minute charger? I've seen it at Wal-Mart and it comes with 2,400mAh AAs, no spec on package though.

I have the 30 minute chargers and each unit came with four 2,100 mAh AAs and charging specs are:

3.4A AA
1.7A AAA

1.7 x 0.5hr = 0.85Ah
3.4 x 0.5hr = 1.7Ah

Realistically, charging requires 110-120% of the rated Ah capacity, so to fully charge a 2.1Ah battery, you need 2.3 to 2.5Ah of cumulative charge.

Theoretically, it can only fully charge 1.5Ah cells in 30minutes. I wonder if the newer 15 minute unit is designed pretty much the same way or have more than double the current to reflect the capacity of more modern cells.

Mine states:

AA - 1.2 vdc 8.3a max
AAA - 1.2 vdc 3.5a max

I would give you actual readings, but the design does not allow convienent access to measure current.

15 min chargers cannot compare to slower chargers, they use a different algorithum to charge.

Do a search for Energizer 15 for a thread I started. It has graphs posted of PWM, charging currents, etc.

EDIT: Here's a link to the thread: http://candlepowerforums.com/vb/showthread.php?t=108661

Bill;

I do not think the Duracell is the same as the Energizer.....At least mine seems to work differently. I have both.

dta116 said:

Bill;

I do not think the Duracell is the same as the Energizer.....At least mine seems to work differently. I have both.

Click to expand...

dta116:

Whoops! I goofed.

How do they work differently? I'll bet you that the Duracell 15 uses PWM, it seems to be what most all currently made chargers use. The Energizer 15 claims to trickle charge but I saw nothing unless it was so low that my current clamp probe wouldn't pick it up. If it's that low it's useless anyway and on a quick charger like that, why have it??

wptski said:

dta116:

Whoops! I goofed.

How do they work differently? I'll bet you that the Duracell 15 uses PWM, it seems to be what most all currently made chargers use. The Energizer 15 claims to trickle charge but I saw nothing unless it was so low that my current clamp probe wouldn't pick it up. If it's that low it's useless anyway and on a quick charger like that, why have it??

Click to expand...

My Duracell 30 minutes trickle charges by applying a low duty cycle full current pulse the whole time.

I've been using the Energizer 15 Minute Charger and it does fine this far. Now, I think I've got to check out the DURACELL 15 Minute Charger. Hmmm. . .

is their a good picture of the Duracell 15 minute charger.

does it have 4 charging led`s, or one light the energizer.

all the pictures i`ve seen have the charger hidden by the packaging.

thanks.

TinderBox (UK) said:

is their a good picture of the Duracell 15 minute charger.

does it have 4 charging led`s, or one light the energizer.

all the pictures i`ve seen have the charger hidden by the packaging.

thanks.

Click to expand...

Looks like 1 LED
http://www.bestbuy.com/site/olspage...CategoryId=pcmcat28800050006&id=1138084368834

AA - 1.2 vdc 8.3a max
AAA - 1.2 vdc 3.5a max

I would give you actual readings, but the design does not allow convienent access to measure current.

dta116 said:

15 min chargers cannot compare to slower chargers, they use a different algorithum to charge.

Click to expand...

True, but even if your unit pushed 8.3A continuously, it can only charge 2.08Ah in 15 minutes assuming 100% coulombic efficiency but realistically I would say NiMH could only accumulate around 1.9Ah.

My 30 minute charger, at 3.4A, not surprisingly does not fully charge 2.5Ah batteries. to fully charge 2.5 and 2.7Ah batteries in this charger, you have to let the whole thing sit overnight in trickle charge (low duty cycle, high current pulse)

After exactly 30 minutes, the charge indicator shuts off, but charging continues until a termination point unbekownst to me. Five minutes after fast charge is completed, the fan shuts off. Instruction manual says charging is done when the LEDs turn off, but LEDs only tell you end of charge if the cycle is complete within 30 minutes.

If you are charging high capacity batteries and you stop charging when the lights go out, the batteries are not full. if you have a capacity tester, check the capacity of a cell after letting it sit overnight, then repeat immediately after charging light goes out.

What do you mean by (low duty cycle, high current pulse)? High current, pulsed with a low duty cycle is just highly controlled low current! That's the way a C808M, C204W, BC900, etc. work, PWM.

wptski said:

What do you mean by (low duty cycle, high current pulse)? High current, pulsed with a low duty cycle is just highly controlled low current! That's the way a C808M, C204W, BC900, etc. work, PWM.

Click to expand...

http://www.sanyo.com/batteries/pdfs/twicellT_E.pdf See the section in trickle charging.



True, but you have to look at the duration and interval.



Let's say you have a 5,000mAh cell. According to Sanyo, you need 0.0025C to sustain a charge. This would be 0.01A on a 5,000mA cell.





If you take an integral from 0 to 24 hours for:

2.5A (0.24 secs on, 59.76 off)

or

0.01A x always on



the area under the curve is the same, so it means the theoretical mAh accumulation is the same, but because of the characteristics of battery chemistry, it actually wouldn't accept any charge at true C/500 rate while it will accept it if given in the form of very short C/2.5 pulses.

Maybe someone will compare the Energizer 15 min. and this one......

nice pics dta116.

I feel like bender from futurama:kewlpics:

I`ve seen the inside of a lot of chargers and thats a big coil.

regards.

dta116:

So, how's the Duracell 15 working for you?

Handlobraesing:

Those specs are for a TWICELL cell not a consumer grade cell like the HR-3U 2.7Ah AA cell which they don't even list! I've checked the Sanyo site before and there still are no specs for the cells on the market today!

wptski said:

Handlobraesing:

Those specs are for a TWICELL cell not a consumer grade cell like the HR-3U 2.7Ah AA cell which they don't even list! I've checked the Sanyo site before and there still are no specs for the cells on the market today!

Click to expand...

There's nothing different about them that makes the concepts different and actually the HR-3U-2500 is the same as 2.5Ah Twicell. The datasheets on Sanyo industrial batteries tells you these have "consumer button top".

I'm not sure why the 2.7Ah AA isn't listed. Perhaps it isn't made available readily to non-retail channels?

Handlobraesing:

Sanyo listing shows non-Twicells and Twicells, why would they give them a different name if they weren't different? So "all" Sanyo cells require a different form of trickle charge? Special chargers???

Bill;

I sent the test results to Silverfox for analysis. Sould be a few days before I really know.

wptski said:

Handlobraesing:

Sanyo listing shows non-Twicells and Twicells, why would they give them a different name if they weren't different? So "all" Sanyo cells require a different form of trickle charge? Special chargers???

Click to expand...

Actually, its not even unique to Sanyo. Even though the rate of self discharge is something like C/500, no NiMH cell will accept charge at C/500 rate.

The electrochemistry of it would not accept C/500 x 100% duty cycle the same as C/5 x 1% duty cycle.

Handlobraesing:

That paper suggests a charging rate of .5/C to 1/C only! So, you shouldn't use your Duracell 30 minute or Duracell 15 charger either and better watch what charging rate you use on a BC900 too! Beginning to wonder after about this paper, it's a bit different than one from Duracell on details like voltage depression.

EDIT: Link to Duracell paper: Ni-MH Cells