Duracell 2650mAh NiMH, test result

[Handlobraesing]

old stuff:

Tested:
Four Duracell 2650mAh AA rechargeable batteries. Available at Wal-Mart

Charge method: 0.36A x 9 hours on a dumb, timer controlled charger.
They were allowed to sit around for an hour or two, then discharged.

Discharge method: 0.5A, end voltage 1.0v (it should be 0.9v, but stupid BC-900 reads 0.1v lower than actual)

Test result:

2.68Ah, 2.78Ah, 2.78Ah, 2.63Ah. This is what I got the VERY FIRST cycle. Amazing!

Average: 2.72Ah. Notice that every cell's capacity is +/- 4% from the average value. This is very good.

The package says "Made in Japan" and charging instruction says "270mA x 16 hours" which leads me to believe these could be Sanyo 2700mAh. The cells lack the "-HR-" symbol on the bottom, which is consistent with the Sanyo's 2700mAh.

These are very good batteries, however I'm not implying that "Duracell" rechargeables are very good per se. The OEM source they used(most likely Sanyo) is very good.

I have some Duracell 2100mAh Made in China batteries and they're very poor quality (requiring many many cycles before they get anywhere near the full capacity and still having very large deviation in capacity between cells)

Update 7/21/06:

I tested the capacity with four cells in series. Since I don't know the accuracy of calibration of the BC-900, it wouldn't hurt to do it a different way anyhow.

4 cells connected in series Cells were fully charged and allowed to rest for about an hour.

~600mA discharge current.

*the watt-hour capacity is of ALL FOUR cells combined.
*measurement uncertainties= thermal coefficient of resistor and 0.025%+1mV voltmeter error.


Great batteries, ghetto testing device.

 

[InfidelCastro]

Excellent report, thank you. I was considering ordering some Sanyo 2700's, but if I can buy them at a retail store instead, I'll probably hold off for awhile until we find out for sure. My Energizer 2500's should tide me over until then.

The numbers you came up with are actually better than the Sanyo 2700's charted at in the NimH shootout, in the forum sticky above.

 

[Handlobraesing]

Excellent report, thank you. I was considering ordering some Sanyo 2700's, but if I can buy them at a retail store instead, I'll probably hold off for awhile until we find out for sure. My Energizer 2500's should tide me over until then.

The numbers you came up with are actually better than the Sanyo 2700's charted at in the NimH shootout, in the forum sticky above.

The difference is probably due to a different charge algorithm. Dumb charging does not suffer premature termination and even though it might not offer the best cycle life, it offers the most consistent, full charging.

I think SilverFox uses smart charging, but I prefer to use dumb charging for repeatability sake.

 

[john2551]

I got these today at Walmart, $15.87 for a pack of 8. That's less than $2 each!

 

[wptski]

The difference is probably due to a different charge algorithm. Dumb charging does not suffer premature termination and even though it might not offer the best cycle life, it offers the most consistent, full charging.

I think SilverFox uses smart charging, but I prefer to use dumb charging for repeatability sake.

Sure, a timed will result in more full charge. You can read that in the specs provided by some manufactures but is that what your going to use "all" the time? Most often, a smart charger is used and that's why SilverFox used one! A real life test.

 

[Long John]

These Duracell 2650 mAh are not the same like the Sanyos 2700 mAh.

I have 20 pieces of the Sanyos and tested them several times. About 10 of them will have a capacity, more than 2,8 Ah, the other 10 more than 2,9 Ah.

Best regards

____
Tom

 

[wptski]

These Duracell 2650 mAh are not the same like the Sanyos 2700 mAh.

I have 20 pieces of the Sanyos and tested them several times. About 10 of them will have a capacity, more than 2,8 Ah, the other 10 more than 2,9 Ah.

Best regards

____
Tom

Tom:

How did you charge you charge/discharge those cells?

 

[Long John]

Hello Bill

With the LaCrosse in test modus.

Best regards

____
Tom

 

[wptski]

Hello Bill

With the LaCrosse in test modus.

Best regards

____
Tom

Does Silverfox's Ni-MH ShootOut include the Sanyo 2.7Ah cells? Because the BC900 is know to produce capacities a bit higher(200mAh) than other means. The low voltage cutoff is being questioned in other threads also. I'm going to have to graph my v33 unit to see where the LVC is. Maybe we ought to start a BC900 accuracy thread!

 

[Handlobraesing]

I don't know the accuracy of calibration on the CBAII or the BC900, so I tried a new method, see first post.

 

[Ikonomi]

Well, that's all well and good, but I can't find them at Wal-Mart.

I will try another. I wish Target carried these, but the only Duracells I can find around here (at Target or Wally World) are the 2500s.

 

[wptski]

I don't know the accuracy of calibration on the CBAII or the BC900, so I tried a new method, see first post.

Sooner or later, you'll run into a problem using those spring type clamps. The Schulze manuals list them in "what not to do".

I've used them to but a while I was using some 4xAA holders, unlike yours, these were two back to back. I was cycling some new cells that were over 2Ah, I don't remember the exact capacity. I was getting good capacity and all of a sudden, I get a 1600mAh. I have a clamp type holder setup for 4/8 AA cells. I used that and every cycle produced about the same capacity. I've marked those holders since then so if I ever run into that again, I'll weed the bad one out.

Get yourself up a good clamp setup. Lots use the Plastic ratcheting wood clamps and that's what I used too. Finding coppet sheet for the contacts was my problem. I ended up buying a small piece of copper gutter. Use double-face tape to keep it put. Soldering a large piece of copper can be fun.

 

[ps56k]

Can I use my Maha C204F to charge these higher capacity NiMh batteries ?
I think I got it (actually 2) back when the NiMh batteries were 1600, etc

 

[wptski]

Can I use my Maha C204F to charge these higher capacity NiMh batteries ?
I think I got it (actually 2) back when the NiMh batteries were 1600, etc

Why not? Use the the fast charge mode or it'll take a long time.

 

[Anders]

ps56k: "and will recharge even the higher capacity batteries of the future"

http://www.thomas-distributing.com/maha-mh-c204f.htm

But, it is always best to charge each battery independently.

Anders

 

[Bullzeyebill]

Anders, why is it best to charge each cell independately. If I was using multiple batteries for an application, I think that charging them in parallel would be best to balance the "pack of batteries". All of the individual cells should be charged to the same voltage and amperage.

Bill

 

[Anders]

Hello Bullzeyebill!

I think its best if you have cells started out at different states of charge or if you have cells that is defect.

The cell who is working properly or is almost full then will be overcharged and therefore take damage.

If you want to charge 1 or 3 cells you have problems.

Anders

 

[SilverFox]

Hello Bill,

It is not recommended to charge NiMh cells in parallel. It is recommended to charge NiMh cells individually or in series.

You can get away with parallel charging if you charge at low currents and follow the charge with an extended trickle charge, or if you use cells matched on capacity. The balancing occurs during the trickle charge phase.

When charging NiMh cells in parallel, the least drained cell will peak first. Once it peaks, the temperature will rise in the cell, causing the voltage of the cell to drop. The charger continues to charge and the cell continues to heat up.

Adding thermal cut off to monitor each cell helps, but it can be difficult to get good thermal coupling with the cells. On top of that, thermal cut offs are usually adjusted for laboratory conditions and can have difficulties in "outside" conditions.

If you have a light that runs on one AA cell, you can do this experiment. Run the light on one cell until it is dead and note the run time. Take the dead battery and connect it in parallel to a freshly charged cell and leave it for several hours or overnight. Then take the dead cell that you would think to be "equalized" by the fresh cell and put it back into the light and note the run time again. You can then take the fresh cell that was supposed to "charge" the dead cell and compare the run time you get with it to the dead cell that was supposed to be "balanced" by hooking it up in parallel to the fully charged cell.

Let us know what you find out...

Tom

 

[Bullzeyebill]

Whoops, I meant to say series. Must have been late when I posted.

Bill

 

[twentysixtwo]

I'll be looking for these on my next trip to wally mart, I have a pile of Energizer 2300 MaH "made in China" which test on the Lacrosse to an average of 1979 MaH. Pretty sad.