With MH-C9000, does reported Discharge Capacity tend to be spec of highest interest?

[L_D_Allan]

Semi-newbie with MH-C9000 and non-EE that finds many electrical concepts to be baffling.

I'm fuzzy on what some of the values mean on the MH-C9000. Is the following more or less correct?
If I had to pick one "figure of merit" value to describe the status of an AA rechargeable battery, would the reported "Discharge Capacity" be appropriate?

(I realize that a "full picture" of the battery's status involves some or most of the values reported.)

Suppose I wanted to keep a simple spread-sheet of how my 6+ sets of AA rechargeables were doing over the next several years, what would the minimum / appropriate value(s) to track for K.I.S.S.?

 

[SilverFox]

Hello L D Allan,

Keeping track of discharge capacity is a good way to go. You may also want to keep track of the discharge current you used to get the discharge capacity.

Tom

 

[L_D_Allan]

You may also want to keep track of the discharge current you used to get the discharge capacity.

I'm fuzzy on what you mean by "discharge current". In a flashlight, would that be the "drain", like "normal brightness for 6 hours"?

What about an external camera flash? Should I try to keep track that the batteries allowed 104 flashes? I wouldn't be able to do that.

 

[SilverFox]

Hello L D Allan,

The C9000 allows you to select the discharge current when testing your cells. The default is 500 mA.

If you are using your cells in a high drain application, you may want to test using 1000 mA for the discharge current. The other side of this is that if your applications are low you may want to use a 100 mA discharge rate.

Tom

 

[MidnightDistortions]

I actually find it best to use a higher discharge current rate to make sure those cells can handle high drain devices. 300-400mA is good for most devices but for flashlights with turbo/high lumen modes and my GoalZero i prefer discharging the cell around 700-1000mA. The end discharge capacity rating shows you how much the battery can produce before they are fully discharged.

 

[Rosoku Chikara]

...If I had to pick one "figure of merit" value to describe the status of an AA rechargeable battery, would the reported "Discharge Capacity" be appropriate?<snip>

I personally use the "Analyze" value as my "figure of merit." I have kept data on every Eneloop cell I have purchased in an Excel spreadsheet. Here is a sample of 16 cells, so that you may judge for yourself how the various values vary from each other:



These are Eneloop "Black" (Pro/XX) cells. All discharges were done at 500mAh. (The first discharge is so low, because that is the initial charge from the factory.) The Analyze is done with a 600mAh charge and 500 mAh discharge. (I charge all my AAs at 600mAh and all my AAAs at 300mAh.) I am not saying that I am "doing it right." Just wanted to show you the values I have gotten using the various modes of the MAHA C9000.

My primary interest is in keeping "matched sets" for each application. So, for example, when a device requires 3 cells, I select a 3 cells with the closest possible ANALYZE values and group them as a "set." So, I end up with lots of 2, 3 and 4 cell "sets" in both AAA and AA, and I try to always keep them together as a set. (Typically, I keep them in the same application.) Once a year or so, I check the set using ANALYZE to verify (and record in my Excel spreadsheet) the performance of the set. I have yet to have to switch a cell out of any set due to a significant change in performance. Some sets have higher capacity and some sets have lower capacity, but so far each set has remained very consistent as far as differences between cells.

Other than the above "set consistency" check, I simply use and charge my cells without ever looking that the values displayed by my MAHA C9000. Frankly, having been at this for a couple years now, I think genuine "Made in Japan" Eneloops are so good, that you hardly need an analyzing charger like the C9000. But, since I have come this far, I intend to keep at it until (someday?) my Eneloops do begin to fail, so that I can see how they are failing.

In conclusion, I am glad I purchased the C9000, and I enjoy the data that it can generate, but I really only "need" it for checking the few old Panasonic non-LSD NiMH cells that I have around.

 

[MidnightDistortions]

I like keeping matched capacity cells as well. It's pretty amazing though since i got Eneloops they all showed a similar capacity so i can pretty much grab whatever and not have to worry too much. I will match cells that are from the same batch regardless. When i bought my first set of Eneloops i didn't realize 4 of the 16 pack were made a month earlier so i try to primarily use those first even though i have a newer set dedicated to a USB charger (for my phone and for a future tablet) but i regularly keep my phone charged to 80% so i do small 3-5 minute charges with the USB charger to keep it around that level so the AA cells are not discharged too hard. Anyway i mostly use the C9000 to top off my cells, HSD or LSD it doesn't matter long as it will charge the cells. I don't really have a set system to what cells i should put in each charger but the older cells that have developed high IR generally will work better in the La Crosse charger but i got a few junk chargers that i use as well.

 

[IonicBond]

You may also want to keep track of the internal resistance measurement. The 9000 will show that value to you only *once* after inserting a cell, and might appear to be a voltage, but it is the IR reading. Very fresh cells - 1.4 or so. Middle aged cells - about 1.8. Cells turning into more of a resistor than a battery - about 2.0, and much more than that and the 9000 will kick them out of the charge loop.

So I guess if you are really keen on building packs, then match capacity and internal resistance values as close as you can.

 

[L_D_Allan]

Thanks to all for the helpful, patient replies.

 

[Grijon]

...Very fresh cells - 1.4 or so. Middle aged cells - about 1.8. Cells turning into more of a resistor than a battery - about 2.0, and much more than that and the 9000 will kick them out of the charge loop...

Thanks for the guideline!