Discharge Curve of NiCd pack looks like RC curve

[radellaf]

Any idea what's going on with this pack? At the 1C rate it looks normal, but look at the start of the .1C "recondition discharge" The curve is like, backwards.

FWIW, running these cycles on the UBA4 has brought this pack from about 1.3Ah back to the 2.2Ah rated capacity. Don't know if more usual 1-stage discharges would do it, but this does a 1C discharge to .9v/cell then .1C to .5v/cell.

Other odd thing - adding the capacity of both discharges should be on the order of the pack capacity, but in this case I got 500mAh or more over the 2.2Ah rating. ???

One Hour Discharge
Duration (h:m:s): 01:00:54
Load current: 2.205A.
Cut-off voltage: 900mV.
Battery discharged: 2.237Ah.
Exit condition: Battery cut-off voltage reached.
Recondition Discharge
Duration (h:m:s): 02:34:50
Load current: 216.5mA.
Cut-off voltage: 500mV.
Battery discharged: 558.6mAh.
Exit condition: Battery cut-off voltage reached.

 

[SilverFox]

Hello Radellaf,

I don't know... It looks pretty normal to me.

After removing the heavy load, the voltage rebounded. It then was able to hold the lighter load for around a half hour off of the rebounded voltage. Once this rebounded voltage is bled off, the discharge continues at a more normal rate.

Tom

 

[radellaf]

Hmm, I'm used to rebound, but not lasting more than a minute or less. And even so, was expecting more of the same shape curve afterwards rather than the sharper knee down to the long sloping part.

<shrug> Have to see how other packs act...or cells. I'm going to be at this for a while, as I have like 10 more cells that need individual attention.