Parasitic drain in remote control weirdness

[SweD]

Hi all,

in a remote for a TV, a TV almost never used, I've had two Energizer 700 mAh AAA cells, always charged at the same time at 300 mA on a C9000.

The other night, for lack of better things to do, I thought to refresh the cells and charge them up, since it was long ago it happened last time.
To start with I put them both in the C9000 and discharged at 100 mA.
To my surprise one of the cells, came back with Done, after only a minute or so, Voltage being 0.94, something, at the start.
I thought ... "What the <bleep>?"
The other cell discharged nicely, and had roughly 550 mAh left.

After a break in, and then a normal discharge, they both show 713 and 723 mAh capacity respectively, so the cells themselves seem just fine, at least at a quick glance.

Can anyone explain what might have happened here?

Two cells in series, charged at the same time and after a prolonged stay in an unused remote control, one of the cells is empty and the other is almost full.

Is something normal confusing me? :-D

Regards,
/Dennis

 

[archimedes]

Re: Parasitic drain in remote control weirdness.

Yes "identical" cells are often not identical. I think this is relatively common.

Especially as cells age, even a "matched" set may develop stronger cell(s) and weaker cell(s)

If the (now mismatched) set is kept together, further demands on them (in series) may widen the performance gap. In other words, the weaker cell may get progressively damaged.

 

[john61ct]

A bad design in the remote, rather than DCDC converter tapping the 2S at midpoint to maintain the time & settings?