Do NiCd Batteries Exhibit Memory?

[Mandarax]

In a column on nickel cadmium batteries’ memory effect, Cecil says “it’s a myth, bud… this kind of thing seldom if ever occurs in earthbound applications.” If it’s a myth, it’s one with quite a technological underpinning, judging from this example:

Chemically, recharging NiCads before they are fully discharged often results in the formation of cadmium crystals on the anodes of the cell. The crystals act like a chemical memory system, marking a second discharge state for the cell. When the cell gets discharged to this secondary discharge state, its output abruptly falls despite further capacity being available within the cell. In subsequent cycles, the cell remembers this second discharge level, which further aggravate the situation by reinforcing the memory of the second discharge state.

I could believe that the NiMH manufacturers would like to keep the myth alive, boosting the sales of their “no mem” alternatives, but my Norelco razor, which contains NiCads, tells me not to recharge until the battery’s run down. Surely they aren’t in league with the NiMH folks, since they’re using NiCad themselves.

Also, the memory effect seems to be something that I’ve experienced, though it could be that the batteries have just been wearing out, and I’ve attributed their reduced performance to the memory effect.

So, is the nickel cadmium memory effect a myth or not?

[royjwood]

Using transceivers as part of my daily life, I can assure you that NiCad’s do exhibit memory loss.
With NiMH and Lithium Ion, we can recharge our batteries over and over again, regardless of level of charge prior to inserting in the charger, without any problems. However, our NiCad’s always get worse, no matter what we do. Even using a discharger to ensure completely dead batteries are inserted into the charger, the NiCad’s will get shorter and shorter “memories”, eventually becoming completely worthless. Now we buy only Li ion.

[Mandarax]

royjwood, it sounds like what you’re describing may be just general crappiness on the part of NiCads, not memory per se, since you say that the NiCads always get worse no matter what. I’m wondering now if this memory idea isn’t just a conspiracy on the part of NiCad manufacturers and those who put them in their products. If the battery goes bad, it must be the user’s fault for not following the proper charging procedure.

[barbitu8]

*Originally posted by royjwood *
**However, our NiCad’s always get worse, no matter what we do. Even using a discharger to ensure completely dead batteries are inserted into the charger, the NiCad’s will get shorter and shorter “memories”, eventually becoming completely worthless. Now we buy only Li ion. **

Sure NiCads get worse, but is that attributable to memory or the fact that they, over time, do not hold as much charge as before? I have NiCads in my NOAA radio, and I’ve always let them run down before recharging. Intervals between recharging get shorter and shorter.