> Date: 14 Dec 1999 21:23:42 -0500 > From: Stainless Steel Rat <[EMAIL PROTECTED]> > Subject: Re: MD: Batteries. > > - -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > * Ray West <[EMAIL PROTECTED]> on Tue, 14 Dec 1999 > | Just a note, which can save you some grief. > | Be aware if you're using Nicads or NiMH rechargeable batteries (both have a > | nominal cell voltage of 1.2V). Nicads tend to have a memory effect, > > Please read the "Battery FAQ" at <URL:http://www.cadex.com/>. The short > version is, memory is a myth. What is commonly called "memory" is usually > the result of crystalline formations or deposits on the internal contacts > caused by overcharging. A deep discharge cycle or two can sometimes undo > some of the damage. I've read the FAQ re: Ni-cads, and many other similar papers. Your summary is ok, but it is perhaps best to prevent the crystal growth in the first place - hence the trend toward Ni-MH and Li-ion. There are other advantages/disadvantages for each type, of course. The point of my original post was, just because a Ni-cad, or Ni-MH will fit in a particular charger, be careful in what you do. I know of folk who discharge Ni-cads with a lamp, or similar, down to zero volts, and then they wonder why the batteries fail quickly. There had been a previous posting to this list which presented, at least to my mind, a rather cavalier attitude to batteries. It is quite possible to overcharge Ni-Mh batteries with the wrong (e.g. Ni-cad) charger, and they can then severely overheat, and even explode. Sharp warn against using Ni-cads in some of there md recorders, but primary cells and Ni-Mh are OK. Although they have not said why this should be, I suspect it is due to the fact that Ni-cads would not last long, since the inbuilt charging circuit does not cater for the discharge cycle. Also, there is a higher power density in Ni-Mh batteries. Maybe they detect the rise in temperature, or the peak voltage, when the Ni-Mh battery is charged, in order to switch off the charge circuitry. Using an external Ni-cad charger and Ni-cads would be OK, but the built in charge circuit would possibly be unsuitable. Best wishes, Ray ----------------------------------------------------------------- To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
