Monday, 19 December 2016

10:36 – Barbara has friends coming up to spend the day. The weather is better than expected. It’s chilly, but no precipitation and little wind. I’m sure they’ll have a good time walking through downtown Sparta visiting shops and stalls.

Ah, the joys of living in a small town. I had a follow-up appointment scheduled with the dentist for 10:30 this morning. At 7:27 a.m. my phone rang. It was the dentist office calling to cancel the appointment because Dr. Flowers is taking a sick day today. She’s something like seven months pregnant, so that’s not surprising. What did surprise me is that the receptionist apologized for the inconvenience and said that they’d be crediting my account for $25 because Dr. Flowers missed the appointment. I’m used to doctors and dentists charging patients a penalty if they miss an appointment without calling to cancel it 24 or 48 hours in advance, but that’s the first time I’ve heard of a doctor or dentist charing themselves a penalty for missing an appointment.

Starting tomorrow, we need to get more science kits built. We’ll start by building another dozen or so biology kits, which we’re shortest of at the moment, and then another dozen or two chemistry kits, which we still have to fill chemical bottles and build chemical bags for. After that, we’ll do another dozen or so forensics kits.

We’ve been buying Costco AA and AAA alkalines for 10 or 15 years, and it’s time to start focusing more on rechargeables. I made an initial foray into rechargeables 10 or 15 years ago, back when NiMH rechargeables were just coming into common use. The problem with those early-generation NiMH was that they didn’t hold a charge very long, so they were mainly useful only in things like cordless phone handsets that could be put on a charger every night. Their rapid self-discharge made them entirely unsuitable for stuff like flashlights, remote controls, and so on. Also, many of them promised 500 to 1,000 charge cycles, but in my experience they often died after 100 cycles or even fewer, even when charged on an expensive “smart” charger. Finally, their mAH capacities were so much lower than alkalines that they weren’t particularly useful for anything that required a lot of current, unless it was something like a camera where they could be recharged easily and immediately.

But now the technology has improved immensely, and the cost has fallen pretty dramatically as well. Low self-discharge (LSD) models keep a high percentage of their charge even sitting on the shelf for a year or more, so they’re now usable in things like remote controls and flashlights. There’s still a three-way trade-off. High mAH capacity; usable recharge cycles; and LSD. Pick any two. And, of course, you can add in price as a fourth factor.

NiMH AA and AAA cells currently sell for $1 to $4 each, depending on specifications, name brand, and so on. That means they pay for themselves after anything from three or four up to ten recharge cycles.