Re: lithium coin cells vs alkaline AA or AAA cells Message #25 Posted by Garth Wilson on 24 Sept 2013, 10:48 p.m., in response to message #4 by Eric Smith
AA's give several times as much energy per dollar as AAA's give. I just bought 100 alkaline AA's for the many things around the house that use them, for $16 at Fry's. That's about eight cents per amp-hour. And while I occasionally see AAAA's, most battery displays in the stores do not have them.
I definitely would not want a battery type, rechargeable or otherwise, that won't be available indefinitely. My HP-41cx has 27 years of service on it and seems to be going strong. I use it every day. Getting N cells is becoming more challenting, but we can still get them. If HP had used a custom battery and had discontinued it 15 years ago, I would be rather upset.
I keep hearing about "pocket calculators;" but I would not consider any of these valuable calculators "pocket" calculators. If you put it in your shirt pocket and bend down to get to a lower file cabinet drawer, what happens? The calculator falls out on the floor. If you put it in a pants pocket and sit down, what happens? You break it. And even if you don't do either of those, you get lint into the keyboards. No, good calculators never go in a pocket.
My first choice would be the AA's, followed by AAA's. I'm not convinced AAAA's will always be available, short of disecting new 9V batteries which is not a practical option.
If you know of a good web page describing how to use SD cards, with their many types of file systems (FAT12, FAT16, FAT16B, FAT32, FAT32X, NTFS, exFAT, HFS Plus, UFS, Ext2, Ext3, Ext4, btrfs, HFS Plus, ReiserFS), partition types, the two or three different CRCs, three different block sizes, different densities, etc., in SPI mode, for dummies, please share it with me. I find SD to be daunting.
Edited: 24 Sept 2013, 10:49 p.m.
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