Eneloop makes D and C batteries but we don’t see them in America, just as we won’t see the generation 4s for a couple of years when they come out, although Japan will have them.
I believe in using AA and AA batteries anyway and having D and C adapters (they hold AA batteries) for emergency use, UNLESS you have money, and then owning and using D batteries is cool indeed because some luxury items like very bright lanterns, use a lot of D batteries, as long as you also put out the money for for the greater charging needs.
A D battery can be 10,000MaH and would never charge on a small solar charger that can handle 2000MaH AAs, and 800MaH AAAs.
The AA is the most common battery on earth, and the AAA is second, so most of my survival gear and flashlights use the AA for power.
Smokin Joe, the Eneloops are LSD (low self discharge), meaning they can sit in the drawer for many years in between charges and still operate at 4 degrees below zero.
“eneloop (3rd generation)
In October 2011 the batteries were again improved to hold their charge for up to 90% after one year, 80% after 3 years and 70% after five years. In addition to the lower self-discharge rate, the batteries can be recharged up to 1800 times compared to 1500 times in the previous revision”
That was in Japan, the generation 3 Eneloops didn't start being sold in America until just recently, that is why almost all the ones you see everywhere and at Amazon and Costco, etc, are generation 2. Amazon does sell the generation 3s BUT you have to look for "1800" cycles, not "1500" cycles, ignore the words, "newest generation".
“believe in using AA and AA batteries anyway and having D and C adapters (they hold AA batteries) for emergency use,”
Part of this post of yours is misleading, but I won’t go into it. Smokin’ Joe can read about batteries as soon as I send him the links to the articles about batteries.
I have some of those adapters I bought years ago. They work, with a caveat: no way a AAA or AA will have the amp hour rating a D or C will, so while you get the voltage, battery life is a lot shorter. Good in a pinch, though.