@manly: OK, that thread at Candlepower Forums was started in January 2006.
I have a La Crosse BC-900 charger since March 2007 and I'm not unfamiliar with issues with it. I prefer the BC-700 (do most of my charging with one), which came out later and La Crosse evidently addressed issues with the BC-900 in designing it. The BC-900 has a nasty habit of showing "null" when inserting a cell that's pretty run down instead of showing a voltage. The BC-700 will do that (very rarely in my experience, only 2-3 times I think). The same cell (AA or AAA I think) that shows, say, 0.85 volts on the BC-700 will show "null" on the BC-900 and refuse to charge, whereas it would charge on the BC-700. I keep a different charger at hand where I keep my BC-900 that requires two cells to work, and slip in such a cell along with another companion for a few seconds (5 seconds are probably enough) to boost the charge on the "null" cell to where the BC-900 will charge it. This has happened dozens of times with the BC-900 -- very annoying!!!
The Candlepower forums (where I am registered) are probably where I learned about the BC-900 difficulty in detecting the fact that a cell has reached the cut-off threshold (which you say is 1.37v) when charging AA cells. As I understand it the problem is particularly if you charge them at the lowest charge rate, i.e. 200mah. The workaround (as I understand it) is to charge AAs at the next higher charge rate, 500mah, and I ALWAYS do that with Eneloop AA's. I charge Eneloop AAAs at the lowest rate, 200mah and AFAIK there's no issue with that. I do these things with the BC-900 and the BC-700. I'm not aware of having had problems personally with these chargers (other than the BC-900 failing to charge a very run down cell without boosting its voltage using a different charger), but yes, as you say, charging AA cells has (anecdotally, for me) resulted in charger "meltdowns" which are very concerning, presumably could cause a fire. I used to have another rechargable cell brand but have stuck with Eneloops almost since the beginning.
When I bought it the BC-700 was selling for less than the BC-900. I think it's a bit less featured than the BC-900 but has the features I use, and doesn't have that annoying inability to charge a very depleted cell without its charge being boosted. These chargers have a lot of great features including being able to charge from one to four cells, each in its own way, or even test one or more of those cells (determining its capacity) simultaneously with charging others, go through a refresh process in which a cell is charged and depleted automatically several times until its capacity reaches something like a maximum for it. I've used those features a few times. Just what's available in chargers now, I don't know. I've been reasonably happy with those La Crosses, but am careful to always charge AAs at 500mah charge rate.
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