new someone was gone beat me to this long response, lol.....
if your battery is rated at 2AH (2000mAH) then a 1C rate would be about 2 amps, (charging or discharging) and it would take about 1 hour to complete a discharge (charging takes longer as power is lost to heat). So a 0.1C rate for discharge just means that you are discharging or charging at about 200mA, or over the course of about 10 hours. So "C" rate is just defining the rate of charge or discharge in relation to time rather than actual amp rates.
[/quote]Not sure what "form" or "balance" means? Actually, clueless.[/quote]
A nice slow long charge gives all the cells in the pack a chance to come to a state of full charge without too much heating up. This gets all the cells into the same state of charge (full) which is important for cycle life. I don't know how to explain forming, I guess you could say that the cells need a chance to "break in" like when you put a new cam in an engine, a long slow charge accomplishes this pretty well I guess... Lower capacity cells tend to require less of this maintenance, cells like the eneloops require basically no pack forming or maintenance as they tend to come out of the box very well balanced and matched.
This mean %30 left or 70% left of life? 70% seems a little ridiculous. (Though considering how power hungry new leds are, 30% seems a waste.)
Means 30% remaining. Over-discharging cells is one of the the fastest way to ruin a NIMH pack, by limiting yourself to ~70% of the packs capacity you are ensuring that none of the cells are being dragged down to the lower limits.
Is this dead? I carry a small batter tester at all times, no desire for volt meter-size and breakage.
First of it's very difficult to determine a state of charge on NIMH cells with a simple tester, some of the more complicated ones might be able to give an indication, but NIMH varies so much in different sizes, internal resistance, etc, that I can't think of any battery tester that could give you any accurate idea of the state of charge for a randomly chosen NIMH cell. A good quality pack charger will do discharges to ~1.0V per cell. 1.0V per cell is indeed very dead.
What is wrong with 2300 to 2650's?
if you are talking AA cells, the highest capacity cells, while good for maximum capacity, are a major tradeoff that they do not mention on the package (informed consumers are dangerous consumers, so they are simply trying to convince you that bigger numbers are better.
Think of a AA cell as a long length of wire coiled up inside the cell. Now, imagine that the longer you make the wire, the more capacity it has. So to fit a longer wire in the same size package, you have to make the wire thinner. Now think about the effects of making the wire thinner. The cell can't deliver as much current, and the wire is more fragile. Tends to be that the lower capacity cells are the most robust (think thicker wire), they handle high current well, they have the lowest self discharge issues, and they tend to survive the most cycles, and are therefor the best choice for pack building. Maximum capacity cells also tend to be the most unbalanced (having larger variances in capacity from cell to cell).
