Spoolin01, I would be tempted to agree with you regarding one brand in particular versus another brand, if the issue is only voltage drop over time with a constant current draw.
But consider the following:
1. Charging the camera is a series of sudden, high demand current draws. For my A720s, the problem was about as bad w/o flash use - do you know how CCD charging and flash card writing compare in draw to the LCD? At any rate, this is a voltage regulation problem, not a power source problem. Strobes are high drain yet work with standard NiMH - what is there about camera circuitry that's more demanding than the circuitry on the strobe boards?
The earlier link to the Eneloop page shows comparative testing of a Sanyo NiMH at 100, 500, and 1000mA loads. The flattest part of the curve, which lasts through the 1st third of so of discharge is depressed from about 1.29V to 1.25V by the load increase, and stays relatively flat down to 1.2V. Not much evidence of a load-induced voltage spike there, unless it's common for cameras to impose >>1A loads (in which case it's still a regulation problem the camera can be built to handle - it's obviously not a battery capacity or internal resistance problem, the Sanyo sustained the 1A load for over 2 hrs and stayed above 1.1V). If the camera operating tolerance is down to 1.0V as was claimed, it makes that standard NiMH look even better.
2. There is no doubt that this particular camera has either/or a very sensitive voltage circuit or very high current demand (or both).
3. Testing (engineering data) is done on correctly working batteries. Both how the cells are handled and production quality control may play a bigger issue here than labratory testing of perfect cells with an constant current demand. I'm still hoping to see a test of one of these (ubiquitous) sub-standard cells to see just how different it is. And an explanation of why it stumps even routine circuit design, or why the designers didn't know this was an issue with essentially all available batteries.
If you would like to see one of the possible issues, just take your favorite NiMH's and do a life cycle test with your favorite device and then drop them on a hard surface from roughly 5 ft (do it several times, as a single drop only has roughly a 15% chance of damaging the cells.. then charge and do the test again. If you have an single channel charger that reports the charging energy, the results can be shocking. Hey I do this test and don't even know it! Maybe this is part of why I see maybe a 10%/year failure rate in my batteries. Does this happen to Eneloops too ?- they seem to be fail-proof as reported so far.
Note: A drop for as little as 2.5 feet can cause this effect.
However, if you have an intelligent charger ( I get nearly identical data from a LaCrosse BC-900 and a MAHA MH-C9000)... it is easy to find individual batteries that will show a sudden voltage drop when exposed to a high current demand (Most good multimeters can do this test ) Not sure I follow you here, are you saying you can see this with the BC-900? Do you monitor the voltage with the charger, during discharge? Or with the VOM?
Before I would call all the people that have had good results using those batteries nuts, I don't at all doubt that their reports with Eneloop-type batteries are valid. That Eneloops work in those cameras is not the issue for me in this thread. It appears that Eneloops are a substantial modification of the technology, not just better QC, so they don't explain how the quixotic behavior of a small subset of camera models can be laid at the feet of an established battery technology. consider the following examples:
1. One of the most common batteries used in dive computers is the Lithium 2450.... this battery is available in two versions...the Japanese version (I suspect there is only one maker of this battery in Japan, as all the Japanese cells perform the same) and a Chinese version. Both work well in trickle discharge condtions....but under high demand/short duration conditions, the Japanese cells have about half the voltage drop. Put a Chinese cell where there is short term, high demand draw and the device will not work. However, if you look up the testing data for both, they only show trickle discharge curves. As I could find no test data on this issue, I had to learn the hard way and eventually put together a test system to confirm if this was really true (as I did not believe several unscientific people that told me to only use one brand of battery).
What I see is a difference in both cell to cell variability from either mfg or shock damage, and some internal resistance differences.
As with the 2450's, there appears to be only two mfg of the low discharge batteries.. one Japanese and one Chinese...and there is significant design differences between the two.
With well over 1,000 charge cycles with Nihm's so far, my experience is that cell to cell repeatability is far better with the Japanese low discharge cells...with the most common issue being variation in internal resistance... which would easily account for what people are seeing. Well,this is the big question. I still have the batteries that couldn't operate my A720 cameras, as well as 100 or so others. I guess I should test them for voltage drop under load. I think the BC-900 can be programmed to discharge as high as 500mA. Is this how you test internal resistance?
