Just finished clearing the 30" of NEMO snow off the driveway, wow that was a big storm. Luckly we did not loose power, and it was fairely light snow.
Have started the lengthy process of cell level cycling of the MaxIMA sticks.
As a control, I have retreved a couple of the best sticks from my old pack that were graphed several years ago here:http://99mpg.com/blog/whatactuallygoeswr/
Stick 13 and stick 7
These old sticks had 160K on them, and have just sat since 3/27 2010 when I did the test.
The cell voltages were all at ~ .5V before I started, and both sticks have responded to a single soak charge by coming back to life. They do better on the second cycle, and show about the same cell condition as when I did the test in 2010. which reinforces my opinion that sitting idle even for nearly 3 years does not cause a stick to deteriorate.
Learning some other interesting things.
The first thing that jumped out was that the famous DeltaV effect seems to be mostly a temperature effect.
I have a small fan on each cell, so the cooling is quite good. When topping at 1.5A, and at 400ma, the voltage will plateau, and then the temp will plateau, but no delta V is seen.
If the fan is turned off, the voltage drops as the temp rises, and if the fan s again turned on, the temp drops and the voltage goes back up to the same place as when all was at thermal equilibrium.
This would seem to indicate that if the charge current applied is small enough (350ma) and the pack fan is running, that one will not see a delta V effect as the temp will rise just enough for the fan to dissipate the generated heat, and then the pack will simply plateau.
One will only see the Delta V if the temperature is allowed to rise by inadequate cooling.
The other effect that seems to be clear, is that the topping voltage at a 350ma current is a good indicator of the cells condition. the higher the voltage that the cells top off at, the weaker the cell and the higher the Internal resistance.
I am being very thorough, so it takes half a day to do one stick, and I am preparing a blog where I will get into the analysis of what I see, in the graphs.
The charge rates with my fixture are 32A, 1.5A, and 400ma, and the discharge rate is ~82A, dropping to ~ 75A at the end.
Now that we have so many people working on their packs, I figured it was time to get a better handle as to what it all means.
Once the 20 MaxIMA sticks are recorded and tested at the cell level, I will put the pack in the car, run a couple of reference reconditioning cycles with the charger, and then use the pack for a year, pull the pack and run the complete series again, to see how things change.
My car may not be the best test vehicle, as I am tending to drive the Prius when I need to go out, so we will see what makes sense next week when the test are finished.