My situation will be unique I think, since I have an essentially new Traction Battery (only used for 4200 miles in a nearly new car before it was totaled) out of the donor car for my Firebrid project that will be well self-discharged by the time I go to charge it again (2+ years total.) It will be a good test of how well that system works for a totally discharged battery that is otherwise in new condition. I plan to buy the device just before I need it, unless it goes on sale for a good discount at some point.
Bill the Engineer