I know that Dyson vacuums are not the standard area for this forum but I was totally surprised to find that google had no links on ways to repair or diagnose a defective battery pack. Actually there was precicely one link where someone wanted to replace the pack with an ac line, but otherwise nothing.

I was cobbling together a couple of 'returned' or whatever Dyson dc44 vacuums from a ebay site that sells store pulls, damaged box etc items. One can't return them as they are being sold for 'parts only'. Anyway: I actually came out well and have a complete totally working vac from purchase of two non working partial units. One was essentially a remanufactured complete unit with (as it turned out) a still defective battery and another unit with many missing parts but fortunately a good battery.

I am reasonably certain that both sets are new. I suppose I should be happy that I have one good battery with no other issues, but being new, I suspect that the other battery may have some minor issue that might be repairable. The charger blinks in a manner to indicate that the battery is 'bad' by Dyson cust. service; or bad as in 'check battery' by the manual.

The one link indicated that there is a logic board in the battery. This is not too surprising because I believe this battery uses unconventional chemistry and probably runs closer to the edge in overheating etc to get more oomph. The warning indicators include one for overheat, or too cold conditions (not my problem, but two of the possible tested situations).

Does anyone know anything about diagnosing these battery packs?