I had a similar issue with our Panda. It appeared to have a parasitic drain, but in fact had a failing battery. We had just had one battery failure and I swapped out my wifes car battery and it too suggested a parasitic drain as well and two days later it was dead as the cars original. It transpired that both batteries were failing and had internal shorts. The car was losing current after its being shut down and from other posts on here it was shown that this was during a period after switching off until the car settled into resting mode. With new batteries in place on both cars the drain has gone, and we have had no further issues. Some drain is to be expected but 0.01A to 0.1A and were were seeing 0.5A The higher level drain goes on in the newer car for c. 15 seconds and the older one (2011) for more like 2 minutes, hte current drain then drops right back as the body computer shuts down.
Even with 0.5 A drain the battery should have been quite happy to have been left for a week without an issue. It wasnt. Initially the first battery died and came back after a charge before failing totally. The slightly newer battery just refused to do anything but again still read 12.9V. Confusing!
Try removing the battery over a weekend if you can and see if it drops. Ours showed 12.6V+that should have been OK. I tried my smart charger on it and it would not even accept it was connected to a battery. I replaced it. After being off the car for two weeks had eventually droped off and would then not take a charge at all even from a conventional charger.
Testing the car showed the charging system was doing as expected.
New batteries dont seem to last like they used to and stop start batteries are even shorter lived. If 4 years old or more suspect the battery!
