If you pull the - battery cable, no chance in Russia you can have a parasitic draw.remove the negative cable from the battery and let it sit until the next cutting. If the battery remains fully charged, you have a parasite draw
And if it is fully charged you don't have a draw either. You have a fully charged battery.
Don't even mention parasitic to the OP. No offense but I think he knows a few words and is dangerous with them. All these things test good but his mower still doesn't crank, doesn't add up.