H-D Night-Train year 2007 does not start.

Hello everybody, I have a problem again. I drove a lap yesterday and at the beginning everything was ok. I stopped at a Norma to get something to drink. When I wanted to start afterwards she went on first and then immediately out again. After that I did not get to her anymore. Then I called my girlfriend and she came with her car and a bridge cable. The cable made it, a time waited and then tried again. But without success. but it doesn’t start. Then I called the ADAC and it finally came after 1.5 hours. I then had myself brought with the moped into a hall from me. After the unloading I tried to start for fun and she was there immediately. Then I drove with her about 25 km without any problems home. This morning the same game. Again it does not start. Then I hung the battery to the charger and then it jumped again. Then I wait again half a day. I have 2 batteries here. Both were so cheap batteries for 65 €. I suppose they are both on the A…. And now my question. Can it be that the battery has enough juice to turn the starter but then has too little to get a decent ignition spark? I took out the spark plugs once. The spark is there but I mean, it’s just that I don’t have enough juice to turn the starter. It would be nice if I got any tips. Greetings Frank P.S. On the picture is the battery I installed.