How much did you pay for that battery? I see here that it’s € 9,59, but during checkout with “Sofortüberweisung” they seem to charge the VAT twice.
Edit: I contacted them and they said that they have indeed a bug in their system.
Edit2: I’ve ordered one of these batteries. I will do some testing and take the battery with me to #efct17. 
In the meanwhile: @HermannMeuth: Using a system monitor app, can you confirm that the battery temperature monitoring works?