It is known winter. After several days with rides of about 30-50 km I notice that the battery performance a bit decreases. Of course, heating, cold start, ventilation, heating, seat heating, driving light, rear window…….. All in all many consumers who also pull proper juice. Well the question: I want to charge the two batteries once to 100 %, with a battery trainer, so identical to Cetek. Can I connect the device to the two connections in the engine compartment, think yes. d are both batteries charged or only the starter battery. ???