Hi guys, i try to solve charging problem on my A6 longer time. The alternator charges the battery, but with weak power. In VCDS the specified voltage for ALT is 14,3V, but charging voltage at iddle only with lights ON is 13,8V. I have new AGM Exide 105Ah battery (correctly coded), i have chcecked al connections from generator to battery. At 100A generator current only 200mV voltage drop = 2mohm all circuit. Also cable between engine and car is new, all connections brushed. I tryed 3 different voltage regulators with no effects (all regulators had 61 channel 10.... OK, OK communication/ generator). Also i tryed new alternator, with no effect. Next test... 3 different J644 modules, all with the same behavior (14,3V specified, 13,88V charging). Last test was uploading software version of J644 from 4xx to 5xx... no change. Today i measured 5A fuse of J644 module.. it is OK. At this moment i really dont know where can be problem, another A6 have 14,7V specified voltage. During winter the car had problems with cold starts due to wek battery.

My opinion is, that in J644 module is some exciter current limiter, or another type of limiter? Really, i dont know. In VCDS, the DF signal never exceeds 50%, so from this information i think it can be some software issue.

thank you for all suggestions