2006 S40 T5 AWD Power System Service Urgent
 

Just bought my first Volvo the other week. Had some weird things happening so I changed spark plugs then found out I had a bad coil pack and changed it out. Car was good for a few trips then I got a Power System Service Urgent with batt light. Tested battery and alternator got a weird reading from the alternator. Battery was old replaced it work fine for about 200 meters then the power system lights came back on. Replaced the alternator car worked fine for a few days. Took it in the highway and on my way back power system lights came back on. Also just before the car died the abs light came on then a message about the power steering came up and power steering died. When I got it towed I started the car and it started great then a minute or two later the power system service urgent light came back on. Any ideas on what the issue might be?