Volvo Repair: 99 S80 Electrical or Transmission, battery mark, service transmission

Question
While driving aprox 70mph, fan for A/c quit, then speedometer went to zero, airbag symbol illuminated, ABS brake svc msg and STS service msg appeared, then the car would not accelerate, engine acted as if running out of gas, but never quit.  Pulled over and could shift into different gears with tires apparently turning in correct direction, but no acceleration, just rev up of rpms. Battery low voltage message after shutting down and turning key to the position just prior to start in order to charge cell phone.     Previous elec problem in early 2005, needed software update, also have gotten the ABS/STS msg's twice in last 3-4 months.  Also gotten service transmission light twice in last year with auto shop recommending drive till it quits then get xmission replaced. What a mess, thanks for your help.

Answer
 Wow, you've got a lot going on. I'm thinking I would check for low voltage first. This can cause a TON of problems. A bad battery can do this too. Check the charging system and all cable connections. Have the battery load tested and get back to me, or substitute with a KNOWN GOOD battery.

Mark