I have a 1990 740 GLE wagon, and it is currently broken down about 6 hours away from me. I have taken it to several places on my attempt to get home (unfortunately i don't think any of them knew enough about volvos)
anyway I had a new alternator, new alt belt, new battery all put in and my car still isn't charging properly. The Battery cable looks fine according to mechanic, they are saying it's the alternator, which is now the second one put in in the past couple days. The car was driving, but barely, and all my dash lights were lit up, and dimming as I stepped on the gas. Am I missing something? Is it electrical ?!

 

Okay, check your battery first thing before starting. It should read ~12.0 VDC or more after a nightly layover. When started, the alternator charges the battery to about 13.5 -14.0 VDC.

If your battery can't hold at least 12.0 VDC overnight, then your battery is faulty. If you don't get a reading of >=13.5 VDC when the engine is running, your alternator is probably faulty (assuming your belt has been properly tightened).

 

Oh, I forgot one more thing. The above assumes that there is no gremlin stealing charge from the battery overnight (short circuit somewhere). Disconnect the battery ground overnight, and then check the voltage in the morning for 12.0+ VDC.

 

The shop I have it at told me the battrey needed to be charged, and now the NEW alternator is running fine. The battery was JUST purchased and the car was barely driven with it in (like maybe 5 miles) . I don't know what the reading was as I am 6 hours away. I'm afraid to get it tomorrow, and break down again. And to top it off the parts were all purchased from a chain store we don't even have in my area, so if one of them goes bad (again) I can't return or exchange them. How would I go about figuring out what could have a short circuit somewhere?

 

Without a meter it's hard. Advance Auto Stores used to check systems for free but I think lately they have had some liability issues.
You could just ball park it, just see if what kind of spark you get when you unhook the negative battery and touch it back. With everything in the car shut off there should be very minimal to no spark whatsoever. If you get an arc you could weld with, you have a problem. Then just start pulling fuses one by one till the arc goes away,