'Service Battery" and other power questions?

Hi everyone

I have a mid 2009 13 inch MBP with the below details on power and battery:

Right now, the battery condition states that it is 'normal' but quite often it will go over to 'service battery' and it gave me the message that the date and time

had changed when I had drained the battery totally the other night. Coconut battery(right now) states that the battery capacity is 77 %.

I have had a look at many different forums on this topic but I cant seem to get a concise answer on this. In other words, should I replace the battery?

The nearest decent Apple store is about 350 miles from where I live so getting it properly tested is not a walk around the block.

I have also upgraded from the original 2 G's of RAM to 8 G's of RAM as well as installing a 256 G SSD Transcend drive. I dont know whether these modifications would have any impact on battery life?

My MBP was originally shipped with Leopard and so I have gone through Leopard, Snow Leopard, Lion and now Mountain Lion. Since Lion and now with Mountain Lion, I have noticed a substantial decrease in battery life.

Whilst I really dont want start another "battery life" thread, I am really interested in why with each new OSX, battery life seems to diminish. I am also aware of the fact my MBP is three years old as well as the fact that my battery has done 648 cycles too.

All feedback would be most welcome.

Charles

Charge Remaining (mAh): 3998

Fully Charged: No

Charging: Yes

Full Charge Capacity (mAh): 4213

Health Information:

Cycle Count: 648

Condition: Normal

Battery Installed: Yes

Amperage (mA): 477

Voltage (mV): 12511

MacBook Pro, OS X Mountain Lion (10.8.1)