New Battery Needed?

[Greggh]

I had something wierd happen yesterday.
98 Stnd with 73 k for miles.
I have owned her for the last five years and have never replaced the  battery.
Yesterday while getting on the highway I noticed my tach went dead, Blown Fuse?
So I proceded to chase down and overtake some crotch rockets with a Buddy and his Wing, then I noticed I was unable to get over 110 mph?
NO concerns because I had a strong 40 mph head wind.
Uppon getting to the garage I notcied she was not sounding right in regards to engine noise, however she was still running and Idled ok.
I shut it down and then tried to start it again and the starter draged like the battery had no juice.
Checked all the fuses and all connections and everything was just fine.
Put her on the battery tender over night and she fired right up this morning and the tach was even working.
Seems lke I got an unexpected length of life out of my battery of five years.
Time to purchase a new battery? 
Any thoughts and or suggestions?
TIA GreggH

[don07tncav]

Battery or alternator. Every time my alternator has died, the tach went out first then the bike would totally go down once the voltage got too low.

[MP]

I would put in a new battery, and try it.
Put a voltmeter on it once you have it at a fast idle, and make sure you are in the 13.5v range or so.  If much lower, than the alt may have taken a dump.

Make sure all connections are tight and clean.

MP

[Greggh]

I will have the alternator tested later this week at my buddies shop.
I am no good with them there volt meter thingys!

[ValkThree]

I would charge the battery and check the voltage when the bike is running - if it's the alternator that will tell you quickly.
No use replacing a good battery especially if you have to spend money on the alternator or regulator.