i need battery help

86 vfr 750 new battery 60 days ago fully charged 12,9 volts on the bench key on not running high beam on for 45 sec drops 11.2 cranking [kill switch off ] 9.5 volts
running 500 rpm 12.3 4500 rpm 11.2 what do i need to fix my baby

 

4500 revs it should be reading around 14.5v the charge coming from the reg rec.


Could be a duff battery. You never mentioned manufacturer of battery.

 

its a crank battery (it was cheep $35 out the door with a years warranty figure cant go wrong ) thinking is not my strong point

 

do an AC voltage check of stator output, should be between about 10 volts at idle up to 65 volts at 5000 rpm. if stator check is good, r/r is probably bad. also, inspect red plug on starter relay for melting or burning which will reduce charging voltage.

 

the red one was fine the yellow one was burnt fixed it now i have 14 volts at 500 rpm but drops to 13.2 when reved up my battery fully charged
is 13.6 v
with just the headlight on for 30 sec drops down to 10.6 v then it takes 1,5 min to recover to 12.8 v would my battery have a weak cell