Threeband
The M1 Does My Talking
This phone is only about a year old. You can buy them at wallmart for $19. However I agree with your statement that old Li batteries can sometimes show full charge but only last a fraction of their stated capacity.
But the sim card is linked to you or your credit card, so it's not really an anonymous burner, unless you mean you never activated it, and figure to use it only for 911.
But in that case, it's of pretty limited usefulness.