How do I know the batteries are dead?

Ver­tigo.

It is good that I’ve just received new sup­ply. It has been the sec­ond set of bat­ter­ies only. I will be test­ing the Ray­ovac Acoustic Spe­cial now (the hear­ing aids kind, not the spe­cial CI ones). And I switch to the fourth pro­gramme today. I should have done it yes­ter­day or on Mon­day, but after the switch to the 3rd I pre­fer to give myself more time to get used to it.