Enthalpy, I doubt that these batteries will ever replace fossil fuels for electricity and travel. There simply isn't enough supply in the world of the right isotopes to fuel batteries on that scale. These batteries need non-penetrating radiation, betas and alphas, to work safely. Anything that has gamma decay will require heavy shielding and will have very low energy efficiency. Alphas, due to their high mass, will cause a lot of damage to the surface. There aren't very many pure beta or pure alpha emitters. And they're not cheap or easy to get. Many of them are under international safeguards. They have to be extracted from sources where they are very dilute and hazardous to handle.
I'm not saying it can't happen, it's just highly unlikely, IMO. Seems to me they will be a specialized niche market if they can be developed to the commercial stage.
Just for fun, calculate how much tritium it would take to power a 100 Watt light bulb (assuming 100% efficiency). Then see how much it would cost. Then tell me if you want one for your house.