Google refuses to accept that there are Kodak batteries actually labelled 'Extra Power'.
If you're using Kodak's 'Extra Heavy Duty' batteries, they're only Zinc Chloride so they're totally unsuitable for digital cameras.
If they're actually labelled 'Kodak Supralife' then they're alkaline batteries, which is at least a bit better.
However, from experience, I'd never use anything other than Lithium batteries in a digital camera. (I was also getting very few shots from both rechargeable and alkaline batteries but lithium batteries just seem to go on and on for an incredibly long time).
Chris