How long do hearing aid batteries last?

I got my first hearing aids a few days ago (one for each ear )
Both hearing aids went dead after about two days but worked well when I put in new batteries. Will I have to replace the batteries that often?

Depends on the amount of gain your hearing aids have to generate, the size of the batteries, and whether or not you have any external devices attached that the batteries are also powering.

The worse your hearing, the more gain the HAs have to generate, the more power they drain from the batteries to generate that gain, and the faster they chew through batteries.

Smaller batteries (like the 10s/13s which are yellow and orange) have less power than the larger batteries (675s, which are blue) so those need to be changed more frequently

If you are using bluetooth or have an FM system attached to the HA, the batteries for the HAs sometimes power those systems as well, and then you require more frequent changes.

Buy your batteries from places that sell LOTS of HA batteries. Ebay is actually a great place to buy them. I would not recommend buying from Radioshack or Rite Aid, both have been busted in the past for selling stale batteries.

My mother recently got a hearing aid, and the technician told her to expect two weeks of life from a battery by turning it off (by opening the battery compartment door) when not in use (during sleep, especially). Sure enough, it will be two weeks tomorrow, and ol' Ma's batts are kickin'. They cost about $1US apiece.
There are five different sizes of hearing aid battery:

5, 10, 312, 13, 675.

Each battery is a different size and has a different life span.

Then there are literally thousands of different hearing aids out there, all of which have a different battery consumption.

So your question is like, me asking you, "What do you think I spend on gas in a year?" Without me telling you, how far I drive, what kind of gas I use, and what kind of car I have, it's a bit difficult to answer the question.

So to answer your question I'd need to know the make and model of your hearing aid, the size of it, the size of batteries you take, how many hours per day you use the aids, if you turn them off at night, what listening conditions you are in, the gain of the hearing aids, the power consumption of the aids and which brand of batteries you are using. All of this information should be available to your hearing professional who should be able to advise you as to what to expect.

The batteries I recommend are Rayovac, and you should get anywhere from a couple of days, to two weeks out of a set, depending on all the factors I already mentioned. Just remember, the smaller the battery and aid, the shorter the battery life you are likely to get.