Smoke detectors have a usefull life period, and most fire departments AND manufacturers recommend "swapping them out" for new at least every 10 years. Most detectors use a sensor strip that is actually a coated strip with a low radioactive decay material (safe no worries). Over time, their natural decay and bi-products and they also can become coated over time (you cannot user-clean them) with smoke, residue, dirt, etc. In homes with combustive source for heat, etc. (fireplaces, oil, natural gas furnaces, etc.) people that smoke, candle burning, potpouri pots, use of those plug-in and battery operated oil or parifin based air freshners, certain hobbys, and certain home projects (like refinishing wood floors)can also contribute to the "aging" of the smoke detector, and an earlier replacement (5 to 7 years) might be warranted.
Also if the detector has had CAUSE to ALARM, one must consider the exposure to soot, coatings etc. and the degree and frequency, and consider replacement, as a dirty (potentially less than fully functional)detector can be more dangerous than no detector in that could be providing a false sense of security! Consider how inexpensive quality smoke detectors are these days (hard-wired AND battery operated)and the tremendous costs involved by smoke damage, fire damage and injury/loss of life in residential home fires -- and the decision to invest in new is a "no-brainer".
Remember that manufacturers and fire departments often recommend that primary or back-up batteries should be changed twice a year (often suggested one does at the same time one changes one's clocks, back and forth from standard to daylight time and back to standard time -- in those areas where that is done), but by all means at LEAST once a year, with NEW FRESH batteries. How many of us actually do that? They suggest that the test button be checked at every battery change and at least once a month (do you do that?) Keep in mind that a battery powered detector/alarm uses a huge amount of battery power to alarm, a significant amount to chirp, but minimal amounts in stand-by mode. Most recommend that you "smoke stick" test your alarms after primary installation, after each battery change, and at regular intervals over its useful life (how many of us have EVER done that?). Do you reqularly vacuum the detectors (free up from collected dust, cob-webs and the like) many manufacturers recommend at least weekly vacumming - how many of us do THAT?) as a detector who's air vents are restricted or clogged is practically useless and most have plastic or metalized housings that maintain a static charge that tends to attract regular household dust.
That your smoke alarms are original to your 10 year old wiring project, would indicate that they themselves are at LEAST 10 years old, and have been "in service" for 10 years, most likely they are due for a change.
check with the manufacturer and your local Fire Chief for additional recommendations.
Modern advice is to consider having one in each sleeping room, each access to sleeping room (for example upstairs hall way leading to sleeping rooms that would be primary exit), and one on each and every floor of the home. Check with your local fire and building code officials as to what the local code requires, and what they recommend (Code might require a minimum, but your officials might RECOMMEND even more). Carbon Monoxide detectors also should be considered -- and it might be a good idea to inspect your existing fire extiguishers and consider their need for re-charging/inspection or replacement -- and if you don't have any, you might consider acquiring some.
Safety first -- your most important asset is the health and life of you and your family. An ounce of prevention is worth a pound of cure.
If your detector uses a 9-volt "transistor radio" style battery, it might also be that if you have the style that uses a "cap" that has two wires that you have to push onto the posts, you may not have full contact to your new battery, or one of the wires may have been pulled and is not making full contact either in the cap or inside the detector. If it uses a spring type connection (9-volt transistor battery head connection or regular batteries) perhaps the battery isn't fully "seated" or the spring isn't pushing completely on the positive or negative side of the battery/batteries. Make sure that you have installed the batteries correctly, for example if it uses two AA batteries - that you have correctly placed them in the appropriate direction/directions.
IMHO like with food, "when in doubt throw it out" when it comes to smoke dectors, carbon monoxide dectors and batteries. They are cheap to replace, and it is one of the most important safety investments you can make for you and your family, and to a lesser extent for your home.