New non-rechargeables of quality should get you well over an hour.
As usual, what firehand10K says about batteries (and many other things) is spot-on. In case you’re looking for high-quality rechargeable batteries, the most common recommendation I’ve seen is Eneloop Pro (in a pinch, the standard Eneloop ones will work), purchased from a reliable supplier. When it comes to battery chargers, it’s hard to go wrong with an XTAR VC4 (or some other charger from XTAR, Nitecore, Eneloop, or the like. Here is a post I made back in June, and it still applies.
Adding to the suggestions above, get AAA Eneloop Pro cells and a good-quality battery charger.
Don’t skimp here; the batteries will be your biggest expense, so if you want to save money over time, get GOOD rechargeable batteries, and get a GOOD charger.
The consensus here is that, because a light saber is a high-drain application, the Eneloop PRO batteries are a better choice than the regular Eneloop ones. Personal experience has taught me that Amazon Basics AAA cells will be disappointing, as will Tenergy AAA cells. Years of experience with Eneloop PRO AA cells in other high-drain applications makes me trust the recommendation to use the PRO version in the AAA size, as well.
Although this charger would be overkill (meaning more features than are absolutely necessary), I highly recommend the XTAR VC-4 as a good choice. Setting aside the ability it has to safely and properly charge lithium-ion batteries as well as NiMH ones because you are using the NiMH batteries right now, this charger has some excellent features that DO apply to your current needs.
Four (4) battery bays, so you can charge all the batteries for a single saber at the same time
Four (4) charging channels, so that each battery will receive EXACTLY the charge it needs, not the average of what several cells need
Charging status indicators (showing progress of charging for each battery)
Automatically identifies input power and adjusts to a suitable charge current
Overcharge protection
Undercharge protection
Overheating protection
Reverse-polarity detection and short-circuit protection
Automatically stops charging when it’s done, so you can leave the batteries in and just walk away (or go to sleep, or leave the house, or whatever)
Some of those are safety features, which I consider an absolute must-have, and some are just nice conveniences, but for under $20USD, this is a really good choice.
This is the larger size of the XTAR VC2 charger that UltraSabers sells on their website. Check your favorite electronics retailer, whether that be online or brick-and-mortar, but if they don’t carry XTAR, you can also go with the Nitecore D4 charger.
Of course, if you can snag a 4-bay (or larger) Eneloop charger when you get your Eneloop PRO batteries, that would be just fine and dandy, too.