The UH-1 also runs on the LFP123A, the high-end rechargeable version of the CR123A. Charge the battery using the Micro USB port and it will recharge while in the sight. This battery does not have as long of life for continuous use as a standard CR123A, but does provide the advantage of recharging.
You can also recharge LFP123A batteries in a separate recharger plugged directly in an AC wall outlet. If you have multiple batteries and an external charger you can always charge one battery while using the other.