In some examples, an apparatus is to adjust charge termination voltage. The apparatus includes a controller to adjust a charge termination voltage of a charger of a rechargeable energy storage device based on a comparison of a first threshold level with the voltage of the rechargeable energy storage device during peak load. The charge termination voltage is a voltage at which the rechargeable energy storage device has capacity to support peak load of a system. The controller is to adjust the charge termination voltage based on a comparison of a second threshold level with an end voltage of the rechargeable energy storage device after peak load.