Hello KKAC,

Thank you for your feedback. We are sorry to hear that you are dissatisfied with the run time of this battery when used in this lawn mower.
It is important to adjust your mowing techniques to make the most out of the battery life! This unit is advertised as running up to 45 minutes, but it goes without saying that that the harder the unit works, the quicker the battery drains.
Here are a few mowing tips to help achieve the optimal run time.
1) When cutting thick grass, reduce walking speed in order to allow for a more effective cut and a proper discharge of the clippings.
2) Only mow 1/3 of the total grass length at a time - no more. For a healthy lawn, always cut off one-third or less of the total length of the grass. The average lawn should be approximately 1 1/2 to 2” (3.8 to 5 cm) long during cool months, and between 2" to 3 1/4" (5 cm to 8.3 cm) long during hot months.
3) Mow when the grass is dry. As this is an electric unit, mowing wet/damp grass is a safety issue. However, ensuring the grass is dry will also help the grass cut cleanly and discharge appropriately. Wet/damp grass carries more weight and will mostly stick to the blade/motor shaft and will not appropriately discharge or cut easily.
4) Make sure the battery is cool before use. When the battery will not be in use, we suggest storing it indoors, in a cool dry area - away from direct sunlight. Leave the charger unplugged and the battery disconnected from the charger unless it needs charging.
We hope these tips will help! If not, we would be happy to investigate to see whether your run time would be considered average; please contact Greenworks at 1-888-909-6757 (1-888-90WORKS). All we ask that you have access to the unit so that we can complete troubleshooting with you and gather necessary unit information.