Thank you for your feedback on the 80V 21" Self-Propelled Mower (SKU 2550402 / MO80L416). Based on your description, it sounds like the conditions, heavy overgrowth, uneven terrain, and thick weeds, were beyond what a single-pass cut is typically designed to handle, which can lead to higher battery draw and reduced self-propel performance. For best results in these environments, we recommend first clearing the area to reduce overall vegetation height, then mowing in stages rather than attempting a full cut in one pass, starting at a higher deck setting and gradually lowering it on subsequent passes to avoid overloading the blade and drive system. Slowing your forward pace and ensuring the underside of the deck is clear of built-up debris can also help improve airflow and cutting efficiency, especially in dense growth. In very rough or uneven lots, breaking the area into smaller sections and avoiding wet or matted weeds will further reduce strain on the battery. For additional guidance, Greenworks Tools also offers an official instructional video on mowing overgrown grass conditions, which demonstrates best practices for tackling challenging terrain and maximizing runtime. We hope you will find this information helpful. If you require any additional support or have questions regarding a product, we recommend trying our Q&A section on products' page or Chat with us direct on our website or call 1-888-909-6757. We are here to help.

Hi Tim the tool man. Thank you for your feedback. We are sorry to hear this was your experience. If you are able to cross-test the batteries with another charger and another unit, this can help determine if the battery may be the issue. Should you have any further questions or warranty needs, please contact us directly through chatbot on Greenworks Tools website that will direct you to a live agent or call us at 1-888-909-6757 (1-888-90WORKS). Check out some helpful tips to extend your run time!

1) When cutting thick grass, reduce walking speed 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.