Hello MikeLuc.

We are sorry to hear of your experience. Ensure both batteries are fully charged before attempting to use the mower, users must use (2) fully charged Greenworks 24V battery packs. Do not use battery packs other than Greenworks 24V. Ensure both batteries are charged 100%. If each battery has a different charge state, the run-time of the machine is subject to the lowest powered battery (For example: one battery is charged 100%, and the other is charged 50%, the unit will only run until the 50% battery is depleted). When using (2) batteries with different amp hours (Ah), the machine will run until the lower (Ah) battery is depleted.
Greenworks mowers can also experience reduced runtime due to factors like overgrown grass or extreme temperatures. Long, thick grass can put a strain on the mower's motor, potentially causing it to shut down or reduce runtime. Make sure the grass is not excessively long and adjust the mower height if needed. Lithium-Ion batteries can be affected by very hot or very cold temperatures, reducing their performance. If possible, try a different set of batteries (if you have them) to see if the issue persists or try a different charger to see if the issue is with the charger.
If you have exhausted all troubleshooting steps and the problem persists, contact us through Live Chat on Greenworks Tools website or call 1-888-909-6757 (1-888-90WORKS). So, our experts can discuss your experience; please have your unit, battery and charger with you along with the model and serial number to complete troubleshooting to ensure quick resolution is provided.