First, I'm not a Invacare representative.
* Check your warranty (18 months - 3 years)on page 63 of manual.
* Check with Invacare vendor for support.
*** Following for information only.***
* Check your fuse.
* As with most Lead Acid battery systems. Care must be taken to assure long life.
* Lead acid batteries have a cycle (recharge) about 200-500 cycles.
* Example, if you charge every day that's 1 cycle per day for 200 to 500 days. Depending on how hard you drain the batteries, charge times, and how hot it gets where you store it.
* Here in Hawaii, most car batteries last 2-3 years tops. For power chairs it's less. (I suspect it's due to having lots of hills.)
* You will need to check the status (Health) of your batteries. (Take it to the shop to test. Battery shops can test it too.)
* Manual; https://www.boardmanmedicalsupply.com/pdf/mfgManuals/Invacare_Scooters.pdf
* No start (Not charging); https://www.youtube.com/watch?v=rgK2l6cMCc4
* Replacing battery; https://www.youtube.com/watch?v=sgosZCiFA6s