Mighty Max Battery ML18-12 - 12 Volt 18 AH SLA Battery - Pack of 2

That 24v battery is just 2x12v in series with a plastic top to make it look like one. You can just get 2x 12v 18ah batteries from Amazon for 70$ which will likely increase your runtime 2-3x. It will add weight and you'll need to find space.https://a.co/d/09N4t8Y9 I'd suggest a new charger that can do 24v charging at a much higher amperage to reduce the overall charge time. https://a.co/d/027DCgD2 You can use drill battery adapters if you have a decent number of batteries of any one brand. However most of them operate around 18-20v so you'd need 2x adapter in series to achieve a voltage that can be stepped down to 24v Lifepo batteries are a good but expensive option they also require a special charger