Going to be using the boat motor or inflator for several days and want lots of extra power to run then? Or maybe you won't have excess to electricity for recharging the ones you have?
Whatever the reason you need "More Power" Sevylor's Rechargeable 12V battery with 110V charger for Sevylor motor, inflator, etc. is what you are looking for.
This product has a limited warranty of 3 months.