The first step to replacing a generator battery is the selection of the right battery as per manufacturer recommendation. Remove the bolts of the generator cover with a socket and a ratchet, and pull the cover off.
Turn off the engine and disconnect the battery charger. Clean all the contacts and terminals with a brush using a solution of baking soda and water or by using the special tools available. Unfasten the nut on the negative black cable, and remove it from the battery. Disconnect the positive red cable in a similar manner.
Remove the old battery and place aside. Clean the tray and the other cable connections. Position the new battery appropriately in the tray in the same alignment as the old battery. Adjust the clamp to hold the battery firm in place. To avoid corrosion, spray the battery terminals with a special corrosion avoiding spray.
Reconnect the positive red cable and the negative black cable to the new battery and tighten the nuts. Ensure that the positive cable is always connected first before connecting the negative cable. Reconnect the earlier disconnected battery charger. Place the generator cover back in place and fasten the bolts. Turn on the engine, then the generator battery replacement is complete.