How long does it take to charge the ESS spraywand when it’s plugged into the charger, and how long do the batteries last?

The charge will take 3–4 hours. Do not charge for extended periods of time. Overcharging can damage your batteries. For a constant spray your spraywand batteries will last 5–6 hours, if used in a more average setting, your batteries will last about 10–15 hours.