We were called to trouble shoot a lift that would not operate for long on battery. The root cause of the problem was that the battery was being left on the lift until the lift would no longer work and then the battery was swapped out for the fully charged spare. Unfortunately if the working battery is run down to a very low state of charge then its chemistry deteriorates and it will no longer be able to hold a full charge. Over time with more full discharges this gets worse. The solution is to charge the battery as frequently as practical so that it only ever gets partially discharged. We have had some lifts where the battery has lasted over 5 years where it is regularly re charged. So, for best battery lift re charge frequently.