This is a big question and can be split into two topics where there are a variety of factors that influence the outcomes.
The following information is related to the Dewert rechargeable, removable battery which is used on Modsel stretchers and chairs.
A battery is firstly charged via a wall mounted charging station or standard mains power cable from the product that it is connected to. From full charge a battery should provide approx. 30 lifts of the product at the maximum safe working load, from the lowest to highest position. This is intended to be enough power to last a stretcher all day in a busy hospital department. It is important to note, that in the majority of cases, the life of a battery can easily extend out to as much as 3-7 days based on the number of daily patient throughput and amount of patient positioning required. Most products are rarely taken from the lowest to highest position at maximum load capacity on every patient.
The operating life of the battery is directly proportional to the amount of daily work it has to do. As batteries do have a memory and will gradually deteriorate if continually run down to low charge, it is strongly recommended to maintain a system where the battery is recharged (or swapped) once in every 24 hour period. It can be determined that the charge has run low by an audible sound that emits from the battery when it requires recharging. If a unit is continued to be used at low charge, it will shorten the life of the battery. The average charge time of the battery if not depleted is approx. 4 hours, and regular top ups will ensure the longest service life of the battery. The maximum time required to fully charge a battery from low power is 6 hours. If the battery is left on charge, it will not be damaged, as the charger will shut down automatically.
Once a battery starts to lose its initial full charge memory, it will start to require recharging at more regular intervals. The more often the audible sound can be heard from the battery, the faster the memory is being reduced. This means that even if left for the entire 6 hours to fully recharge, the amount of power it will yield is less than when it was new. It will become evident over time when a battery has a short power cycle and must be replaced. If you are not receiving a full day’s use from a fully charged battery, it would be recommended to replace it. You can never re-charge a battery too often, the more it is done, the longer your battery will last. Through the average use in medium sized facilities, it would be expected that a battery will last for 3-5 years, in a small facility it could last up to 8 years and in a large, busy department (such as ED) may only be 2-3 years.
Due to the potential of a battery being damaged through mismanagement, most electrical manufacturers do not offer any warranty. Modsel provides its own initial three month warranty so you can be confident that the product is working correctly and there is no manufacturing fault.