
Deep Cycle Batteries

Deep cycle batteries are designed to provide steady power over an extended length of time. This is in contrast with high cycle batteries which provide a large burst of power over short length of time. Deep cycle refers to the battery’s ability to discharge most of its capacity before needed to be recharged.
Lithium and lead acid batteries can have deep cycle capabilities. Lead acid batteries can be flooded or sealed. Sealed batteries are commonly known as VRLA (Valve Regulated Lead Acid) and SLA (Sealed Lead Acid). VRLA batteries can either be Absorbed Glass Mat (AGM) or gel cell.
Flooded lead acid batteries have a usable capacity up to 50%. This means that 50% of the battery’s total capacity can be used before it must be recharged. The charging efficiency is approximately 70-85%. Although affordable and tolerant of overcharging, flooded lead acid batteries have a shorter lifespan than other battery types. They also require maintenance, proper ventilation and must remain in an upright position.
AGM batteries have a usable capacity of 80% and a charging efficiency of 95%. They are more expensive than flooded lead acid batteries and are sensitive to overcharging, however, they are maintenance-free, fast-charging and position insensitive.
Gel cell batteries have a useable capacity of 75% and a charging efficiency around 85-90%. They are more expensive than flooded lead acid and AGM batteries and cannot tolerate fast charging or overcharging. They are maintenance-free, have a high heat tolerance and are position insensitive.
Lithium iron phosphate batteries have a useable capacity of 80-100% and have the fastest recharge rate. They have an extremely long cycle life and provide constant voltage over any rate of discharge. They are much more expensive than lead acid batteries and require a battery maintenance system.
It is very common to see industrial control panels that have a UPS or Uninterruptible Power Supply. This UPS allows for continuous power to be supplied to the control panel in the event of a utility power failure. This protection is provided with the help of batteries. When power is lost, the UPS will switch power automatically from utility power over to battery power.
- How much time does a system need to run in the event of a power failure? In most cases, battery backup systems are designed to run for no more than just a few hours. This is typically more than enough time for power to be restored and to prevent losing valuable data in the system. However, there are cases where more time is required depending on the scenario. For instance, a remote site that relies on solar power needs to be able to supply power for multiple days depending on the weather. If it's cloudy, and in the wintertime, the sunlight will be very limited and the power that is generated will most likely not be enough to energize the hardware needed for that particular site. In this case, a larger battery backup system will be needed so that the site can continue to run through these types of weather events.
- What critical hardware needs to be backed up? Once the hardware that needs to be backed up has been selected, it is important to determine how much current each of those pieces of hardware will draw. Most batteries are rated for a specific amount of AMP hours. So if a battery is designed to last for 10 AMP hours, that means it can supply one amp for 10 hours or another way to look at it is it can supply 10 amps for one hour. Once the current draw is known for all of the hardware, the size of the battery can be determined.
FAQ
What is the difference between a deep cycle battery and a regular battery?
Deep cycle batteries are meant to provide power for long periods of time and drain the battery more fully. Most general purpose batteries only deliver power for a short time before being recharged.
Why use a deep cycle battery?
Deep cycle batteries will maintain their capacity for a longer life span before needing to be replaced because they are designed to be drained and recharged more fully than a general purpose battery.