Differences in Battery Types
General SLA - are designed to be a general purpose battery that can be used in a wide variety of applications such as toys, consumer level UPS, alarm systems, etc. General SLA batteries can provide a large discharge current over a short time period and the life cycle of the battery is 1-3 years depending on use. Capacity is usually calculated at 20HR. These batteries generally have regular sized plates.
Deep Cycle (EV) – are designed to provide a steady amount of current over a long period of time and are able to drain completely and recover to almost 100%. These batteries are designed for electric vehicles, golf carts, wheelchairs, etc. Typical life cycle is 2 years or less depending on depth and frequency of discharge. These batteries generally have thick plates.
High Rate Discharge - are designed for when a large amount of amps are required in a very short amount of time. These batteries are used primarily where high power is required for a short duration of time (less than 30 minutes). Mainly for high powered UPS applications. Capacity is usually calculated at 10HR or lower. These batteries generally have thinner, but more numerous plates.
Long Life – are constructed to have long service life in float or cyclic applications. Life expectancy in float service is up to 18 years @ 25C (typically 10+ years). Typical applications are communication, stand-by power, security systems, power systems, etc.
What Does Hour Rate Mean?
HR (Hour Rate) – All SLA type batteries have their capacity rated depending on the amount of amps they can discharge over a certain period of time. General SLA batteries are usually rated at 20HR, meaning their current over a period of 20 hours. If a battery is rated at 20Ah capacity at 20HR, it means that the battery can discharge 1 amp per hour over that 20 hour period. A High Rate Battery will typically be rated at 10HR or less. So a High Rate Battery that is 20Ah capacity at a 10HR would be able to discharge 2 Amps per hour over a 10 hour period.
Generally, a battery will have more effective capacity if it is discharged slowly and, conversely, the battery will have less effective capacity if it is discharged quickly. For example, if a 20Ah (10HR) rated battery is discharged over a 20 hour period (20HR), the effective capacity could be 23Ah. If the same 20Ah (20HR) battery is discharged over a 5 hour period, then the effective capacity may only be 15Ah—a loss of 25%.
High Rate Batteries are manufactured in a way to maximize quick discharge at the expense of deep cycling and cyclic life. They can discharge high amps in very short periods of time. For example, a 20Ah (10HR) High Rate Battery can discharge 70 amps over a 5 minute period, while a General SLA Battery may only be able to do 45 amps.