Battery Buying Guide
SLA batteries have a different number of cells depending on their voltage. Every cell has 2 Volts, so a 6-Volt SLA battery has 3 cells and a 12-Volt battery has 6 cells. If a battery is not performing as expected it may have a dead cell.
The power of a battery is calculated in Watts. To calculate Watts you simply multiply the Volts of the system by the Amps, and then you can convert Watts per cell into Amps per cell.
SLA batteries have the lowest self-discharge rate of any rechargeable battery. Left unused for a month SLAs lose only 3-5% of their total charge. If left at room temperature SLA batteries could be stored for up to a year and they will be ready to use with no need to be top charged.
SLA batteries have a life expectancy ranging from 4 to 7 years. However, the overall life expectancy depends on battery application, frequency of usage, temperature and discharge cycles.
SLA batteries need to be top charged for 24 hours after their complete exhaustion. When connected to the charger they reach 70% of their capacity in the first 7-8 hours (rapid charge stage). The remaining 30% of the charge is completed at a much lower speed during the next 16 hours.
There are two things you need to remember when charging a battery. First, charge the battery back to the level it was at before any discharge. Second, to charge a 12-Volt battery you will need a 12 Volt charger and for a 6-Volt battery you will need a 6-Volt charger.
Most SLA batteries are rarely cycled due to their application (UPS, burglar alarms, exit lights), rather they are kept in a standby mode and are constantly charging or in other words receiving a float charge. A float charge comes at a constant float voltage of 2.25 – 2.30 Volts per cell. This low voltage prevents the battery form losing capacity and prolongs battery life expectancy.
SLA batteries can complete between 200-400 cycles before they get fully discharged. If you do not discharge your battery completely on each use, but rather discharge the battery to 60% capacity, you can get up to 600 cycles. The less you discharge the battery, the more cycles you will get.
By connecting the batteries in series you are doubling the voltage and maintaining the same capacity (amp hours). Connect the positive terminal of the first battery to the negative terminal of the second one. From the two free terminals connect the positive to the power lead on your devise, and the negative to the ground connection of your application.
By connecting the batteries in parallel you are doubling the capacity (amp hours) and maintaining the same voltage. Connect the positive terminal of the second battery to the positive terminal of the first battery. Do the same with the negative terminals. Connect your application to the positive and negative terminals of the first battery.
In order to find the best replacement for your original battery you need to compare the physical dimensions, Volts and Amp power of your original model to what we have listed as a recommended replacement on our website. Besides physical dimensions you also need to check battery terminals (F1, F2, NB, WL, U, F1/0), which are the metal connectors on top of the battery. To determine what terminal your battery has, you will need to look at their form and determine if they have a flat connector, nut and bolt or wires, and then measure their sizes. Please see Appendix 1 for more information about battery terminals.