Connecting Your SLA Batteries Together

Joseph Lopez

3/26/2008 5:22:09 PM

Battery packs are configured to suit their proper voltage (power) and amperage (runtime) by connecting its individual cells in different ways. A single cell holds a fixed voltage and amperage on its own, however; these cells are combined in different ways to form a battery pack that generates the desired rating.

Let's say we're dealing with 12V, 4000mAh single battery cells and we need to combine them to create a battery pack with a certain voltage and amperage. In order to do this we need to know the 3 different configurations and the rules associated with each of them.
Serial Configuration When two or more cells are connected in a string, it is called a serial configuration. This connection doubles the voltage, however; the amperage stays constant. Notice how the terminals are connected to their opposite currents. To connect your device, run your negative wire off of the open terminal of the first battery and your positive off of the open connector on your second battery.
	Parallel Configuration When all the positive and negative terminals are connected to their same currents, it is a parallel configuration. This produces the opposite effect of a serial configuration because it doubles the amperage while the voltage remains constant. Connect your positive and negative wires to the same battery to run to your application.
Serial/Parallel Configuration Since the previous two configurations only allow you to increase either the voltage or the amperage, there is a third configuration you can use to increase both at the same time. This is called a serial/parallel configuration. The output voltage and amperage is equal to half of the combined voltage and amperage of all the battery cells. (12V/4000mAh+12V/4000mAh+12V/4000mAh+12V/4000mAh = 48V/1600mAh � 2 = 24V/8000mAh total) Use the diagram below for connection referencing IMPORTANT NOTICE: When connecting batteries together and dealing with positive/negative currents you must remember to follow these guidelines: -Never connect cells in parallel and/or series that are not designed for that purpose. A cell mismatch may cause overcharge and venting with flame. - Never charge or discharge the battery without connecting a working protection circuit. Each cell must be monitored individually and the current disconnected if an anomaly occurs. - Always attach a temperature sensor when charging and discharging the battery. The temperature sensor must disconnect the current on excess temperature. - Only connect cells that are matched and have the identical state-of-charge. - Pay special attention when using an unknown brand. Not all brands contain intrinsic safety features that protect the cell when stressed. - During experiments, place the test battery into a well-ventilated fireproof container. - Never leave the battery unattended while under charge or discharge. - Do not charge a battery hat has physical damage.

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