The Ultimate Power Source ™


Posted: Feb 15, 2013

OPTIMA® Mailbox- Using OPTIMA Batteries in Trailers


If you have a question, you can always call us on our customer service line at 1-888-8-OPTIMA (867-8462) during normal business hours, send us an e-mail at or if you'd like your question answered here on the Power Source blog, click on the link on the left-hand side of this page.

Today's question comes from Peter D, who asks: What is the benefit of the OPTIMA® versus a regular 12-volt battery in a trailer? Which is better- two 6-volt batteries vs 2 12-volt batteries?

Those are great questions Peter! OPTIMA Batteries are "sealed" batteries, so they are far less likely to vent dangerous fumes or leak acid inside your trailer than a traditional flooded battery. However, all lead-acid batteries can vent gas that is both flammable and toxic in extreme situations, so if you are mounting any battery inside your vehicle, be sure it is either located in a sealed battery box that is vented to the outside air or the battery itself has vent ports for external venting. These would include both our Group 27 and 31 BLUETOP® and YELLOWTOP® batteries. Those batteries are also ideal for deep-cycling applications that are common in many trailers and recreational vehicles. OPTIMA batteries can also be mounted in a variety of orientations, which can be handy in some tight spaces and they can last up to twice as long as their flooded counterparts.

As for which batteries are best for your application, 6-volt or 12-volt, that probably depends on the design of your application. Two 50 amp-hour 6-volt batteries wired in series will double voltage (12 volts), but the capacity would still be 50 amp hours. However, two 50 amp-hour 12-volt batteries wired in parallel will double the capacity to 100 amp hours, while the voltage remains the same (12 volts).

When shopping for batteries for auxiliary use typical of trailers, it is a good idea to only consider batteries designed for deep-cycle use, like our YELLOWTOPs and BLUETOPs (except for the 34M BLUETOP) and batteries that have equal or greater reserve capacity than the batteries they are replacing. Cold Cranking Amps (CCA) are often promoted as a benchmark for selecting a battery, but in auxiliary applications, a battery's ability to provide cranking power at very low temperatures is usually not as important as a battery's ability to provide continuous power at lower rates, over an extended period of time.

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