Charged up: Maintaining your trailer’s house battery

Charged up: Maintaining your trailer’s house battery


Charged up: Maintaining your trailer’s house battery


It began with a burble and hiss, ending with a dead battery and the realization that the trailer’s built-in battery charger was doing more harm than good. “To the internet!” we yelled, where it was soon discovered that our option was to replace a large component of the trailer’s electrical system – the part that charges the “house” battery – or go with a standalone charging solution. Which is right for you? We can’t tell you that, but we can tell you what we did.

The trailer in question utilized a single 12-volt deep cycle marine battery to supply power to the trailer’s interior lights and accessories. This setup, which is similar to many found in car trailers, toy haulers and motorhomes, generally allows for a weekend at the track without the need for power hookups, known as “shore” power. Yet while this trailer was new to the owner, it was also used – to the tune of 20 years – and the electrical system is now widely considered sub-par. You see, when connected to shore power, the trailer’s outdated electronics were actually overcharging the 12-volt battery, boiling its usefulness to kingdom come.

“When more current is being pushed into any battery than it is capable of handling, whether because the battery is already fully charged or has too much internal resistance to accept that current, the battery may vent to varying degrees,” explains Daryl Brockman, Manager of Global Sales and Marketing for Optima Batteries. “These fumes are dangerous, as they are both toxic and flammable, and if the internal pressure exceeds the ability of the venting provisions, the results can be catastrophic. If any charging system is not properly regulated to prevent overcharging, it could permanently damage the battery and create a very dangerous situation.”

There were two ways to resolve our issue: replace the trailer’s electronics (which can be complicated and pricey) or use a stand-alone battery charger. We opted for the latter, which would enable us the flexibility of using the battery charger on tow vehicles and racecars, should the need arise.

When battery charger shopping, especially for a trailer that may discharge its 12-volt battery deeply during a weekend, a multi-stage charger is key. “Some batteries that have sat in deeply discharged states for an extended period of time may have a buildup of sulfation in the plates,” Brockman says. “Also, a battery left at rest even in a fully charged state can also develop some sulfation.”

Optima Batteries sells two chargers; we were leaning toward the company’s more powerful Digital 1200 charger, offering the ability to quickly charge a battery at the track should the need arise. While amperage of its two chargers differ, both offer a maintenance mode.

“Our desulfation mode will vary amperage and voltage during maintenance periodically – after charging is complete – to help minimize and break up that sulfation, where other chargers without this feature may just provide constant or gradually decreasing current, which may not be as effective at desulfating and prolonging the life and performance of your batteries.

“Chargers that use microprocessors, like the Digital 1200 and Digital 400, go through a series of steps during the charging process, to understand the current state of charge of the battery and how capable it is of accepting current and how the battery needs to be charged, in order to maximize performance and lifespan while minimizing charging time,” Brockman continues. “It’s not a one-size-fits-all scenario, so having a charger with enough technology behind it that can vary amperage and voltage as needed will allow the battery to reach its fullest state of charge and be properly maintained while in storage without overcharging so it is ready to use when you need it.”

The next question is charging amperage rate – is higher better? “Higher amperage chargers can obviously deliver more current and charge batteries faster,” Brockman points out. “The higher amperage rate can also help break up sulfation and restore some performance in batteries that have been sitting in a deeply discharged state for an extended period of time.

“Conversely, a lower current charger is generally more of a maintenance device, meant for keeping a battery that is at or near full state of charge at that state,” Brockman says. “If connected to a battery that isn’t fully charged, it can take a very long time to charge fully, if it is even capable of getting the battery fully charged.”

Prior to charger shopping, we’d replaced the trailer’s dead battery with high amp hour, dual six-volt lead-acid golf cart batteries run in series. An option down the road would be an Optima Blue Top deep cycle AGM battery (or two run in parallel to increase the usable amp hours), since Optima batteries are maintenance free, never requiring us to check battery water levels as lead-acid batteries do. In either case, with a high amp hour setup that also involves the potential of repeated deep discharging, Optima’s higher amp Digital 1200 charger with maintenance mode was ideal.

Budget is, of course, a consideration, but considering you can spend $500 or more on a dual battery setup for a trailer, the $220 for the Digital 1200 charger doesn’t seem outlandish, especially knowing that the trailer’s existing built-in charger would otherwise boil the life out of the new batteries, putting us back to square one. Optima’s Digital 400 four-amp charger, meanwhile, retails for about $100 and would have easily handled the trailer’s batteries – we would have gone this route, but the ability to charge at 12 amps should the need arise was very attractive.

Yes, a stand-alone charger does require more work when maintaining the trailer’s batteries when compared to a system integrated into the trailer, but it’s also offering flexibility that a trailer-based system cannot. Is this the right setup for you? Only you know the answer to that, but for us, it’s ideal.