Secrets of Power: The Xantrex TrueCharge 2

Most travel trailers are built for weekend use. That mean the factory equips them with a battery or two that is sufficient to power the trailer for about two nights without being plugged in. After that, it’s time to find a source of power.

So it’s not surprising that not long after an Airstream owner begins to travel a bit more away from the KOAs and toward bucolic and private boondocking sites, they begin to look for ways to extend their power capacity. The next step is often a generator or solar panels, and a new set of batteries with greater capacity. Absorbed Glass Mat (AGM) batteries such as Optima and Lifeline are a typical choice because they last a long time, can be deeply discharged, and are maintenance free.

But then an interesting problem crops up, one that most Airstreamers—and even many RV repair technicians—don’t know about. The power converter built into your Airstream isn’t optimized for charging AGM batteries. Often it will undercharge them, particularly in cold weather.

People tend not to notice this unless they have also installed a highly accurate battery monitor, because the factory installed monitors are only rough estimators of the battery state of charge. So they are often misled into thinking the batteries are being fully recharged. But incomplete charging results in shortened battery life. Batteries will only have their longest possible life if they recharged to full after every use.

To truly get the most out of your new AGM batteries you need to replace the factory installed power converter too.

Only a few brands of power converters have the built-in capability to provide the correct voltages needed for AGM batteries. For this review, we upgraded an Airstream Safari to a Xantrex TrueCharge 2 (60 amp model) to see the difference in performance and the ease of installation.

The conversion job is fairly straightforward for a handy person, taking about 2-4 hours. Installing the Xantrex is easy; it’s removing the old converter that gets into a little mechanical surgery, because the factory charger is built into the same case as the fuse panel and circuit breaker panel. Separating the lower charging unit from the rest requires a drill, wire cutter/stripper, screw drivers and Torx drivers, a nut driver, and a few other basic tools. (Documentation for this job with photos can be found around the ‘net by Googling “replace power converter Airstream”.)

Once the old power converter is removed, installation of the Xantrex is painless. The Xantrex TrueCharge 2 is a beautifully crafted device that looks like it should be on display somewhere. As one friend commented, “It’s way too pretty to be installed inside,” but indeed that’s where it goes. It screws down to the floor securely, and then connecting it is a matter of butt-splicing six wires (ground, DC – and DC+, and three wires for AC), which takes only a few minutes. Since it’s designed for marine and RV use, everything on it is marine grade. Providing rubber covers for the wire connections is a nice touch, typical of this high-end unit.

The TrueCharge 2 is pre-programmed for 3-stage charging of “wet cell” batteries. Changing settings to provide optimal charge for AGM batteries is a matter of pressing two buttons. Once done, the output voltage jumps to the correct level for AGMs, which means those batteries will be charged to their fullest capacity. This was the feature we were looking for in our test Airstream, since other brands such as Parallax and Intellipower provide just one output voltage for all types of batteries.

The TrueCharge 2 can also support up to three separate battery banks, and can even run in parallel with a second charger for really large installations, but most Airstreamers won’t need those features. A single 40-amp or 60-amp TrueCharge 2 will be sufficient to replace the original factory unit.

TrueCharge Remote
TrueCharge Remote

The LED display on the case shows exactly what the unit is doing (rate of charge, type of battery, etc), but since it will be hidden out of sight, adding the optional Remote Panel is a wise choice. This panel connects with a simple telephone-style cable, and can be mounted on the wall anywhere within 25 feet. As a bonus, the Remote Panel adds a few features that the onboard TrueCharge 2 display doesn’t provide. If we are to be totally honest, it is also just plain cool-looking. You might never touch it again, but all those colorful LEDs certainly make for a nice display.

Battery Temperature Sensor
Battery Temperature Sensor

A particularly useful option is the Battery Temperature Sensor. This measures the temperature of the battery and allows the charger to compensate. Warm batteries need lower charging voltages; cold batteries need more voltage. If you simply slip the sensor over the negative post of the battery and run the provided wire back to the TrueCharge 2, it will figure the optimal temperature compensation automatically. If you don’t use the Battery Sensor you can still manually compensate for temperature using buttons on the Remote Panel.

Interestingly, since the TrueCharge 2 was designed for worldwide markets, it can accept input voltages of 90 to 265 volts AC. With that and other protections built into it, it’s unlikely to be damaged by excessively high or low voltage at the campground. It also has a battery equalization (or “de-sulfation”) mode that helps maintain the batteries.

Once the TrueCharge is in place and power is applied, it checks the batteries and then starts silently maintaining them. Although it has a built-in fan like the original converter, it rarely runs and when it does it’s much quieter. It’s also considerably lighter than the old converter because it isn’t mounted in a bunch of heavy sheet metal. Overall: it looks, feels, and operates like the major upgrade that it is.

Xantrex is known for premium products, and the TrueCharge 2 doesn’t disappoint. Running about $600 online for the 60-amp model, Remote Panel, and Battery Temperature Sensor, it’s a good investment for Airstreamers who like to get the most out of their power system. Smart, well-designed, flexible, and in every way an improvement over the original gear, it’s a device befitting an Airstream.

Questions and answers about power, batteries, and solar

Solar power, shore power, generator backup…the configurations are as varied as the number of rigs on the road, and the answer to most power questions is “it depends”.

While each Airstream is uniquely outfitted, many Airstreamers have common queries. Following are answers to questions posed at one of our recent Aluma-events.

I’m a solar user, but what happens to my batteries when I plug in to shore power?

Your solar panels are still active when you use shore power, and a built-in regulator prevents the batteries from overcharging. Put simply, solar panels always produce power when exposed to light, and that power is sent to be stored in the battery. Shore power (AC, which gets converted to DC) also goes to the battery, so both sources are working to keep the batteries charged. One source might contribute more than the other, but it’s all good power input.

How can I extend my battery life?

Baby it. Your battery will last nine years and counting, depending on how it’s maintained. If you’re plugged in often, it’s a good practice to check the battery water every 30 days. Pop the caps off and fill them up over the lead plates; otherwise, they’ll sulfate and corrode the other batteries.  A dead cell in one battery will drag the other battery down with it, over time.

If it freezes outside in winter it won’t last it’s full life expectancy. Don’t leave it dead; if the electrolytes aren’t excited in the battery, they’ll freeze. Take your battery out and let it winter over in the garage.

Can my family multitask in the trailer?

Yes, but to a reasonable limit. If you’re using a curling iron, the air conditioner, and a microwave all at the same time, you’ll draw too much and flip the breaker. Overloading the outlets (a.k.a. AC power system) with too many plug-in appliances will trip the circuit breaker.

DC power differs, and if your battery has drawn down too low you’ll have trouble with the vent fan, lights, or water pump—and there’s no circuit breaker on the DC power system. When lights dim and the pump and fan are sluggish (or non-working), it’s past time to recharge. Try not to draw the batteries down more than 50% between charges, because doing so will shorten its life. Consider installing an amp-hour meter to more accurately keep track of the power in your batteries.

Where is my converter? And what does it do?

Your converter changes 120 volts AC shore power to Airstream appliance-friendly 12 volt DC power, and prevents your Airstream battery from draining. You’ll have to snoop around to find it, as the location depends on your Airstream floor plan. Often the power converter (a “black box”, literally) will be installed under the refrigerator or sofa, or inside the closet. Open the door and you’ll see the 110 breakers and fuses inside.

I want to go solar. How much do I really need? How much does it cost?

These and other questions about solar conversion are like asking “how long is a rope?” Answers will vary, depending on the panel size and watt capacity. Some users claim that one hundred watts of solar provides enough power for a family; others require nearly three times that amount.

Your location and weather play an important factor as well, as the battery charges through the day for the night, and recharges the next day—and the more panels you have, the merrier you’ll be. The number of permanently-attached solar panels you can accommodate depends on your Airstream model and the available real estate on the roof.

What’s that rotten egg smell?

Could be the converter is overcharging the battery, but more likely you have a battery low on water (assuming it uses water). Allow the battery to cool before adding more water.