While some RVers associate their 12-volt direct current (DC) coach battery with simple components like overhead lights, the water pump, and vent fans, it’s one of the most important power sources in the RV. Your 12-volt battery system works in tandem with all of the other power sources by way of thermostats, control panels, and circuit boards on appliances to power appliances like your heater, furnace, and refrigerator. The 12-volt system is the command center that tells all other power sources what to do.
Here are a few important tips to keep in mind when troubleshooting and caring for your RV’s deep cycle 12-volt DC batteries.
Troubleshooting: Lights Only Work When Plugged into Shore Power
The short answer—there’s a good chance the coach battery is dead and the converter charger is the only thing operating the 12-volt systems. If the coach batteries are older, they’re probably not receiving much, if any, charge and the converter is doing all of the work.
Your RV converter charger has several functions. In addition to charging the 12-volt DC coach batteries when the RV is plugged into shore power, it can also assist the batteries in operating certain 12-volt systems that might have more power, like a large slide room. If the batteries have lost their ability to hold a charge, the converter will use the 120-volt alternating current (AC) power coming in from the shore pedestal and step it down to 12-volt DC to then operate all of the 12-volt systems in the RV. If the converter is the only reason the 12-volt systems are operative, it’s probably time for new coach batteries.
Troubleshooting: Battery Continues to Drain When Your RV Is in Storage
When your RV is in storage, you want to pay attention to battery care. Did you know that the LP detector is hardwired directly to the 12-volt DC coach battery? There are also other parasitic loads, like your TV’s antenna booster, some electronic devices, and circuit boards, that can drain the battery charge. If you forget to turn off all the 12-volt lights when you put the rig into storage, it won’t take long to drain the battery.
If I activate the battery disconnect switch, will that prevent my RV battery from discharging?
Even with the battery disconnect switch activated, the coach battery will self-discharge approximately 1 volt per month. If you’re unable to keep it plugged into shore power, put it on a charger when not in use.
Your lead acid battery loves to stay charged, and keeping it charged above 50 percent will help extend the life of the battery. This will prevent it from self-discharging, and it won’t ruin your battery.
Troubleshooting: How to Test Your RV’s Power Converter
Your 12-volt DC battery is 12.7 volts or higher when fully charged. When plugged into shore power, the voltage reading should increase by at least half of a volt. This confirms that your converter is operative. You can check it at the battery monitor panel or by using a multimeter. Set the multimeter to volts DC and touch one lead on the negative post and the other lead on the positive post of the battery. The reading should be approximately 13.2 volts DC or higher when plugged into shore power.
Troubleshooting: How to Maintain Battery Fill Wells
Some deep cycle lead acid batteries require regular servicing while others are enclosed or contained and do not. The FLA (flooded lead acid) battery has water inside, and eventually, the water will evaporate. If you have serviceable lead acid batteries, you’ll need to periodically remove the water fill well caps and top them off with distilled water. Water needs to be just to the bottom of the fill well area and not overfilled. This simple maintenance task will extend the life of your batteries. The more you use them, the more water they’ll need, so be sure to check them at least every 30 days.
When you have multiple-battery systems, matching a new battery with an old battery is never a good idea.
When to Consult an RV Tech
These troubleshooting tips can help you handle some common RV battery issues on your own. However, there are going to be problems that require the expertise of an RV technician, like rewiring 12-volt appliances or components, circuit board issues, and replacing the converter charger.
If you need to find a certified RV technician, use the Togo RV app’s “Find Service” feature to locate a technician near you.