RV batteries dead or not charging: converter, battery, or something else

Dead house batteries are one of the most common calls we take here, especially on a rig coming out of a winter in storage: a rig that sat unattended, the owner arrives, the slide will not move, the jacks will not run, and the panel shows nothing. Some of those batteries are genuinely finished. A good number are fine and the converter stopped charging them months ago, which is a different repair with a different price.

Check this first (fifteen minutes, one multimeter)

1. Measure resting battery voltage with shore power unplugged and everything off. 12.6 volts or better is a healthy full charge. 12.2 is about half. Under 12.0 is deeply discharged, and a battery left there for months has likely lost capacity permanently.
2. Plug in shore power and measure again at the battery terminals. A working converter should push the voltage up into the 13.2 to 14.4 range. If it reads the same as it did unplugged, the converter is not charging.
3. Check the pedestal or generator and any breaker. A tripped breaker or a dead power source means the converter has had no power for however long it has been tripped, and the batteries have been carrying the rig’s parasitic loads alone.
4. Check the battery disconnect. Many rigs have one, and it is frequently the answer. Also check the main fuse or breaker between the converter and the battery bank.
5. Look at the terminals. Corrosion at the posts creates enough resistance to stop charging entirely while still passing enough current to power a light. Green or white growth means clean the terminals before diagnosing anything else.
6. Check the water level if the batteries are flooded lead-acid, and note that cold reduces a battery’s available capacity temporarily, so retest after the battery has warmed to room temperature if it was very cold when you measured it.

What is usually wrong

These sit inside the 12V electrical range on the pricing page, on top of the $75 to $150 trip fee and $125 to $190 hourly labor.

Why storage is hard on batteries here

The mechanism is different from the desert but the outcome is similar: a bank left unattended for months loses charge. In the low desert, heat accelerates self-discharge. Here, a battery sitting through a cold winter with no maintainer discharges more slowly from temperature alone, but months at partial charge still sulfates the plates, and a hard freeze on a deeply discharged flooded battery can freeze the electrolyte and crack the case outright, which is permanent damage a warm-climate battery never risks.

Parasitic loads that never truly switch off, propane detectors, control boards, radio memory, and some slide controllers, drain a bank slowly all winter regardless of temperature. A bank left unattended from fall through spring has no chance without a charger, a solar maintainer, or someone checking it periodically.

The practical version of that advice:

• Leave it on shore power with a working converter, or on a solar maintainer, if the property allows either.
• If it must sit unpowered through winter, pull the batteries and store them somewhere that will not freeze, charged.
• Check water monthly on flooded batteries if you are checking on the rig at all.
• Do not trust the panel gauge. Those meters are approximate at best. A twenty-dollar multimeter tells you more.

Converter, inverter, and what people confuse

A converter turns 120V shore power into 12V to run the coach and charge the batteries. An inverter does the opposite, turning battery power into 120V for outlets. Many rigs have both, sometimes in one box. When someone says “my inverter is not charging,” they nearly always mean the converter, and getting that straight on the phone saves a wasted trip.

What to expect on the call

Give us resting voltage, voltage with shore power connected, the battery type if you know it, and how long the rig has been sitting. That is enough to tell you whether you are buying batteries, a converter, or a terminal cleaning. We work on site at campground sites, storage lots, and rural properties across Prescott, Prescott Valley, Chino Valley, Williamson Valley, Paulden, and Mayer, and the electrical repair page covers converters and the rest of the electrical side. If the dead bank showed up as a slide that will not move, start there.