RV batteries dead or not charging: the check, the cause, and the cost

Dead batteries after months in a gated storage yard or sitting at a dock are one of the most common calls we take. Before assuming the batteries themselves are bad, the check below usually narrows it to one of three causes in a few minutes.

Check this first (ten minutes, multimeter helpful but not required)

Check the battery disconnect switch. Sounds obvious, but a disconnect left in the wrong position after a repair or a tow looks exactly like dead batteries.
Measure resting voltage if you have a meter. Roughly 12.6V or higher is a healthy resting charge; 12.0V or below is significantly discharged; under 11V for a lead-acid battery often means damage from deep discharge.
Plug into shore power and watch for a change over a few hours. If voltage climbs steadily, the converter is at least attempting to charge. If it stays flat, suspect the converter or a bad connection before the batteries.
Check for anything left on. An interior light, a fan, or an inverter left switched on can drain a battery bank over weeks even with a small draw.
Look at the terminals. Corrosion (white or greenish crust) adds resistance and can make a healthy battery act dead.

What is usually wrong

What you find	Likely cause	Fix and cost
Disconnect switch in wrong position	User error, no fault	No charge, trip fee if you need us to confirm
Voltage climbs on shore power over hours	Converter working, batteries recovering	Often nothing to fix; recheck after a full charge cycle
Voltage stays flat on shore power	Converter not charging	Converter replacement: $400 to $900
Corroded or loose terminals	Connection resistance	Clean and re-terminate: $150 to $300
Batteries will not hold a charge overnight	Batteries at end of service life	Replacement: $150 to $900 depending on bank
Small steady drain with everything off	Parasitic draw (propane detector, radio memory, etc.)	Trace and fix: $150 to $400

Ranges from the pricing page, on top of the $75 to $150 trip fee and $125 to $190 hourly labor.

Why this happens after a Montgomery County storage-yard sit

A rig that sits for months in a gated storage yard is exactly the setup for a quiet parasitic draw to run a battery bank flat, since nobody is around to notice a slow decline. Heat is also hard on batteries generally, and a Texas summer inside a closed storage bay does batteries no favors over the years. If the rig is going to sit for an extended period, disconnecting the batteries or putting them on a proper maintainer (not just leaving shore power connected and hoping) is the cheapest insurance against this call.

What to expect on the call

Tell us the battery type and age if you know it, whether the rig has been plugged into shore power recently, and any symptoms (dim lights, slow water pump, an inverter that will not power on). We work on site across Conroe, Montgomery, Willis, The Woodlands, Magnolia, New Caney, and Huntsville. The electrical repair service page covers converters and transfer switches in more depth.

Frequently Asked Questions

My batteries were charged when I left them in storage and now they're dead. Why?

Either a parasitic draw (something in the rig pulling a small current even when everything is off, like a propane detector or a radio memory circuit) slowly drained them over weeks or months, or the batteries are old enough that they no longer hold a charge well. A load test tells the two apart in minutes.

The converter light is on but the batteries never seem full. Is the converter bad?

Possibly, or the batteries themselves may no longer accept a full charge. We test converter output directly rather than trust the indicator light, since a converter can show a charging light while actually underperforming.

How much does battery replacement cost?

It depends on chemistry and how many batteries the rig takes: figure $150 on the low end for a single small battery swap up toward $900 for a full lithium or multi-battery lead-acid bank. We will tell you what your rig actually needs before quoting a number.

Can I just leave the rig plugged in at the dock or storage yard all the time?

Generally yes, as long as the converter is healthy and the batteries are the right chemistry for continuous float charging. What we check first is whether the converter is actually doing that job correctly, since a marginal converter left running for months can also overcharge or undercharge a bank.