Should RV battery be on when connected to shore power?

Yes, RV batteries should generally remain ON when connected to shore power to enable proper charging through the converter/inverter system. Exceptions include older RVs without automatic charging controls, where manual disconnection prevents overcharging. Modern systems use shore power to maintain battery health while powering 12V appliances like refrigerators and LP gas detectors. Always verify your converter’s voltage output matches battery chemistry (e.g., 14.4V for flooded lead-acid vs. 14.6V for LiFePO4).

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Why do converters require batteries to stay active?

RV converters transform 120V AC shore power into 12V DC power for both charging batteries and running onboard systems. If batteries are switched off, most converters can’t route DC power to appliances—leaving lights and safety systems unpowered. Pro Tip: Use a multimeter to confirm converter output reaches 13.6V–14.8V when shore-connected—lower voltages indicate faulty voltage regulation.

Modern three-stage converters (bulk/absorption/float) require continuous battery connection to manage charging phases properly. For example, Interstate’s Converter-Charger series disables float charging if battery voltage drops below 12.8V, potentially leaving batteries undercharged. Transitional systems like inverter-chargers add complexity—if the battery is off, they can’t pass through shore power to AC circuits. But what happens in older RVs? Non-smart converters from pre-2010 might overcharge batteries at 15V+ if left unattended for weeks. Always install a voltage meter on legacy systems.

Can parasitic drains deplete batteries on shore power?

Yes, if converters malfunction or loads exceed their 12V supply capacity. Common parasitic drains include LP gas detectors (0.3A), clocks (0.1A), and phantom inverter loads. Parasitic discharge rates of 0.5–2A can drain batteries despite shore connections if converters lack adequate amperage.

Practically speaking, a 45Ah battery with 1A parasitic drain would fully discharge in 45 hours even on shore power if the converter only outputs 5A—insufficient to offset consumption. Transitional solutions include installing a dedicated DC-DC charger or using a battery cutoff switch for non-essential circuits. For example, Winnebago’s EcoFlow upgrade adds secondary converters specifically for phantom loads. Pro Tip: Measure voltage differential between converter output and battery terminals—a >0.5V drop indicates undersized wiring.

Do lithium batteries need different handling?

Lithium-ion (LiFePO4) RV batteries require voltage-specific charging but benefit from continuous shore connections. Unlike lead-acid, they don’t suffer from float charge degradation and can stay at 100% SOC indefinitely. However, their higher 14.6V absorption voltage demands compatible chargers.

Battle Born’s 72V systems, for instance, use onboard BMS to regulate input from shore-powered converters. Transitionally, lithium batteries actually improve efficiency—they convert 85%–95% of shore power versus 70% for AGM. But why risk incompatibility? Always verify your converter’s absorption voltage matches lithium specs. A 2018 study showed 22% of RV converters overcharge lithium packs by default. Pro Tip: Install a shunt monitor to track net current flow—negative values during shore connection reveal charging deficiencies.

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