Does plugging in RV charge the battery?
Yes, plugging an RV into shore power typically charges its house battery through the built-in converter charger, which converts 120V AC shore power to 12V DC for battery charging. However, charging efficiency depends on the converter’s amperage rating (typically 30–60A) and battery health. Modern RVs with multi-stage smart chargers optimize charging, while older models may require manual converter activation.
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How does RV shore power charging work?
When connected to shore power, the RV’s converter-charger unit routes 120V AC through a transfer switch, converting it to 12V DC for battery charging while powering DC appliances. Charging follows bulk/absorption/float stages, with 14.4V bulk charging for lead-acid batteries.
Older magnetic converters charge at fixed 13.6V (trickle only), while modern units like Progressive Dynamics adjust voltage based on battery state. Pro Tip: Test charging voltage at battery terminals—if below 13.2V during shore connection, your converter likely needs replacement. For example, a 45A converter adds ~540Wh hourly to batteries (45A × 12V).
What limits RV battery charging via shore power?
Three key factors constrain charging: converter capacity, battery chemistry, and parasitic loads. A 30A converter can only deliver 360W (30A×12V), while simultaneously powering lights/fans may reduce actual charging current by 40%.
| Converter Type | Charge Rate (12V) | Time to 50% Charge |
|---|---|---|
| Magnetic (15A) | 180W | 8–10 hours |
| Smart Charger (55A) | 660W | 2.5–3 hours |
Lithium batteries accept full converter current until 90% SOC, while lead-acid slows after 75%. Practically speaking, running the AC while charging might starve the battery of power—always prioritize charging during low-usage periods.
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FAQs
Check converter output voltage—if below 13V, faulty diodes or blown fuses are likely. Test with multimeter at battery terminals during charging.
Can I charge lithium batteries via standard RV converters?
Only with converters supporting 14.4–14.6V absorption. Most pre-2015 units max at 13.6V, insufficient for lithium chemistries requiring higher voltage thresholds.
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