When your RV house batteries have a low charge, it becomes paramount to recharge them ASAP. Other than Lithium-ion ones, other 12-volt battery types cannot decline below a 50% load otherwise they risk damage to the battery’s cell.
Determining the fastest way to charge RV batteries becomes important at this stage. However, your options for how to recharge your motorhome, trailer, or camper depend on your situation at the time.
Also, if you’re using the house batteries while needing to charge them up, faster charging is necessary to get ahead of your current usage.
Here are the different options on how to proceed effectively:
How to Charge RV Batteries Quickly
Shore Power Charging at an RV Campground or RV Park
When staying at a paid RV campground or a more luxurious RV park, you’ll likely have hook-ups. These have power pedestals that you can plug your RV into and charge up the batteries.
It depends on the hook-up, but most are 30-amps or 50-amps, while others are limited to 15 or 20-amps. Thirty or 50-amps is far more typical, which potentially allows for RVers and Van Life enthusiasts staying at a campground to give their batteries a much-needed boost.
Unlike other options, this is usually simpler and offers a greater number of amps to charge up the fastest too.
Some things to be aware of with hook-ups are:
- Use a Converter Charger or possibly an Inverter Charger to get the juice to the house batteries. A battery converter charger takes AC power and converts it to DC for the 12-volt batteries. Inverter chargers swap power from DC to AC for household appliances and other equipment that requires it.
- A need for a high gauge wire to take full advantage of the greater amperage charging rate.
- Use of a surge protector with an electrical management system (sometimes referred to as “EMS”). These protect against unexpected surges, spikes, etc. while charging.
The battery charger used must match well with the batteries to be charged. Whether you have reliable lead acid, some AGMs, or a set of Lithium batteries, the battery charger needs to play nicely with them. Otherwise, there is a risk of an inability to charge up, slower charging speeds, or potential battery damage!
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Also, be sure that your charging method prevents overcharging the batteries. This is the number one way that RV batteries are damaged, leading to a shorter lifespan and/or lower future capacity.
Relying on shore power when traveling around could well be the best way to charge RV battery banks. If the 12-volt house batteries aren’t overly drained during that day’s journey, then being parked up in a campground with hook-ups ensures you’re all set by the morning.
Read Also: How to Charge an RV Battery from a Vehicle
Use an RV Generator or a Portable Generator
When you’re not at a campground with hook-ups or you’re completely off-grid, then the fastest charging method necessarily changes.
If your RV is equipped with an RV generator or you own a portable generator, it’s possible to use this to recharge your 12-volt house batteries. Our “How to Charge RV Battery with Generator” article covers it in more detail than we can here.
Some generators already have a 120-volt outlet. These are fine because the same equipment is needed, like charging via shore power at a campground.
Newer RV models and newer generators may already have a DC power outlet. This makes it simpler to charge a 12-volt battery bank.
The generator needs to be confirmed as providing Pure Sine, not Modified Sine power. This is more relevant to 120-volt electronics plugged directly into the generator, but it’s worth mentioning either way to safeguard our readers.
Also, be aware of the risk of dirty power from a generator. This is where the generator doesn’t deliver consistent, smooth power. Instead, in electrical terms, it runs in fits and starts. This can damage the batteries that you’re using for charging. Therefore, an inverter generator is far safer because it smooths out this potential issue. If your RV doesn’t have this type, it’s worth upgrading.
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Note the fuel levels too. Generators are powered using gasoline and sometimes propane. If it’s the RV’s generator and runs on propane, then it’s draining the gas that runs your furnace, the cooking stove, etc. Monitor your usage and the propane that remains.
Read Also: How to Charge RV Battery with Generator
Charge RV House Batteries from the Alternator
Pumping up the stable charge on your house batteries direct from the RV’s alternator is another option. It’ll work wherever you are at the time too.
Alternators aren’t designed for or are always powerful enough to charge a house battery pack. There is a risk with weaker ones of trying to deliver too much amperage, struggling, and using the starter battery to make up the difference. This can lead to a drained starter battery that won’t get the engine running. Also, a factory-fitted alternator may fail when repeatedly used for deep-cycle battery charging purposes.
To avoid this, sometimes it’s necessary to replace the alternator with a more robust, high-output one designed for this task. The newer the RV, the likelier it is that it can manage but it needs some review.
A DC-to-DC charger is also a good choice to support charging the house batteries via an upgraded alternator. These specialized chargers increase the voltage supplied to a level where the better, three-stage charging method becomes available. It provides stability, solid charging, and support for long-term battery health too.
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3-stage battery charging includes the following:
- Bulk Charging – A smart battery charger automatically detects the battery type and its requirements. From there, it controls the high voltage and stronger amperage charging levels through this first stage up to approximately 80 percent capacity.
- Absorption Charging – After the battery is charged to 80 percent capacity, the input is reduced. As a cooling down cycle, it fills in the gaps in charge vs available capacity.
- Maintenance Charge – The float or trickle charging stage kicks in at the 95% capacity level. It adds small amounts of current to increase the charge to eventually attain full capacity. This is the same system as trickle chargers use to keep a battery topped up for RVs in storage.
For effective DC-DC charging tasks, it’s important to always use larger gauge charging wires. Otherwise, smaller gauge ones will lose some of the electrical currents before it ever reaches the batteries. The energy loss due to inferior wiring is almost always overlooked and leads to longer charging times.
Do It Before Hitting the Road: How to Charge an RV Battery at Home
Just as you might make use of shore power at an RV campground, charging your 12-volt house batteries before heading on a trip is a solid choice too.
While you won’t likely enjoy the same 30-amp or 50-amp charging rate, most homes can deliver 15-amps or 20-amps to an RV. This is still quite fast and will sort out half-drained batteries in no time at all.
Also, when home, there’s the potential to remove the 12-volt batteries and charge them indoors or in the garage. If this is easier, then do that. It also allows you to clean the connections and look over the battery’s condition too.
Charge the Batteries While Towing an RV
For RVers who have a tow vehicle and a travel trailer, camper, or another towable behind, it’s possible to charge as you drive. This won’t be as speedy as being parked up and charging via shore power, using a generator, or from home, but it’ll do in a pinch.
It requires a reliable and powerful alternator in the tow vehicle (it may need to be upgraded) and a 7-pin adapter as an auxiliary power source. This allows the electrical current to be shared between the tow vehicle and the towable RV while driving.
We’re already written in detail about this in our popular “How to Charge an RV Battery from a Vehicle” article.
Charge RV Batteries Using Solar Panels
Supplying additional energy from the sun to charge 12-volt batteries is an extremely useful addition to any RV. In a situation where power is everything, you never want to miss an opportunity to grab more.
Our Solar Basics for RVers article will get you started.
As faster charging methods go, however, it’s not a standout. It should be seen more as a useful extra. If you’re stranded, out of power, and your generator has no more fuel to get it going, then it might be all you have. But you should never let things get that bad.
Read Also: Do RV Outlets Work on Battery?
Charging RV Battery with Jumper Cables
Can you charge a deep cycle battery with jumper cables? It’s possible to do so, but it’s not the best idea.
If the starter battery is dead in the RV, then getting a jumpstart from a friendly RVer nearby is a no-brainer. Finding a way to charge your starter battery will be important to avoid getting stuck somewhere.
However, if you’re planning to recharge 12-volt house batteries using jumper cables, we’d suggest against it. The deep cycle battery type charges lowly. By the time the house batteries are coming back to life, the source of the charge will have low battery power themselves and regret making the offer!
RV jumper cables are for starter batteries primarily, and not 12- volt RV house batteries. And if you’re thinking of using your RV starter battery to charge your house batteries, it’s the same answer. You could get stuck where your RV won’t start and you’re in a neighborhood that’s not so safe overnight.
Read Also: How to Tell If a Deep Cycle Battery is Bad
Closing Thoughts
Most battery types become damaged when their charge falls below 50 percent. Therefore, it’s imperative to have multiple available options to avoid this ever happening.
Also, when using the 12-volt while simultaneously charging them, faster-charging methods are better to get ahead of the drain on the battery pack. This is where using one of the quickest charging methods above is preferable.