Will the RV Inverter Keep My Motorhome Chassis Battery Charged?
There are generally two batteries in motorhomes.
One that’s for running the 12 volt appliances inside the RV, also called the house battery.
Then there’s the automotive battery that’s for the engine, also called the chassis battery.
Related Product: We use the reliable VMAX 100Ah AGM battery (click to view on Amazon) in our RV.
In most cases, the RV inverter will not charge the RV chassis battery.
This isn’t a problem if you drive your motorhome once every few months to recharge the battery.
But if you are planning on staying in an RV park over the winter or longer, you are going to need to keep that 12 volt engine battery maintained.
One thing to note is there is usually a switch somewhere on the driver’s side of the cab that is for jump starting the RV chassis battery with the house batteries if it dies.
I’ve never had to use this feature but it’s good to know about if you’re ever camping far away from humanity and your motorhome won’t start because of a dead chassis battery.
Here are a few ways you can keep the chassis battery in your RV charged if you won’t be driving it for a while.
See Also: When To Charge A Deep Cycle Battery
Ways to Keep an RV Chassis Battery Charged
1. Start the Engine
The simplest but most time consuming way to keep your RV chassis battery charged when parked for a long time is to start the engine and let the alternator do its thing.
Driving it around is how vehicles keep their batteries charged so starting the engine for a while should help keep the starting battery in good health.
The main downside to this method is it’s going to be noisy since the engine will have to be running and it will use up fuel.
If you’re in an RV park or campground with lots of neighbors they might not appreciate the noise.
It’s also the most inefficient way to keep the RV chassis battery charged but in a pinch it’s one way to do it.
2. External Battery Charger
The most common way RVer keep their batteries charged when plugged into shore power is with good old fashioned trickle or smart chargers.
You can actually disconnect the house batteries when you are plugged into a main power supply and you will want to make sure you keep those charged up as well.
I recommend getting a good smart charger over a trickle charger since they will not damage your batteries if left connected a battery for a long time.
They can normally also charge lots of different types of batteries which is useful if you have lithium or AGM house batteries and a flooded lead acid chassis battery.
For this method, you can either get a few smart battery chargers or periodically transfer the charger to each battery that needs to be charged.
A good chassis battery should only need to be charged once every few months but some motorhomes might have things connected that leach power.
Over time you will start to learn how fast the chassis battery discharges on its own and you can adjust your charging schedule accordingly.
You can also get a battery meter that connects to the chassis battery with a screen in the cab or somewhere you can easily see it.
I recommend getting a battery meter even if you use the built in battery charger method below because you will want to know if the charger is working correctly.
Since the built in battery meters in RVs can be very inaccurate I recommend getting one for the house batteries as well.
It’s a super simple install that’s worth it since a battery meter can help keep your batteries from discharging to damaging levels.
Healthy batteries last longer and won’t need to be replaced as often.
3. Built-In Battery Charger
If you plan on leaving your RV house batteries connected so the inverter will charge them while you are parked and plugged into shore power there is a built-in chassis battery charger option that’s easy to install.
This option also works if you have an external battery charger or solar panel connected to your RV house batteries so they stay charged and have enough juice left over to keep the chassis battery charged.
The Xantrex Echo connects your RV house batteries to the chassis battery.
It then draws power from the charger connected to the house batteries and uses that to maintain the other battery it’s connected to.
It will only switch on when the house batteries are being charged, so it won’t kill the RV batteries to keep the chassis battery alive.
This also keeps the Xantrex from overcharging the battery, which means it’s better than a standard trickle charger that’s constantly charging no matter what.
It can charge 12 or 24 volt batteries and it will automatically adjust for either kind.
The max output amperage is 15. When connected to a 12 volt battery the charger will switch on when the battery discharges to 13.0 volts, 26.0 volts on a 24 volt system.
The unit has over-voltage and thermal protection as well.
The main thing you will need to think about when installing the Xantrex Echo Charge will be the placement of the charger.
It needs to be no more than 2 feet from either the RV chassis battery or the house batteries in a dry, clean, well ventilated area.
In most cases, you should be able to install it somewhere inside the motorhome because the house batteries are usually located just underneath the floor.
The battery compartment is also a great option.
If the chassis battery isn’t too far away you could also install it somewhere in the cab.
There are some necessary cables, battery connectors, and fuses included, but you will probably also need some extra wire to extend the connection between the charger and the other battery.
Xantrex recommends using 12 gauge wire (click to view on Amazon) as extension wires even though the included wires are 16 gauge.
An installation diagram and more instructions are included with the battery charger.
As I said in the above section I recommend getting a battery meter (click to view on Amazon) for the RV chassis battery since there’s always a chance that something isn’t working with the charger.
That way you can catch and correct any issues before the chassis battery gets completely discharged and damaged.
Have any more questions about charging an RV chassis battery when long term camping? Leave a comment below.