Properly Monitoring Your RV Batteries for Off-Grid Camping

Properly Monitoring Your RV Batteries for Off-Grid Camping

Many RV campsites in state parks and national parks don’t have electrical hookups, so knowing if your batteries will get you through a 2 or 3-day weekend camping trip is pretty important to help keep it a fun and safe trip for you and your family.

For many people, off-grid RV camping for a week or more is an enjoyable way for them to use their RV. Camping in a secluded area is more peaceful than a campsite with closer neighbors.

But, an off-grid camping trip in your RV can quickly turn into a bad experience if you are not prepared and run out of propane and/or battery power. For example, imagine going on a week-long RV camping trip into the middle of nowhere and waking up to freezing cold temperatures inside your RV at 3:00 in the morning on the second night. This is one reason why you should monitor your propane levels. Many RV owners have had this happen to them (usually only once) – and that event is never forgotten.

As important as it is to monitor your propane levels, even more critical is monitoring your RV house battery’s state of charge (SOC) – not just the battery’s voltage, but the actual state of charge as in 50%, 75%, or 100% SOC. You will need to make sure that your batteries get sufficiently recharged every day or two on your off-grid camping trip for pretty much everything to keep working in your RV including your lights, refrigerator, and propane furnace. If your RV has a built-in generator, it even uses your RV house batteries to start it.

If your RV house batteries run out of charge (0% SOC) during one of your off-grid RV trips, then it is more than just “lights out”. You will have no heat from your propane furnace, no refrigerator so possibly spoiled food, no water pump so no running water if you don’t have a water hookup site. And if this were to happen when you still have a few days left on your trip, then your vacation plans probably just got changed.

If you are not able to accurately monitor the SOC of your RV house batteries, then you don’t really know if your solar and/or generator are adequately charging your batteries. And you don’t know if (and how much) you need to conserve your battery power. If you use a generator to charge your batteries, you won’t know if you are running your generator too much or too little to get through your trip.

Monitoring the SOC of your RV house batteries helps you more confidently enjoy your off-grid camping trips.

RV Battery Monitoring When You are Off the Grid

Being able to monitor the state of charge (SOC) of your RV house batteries while you are camping off the grid will help you to know how much energy you need to get through your trip. But unfortunately, accurately monitoring battery SOC is a little more complicated than monitoring something like a propane tank.

Propane is easy to measure. Accurately measuring how much energy is left in a propane tank can be done in several ways. For example, propane sensors from Mopeka can be placed on the bottom of the tank to measure the height of the propane level and show the percentage of propane that is remaining. The Mopeka propane sensors also integrate with the RV Whisper Monitor Station to provide easy graphing of historical data so you can see how much propane your RV uses on a cold night.

You can also get a rough idea of how much propane you have left by how heavy the tank is. If you have a scale, you can weigh the tank and get a more accurate measurement of how much propane is in the tank. Basically, there are several ways to accurately measure how much propane is left in a propane tank or cylinder.

Unfortunately, measuring the amount of energy (SOC) the battery has left is not so easy. You cannot weigh a battery to find out its SOC. Measuring just the battery voltage is not an accurate way of getting the SOC. There are numerous variables that make a simple battery voltage reading an inaccurate way to measure SOC. The variables include the temperature of the batteries, the type of batteries, whether the battery is being charged or is in use, and many others.

The best way to obtain an accurate measurement of your battery’s state of charge is by using a “shunt-based battery sensor”. A shunt is a precision resistor that gets wired into your battery cables and measures how much electricity flows into and out of the battery.  A “shunt-based battery sensor” is an electronic device that connects to the shunt to measure how much current is flowing in and out of the batteries, allowing it to calculate an accurate SOC.

A shunt connects to one of the battery cables that is connected to one of the battery terminals. The shunt essentially becomes a part of the battery cable or a short “extension cord” of the battery cable. Every amp of electrical current that goes into and out of the battery bank flows through the shunt.

The battery sensor uses the shunt-based current measurements (Amps) along with battery voltage (Volts) to calculate an accurate battery SOC. Shunt-based solutions are the gold standard for monitoring an RV battery’s state of charge.

Some modern Lithium Iron Phosphate (LiFePO4) batteries even come with an internal built-in shunt-based battery sensor that communicates with a bluetooth phone app to measure and display an accurate SOC – for that single battery. If you want to monitor the SOC of a battery bank made of multiple Lithium batteries, you can still use a single external shunt to measure the SOC of the entire battery bank.

Shunt-Based Battery Sensors Plus RV Whisper Monitoring: The Protection You Need to Get the Most Out of Your Off-Grid Camping Trip

With a shunt-based battery sensor attached to your battery cable, you will be able to obtain the most accurate reading of your battery’s state of charge. And if you use a shunt-based battery sensor that you can add to your RV Whisper Monitor Station your RV batteries SOC, volts, and amps will be logged every few minutes so you are able to easily see both current data and graphs of historical data that to help ensure that you will have enough battery energy to get through your entire camping trip.

The RV Whisper Monitor Station currently works with two of the top shunt-based bluetooth battery sensors on the market: the Victron SmartShunt and the Thornwave Powermon / DC Power Meter. Both of these shunt-based battery sensors come with a bluetooth phone app so you can see your batteries SOC on your phone when you are in your RV.

They can both also be easily added as a bluetooth battery sensor to your RV Whisper Monitoring Station to provide you with detailed SOC information about your batteries including being able to see the data over the internet. When added to your RV Whisper Monitor Station you can see on your phone or computer:

  • How full the battery is, expressed in a percentage from 0% to 100% SOC
  • How many amps are going into and out of the battery at various times of the day.
  • All battery monitoring data (volts, amps, SOC) is logged every five minutes, and easily displays graphs and trends that allow you to accurately track battery usage over a trip whether it is a 3-day event or a weeks-long vacation.
  • The ability to receive email and text alerts when the battery is getting low (based on pre-set thresholds that are set by the user).

You also have the ability to add other bluetooth wireless sensors to your RV Whisper Monitor Station including:

With adding one of the shunt-based battery sensors to your RV Whisper Monitor Station, you will be able to see critical data, such as how fast electricity goes into and out of the battery (amps) when it is on a charger, how much batteries discharge overnight before the sun comes up (very useful if you are relying heavily on solar power to keep the battery charged), and many others.

The data you obtain from the RV Whisper Monitor Station allows you to adjust your activities during the course of your trip and do what you need to do to preserve your battery power. This gives you the peace of mind you need to fully enjoy your trip knowing that your battery is not going to run out of charge at an inopportune time.