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RV Battery Switch Installation for Power Economy & Safety

RV Battery Switch Installation for Power Economy & Safety

avatar   Scott
Trip Date 03/24/2018
Posted On 07/30/2018 02:00:31

Camping | Battery | Customizations | Safety | Save Power | Boondocking | Master Switch | Deep Cycle | Save Battery

When I was planning our RV purchase, I wanted to ensure that I had a battery switch to turn off all of the DC power in the RV. My goal was to make sure that when in storage or boondocking I wasn't wasting battery power. There are several reasons to have an easy to reach battery switch. Beyond saving battery power, there are potential dangers in fueling the tow vehicle while towing a trailer - a battery switch makes it much safer. Read on to learn more about these master switches including how they make refueling your RV or tow vehicle much safer.

Battery Master Switch Confusion

When we purchased our RV, I had asked my dealer to install a battery switch. When I picked up the RV, I learned that there was some confusion about the switch. The guy who was instructing us about the operation of the RV was not the person who had arranged for the switch installation. He showed us a master switch that was in the storage room in the front of the trailer, so we all thought that was the switch and all was well and good.

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When I was preparing to install some 12v accessory plugs (see post titled "Boondocking Prep for RVs: More 12v Accessory Outlets") in the bedroom of the RV trailer (Highland Ridge Open Range 2910RL), I had my first occasion to use the battery switch. I had turned off the switch and when I got to the step of connecting wires to the new accessory plugs which included a volt meter I realized that the wires where hot. Hmm, why is this? I double checked the switch and it was off. Also I was not plugged into shore power, so the charging controller wasn't generating 12v DC current. I also was not connected to the tow vehicle. I did a quick survey of the 12v usage in the trailer and found several devices not wired through the master battery switch. You might have the same issue. Perhaps this is by design but not what I intended. I wanted to be able to turn everything off at one switch. The devices that remained on when the master was off included the carbon monoxide alarm, USB plugs in the bedroom (incidentally very near the master switch), some external LED lights and the light in the storage locker. Hmm, the switch would not achieve my goal of saving power while in storage.

The Real Master Switch

I opened the battery box to disconnect the battery so I could continue with my project at hand. Well, I found another switch that really would cut off all the power in the RV. I then remembered the RV salesman using the words "blade switch" which this was, and the switch in the storage locker was not. This must be the actual switch that the dealer installed. The problem was that I wanted an easily accessible switch and this one was a hassle getting to as the battery box had a strap and buckle securing it.

After doing the accessory wiring, I turned my attention to the battery box. I had several issues with it. I decided to correct the switch issue by rewiring the blade switch so it that was mounted on the trailer frame outside of the battery box so that it was easily accessible. I also didn't like the difficulty of the belt strap that came standard with the battery box, so I replaced it with two bungee cords. Additionally, when I had opened the battery box to investigate and disable the power, I found that the box was full of water. That can't be good. How did it get there? Luckily the water level was only up to about 1/2" below the top of the battery where the terminals were, and it didn't seem that the battery had shorted out. I did a quick Google search about this issue and learned that there is a small vent on the top of the battery box and heavy rain can flood in there. Others had this issue and solved it by drilling a hole in opposing corners of the bottom of the box (in this case plastic) which allows the water to drain immediately.

It amuses me that things like this are designed with these obvious flaws that are never fixed in the products by the manufacturers. I'm sure these plastic battery boxes have been around for decades, and water flooding can't be a recent problem. The fix is easy but why doesn't the manufacturer do it?

Battery Master Switch Under Frame

Battery Master Switch Under Frame

I finally was able to rewire the blade switch by changing the wiring so that it was outside the battery box and easily reachable. There was an existing bolt on the frame where the negative power line goes to the negative terminal of the battery. I used that cable and moved the switch to the bolt, and moved the cable directly to the negative pole of the battery. This makes the switch easy to reach. The blade switch hangs down a bit from the bottom of the frame near the front of the RV trailer. I can easily turn it off when parking the RV so that the power vampires don't suck up all of the power in the battery.

Charging the Battery When Not in Use

I use my battery switch anytime I am parking the RV for more than a day and always when it is in the storage lot. However, during the winter when I'm not using it for a long period of time, I bring the battery home and charge it with a Battery Buddy which has worked well for me. (It was a little cheaper than the market leader, Battery Tender.) These devices both work the same by slowly charging the battery and using a multi-stage technique so that the battery can be most efficiently charged, but not overcharged.

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Fueling Safety

After I was all done with the battery box and master switch fixes and had been using them for a while, I learned about another related issue. When driving or fueling an RV (trailer or motor home) there is a potential danger of fire. I did some research on the danger and the recommended solutions. The issue is that many say you should not travel with the propane turned on because if you have an accident, there could be a fire or explosion. Also, you should not fill up your vehicle if the refrigerator or furnace (and possibly the water heater) are on because the spark or open pilot flame can ignite fumes from the gasoline.

Driving with the propane valve open (which most do as it is necessary to run the fridge in gas mode) doesn't seem to be a large danger since the modern propane tanks are required to have a safety valve that stops excess propane flow if there is a rapid depressurization. To make sure that the excess flow valve works properly, the tank must be completely open. See Traveling With Propane for a good explanation.

I do believe that igniting fumes at the gas station is a potential danger. All states have laws and warnings about smoking while filling up. Some states have laws about electric sparks or open flames in the vehicles while filling up. The other issue is that even though you may be careful, you don't know what the person next to you may do while you are parked there. They could spill fuel that causes a bigger fume cloud than normal, or there may be a wind or lack of a wind that allows the fumes to drift near your RV. Then, in a flash, you have a problem.

In my research, it is recommended that you turn off the fridge, furnace and water heater before you are on gas station property. This requires parking, opening the trailer door and turning off the fridge - which takes some effort. Most people probably don't drive with the water heater or furnace on, but there could be an oversight ... or maybe in cold climates people do leave these on - I'm not sure.

This is where the master battery switch comes in. It is a great safety feature for your RV and trip. When we are driving and need to fuel, my wife can hop out quickly at a red light or on the roadside and turn off (or on again) the master battery switch. We don't have to worry about sparks from the fridge or anything else contributing to a fire at the gas station. I verified that the refrigerator will restart and go into auto gas mode when the power is restored.

After this research I was glad that I already had implemented an easy modification on my trailer that improves the safety in a situation that I had not previously considered. Now we just have to remember to use the power turn off procedure consistently when fueling.

Finding The Parts

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RV Battery Switch Installation for Power Economy & Safety

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