There are basically three ways to check the condition of your RV batteries. You can check the monitor panel in the RV, you can measure the voltage with a digital voltmeter or you can check the specific gravity with a hydrometer. When you check the condition of your battery using the monitor panel make sure the RV is not plugged in to shore power. If it is you will get a false, fully charged reading. To get a more accurate reading of the battery’s condition check the monitor panel when the unit is not plugged in and turn a couple of over head lights on to place a small load on the battery.
Measuring voltage with a voltmeter has its advantages. If you have sealed batteries your only choice is to use a voltmeter, and measuring voltage can give you a quick picture of the batteries depth of discharge so you know when they need to be recharged.To measure the voltage you need a good digital voltmeter. Set the meter on DC voltage and connect the red lead to the positive terminal and the black lead to the negative terminal. A 12-volt battery that is charged should read 12.5 to 12.7 volts. Readings less than 12.5 indicate the battery state of charge is less than 70% and the battery needs to be charged. A 6-volt battery that is charged should read 6.25 to 6.37 volts. The battery should not be tested if it has been charged or discharged in the last 6 hours and preferably 24 hours.
The preferred method for testing the battery’s state of charge is to check the specific gravity reading of each cell. You can purchase a hydrometer at an auto parts store for about ten dollars. The electrolyte is a solution of acid and water so you need to wear safety glasses and gloves and avoid skin any contact.Remove the vent caps and check the electrolyte levels. There has to be enough electrolyte in the cells for the hydrometer to pick it up. If you have to add any water you’ll have to charge the battery and let it sit for at least six hours before testing. Fill and drain the hydrometer at least twice in each cell before taking a sample. Take the reading and record it then drain it back into the cell.Test all of the cells and replace the vent caps. Specific gravity readings for a charged battery should read between 1.235 and 1.277. Specific gravity readings below 1.235 indicate the battery state of charge is less than 70% and the battery needs to be charged. If there is a .050 or more difference in the specific gravity reading between the highest and lowest cell, you have a weak or dead cell in the battery.
I was recently asked a question and felt like the answer could be useful to lots of RVers, so I am using the question as the topic for this article.
Q: Hi Mark, we live in Virginia and are preparing our RV for winter storage. I just had the RV winterized, but I am concerned about how or what to do to properly store my RV batteries. Do you have any advice?
Mark's Answer: The two most common causes for RV battery failure are undercharging and overcharging. Undercharging is a result of batteries being repeatedly discharged and not fully recharged between cycles. If a battery is not recharged the sulfate material that attaches to the discharged portions of the plates begins to harden into crystals. Over time this sulfate cannot be converted back into active plate material and the battery is ruined. This also occurs when a battery remains discharged for an extended period of time, like during storage. Sulfation is the number one cause of battery failure. The second leading cause of battery failure is overcharging. Overcharging batteries results in severe water loss and plate corrosion. With that said let’s look at how to properly store your RV batteries.
Before we talk about storing the batteries we need to talk about battery safety. Lead acid batteries contain sulfuric acid which is extremely corrosive and can cause severe burns or even blindness. And the hydrogen gas that batteries produce when they’re charging is very explosive. When you work around batteries you need to wear goggles and gloves, remove all jewelry and do not smoke or use any open flames.
Caution: If you accidentally get battery acid on your skin, flush it with lots of water and if it gets in your eyes flush with low pressure water for 15 minutes and call a doctor.
When you put the RV in long term storage it’s a good idea to remove the batteries and put them in storage too. This is quite simple to do. The first thing we want to do is visually inspect the batteries for any obvious damage. Any fluid on or around the battery may be an indication that electrolyte is leaking from the battery. A damaged or leaking battery should be replaced immediately. Whenever you remove any battery always remember to remove the negative terminal or cable first, and then the positive cable.
Battery Tip: When you remove a battery turn off the ignition switch, all electrical switches, and any battery disconnect switches before you disconnect the battery cables. Whenever you remove any battery cables label them first so you remember how they go back on the battery. When you reinstall the battery do it in the reverse order. Install the positive cable first and then the negative cable.
Clean the batteries with a 50/50 mixture of baking soda and water if necessary, i.e. use one pound of baking soda to one gallon of water. Now you can check the electrolyte level in each cell and add distilled water if necessary. The minimum level required is at the top of the plates. If it’s below the plates add enough distilled water to cover the plates before you charge the battery.
Test the battery state of charge with a voltmeter or hydrometer and charge any batteries that are at or below 80%. An 80% charge is approximately 12.5 volts for a 12 volt battery and 6.25 volts for a 6 volt battery. Lead sulfation starts when a battery state of charge drops below 80%. After charging the batteries check and fill each cell to 1/8 inch below the fill well with distilled water. Overfilling cells will cause battery acid to overflow.
Caution: Batteries should only be charged in a well ventilated area and keep any sparks and open flames away from a battery being charged. Check the electrolyte levels before and after charging batteries.
A discharged or partially charged battery will freeze much faster than a charged battery. Store the batteries in a cool dry place but not where they could freeze. Batteries in storage will loose a percentage of current through internal leakage. It’s not uncommon for a battery to discharge up to 10% a month when it is being stored. Cold temperatures slow this natural discharge process down and warmer temperatures speed the process up. Test the stored battery state of charge every month and charge batteries that are at or below an 80% state of charge.
Completely charge the batteries before re-installing them next spring. For optimum performance you can equalize the batteries after they are fully charged. An equalizing charge is an increase in charging voltage similar to a bulk charge to convert any crystallized lead sulfate back into its original components.
If you decide to leave the batteries in the RV while it is in storage remember to check the state of charge monthly and charge any batteries at or below an 80% charge. Some RV converter multi-stage chargers and aftermarket chargers are designed to maintain a float charge on the battery without removing the batteries from the RV. Remember, for the converter charger to work the RV will need to be plugged in to electricity.
I reflect on how I got hooked on this thing called RVing. In 1975 I towed my first travel trailer. Of course at the time, like most teenagers, I thought I knew everything. I tent camped for years and had experienced camping in travel trailers and motor homes with a friend of mine and his family, but this was my first real RV adventure, out on my own. I had recently graduated from high school and was working for an RV dealership in Pennsylvania. I started out washing campers and eventually worked to the position of an apprentice technician. I was always mechanically inclined and had an interest in how things worked; from age twelve when I disassembled our perfectly good lawn mower to see how it worked, to age sixteen when I rebuilt my first VW engine.
It was Thanksgiving and deer hunting season was quickly approaching, which in North Central Pennsylvania is very similar to a Federal holiday. I asked my boss if I could borrow an old travel trailer to use for a deer hunting trip and to my surprise he actually said yes. I don’t remember all of the details about the travel trailer, but I do know it was a Shasta because it had the classic wings on each back corner. I would guess that it was a mid-to-late 60’s model and it was close to 20-feet long. The only conditions for borrowing the trailer were:
1) To bring it back in one piece and
2) Not to use the water system because it was winterized and the temperatures were in the low teens.
Antlered deer hunting season started the Monday following Thanksgiving and I invited my best friend to go with me. We were going to head up into the foothills on Saturday to set things up and do some last minute scouting. I had a 1969 Chevy Blazer. It was a full size, K5 model, with a six-cylinder engine and rust holes in the body the size of softballs. Now, you would think that working for an RV dealership I would have access to, and use, the proper hitch work and brake control to tow the trailer. I do remember wiring a plug for the trailer lights, but figured since I wouldn’t be towing the trailer on a regular basis I would forgo the brakes and just drop the trailer on the ball and go.
Keep in mind I was a teenager, and knew everything back then. Kind of like how my teenage son knows everything now! There were no pre-trip checks or inspections. We picked up the bare essentials, a pot and pan, some groceries, our sleeping bags and hunting equipment and off we went. It was about a sixty-mile trip to our favorite hunting destination. The first thirty-five miles was on two-lane paved roads and the last twenty-five miles was a winding, snow covered dirt road barely wide enough for one vehicle. If you encountered traffic going the opposite direction somebody had to back up until there was a spot wide enough for both vehicles to safely pass. I do remember the Blazer didn’t seem to steer quite like normal and if I had to stop quickly I would have hit whatever it was that was making me stop so quickly. I took a deep sigh of relief after the white-knuckle experience of getting to our destination and thanked my lucky stars that the trailer was still in one piece. Little did I know that getting there was just the beginning of my first real RV adventure!
We set the trailer up, which at the time was really nothing more than leveling it from front to rear using the tongue jack and turning the LP gas supply on. Then we settled in the trailer for the first night. We figured since it was cold outside we didn’t need to use the refrigerator, so we left our groceries in the Blazer. The furnace was the old style that you had to light manually. Soon after I got it to light it warmed up enough inside to take our gloves and coats off. For dinner we heated up some pork and beans on the range top and ate them out of the pan because we forgot to bring any plates. Afterwards we played a card game called set-back and eventually turned in for a good nights sleep. The next morning I went to the Blazer to get some bacon and eggs for breakfast. The eggs were frozen solid. We fried some bacon and later that morning we used the frozen eggs for target practice to sight our hunting rifles in. We washed the pans in a nearby, nearly frozen stream, since we didn’t have any water, and the rest of the day was spent scouting the snow covered hills for signs of deer. Then it was back to the cozy, but somewhat drafty Shasta trailer.
After another entree of pork and beans I put all of the empty cans and other garbage in a plastic bag and set it outside the door. The next morning was opening day. It was difficult to relax and go to bed that night, but knowing we would be getting up early we forced ourselves to turn in for the night. The first major event of the night was waking up around midnight because it felt like 10 degrees below zero inside the trailer. The trailer only had one full and one partially filled 20-pound LP gas bottle, and with the furnace running non-stop since we arrived they were both empty. Fortunately I did have enough forethought to bring two spare 20-pound LP bottles with us. I told my friend that since I got the trailer for us to use he would have to get out of his sleeping bag, change the bottles and re-light the furnace. After some reluctance and a few choice words he stumbled outside and changed them over. Soon it was warm again and we were both back to sleep.
Sometime around three in the morning the trailer began to shake, I mean literally shake back and forth. At first I thought I was dreaming but soon realized I wasn’t. I reached up and turned a small overhead light and looked over at my friend to see if he was awake. Not having any clue what was happening we both stared, wide-eyed, at each other. I pulled the small curtain away from the window and peered outside. It took a minute to focus my eyes in the dark, but I soon realized that there were two bears outside; a small black bear cub and its not so small mother pushing against the side of the trailer. Not really sure what to do we both got our hunting rifles, loaded a round in the chamber, and stood back, ready for when the bear would come busting through the door or a window. We waited for what seemed like forever at the time, but it was probably a minute or two before the shaking stopped. We glanced out the window again and there were no signs of the bears anywhere. Needless to say we didn’t get anymore sleep before it was time to head out to our favorite hunting spots early that morning. When we walked out of the trailer, with flashlights in hand, we soon realized why the black bears stopped to visit us that night. There were pork and bean cans and other garbage scattered everywhere around our makeshift campsite.
Another reason this memory remains so clear in my mind is because at 8:10 AM on opening day I shot my first 8-point whitetail buck on a ridge about 80 yards from where I was sitting. My friend heard the shot and came over to check it out. After field dressing the deer it took us about two hours to drag it down the long ravine, back to the trailer. Knowing that we had enough LP gas for one more night we fired up the furnace and ate some more pork and beans. After making sure there was no garbage outside we settled in to the warm, cozy Shasta trailer and played cards while I recounted the events of the great whitetail deer hunt over-and-over again.
We did manage to get the trailer back home safely, and other than some remnants of hungry black bear paw prints on the side of the trailer it was still in one piece. That nearly disastrous weekend hunting trip, in freezing cold weather, spent in the small Shasta travel trailer, is when I got bit by the RV bug. Forty-one years and six RVs later, we are still making new RV memories every year.
There are many different types of RVs. In our RV101® video get some helpful tips on selecting the right type of RV for you.
https://youtu.be/5uqxd9nuqaQ
Happy Camping!
I am the founder of a company called RV Education 101. We produce videos on how to use and maintain Recreation Vehicles, and I am the author of a book titled “The RV Book”. I started the company because I was concerned about the lack of education and safety awareness for the RV consumer.
Mark Polk is a retired Army Chief Warrant Officer Three, specializing in wheeled and track vehicle fleet maintenance operations. In addition to owning and operating RV Education 101 since 1999, Mark also has a very extensive RV background working in RV sales, service and management.
Dawn Polk is Mark’s wife and is RV Education 101’s Sales and Marketing director. After 3 years in RV sales, she left her position to help start RV Education 101.
http://www.rveducation101.com
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There are basically three ways to check the condition of your RV batteries. You can check the monitor panel in the RV, you can measure the voltage with a digital voltmeter or you can check the specific gravity with a hydrometer. When you check the condition of your battery using the monitor panel make sure the RV is not plugged in to shore power. If it is you will get a false, fully charged reading. To get a more accurate reading of the battery’s condition check the monitor panel 
Measuring voltage with a voltmeter has its advantages. If you have sealed batteries your only choice is to use a voltmeter, and measuring voltage can give you a quick picture of the batteries depth of discharge so you know when they need to be recharged.
To measure the voltage you need a good digital voltmeter. Set the meter on DC voltage and connect the red lead to the positive terminal and the black lead to the negative terminal. A 12-volt battery that is charged should read 12.5 to 12.7 volts. Readings less than 12.5 indicate the battery state of charge is less than 70% and the battery needs to be charged. A 6-volt battery that is charged should read 6.25 to 6.37 volts. The battery should not be tested if it has been charged or discharged in the last 6 hours and preferably 24 hours. 
Remove the vent caps and check the electrolyte levels. There has to be enough electrolyte in the cells for the hydrometer to pick it up. If you have to add any water you’ll have to charge the battery and let it sit for at least six hours before testing. Fill and drain the hydrometer at least twice in each cell before taking a sample. Take the reading and record it then drain it back into the cell.
Test all of the cells and replace the vent caps. Specific gravity readings for a charged 
