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Your RV may have all the amenities you can afford to cram inside – a TV, air conditioning unit, shower heater, among others.
Notice that they commonly use 12 volts of power to operate? And they all rely on your RV deep cycle battery to provide your needs without interruption for as long as it can.
You see, RV deep cycle batteries are built to house an enormous amount of power that allows usage of our living conveniences for a longer period of time. When these batteries are well-maintained, they can last for five years or more depending on usage.
Without them, there is no way you can power up your 110-volt electrical devices in the middle of nowhere. They are one of the camper accessories I cannot do without.
HOUSE BATTERIES AND ENGINE BATTERIES
Let’s differentiate one from the other by their energy supply. A house battery is designed to supply longer continuous power to electrical appliances. This makes using major appliances such as the A/C for days possible. If it doesn’t work that way, it will not be able to operate properly and for long.
On the other hand, an engine battery is only required to fire up the RV engine itself by delivering high bursts of energy at an instant. So when your vehicle’s engine is already running, it already does it on its own without having the battery to continuously supply power to it.
Also referred to as a starting battery, another difference it has from the house battery is its larger size and higher CCA (Cold Cranking Amps) rating, which I’ll discuss later in this article.
For house batteries though, you could need up to 4 of them in a luxury motorhome, which can provide more than 1000 amp hours. An RV with not much need for electrical power can make do with just one battery that has about 50 amp hours.
Earlier I mentioned about RV deep cycle batteries. So house batteries actually go through deep cycling- a process that requires discharging and recharging of the battery without damaging it. With this method, a deep cycle battery has more longevity and durability than your typical starting battery. Moreover, there is also its dual purpose battery model, which is capable of solar energy storage.
MORE ON THE RV BATTERY
It is important to emphasize that an RV battery does not produce power, it simply stores it as transferred from a source. It is a useful tool that supplies steady power to many RV appliances even when there is no electrical power grid available. Such creature comforts have to rely on a battery system of 12 volts in order to perform accordingly. That’s why you can achieve your home away from home lifestyle, and be able to regulate your indoor temperature with an AC, cool your drinks in a portable fridge, etc., all of which are made possible with your RV battery.
As mentioned earlier, RV electrical devices use a house battery which I have already differentiated from a starting battery. A house battery is built to provide energy for an extended period of time, something that a starting battery is not capable of. Starting batteries have several thin plates that are maximized with their exposure to the electrolyte that provides that instant bursts of energy. As such, they cannot be used as an RV battery which requires a continuous supply.
HOW THE RV BATTERY WORKS
In order for you to provide proper maintenance and a prolonged lifespan for your battery, you should understand what it really is and how it works in the grand scheme of things that is, the RV lifestyle. It is a little complex as you might think, but I’ll discuss the important aspects of voltage, amps, among other things.
The battery that is commonly used in an RV is the lead-acid type. Lead acid batteries work by having series connections in their cells. Approximately, each cell has 2.1 volts. What you know as a 12-volt battery actually has 6 cells with a total output voltage of 12.6 volts produced in series.
Lead acid batteries are typically made from lead plates, submerged in an electrolyte that consists of 64 percent water and 36 percent sulfuric acid. That said, they only serve as a storage room for electricity; they don’t make it.
The battery that I have previously discussed in the house battery, used to supply 12 volts to RV amenities. House batteries should be deep cycle types, which are built with thicker plates to handle repeated discharge and recharge processes. Such batteries are rated in terms of amp hours and reserve capacity.
When shore supply is available, this can power your RV devices using 120 volts AC power and at the same time, recharge your RV batteries. Monitoring the battery levels should be done to maintain its efficiency and longevity. If you see it running low, you should be able to charge it as soon as you can.
If you’re going to plug it in to recharge, check if you have a converter so you don’t encounter electrical mishaps while you’re at it. You should expect a longer charging time as it is incapable of fast operation as you would want it to be. Prepare to wait before your battery becomes fully charged.
DEEP CYCLE BATTERY TYPES
It’s safe to say that RV house batteries should be deep cycle. Pumping water to the tank, or cooling your air with an electric fan is possible because of them. Practically every electrical device can be powered with the right battery setup.
Deep cycle batteries have three salient points to them, namely: life cycle, build life and warranty.
You would want your deep cycle battery to have superior construction that results to a higher life cycle and lower depth of discharge. Many low-quality batteries are rated with lower cycles, which will not make it last as long as the premium types.
You should consider the build life when getting deep cycle batteries. The good ones can last up to 12 years, which is determined by scientific testing. Simply put, a longer build life means a high-quality battery.
Deep cycle batteries come with a warranty, and some manufacturers are offering it for up to five years. Again, this is a good indicator of a quality product. These batteries come in two categories to suit a specific need. They are: flooded lead-acid (FLA) and valve-regulated lead acid (VRLA).
FLOODED LEAD-ACID BATTERIES
Also referred to as wet batteries, the term flooded is being used due to an electrolyte fluid excess necessary to maintain the submerged plates. This electrolyte is composed of sulfuric acid and water. Ideally, the fluid level is filled on top of the plates. This serves as a reservoir to ensure that there will still be enough fluid to cover any water loss from charging the battery.
This type of chemistry was discovered in 1859 by French physicist Gaston Plante, which became the first commercially-marketed rechargeable battery. As a deep cycle battery, a lead acid battery has long discharged and low current capabilities. It can be used in many applications, one being an energy storage component in an off-grid system such as in an RV.
FLA batteries are suitable for a prolonged power supply with their ability to hold a high charge, deep discharge, and repeated cycles many times over. Each lead-acid cell is made of the following parts, which are the anode and cathode that form the electrodes, and the electrolyte.
Inside it, there is a solid lead negative plate and a lead dioxide positive plate. Sandwiched in between is a separator that prevents short circuit and the contact of plates.
When discharging occurs, the current flows from the negative plate with oxidation to the positive terminal. On the other hand, recharging does a reversal of the discharge process by converting back the lead sulfate into the lead and sulfuric acid. During this time, it also removes sulfate crystals, which can potentially damage the plates.
The thickness of the plates come to play here with the frequent charging and discharging systems because the positive plate becomes corroded in the process. That is why a thicker plate will provide more lifespan to a battery than a thin one.
ADVANTAGES OF FLOODED OVER OTHER SEALED TYPES
- Cheaper cost
- Longer lifespan
- Simpler maintenance using distilled water
- Capable of high discharge
- Performs well in hot temperatures
- Wider availability
- Better performance even with a partial charge
- Requires periodic maintenance
- Should be installed in an upright position
- Produces gas during charging
- Emits acid sprays when overcharging occurs
- Needs ventilation
- Higher self-discharge rate
- Requires storage away from anything highly flammable or electrical
- Valve-regulated lead-acid batteries
VRLA batteries also called sealed lead acid and maintenance-free batteries, are built to function via an internal oxygen cycle. During this process, oxygen evolves in the latter stages of charging and overcharging the positive electron. The sealed feature prevents any leakage.
The VRLA battery improves the earlier FLA type by preventing gas buildup that may cause a battery explosion. It is done by restricting electrolyte movement and trapping the hydrogen on the plates for recombination during a battery recharge. This system reduces water loss, which makes for its maintenance-free feature and keeping it sealed. This also accounts for having no required positioning of the battery.
HERE ARE THE ADVANTAGES OF VRLA DEEP CYCLE BATTERIES OVER STANDARD BATTERIES.
- They don’t require water.
- They generally have a low discharge rate of 1 to 2 percent each month.
- They have a longer lifespan.
- They are vibration-resistant.
- They can be used in saltwater applications like powering up a motorboat.
- They can be mounted in any position without any spillage.
- They can store in a tight space.
- They diminish the occurrence of terminal corrosion.
- VRLA batteries come in two types: the gel cell and absorbed glass mat (AGM).
- Gel cell batteries
These VRLA batteries have a jellylike electrolyte produced from a mixture of sulfuric acid and silica as thickening agents, hence they’re called gel cell. The immobility of this gel makes it possible for the battery to be mounted in any position. This battery type is used in very deep cycle applications and also works well in extreme temperatures, absorbing shocks and vibrations at the same time.
Although not as common as the other VRLA batteries, gel cell batteries are used in electric wheelchairs, generators, and vehicles. The recharging voltage of these batteries is considerably lower than the other battery types.
However, the gel cell is perhaps the most sensitive when it comes to overcharging, which can cause adverse reactions on the voltage. The voids this creates in the electrolyte becomes an irreversible damage. And because of this, many people avoid using this battery, especially those that do not really understand battery technicalities.
ADVANTAGES OF GEL CELL
- No maintenance is required
- No leaks
- No required mounting position
- Less risk of explosion
- Resists vibrations
- No fumes
- High discharge rate
- Higher price
- Slower charging cycle
- Shortened lifespan when exposed to heat
- Absorbed glass mat batteries
The AGM is an upgraded lead acid battery providing superior power to devices with higher electrical demands. Instead of using a gelled electrolyte, it has what is referred to as a recombinant gas-absorbed electrolyte. This characteristic almost entirely eliminates water loss during which, the gases recombine inside reducing their emissions in the process.
For these VRLA batteries, acid is absorbed, and its movement is restricted by ultra-thin fiberglass mats located between tightly compressed plates, as opposed to flooding them, as the case is with FLA batteries. Theoretically speaking, this design enhances the efficiency of the discharge and recharge processes.
The internal compression protects the plate material from too much shedding brought about by frequent cycling. It also enables the acid to be accessible to the plates, allowing quick reaction. AGM batteries are flexible in such a way that it allows any shape of the plates without affecting their integrity.
The low internal resistance from the element compression and its quick acid flow provide such batteries with high amp ratings during charging cycles. They can meet higher current demands and last longer even with a deep cycle.
The AGMs are generally lighter than FLAs. This battery type is sealed, prevents acid spillage, making it the ideal choice of ATVs and motorcycles. It is also used to house power from solar and wind installations. And because the AGM does well in colder temperatures, it is the preferred battery for marine and robot applications, aside from high-end industrial vehicles.
Unlike FLA batteries which need maintenance using distilled water, and a topping charge twice a year, AGMs require none of these. They offer less risk of sulfate accumulation, therefore allowing longer storage without being damaged up to one year. From this hibernation, it can be recharged without a hitch in case you want to use it again.
Another important feature of AGMs is their lack of hydrogen emission during a charging cycle. Thus, they don’t require proper ventilation during this process, making it safe to use in your RV.
And during the winter season, frigid temperatures can wreak havoc on any vehicle, including the battery. Fortunately, these batteries don’t freeze up and remain stable all throughout when charged with their higher CCAs. If there’s one thing to avoid doing on AGMs, that is not to overcharge them.
Aside from being an RV battery, AGMs can also be starting batteries when you consider the lower CCA of its deep cycle variant. Usually, they should be upsized by twenty percent to match the amount of cranking amps from a regular deep cycle battery.
BENEFITS OF AGM BATTERIES
- Doubled lifespan compared to FLAs
- Can withstand harsh cold climates
- Capable of high electrical loads
- Recharges quickly
- Can be used in start-stop applications
- Resists vibrations
- Leak and maintenance free
- Less lead and electrolyte composition
- Low self-discharge rate
- Higher DOD at 80 percent
- Limitations of AGM batteries
- Higher cost
- Sensitive to overcharging
- Lower specific energy
- Requires storage in “charged” status
- Declines capacity gradually
- Lithium-ion battery
Another type of battery that uses deep cycle technology is the lithium-ion battery (LIB). A more recent invention which first came out in the 70s and has seen widespread use in the 90s, it uses lithium compound as an electrode instead of metallic lithium found in its disposable variant.
By limiting its DOD by 80 percent of its rated capacity, its battery life will be significantly increased. Below is a quick comparison between LIBs and lead-acid batteries.
- LIBs are much lighter in weight. Lead by itself can be weighty, which makes lead-acid batteries more than thrice heavy compared to LIBs.
- LIBs are deemed safer with their integrated safety mechanism where it shuts down once they are near extreme heat temperatures.
- LIBs are highly efficient at charging and discharging compared to lead batteries. There is amp loss with the latter, which decreases the battery capacity.
- LIBs are capable of virtually 100 percent discharge compared to lead batteries which top out starting at 50 percent and never more than 80 percent.
- LIBs have more life cycles, reaching 800 compared to the 300 cycles of lead batteries.
- The life cycle of a LIB is not affected by the discharge level, unlike a dead battery which is highly dependent on it.
- LIBs have better voltage consistency than lead batteries which typically experience a drop every now and then.
- While LIBs may be slightly expensive compared to lead acid batteries, you will likely save cost in the long run if you factor in their efficiency and lifespan.
- LIBs are far superior to lead batteries with their less environmental impact given their capability to decrease carbon monoxide emissions when in use and their recycled composition.
While LIBs have a clear advantage over lead acid batteries, they still have their fair share of limitations such as the following:
- Requires a protection circuit that limits the current and voltage power
- Ages even when not being used, but can be slowed down when the battery is stored in a cool location and maintaining a 40 percent charge
- Has a moderate discharge current
- Special handling is required during transport
- More expensive to manufacture
- Metal components and chemical combinations may change which can affect test results
Nonetheless, the use of lithium batteries has been considered a big step in the right direction, especially for off-grid living.
FEATURES YOU SHOULD LOOK FOR
Just like other consumer products, not all RV batteries are alike. One may have more amp hours than the other. That’s why picking the best battery system is crucial so that all the creature comforts in your rig are working properly.
It’s not enough that you have the best deep cell battery setup in your RV. You have to learn how multiple batteries should be connected so that you will get the correct capacity for any of your RV applications.
This capacity can be rated in terms of ampere-hours or AH. The amp hour rating measures the number of amps a battery can provide in a given number of hours before it gets discharged. This is computed by multiplying the values of the amps and the corresponding hours.
I’ll use a 100-amp hour rating as an example. This could mean it can deliver 5 amps for 20 hours before discharge. At the same time, it can be used to deliver 20 amps for 5 hours as these equal to the 100-amp hour rating. Or, it can also provide 100 amps for an hour.
Then there’s reserve capacity or RC, which is the value in minutes that the battery can provide 25 amps at 80 degrees Fahrenheit before it goes down to less than 10.5 volts. You can also derive your AH rating from the RC by multiplying it to 60 percent.
When you use many electrical appliances in your RV, you will consider the high-capacity type of battery. This will be more equipped to store large amounts of power for much longer. In other words, the more appliances you will use, the higher your battery capacity should be. Be conscious of the battery size and weight as having more connected batteries means more space needed to house them in your RV.
Deep cycle batteries have designated group sizes such as 24, 27, and 31. To check the appropriate capacity for your RV, it will depend on your energy needs on a daily basis. You then have several options for your battery setup. You can get one group 24 battery with 12 volts, which can deliver up to 85 amp hours. Or use two of these group 24 batteries that have parallel wiring, as they will be capable of up to 170 amp hours, with voltage remaining at 12 volts.
Noting the reserve capacity, you should make sure to use a battery that works more than 60 percent, especially if you are going away for days in your RV. Interestingly, there are deep cycle batteries that allow recharging by different power sources. These include solar power, electric hookup or a generator.
THE DEPTH OF BATTERY DISCHARGE
Also referred to as DOD, the depth of discharge is another factor to consider when buying an RV battery. This is named as described – it measures how deep the battery has been discharged. For instance, a fully charged battery will have zero percent DOD. When there is 70 percent left, this means a DOD of 30 percent.
Deep cycle batteries are made to be discharged by up to 80 percent every now and then. Their thicker solid lead plates give them less surface area than starting batteries. A lead acid deep cycle battery would have more than 1000 cycles at 50 percent DOD. In other words, the lower the DOD, the higher the cycle is.
For RVs, starting and house batteries that are deep cycle are rated for 12 volts DC. When there is enough space for batteries in the rig, most RVers utilize two 6-volt batteries in lieu of one 12-volt battery. Series wiring is required for this setup to deliver the 12-volt requirement while keeping the amp hours the same.
If you still need more, you can even use for 6-volt batteries with series and parallel wiring to increase both your voltage to 12 volts and double the amp hours.
When you have solar power or other types of chargers, they can work with high voltage batteries such as 24 volts. In this case, though, you will require an inverter in order to convert to AC from DC with your battery.
What chargers should you use for your batteries? Will you be using solar power, short supply, or your RV generator to charge them? You can take comfort in the fact that you can use any of those, in fact, you can combine all of them. Alternatively, you can also get a charge controller or a smart charger. This device displays the charging info which you can use as a reference for the appropriate charging time of your battery.
Meanwhile, the charge controller is usually a small box placed between the power source and the battery. These sources could be solar panels, plug outlet, or a power generator. It regulates the amount of charging from the source flowing into the battery bank to prevent it from overcharging as protection.
BATTERY POWER ACCORDING TO TEMPERATURE
The supply of energy of a battery can depend on the ambient temperature. You can get an optimal battery performance with a moderate climate at 77 degrees Fahrenheit. However, there are deep cycle batteries such as the sealed types which are designed to work during winter. In this situation, the cold temperature will still increase the internal battery resistance while decreasing its capacity. That’s why some people would store their batteries indoors to avoid the negative effect of sub-zero temps outside.
As for higher temperatures, heat basically kills batteries. Essentially, for every 8-degree rise in temp, half of the life from a sealed lead acid battery is lost. Temperatures of over 95 degrees Fahrenheit diminish load capacity and reduce the lifespan of the battery, increasing its discharge rate in the process. Remember to choose the battery that suits the climate it will be used in.
Wet cell batteries are typically susceptible to impact and vibration while the opposite can be said about gel and AGM types. Deep cycle batteries are able to absorb shock and resist vibration pretty well, better than any standard battery, making them ideal for RVs. They may have lower amp-hour ratings than traditional battery constructions, but their sturdy designs are highly recommended for high-performance applications and wherever strong vibrations are likely to present.
Now that you have learned about RV deep cycle batteries, you should check out the many options in the market. I have come up with my top ten, with the following that have made the cut.
WHAT TYPE OF BATTERY SHOULD I USE?
It’s always good to use a deep cycle battery for your RV instead of relying on your vehicle’s starting battery. As discussed earlier, deep cycling means you can discharge and recharge the battery many times over.
During each charged state, you can use it to supply continuous power to your chosen application/s. A starter battery will not be able to perform at this level given its limitations; it can only provide an instant high burst of power for a short time.
Perhaps lithium-ion batteries are the best deep cycle option because of their performance and lightweight size. However, this battery is priced much higher than other deep cycle types. FLAs are cheaper, but they require water maintenance. As such, SLAs which are maintenance-free variants may be considered.
Once you have chosen the type of RV battery, factor in the amps, operating temperature, storage, among others to get the right one for your needs.
WHAT HAPPENS IF I OVERCHARGE MY BATTERY?
Overcharging batteries can corrode plates prematurely and lose water, which will lead to battery failure. For gel batteries, it can cause irreversible damage to the cells and die before they’re due. That is why more often than not, manufacturers warn against this when you buy VRLA batteries. And often, regulators or charge controllers are recommended to protect an overcharge.
HOW DOES A BATTERY CYCLE DIFFER FROM BATTERY LIFE?
These two terms may refer to the same thing and are actually related to one another, but differ by definition. A cycle is a set of one discharge and one recharge. Factoring in the depth of discharge, a battery that’s said to have 500 cycles given a DOD of 50 percent, will achieve optimal performance.
On the other hand, the lifespan is the period of time a battery can function before it practically dies down. This is directly connected to the DOD during battery usage. For example, if you subject your battery to an 80percent DOD every time, by estimates, you are cutting your battery life in half. This does not necessarily mean going 80 percent DOD is entirely prohibited, but by virtue and to maximize your battery, you should follow your DOD which is 50 percent for most.
WHAT CHARGERS DO I USE TO RECHARGE MY BATTERY?
While most deep cycle batteries can be charged using a smart charger or generator, there are other chargers you can use for this purpose. There’s the basic converter that converts 120 volts into 12 volts DC power and at the same, it can charge your battery when there is extra capacity. An inverter does the same thing, but instead, it can produce 120 volts AC from a 12-volt battery.
There are single and multi-stage chargers. The single stage charger is common in older motorhomes. The multi-stage type is a modern device that uses three stages, namely bulk, absorption, and float. These keep the battery safer for a much longer time, which make the multi-stage charger a better option than the single stage.
Then you can use an innovative charger such as a solar panel. Typically a 100-watt large solar panel can power up your entire day’s use of energy. A wind charger can be a novelty option as well by having a propeller drive an alternator. This will provide an energy surplus to recharge your battery.
A trickle charger is a small unit that maintains a 100 percent charge on your battery, which uses a single stage design. On the other hand, an echo charger does not exactly recharge the battery but combines and switches energy between two types of batteries. This is a great way to charge one battery with a house battery and act as a backup power supply.
HOW WILL I MAKE MY BATTERY LAST LONGER?
An RV deep cycle battery generally lasts for 6 years or more. If you want to extend it further, proper care and maintenance should be implemented.
Basically, you should recharge a discharged battery in a timely manner to avoid sulfation, which is when small crystals are formed on the plates. If they remain long enough in the discharged status, this can ruin your battery.
We know that 12-volt batteries actually have 12.6 volts, so you shouldn’t allow it to discharge below 12 volts or a DOD of 50 percent. This can be measured using a voltmeter. Going beyond 50 percent will essentially reduce your battery lifespan when it happens frequently.
You must be aware of the parasitic load on your RV that can quickly discharge your battery. They include the TV antenna booster, stereo, and circuit boards. So it’s good for your battery to have a disconnect switch when it’s not in use.
I would like to reiterate that overcharging is not good for batteries unless the variant you are using has a protective mechanism for this. For FLAs, never use tap water as it can bring about calcium sulfation. Distilled water is the only kind you should refill your FLA battery with. And it should be done after charging except if the plates are exposed.
Furthermore, the housing of your batteries is recyclable and you can always trade it in whenever you buy a new one.
Always note the limitations of each type of battery such as the amp hour rating, discharge rate, etc. all of which have an impact on the battery’s capabilities. Stay powered!