To properly maintain and extend the life of batteries used mainly in Off-Grid scenarios for powering your RV or a Camper Battery Bank used in conjunction with Solar Panels you need to have a basic understanding of what a Deep Cycle Battery is, how & why it works, and which type of Battery is the best for your situation. What does Deep Cycle Battery mean?
A Deep Cycle Battery rated in Amp Hrs. (AH) used in off-grid scenarios, designed to cycle (discharge & recharge) many times with an average “depth of discharge” (DOD) of 50% suggested as the best for storage vs cost
Types of Deep Cycle Batteries are:
AGM (Absorbed Glass Mat)
Batteries used to power RVs are Lithium or lead-acid batteries, which means they have several cells connected in series. Each cell produces approximately 2.1 volts, so a 12-volt battery with six cells in series produces an output voltage of 12.6 volts. Lead-acid batteries are made of plates, lead, and lead oxide submersed in an electrolyte that is 36 percent sulfuric acid and 64 percent water. Lead-acid batteries don’t make electricity they store electricity. The size of the lead plates and the amount of electrolyte dictates the amount of a charge that a battery can hold.
In an RV the Battery is an important part in providing energy and keeping everything working properly and keeping all the devices you depend on for a lack of a better way of saying it “dependable” The secret is to use the Amps that the battery provides in a conservative fashion by being aware of how the batteries are working. Drawing too much amperage too soon will waste energy, amp-hours, and loss of efficiency.
How the Battery is rated depends on Amps per hour and Depth of Discharge where the Battery is run down to 50 % and recharged back up to 100% which most manufacturers recommend. That is the depth of discharge for that battery.
The other differences are whether the batteries are wired in Series or Parallel. In Parallel wiring, two 12-volt 100 amp Batteries are wired together-the Positive on # 1 Battery to the Positive on the # 2 Battery. Then the Load and Charger are connected to both of those batteries.
In doing this Parallel wiring connects the 2 batteries together creating a Battery Bank. If they are 12-volt batteries then they remain a 12-volt Battery but the Amperage is added together creating a 12-volt 200 Amp Battery Bank. So it would look like this 100 amps + 100 amps = 200 amps.
Connecting 2 Batteries together in a Series work like this; If two 6-volt batteries are used, the first 6-volt battery is wired from the positive terminal to the negative terminal of the second battery. Then the load along with the Charger are connected to the open terminals on both batteries. You add the volts when using the Series wiring. So it would look like 6 volts + 6 volts = 12 Volts. The Amperage stays the same.
12 Volt Deep Cycle RV Battery
The Amp Per Hour rating is basically, how many amps the 12-volt battery will deliver for how many hours before the battery is discharged. Amps x hours. In other words,
- A 12-volt battery that can deliver 5 amps for 20 hours before it is discharged would have a 100 amp hour rating of 5 Amps X 20 Hours = 100Amp Hours.
- This same battery can deliver 20 amps for 5 hours –20 Amps X 5 Hours = 100 Amp Hours.
- Reserve Capacity rating (RC) is the number of minutes at 80 degrees F that the battery can deliver 25 amps until it drops below 10.5 volts. To figure the amp hour rating just
- Multiply the RC rating by 60 percent. RC X 60 percent
Deep Cycle Batteries Deep cycle batteries are energy storage units in which a chemical reaction occurs that develops voltage and results in electricity. These batteries’ design is to cycle (discharge and recharge) many times increasing their overall life.
They come in different sizes but basically the larger the battery the more Amp-Hours and Depth of Discharge. The battery or Battery Banks are used to supply power to Camp Batteries and RVs and are normally referred to as House batteries. House batteries need to be Deep Cycle Batteries that are designed to provide a steady amount of current over a long period of time.
Picking out what kind of Battery or Battery you use is important still you can use a basic standard type automotive lead-acid Battery from K-Mart it wouldn’t really matter they will do the same job but on different performance levels. There are a few ways to increase the performance of your RV or Camper Battery system.
Using a higher performance Deep Cycle Battery with 100 Amps, then adding another using Parallel wiring or more will increase the power and Amps hours that you’ll have available for your RV. With any size Battery, you add to the Battery Bank, drawing more than 50% of the power from them will end up damaging them. So if you have 200 Amps the most you can utilize is 100 amps.
1. Lead-Acid cheaper batteries need to be dedicated to a vented compartment in the RV or Camper. Just as with an Automotive Battery needs maintenance and the fluids are checked now and again. They need to vent because of the toxic fumes they expel and should be tied down in their own space or compartment in the Camper.
Stepping it up with Two 6-volt batteries is a popular and superior choice for RV’ers motorhomes or campers instead of the normal 12-volt battery. The 6-volt battery contains more lead per cell than a 12-volt battery. It has a lot more life cycles of discharging down to 80% or Depth of Discharge and charging back up than a regular 12-volt battery. A good 6-volt battery can get 600 to 700 life cycles. A 12-volt battery may have 100 to 200 life cycles.
2. Six Volt Batteries (Golf Cart Batteries)are not the best solution for Boondocking Camping or Dry Camping. It has a limited amount of battery and just won’t perform as well as a 6-volt camper battery. A well-rated 6-volt AGM Battery will contain 235 amp-hours or more and wired together in series for 12 volts will double the amps up to 470 amps per hour. These types of batteries are shaped differently and are taller than the standard type of battery. They also need to be vented like the Lead Acid cheaper type.
3. The next step-up in Battery is the AGM Battery– These batteries are sealed and need no maintenance. An AGM which stands for absorbed glass mat battery contains a special glass mat separator that wicks the electrolyte solution between the battery plates. This material’s design enables the fiberglass to be saturated with electrolytes and to store the electrolyte in a “dry” or suspended state rather than in a free liquid form.
An AGM battery is a car battery designed for two jobs: delivering powerful bursts of starting amps and running electronics for a long time. They are built with more lead made in the design of the battery. In the world of Batteries, more lead means more power. There are many advantages to using an AGM over a 12 Volt Battery some of them are:
- More starts per battery
- Faster recharging
- More durable construction
- Safer to handle
- Special valves protect the battery’s lifespan by storing without any power loss
They are more money but again, the advantages outweigh the cost especially if you are a seasoned Boondocking, Dry Camper looking for more than weekend trips to the nearest campsite.
4. Lithium Battery- These batteries are extremely efficient, and lightweight basically the same size as a standard size battery. They need to avoid extremes on either side of the temperatures. The life cycles of Lithium Batteries can run from 3000 to 5000 cycles. Along with their life expectancy, the Lithiums can charge 4x faster than a 12-volt Lead-Acid Battery.
The Amp-hour capacity on the Lithium Battery is listed as 100 Amps per hour but on these batteries, there is no restriction when it comes to 50% Depth of Discharge as you are with the other types of batteries. You can take these guys down 100% so with 2 Lithium Batteries in your Battery Bank you will have a full 200 Amp-hours out of these Lithium Batteries. The right size Battery and type should be what you and your family need for the type and amount of camping you do. They can get costly but in the end, so learn about what RV Battery you need and you can get what you pay for.
How to Charge RV Batteries
No matter how new your camper battery is, if you over-discharge you are going to ruin your battery over time. For Off-Grid RVers, you need a true Deep Cycle Battery. They will discharge to low voltage devices safely. This is because of how they are made. With most batteries, you need to factor in the Depth of Discharge but with a good quality Deep Cycle Battery you can discharge as much as 80% and the battery won’t be destroyed. Keep in mind that 50% rule that we talked about earlier and use that as a general rule. Don’t discharge excessively or your battery will give up life cycles.
If you stay with the general rule of Depth of Discharge you’ll get 1000’s Cycles and your battery Bank will last for years. For this reason, the smartest people in this field always recommend an AGM Deep Cycle Battery or a highly rated Lithium Battery. The initial cost of a Deep Cycle AGM or Lithium Battery is hard on your pocketbook but in the long run Depth of Discharge and Cycle Life, it becomes much cheaper than a cheaper Automotive Battery. This leads us to the Charge Rate of the Battery.
You need to charge the Battery for what it’s rated for. Charging too many amps to your battery will degrade your Battery. To avoid this you want to charge the battery for what it’s rated for. A standard Lead-Acid Sealed AGM battery will be around 30 amps. A decent battery will have that information on the Battery. When you design your Solar System-determined the Amps you’ll need-so if you want a 30 Amp Solar System uses a 30 Amp Battery.
Using a smaller battery with a larger rated Solar system on a camper battery will end up damaging the Batteries. Some people believe that having a larger Battery Bank connected to a smaller Solar System can work much safer and will also charge the batteries a lot faster.
Charging in smaller increments will be healthier for the life cycle of the Battery. Slow trickled-down current charges are an ideal way of charging a Camper Battery.
- Purchase a Deep Cycling Battery that can operate with Depth of Discharge
- Use a Solar Panel System that is not excessively larger than your Battery Bank
- Keep the Battery Bank as large as your RV can safely accommodate
- Look up the Charge Rate of the Batteries you want to buy
- Compare that rate to your Solar System
- For every 100-watt Solar Panel, you have-Call it 6 Amps
- For a 400-watt Solar Panel System on your RV that would convert to 24 Amps
- That will safely charge a 30 Amp Sealed AGM Deep Cycling Battery.6.
5. Buy an MPP Charge Controller– not a cheap one instead use the ones that will save the investment you made on quality Batteries. like this one available on Amazon called Blue Sky Energy Solar Boost SB3024iL MPPT Charge Controller 30A/40A, 12V/24V, Dual Battery, or DC Load 20A
Charging Deep Cycle Battery with Generator
- Fully charge the Inverter Generator -Check oil and gas levels-or plug it directly into Shore Power
- Before recharging the Battery clean it-a dirty battery will drain even without using it
- Inspect the battery from top to bottom to spot any cranks, leaks, corrosion, or bulges. Use baking soda and a toothbrush, just like you would in your car. There could be dirt build-up on the terminals too clean with a wire brush.
- In a Flooded Lead Acid, Battery-The first step is to look into the electrolyte level. If the fluid level is low, fill it up to the ‘Full’ point with distilled water.
- Shut off all juice going to the RV and all devices in the RV-Unplug other electrical devices so the battery gets the optimum charging. You should also turn off the lights. In other words, there should be nothing that can draw the power from the generator, which should be connected to a 120-V AC outlet.
- Plug the RV generator in and connect it firmly to the battery. In ideal conditions, you might be able to charge it up within two to four hours depending on the temperatures
Some motorhomes have power inverters that allow you to directly charge a 12 Volt battery off of shore power. If you have a 12 Volt battery charger, you can essentially charge a battery from just about any standard 110 electric outlet. You can buy a 12-volt battery charger anywhere in an automotive store or a hardware store.
If you decide on a 12-volt charger buy a Smart Charger that essentially reads the power level of the battery, and won’t overcharge it. A cheap battery charger just keeps dumping juice into the battery, which can eventually start to wear down the internal components and potentially damages the battery. Considered this one NOCO Genius G15000 12V/24V 15 Amp Pro-Series Battery Charger and Maintainer Available through Amazon.
- A 30 amp (10 amp per bank) onboard battery charger for charging and maintaining three 12-volt batteries independently.
- Safely charges all types of lead-Acid batteries from 25-230ah, including wet, gel, AGM, and deep-cycle batteries.
A Smart Charger can be set up for different types of 12 Volt batteries. You can set it for lead-acid, or gel batteries, which will adjust the way it delivers the charge. If you have the time, you can also set it for trickle charge, to maximize the stored power. The life expectancy of a battery depends on how soon a discharged battery is recharged.
The sooner it is recharged the better. So charging your Rv’s or Camper Battery is an important function in an Energy-dependent System. If you are staying in 30-50 Amp service hookup campsites maybe it won’t matter as much but if you are on the move Boondocking or Dry Camping then this is what you need to pay attention to.
References: What Is an AGM Battery and What’s the Big Deal?
KOA Campgrounds- 10 TIPS TO EXTEND RV BATTERY LIFE | HOW TO CHARGE RV BATTERIES