When selecting batteries for your RV coach, it’s important to understand the differences between a 12-volt battery and a 6 volt one. Your electrical system in a motorhome or travel trailer usually consists of both alternating current (AC) appliances and 12-volt lines. We’ll be discussing the 12-volt side of things when talking about batteries.
To achieve 12 volts to run your electrical system, you need to have batteries that crank out a total of 12 volts. This can be accomplished with a 12-volt battery or two 6-volt batteries. Here’s a look at the benefits and drawbacks of each:
Table of contents
- Pros & Cons
- Why Use 6 Volt Batteries?
- How to Connect RV Batteries
- Battery Types
- Battery Life
Pros & Cons
12 Volt Pros:
- 12 volt batteries usually have fewer amp hours (how much storage the battery has), but you can connect several 12 volt batteries in parallel to double the number of amp hours available.
- 12 volt batteries are usually a little less expensive than 6 volt ones.
- Your electrical system only requires one battery, if desired.
12 Volt Cons:
- 12-volt batteries usually have fewer amp hours than 6-volt ones
- 12-volt batteries are usually heavier than 6-volt ones, and if you purchase a 12 volt with more amp hours, the battery becomes larger in size.
- 12-volt batteries with higher amp hours may not fit in your battery compartment.
6 Volt Pros:
- The plates in 6-volt batteries are much thicker, meaning they can be charged and discharged more frequently. They have a longer lifespan.
- Because they have half the number of plates in their cells, 6-volt batteries weigh less.
- When wired in series, you can double the number of volts with smaller, lighter batteries in your battery compartment.
6 Volt Cons:
- 6-volt batteries are usually a little more expensive.
- You will need double the batteries.
- You will probably only find them at auto parts stores and big-box stores like Costco.
Why Use 6 Volt Batteries?
Because most 6 volt batteries have a higher number of amp hours for each battery, it makes sense to purchase two 6 volts and wire them in a series – that gives you 12 volts, meeting your electrical system’s needs. The 6-volt batteries last longer than most 12 volt ones, and they are lighter, as well.
How to Connect RV Batteries
Connecting 6 Volt Batteries in Series
This means hooking the positive terminal on the #1 battery to the #2 battery’s negative terminal. Then, hooking the remaining positive terminal on battery #2 to the ground and the negative terminal on #1 battery to the coach’s 12-volt wiring. It will double the batteries’ voltage to 12 volts, but the amp hours will remain the same as what is marked on one battery.
Connecting 12 Volt Battery Pairs in Parallel
This means hooking the positive terminal on #1 battery to the positive terminal on the #2 battery, then hooking the negative terminal on #1 battery to the coach’s 12-volt wiring and the negative terminal on #2 battery to the ground. This keeps the voltage at 12, but the amp hours double.
Once you’ve decided on the battery voltage you will use, you need to decide if you will purchase them as Lithium, AGM, Gel, or Lead Acid batteries.
LiFePO4 is a newer form of lithium-ion battery solution. This lithium iron phosphate-based solution is inherently non-combustible and allows for a lower energy density, making it a good choice for applications such as an RV battery bank.
AGM stands for Absorbed Glass Mat. These batteries have fiberglass between the plates in their cells for the electrolytes to pass through. It is considered a “dry” battery, therefore, maintenance-free, as you won’t need to add distilled water.
Gel batteries, like AGMs, are maintenance-free. They transfer electrolytes through a gel substance created by sulfuric acid and silicate. These batteries can even be placed on their sides.
Lead Acid batteries use distilled water as the transfer substance, which needs to be topped off monthly. They are usually the least expensive choice for coach batteries.
There are many ways to keep your batteries in healthy condition so that they can perform for years to come. Here are some things to consider:
With all batteries other than lithium, you must not go below 50% of the storage (amp-hour) level. So if your 6 volt series of batteries have 210 amp hours, count on using no more than 105 ah before recharging.
Most batteries will be fine if overcharged with a low current that is 5 times less than your amp hours. But if the current is higher, you run the risk of the battery overheating and losing its capacity to hold a charge at all.
If you have lead-acid batteries, be sure to top off with distilled water, checking them at least monthly. Other batteries are maintenance-free.
If your batteries will sit unused for long periods of time, you can add a trickle charger or even utilize a small solar charger to make sure they stay in tip-top condition.
Take battery weight into consideration when you narrow down your choices of 12 volt or 6-volt batteries. If you need to keep your rig lighter or you just want to save your back, a 6-volt series may be a good alternative.
Cable thickness and length
Be sure that the cables connecting the terminals on your batteries are a large gage (small number), able to carry the current easily without any heating or corrosion problems. They should also be long enough to handle wiring in a series or parallel.
Battery monitoring system
Consider adding a battery monitoring system to keep an eye on your voltage. Many solar setups have charging monitors, but you can find a simple battery reader at an auto parts store to attach directly to the batteries any time you want to know how they are performing.