The way batteries are charged and discharged in an RV is crucial to their lifespan, efficiency, and effectiveness. There are several types of charging stages that RV batteries go through during charging and discharge, and the charging state of the battery depends on the current use of the battery. With this in mind, what happens when an RV battery is float charging?
Float charging on an RV is a system that maintains full or near full charge in RV batteries without overcharging and allows electricity to bypass the batteries when the RV is connected to a power source, without discharging the batteries, extending their lifespan significantly.
All RVs need a battery for something. Whether you use a solar array and battery banks for your onboard power or you use an external electrical outlet to charge the onboard batteries for the engine and operations of the RV, these batteries need to be charged and used correctly to maintain proper function. Let’s explore float charging to learn more about it and what it means for your RV.
Definition of ‘Float Charging’ On An RV
Float charging is a type of battery charging state that is not only used for RVs but for all manner of large-capacity batteries that are charged and discharged regularly or left to hold a charge without being discharged for a long period of time. Even modern smartphones use a form of flat charging.
Float charging on an RV is when the battery for the RV, or the battery banks used to power the internal electronics of the RV, are held at full or near full capacity by reducing the power input to the battery to maintain its charge level.
In the float charge state, the electricity that is input to the battery can bypass the battery and be used directly by the appliance or device using the power to maintain the charge of the battery while it is connected to power so that it is at full capacity when the electrical supply is cut off.
Float charging helps to prolong the life of the battery or batteries in an RV by reducing the charge cycles of the battery, which is the main cause of battery deterioration. It ensures that the battery or batteries are fully charged when you need them.
Some RV battery systems, especially those that are used with solar power systems and RVs that use large battery banks, have a float charge mode that can be manually engaged when the RV is connected to power or when the solar panels of the system are generating power that the batteries cannot use due to being fully charged.
In this mode, some of the power will be used to maintain the battery charge. The rest will be diverted for direct use wherever it is needed until the solar panels are no longer producing power or the RV is disconnected from the external power source.
Most RV batteries have an automatic float charge mode. Float chargers are available for batteries that are not equipped with this feature.
What Should Your Float Charge Setting Be?
Float charging is an important feature for any RV that has solar power or is connected to electricity for long periods. Most modern RV batteries and battery banks have charge controllers that allow the battery input voltage to be set according to the requirements of the battery.
What should the float charge mode be set to for your RV battery to maintain this charging state safely?
The correct float charge voltage for RV batteries and battery banks is the following:
- Single-cell 2V gel battery – 2.18V
- Three-cell 6V gel battery – 6.53V
- Six-cell 12V gel battery – 13.05V
- Single-cell flooded lead-acid 2V battery – 2.23V
- Three-cell flooded lead-acid 6V battery – 6.7V
- Six-cell flooded lead-acid 12V battery – 13.4V
- Single-cell absorbent glass mat 2V battery – 2.27V
- Three-cell absorbent glass mat 6V battery – 6.8V
- Six-cell absorbent glass mat 12V battery – 13.6V
It is important that the input voltage of the flat charge state is correct for the battery, or the battery may not hold its charge well. It may be damaged, degrade quickly, or even cease to charge when the voltage is increased to normal levels.
When Should You Use Float Charging For An RV?
Most modern RV batteries and battery systems have automatic float charging modes. If your RV battery or battery bank system has a manual float charge mode, when should you engage it?
Flat charging mode should be used for an RV or in an RV battery bank when the batteries are left connected to a power source for a long time.
If a battery is over-charged, without the mitigation effects of systems such as flat charging, they quickly deteriorate and lose the ability to hold charge effectively.
However, if the battery is allowed to discharge slightly and is immediately topped up, this damage and deterioration are significantly reduced, or entirely removed, depending on the battery.
This means that if you have your solar panels connected to full or near-full batteries while they are generating power, ensure that the charging system is on flat charge mode. If you leave your RV connected to power at an RV park or at your home for a long time, ensure that the charging system for any batteries is in float mode.
This will ensure that your batteries last for as long as possible and are kept as close to fully charged as possible, ready for when you need them.
Can Float Charging Damage An RV Battery?
Overcharging is a serious risk for all batteries, regardless of their capacity and type, but when a battery is left to float charge for a long time, is there a potential for harm?
Float charging is the safest way to keep a battery at a high charge for extended periods, and it is not likely to cause damage to a battery unless the battery is never discharged.
So long as you use your battery or battery bank periodically, there should be no damage done to it by flat charging.
However, flat charging is not a perfect technology, and the system can fail. If a failure occurs and the float charging system does not maintain the battery charge and input correctly, it can result in damage to the battery due to over-discharge or overcharging.
Flat charging is effective and safe for almost all RV battery types and battery banks. It is critical to use a flat charging system when your RV is connected to a power source for extended periods, especially when the RV is not in use.
Take the time to understand the batteries in your RV and what their requirements are to fine-tune the flat charging system that you use. This will help to significantly prolong the life of your batteries and keep your RV ready to go at all times.
David is an accomplished mountain endurance athlete who has completed over 25 ultra marathon races (follow on Strava). He is most proud of his finish at The Drift 100 – a high elevation, 100 mile winter foot race that zigzags along the Continental Divide in Wyoming. In the future he hopes to compete in the ITI 350 and ultimately the full 1,000 mile Iditarod Trail Invitational that follows the same path as the historic dog sled race.