Lithium Batteries: Frequently Asked Questions
In most cases, lithium batteries in RV applications use the Lithium Iron Phosphate (LiFePO4) chemistry. This cobalt free compound is inherently non-combustible and safe for mobile power systems. These batteries are cleaner, lighter, longer lasting, and more energy dense than lead-acid alternatives. There are dozens of companies manufacturing these batteries for the RV market. AM Solar prefers to use Victron and LiFeBlue because of their dependability and quality.
- Why Choose Lithium Batteries Over Traditional Lead-Acid Batteries?
Lithium batteries have several advantages:
-Higher Efficiency: They can be discharged more deeply (up to 80-100%) without damage, unlike lead-acid batteries.
-Longer Lifespan: They last longer, typically providing 2000-5000 charge cycles compared to 300-500 for lead-acid batteries.
-Lighter Weight: They are significantly lighter, about half the weight of comparably size lead-acid battery banks, which is a critical factor in RV applications.
-Faster Charging: Lithium batteries can accept a higher charge current, allowing for faster recharging.
-Low Maintenance: They don’t require regular maintenance like watering, or regular charging, unlike lead-acid batteries.
-Expandability: New batteries can work in the same system as old batteries because balancing is controlled digitally by a Battery Management System.
- What voltage do I want my battery bank to be?
If your biggest loads can be powered by a 3000W inverter, use a 12V battery bank. Only go to higher voltages if you need more than 3000W, which would be very rare for most applications. While going up to 24V allows for skinnier cables, it makes for more complicated DC distribution systems and alternator chargers. A 24V battery bank also forces you to have an even number of batteries, or to use less common 24V or 25.6V batteries. A higher voltage battery bank also forces you to have more series connections in your solar array, which reduces performance in partial shade conditions. The added cost and complexity of a 24V system easily offset any gains you might experience from using smaller cables.
Learn more here:
What voltage is best for my off-grid system?
- Are Lithium Batteries Safe for Use in RVs?
Yes, lithium batteries are safe for RV use when configured correctly. They do not emit any gas and the LiFePO4 compound is inherently non-combustible. Fears of lithium battery safety have to do with some of the other, less stable lithium battery chemistries. See this blog article to learn more: LITHIUM IRON PHOSPHATE (LIFEPO4) BATTERIES AND THE ADVANTAGES Most high-quality lithium batteries have a built-in Battery Management Systems (BMS) that protect against short circuits which may cause fires. Lead-acid batteries do not have this protection.
- Doesn’t the heater in a lithium battery system throw off the State of Charge ready by a shunt-based monitor?
Yes it does, but only temporarily. If you have something consuming energy between a shunt and the battery bank it is monitoring, the shunt will record a higher State of Charge (SoC) than the actual state of charge of the battery. Fortunately, the shunt will automatically recalibrate the next time the battery is brought back up to a true full charge.
- How Do I Size Lithium Batteries for My RV Solar System?
There are several methods for finding the ideal lithium battery capacity for your project. In most cases, it isn’t doesn’t involve complex electrical calculations as much as financial calculations. As long as it fits, more is better, and people buy what they can afford. That being said, before you write the check, you need to make sure that the system will work, and for this, we need to consider the discharge limits on the batteries. Most lithium batteries discharge about 100A per 100Ah of capacity. If you need to support a 2000VA inverter, you are going to need a maximum of 200A, which means you will need at least 200Ah of lithium batteries. With a 3000VA inverter, that’s 300Ah. If you have heavy loads that you want to run for a long time, like an air conditioner, that will take you closer to 600Ah. We find that 200Ah of lithium will give you about 1 hour of full blast runtime on a 15,000BTU air conditioner. But, if you want to do calculations and feel good about your plan, consider how many days of autonomy (days you can go without a charge) you need. Choose a battery or combination of batteries that meets these requirements.
- Can I run a blender, TV, hairdryer all at once?
Typically, you can power about 1000W of loads per 100Ah of battery capacity. This limitation has to do with the output current limit of most lithium batteries. With lead-acid batteries, it has to do with voltage sag.
To simplify this in terms of specific loads:
-If you have an Induction Cooktop or an air conditioner, you’ll want at least 300Ah of battery capacity.
-If your biggest loads are a microwave, or blender, you’ll want at least 200Ah of battery capacity.
-If your biggest loads are computers or an Instant Pot, you can probably get away with just 100Ah of battery capacity.
The capacity recommendations for loads that I just mentioned are minimums, required to turn on a particular appliance. If you want to run the appliance for a long period of time, you’ll need to design your battery system accordingly, and probably add more batteries. For example, if you have a DC air conditioner that draws 100-amps, and you need to to be able to run it on full power for four hours per charge, you are going to need at least a 400Ah battery, probably closer to 600Ah just so you can power other loads and have some wiggle room.
- How do I make sure I can get enough runtime on my loads? When you say amp hours, what do you mean by that?
A 100Ah battery will output 100A for 1 hour, or 50A for two hours, etc. To turn the amp hour rating into Watt-hours, just multiply it by 12.8V and you get a 100Ah battery storing 1,280W of energy.
- Can I expand my system? What is the longest period of time I can wait to add batteries?
One of the major selling points for lithium batteries is that you can add to a system over time. You can’t do this with lead-acid batteries. With this in mind, it might make sense to start out with minimal battery bank, just enough to start up your loads, then be prepared to add more batteries after you have some experience with the system. Manufacturer recommendations for adding additional batteries varies from within 2 years to the life of the battery, depending on the BMS’ ability to compensate for different age batteries.
- How Do I Charge Lithium Batteries in My RV?
When upgrading to lithium batteries you need to make sure all your charging sources are lithium-compatible. These include:
-Solar Panels: Through a solar charge controller specifically designed for lithium batteries.
-Alternator Charging: While driving or idling, through a DC/DC charger or battery combiner.
-Shore/Generator Power: Using an RV charger that is compatible with lithium batteries.
- What Maintenance Do Lithium Batteries Require?
Lithium batteries are relatively low maintenance. However, it’s important to:
-Regularly check the connections.
-Keep the batteries clean and dry.
-Monitor temperatures and make sure your batteries aren’t exposed to anything colder than -10℉ or hotter than 120℉
- How Long Do Lithium Batteries Last in RV Solar Installations?
Lithium batteries can last significantly longer than traditional batteries. They are typically warrantied to last ten years, but should be able to last 15 years with light usage and proper maintenance.
- What safety concerns should I have when planning a battery bank?
With a lot of people, they get nervous when they hear the term “Lithium”, so let’s talk about what that really means. “Lithium” generally refers to any battery that has lithium in it, but there are dozens of different lithium chemistries that all have different properties. We use the lithium iron phosphate (LiFePO4) variant, which is inherently non combustible, doesn’t off-gas, doesn’t make noise, has zero Cobalt, and is considered safe to mount inside your rig. I would have no issues with mounting this reliable battery and monitor system right under my bed. Whatever you do, don’t put a flooded battery inside your living quarters. That will off-gas, and it isn’t healthy to be around that.
- What is a Battery Management System (BMS) in Lithium Batteries?
A BMS is used to:
-Balance the charge between cells and between batteries
-Protect the cells from excessive current, like a short circuit
-Disconnect when temperatures get too high
-Prevent charging when temperatures are too low
-and in some cases, report the status of the battery
Modern lithium batteries have an Internal BMS, partial Internal BMS, or External BMS.
Victron SmartLithium batteries have a partially internal BMS to handle cell balancing, and use an external portion to control current flows. We most commonly use the VE.Bus BMS, or the Lynx Smart BMS. LiFeBlue batteries have a completely internal BMS.
- Can I Use Lithium Batteries in Tandem with Other Battery Types?
It’s generally not recommended to mix lithium batteries with other types of batteries (like lead-acid) in the same system due to differences in voltage, charging profiles, and discharge rates.
- How Should I Store Lithium Batteries When Not in Use?
For long-term storage:
-Store in a cool, dry place.
-Charge to about 50-60% before storage.
-Check the charge every few months and recharge if needed to maintain the recommended storage charge level.
See our blog: RV Lithium Storage Guide
- Why Choose Lithium Batteries Over Traditional Lead-Acid Batteries?
Lithium batteries have several advantages:
-Higher Efficiency: They can be discharged more deeply (up to 80-100%) without damage, unlike lead-acid batteries.
-Longer Lifespan: They last longer, typically providing 2000-5000 charge cycles compared to 300-500 for lead-acid batteries.
-Lighter Weight: They are significantly lighter, about half the weight of comparably size lead-acid battery banks, which is a critical factor in RV applications.
-Faster Charging: Lithium batteries can accept a higher charge current, allowing for faster recharging.
-Low Maintenance: They don’t require regular maintenance like watering, or regular charging, unlike lead-acid batteries.
-Expandability: New batteries can work in the same system as old batteries because balancing is controlled digitally by a Battery Management System.
Learn more here: Battery Basics
- Are There Any Special Considerations for Installing Lithium Batteries in an RV?
When installing lithium batteries:
-Ensure the charging system (solar, alternator, shore power) is compatible with lithium batteries.
-Make sure they aren’t exposed to dust and moisture.
-Make sure the batteries aren’t exposed to extreme temperatures (e.g. colder than -10℉ or hotter than 120℉
- How Do I Dispose of Lithium Batteries?
Lithium batteries should not be disposed of in regular trash. They need to be taken to a specialized recycling center or a facility equipped to handle lithium battery disposal. A quality lithium battery will typically last more than a decade.
- Can I Upgrade My Existing RV Solar System to Use Lithium Batteries?
Yes, you can upgrade to lithium batteries, but ensure that your existing solar charge controller, shore power charger, and if you have one, alternator charger are compatible with lithium batteries.
- I’ve heard lithium batteries don’t like cold temperatures. What do I need to be concerned about?
Compared to lead-acid batteries, lithium batteries have a narrower window of temperatures under which they can operate. If it gets too hot, say above 158℉, the battery will be damaged. This means you don’t want to install lithium batteries in an engine compartment. If a lithium battery gets below freezing, it won’t take a charge. Usually, a quality battery management system or BMS will prevent charging when under about 32℉. When you get below about -49℉, the plastic encasing the lithium becomes brittle and may break.
- Can Lithium Batteries Operate in Extreme Temperatures?
Lithium batteries generally operate well in a wide range of temperatures, but extreme cold or extreme heat can affect their performance and lifespan. It’s important to follow the manufacturer’s guidelines regarding temperature limits. Lithium cells cannot take a charge when they are below 32℉. They discharge fine, but the internal battery management system will prevent charging until the cells warm up. Some high-end lithium batteries come with built-in heaters. Lithium batteries should not be stored at temperatures below -10℉, not because it will damage the LiFePO4 compound, but because it will make the plastic housing the cells very brittle. Lithium batteries should not be exposed to temperatures over 120℉. This means storing them in an engine compartment is a bad idea.
- What Should I Do If My Lithium Battery Is Not Holding a Charge?
If your lithium battery is not holding a charge:
-Check all connections and the health of the battery via a monitoring system.
-Consult the manufacturer’s troubleshooting guide.
-Seek professional assistance if necessary.
- What happens when you mix different LiFeBlue battery models in the same system?
Over the years, we have had customers mix all sizes of LiFeBlue batteries. No one has reported any issues yet. Technically, there should be no issues since LiFeBlue’s robust Version 3 BMS has such high inrush capability as well as a high continuous duty current. In the case of 1x 200AH and 1x 100AH, if the 200AH battery is turned off, all loads or charge current would be suddenly placed on the 100AH battery, possibly overloading the BMS. In practice, this would be a rare event and the BMS recovers nicely from such events. The Ultimus battery should have no issues combining with any other LiFeBlue Battery in parallel.
Temperature Sensor for BMV-712
Support from AMSolar is definitely 5 stars. 1st line of support for Victron equipment provided through distributors. AMSolar likely one of the best when it comes to RVs.
Tom B