Let’s talk about lithium batteries, the new media darling in the RV industry. With their growing popularity have sprouted the weeds of myths and misconceptions. Let’s dispel the top six.
Myth: Lithium Batteries Are Explosive
Like a game of telephone, this myth is based on a true story.
In 2017, exploding lithium-ion batteries in Samsung Galaxy tablets and phones caused international uproar. Airlines even banned the phones. Samsung eventually ‘fessed up and recalled more than 2 billion units, even though the flaw affected a tiny percentage of devices. The problem, they discovered, was a short circuit in the PCB.
But somehow “exploding phone batteries” turned into “all lithium batteries are explosive,” and that’s simply not true.
Fact: Today’s RVs use LiFePO4 (lithium iron phosphate) battery chemistry, which is essentially non-combustible and non-flammable in normal use. LiFePO4 batteries just aren’t as susceptible to thermal runaway as other chemistries.
Secondly, all RV lithium batteries have an integrated Battery Management System (BMS). A BMS is like an electronic brain that controls how the battery is charged, discharged, and cycled. EMS software prevents lithium batteries from being overcharged or short-circuited (except in cases of mechanical failure).
Myth: Lithium Batteries Can’t Be Used in Freezing Weather
“Baby it’s cold outside!”
Sorry, I had to. Anyway, this myth also has a grain of truth. Regular lithium batteries cannot be charged at temperatures below freezing (32 degrees Fahrenheit).
Note I said “charged,” not “used.” Lithium batteries can actually be discharged well below freezing. Many can be discharged as low as -4 degrees Fahrenheit! In fact, they excel in cold temperatures, where unlike lead-acid batteries, they retain most of their usable power.
Fact: A non-heated lithium battery can’t be charged at freezing temperatures. Charging a frozen LiFePO4 RV battery can do sudden, irreparable damage to the battery cells. There is no fix.
Better yet, buy smart. Most lithium RV battery manufacturers, such as Expion, RE-liON, Victron, and Battle Born, now offer batteries with integrated heating systems. These heating pads are controlled by the BMS (remember the electronic brain?). If the BMS detects subfreezing ambient temperature, it will use incoming electricity to warm up the battery first, and then switch to charging thereafter.
Myth: Lithium Batteries Have a Chemical “Memory”
Fact: No, they don’t. The “memory effect” of batteries has become an urban legend. Yes, nickel-based chemistries like Ni-Cd and Ni-MH rechargeable batteries are subject to a memory effect if repeatedly charged/discharged to the same state of charge, but neither lead-acid nor lithium batteries are subject to this effect.
(Lead-acid batteries can be sulfated if repeatedly undercharged, but that’s a distinct and separate problem.)
Myth: Lithium Batteries Are Interchangeable with Lead-Acid Batteries
I wish, my friend. I wish. But the two have completely different chemistries.
Lead-acid batteries have been used in automobiles since time immemorial. There are many types and names: flooded, wet, AGM, SLA, VRLA, gel, etc. – but all are based on the same chemistry.
Fact: Lithium batteries are a different animal. They are not interchangeable with lead-acid batteries.
- Lead-acid batteries prefer 3-stage (bulk-absorption-float) charging, while lithium batteries prefer CCCV charging (constant voltage constant current).
- Lead-acid batteries, even deep-cycle versions, shouldn’t be discharged to less than 50% or so. Lithium batteries don’t mind being discharged as much as 80-100%.
- Lead-acid batteries have a capacity that varies with rate of discharge. The faster you discharge a lead-acid battery, the less energy you get! But lithium batteries are essentially insensitive to rate of discharge, so you get full capacity no matter what.
In more practical terms, your converter/charger, solar controller, and battery monitor might be incompatible with lithium batteries. For more information on upgrading your equipment, read my guide to upgrading to lithium batteries here.
Myth: Lithium Batteries Can’t Be 100% Discharged
I suppose we should define the term “100%.” No battery can be fully, exhaustively discharged to 0v. At zero voltage, the battery is dead and irreparable. It’s a paperweight.
But a battery BMS won’t let you discharge below the minimum healthy voltage. For a lithium iron phosphate battery, a cell has a fully charged voltage level of around 3.65v and a “fully discharged” voltage of 2.0v, not 0v.
Here’s a State-of-Charge table for lithium iron phosphate batteries:
When we say “full discharge,” we’re referring to the battery’s stated amp-hours. If you buy a 100Ah battery, can you truly get 100Ah out of it, or do you have to stop at 50Ah, like a lead-acid battery?
Fact: The simple answer: Most RV deep-cycle lithium batteries can be discharged 100% without suffering damage. However, manufacturers recommend you not discharge below 80% depth of charge to maintain a long battery life.
Myth: Lithium Batteries Are Too Expensive
Touche. Lithium batteries do carry a hefty sticker price. In a world of Dollar Menus and $10 jeans, it can be hard to swallow the cost of a $700 lithium battery.
But when looking at lifecycle cost, or cost of ownership, there’s no comparison. The math is clear: Lithium batteries are cheaper in the long run.
Fact: Lithium batteries can endure several thousand charge/discharge cycles. Renogy states their 100Ah 12V smart lithium iron phosphate battery will last about 4,000 cycles until the efficiency of the battery drops to 80% (which is still pretty good!). Some batteries are rated up to 5,000 cycles!
In comparison, the lifecycle for deep-cycle lead-acid batteries ranges from 400 to 1,500 cycles, with better-built brands offering a longer lifespan.
In summary, a lithium battery can last up to 10x longer than a lead-acid battery! Comparing topnotch lead-acid batteries to brand-name LFP batteries, you can expect a 4-5x longer lifecycle – yet the battery only costs 2-3x as much!
So the lifecycle cost of a lithium battery is much lower than a lead-acid battery. In fact, your lithium battery will probably outlive your camper! Some manufacturers claim a 30-year lifespan. You could include lithium your batteries in your last will and testament.
Advantages of a Lithium Battery for Your RV
- Can be fully, repeatedly, and safely discharged.
- Good for 3,000-5,000 lifecycles (5-10x that of a lead-acid battery!)
- Can last well over 10 years! Manufacturers may even offer 10-year warranties.
- Weighs just one-third that of a comparable lead-acid battery.
- No periodic water replenishment (no need to go hunting for distilled water).
- No flammable or explosive fumes while charging or discharging.
- Can be safely stored and used inside an RV.
- Constant voltage throughout the discharge cycle.
- Quickly and efficiently recharged without overheating. Very fast charge rate!
- Almost fully recyclable.
- Don’t contain environmentally dangerous metals.
- Terminals don’t corrode like lead-acid batteries.