The Path to Lithium Started with Cold Dead Lead
Why LiFePO4 batteries became our go-to for off-grid & backup energy systems
For the past 48 years, I ran a general store serving ranchers and grid-independent homeowners across Montana, Idaho, and Wyoming. We sold generator and hybrid battery-inverter systems before solar panels were even remotely practical.
For decades, the flooded lead-acid battery was the building block of most systems. They were heavy, smelly, and needed regular attention. We became accustomed to a continuous conversation around fluid levels, sulfation, equalization, and corrosion as well as constantly tweaking charging parameters. Lead-acid batteries were cost-effective and had a known life and behavioral record that people could understand. We could add value to customers by helping them navigate the issues associated with lead-acid batteries, and it was a good business.
About 20 years ago, AGM (absorbed glass mat) batteries became popular. AGM is still a lead acid battery but filled with a gel solution. They were twice as expensive but required less maintenance and were sealed and odorless. Both flooded and AGM batteries still needed to be brought to a state of full charge every few days to ward off sulfation. Sulfation in a battery is like emphysema for the human lung, significantly reducing battery life and efficiency.
In order to charge these lead batteries, a generator would do a hard initial bulk charge and move fairly rapidly on to the absorption charge rate to avoid overheating and damaging the individual cells. The final float charge would be a long and slow process that required the generator to be running but the batteries at this stage could not absorb much power. Because battery voltage was influenced by recent charging or discharging checking, the true state of charge was best determined by the use of a messy hydrometer where each cell needed to be checked.
That is how it was for the last 30 years.
Our world turned upside down with the advent of the lithium-iron-phosphate (LiFePO4) battery in a closed-loop communication relationship with the inverter. Issues with battery performance over time are gone. This results in a wildly different user experience, and for those who have lived the off-grid lifestyle, it's almost too good to be true.
In 2017, we installed our first Victron inverter system with LiFePO4 batteries for a homeowner who wanted to try something better. We were hesitant because we had heard horror stories about expensive lithium batteries going bad.
Before Victron came along, there honestly wasn't a battery-inverter system that we believed in. Also, many inverter manufacturers did not support lithium, and some still don't. We received exuberant feedback from this customer on his system's performance. His neighbors told their neighbors and things really took off with lithium systems. It was obvious within a few months that lead-acid was on its way out. The challenge now became how to help our off-grid customers upgrade their systems to take full advantage of this new battery technology.
Our customers using LiFePO4 batteries today report vastly lower generator run times and, as a result, much lower fuel costs. We also see very happy customers getting exactly–or more-than they expected from their systems. The self-balancing, well protected battery cells in a quality LiFePO4 battery provides a more accurate state of charge. There are no maintenance requirements, odor, or mess. Because of their very stable battery chemistry, LiFePO4 batteries don't have the thermal runaway issues that Lithium iron has, making them safe to put right in the home, not out in a shed or garage.
Lead-acid and LiFePO4 are typically compared to each other based on performance parameters that don't paint a very complete picture.
There are many factors at play but two are critical to compare:
Battery Cycle Life and Depth of Charge
Cycle life is usually referenced, and it is significant (6 years for lead-acid vs 16 years for lithium). Depth of discharge is often mentioned (30% vs. 98%), but this number is misleading as the primary value to off-grid users is that the lithium batteries don't require a full regular charge for chemical health. A larger lead-acid battery discharged 30% might have just as much capacity as a smaller lithium battery pulled down to 98%. The difference is that lithium does not need to be charged every night. If a lithium battery is discharged to 50% and it still has enough capacity to get through the night, there is no reason to start the generator. If a lead-acid battery is discharged, say only 20% for any length of time, you should start the generator and get it topped off.
Another main advantage of lithium batteries is their charge profile; they charge at the maximum bulk rate to 98% full. That means the generator run time at a customer's home will be dramatically cut (often by 50%). This reason alone is why many people have chosen to upgrade their systems using lithium batteries. For those of you who are new to off-grid living, the older lead acid batteries resulted in much more frequent and longer charging times than lithium. These batteries, like pouring a glass of root beer, needed a fast initial fill and then a long slow topping off which could last until your next birthday. Much of the time, therefore, your generator was oversized and very inefficient.
Long-term system health & performance
Guess what also happens? The solar performance also shoots up with lithium systems. No more float charge means full solar output all the way to a full charge. That's hard to do without good communication between the inverter, solar, and batteries. The intelligent battery management system (BMS) built into high-quality lithiums (like Pylontech and BYD) communicates seamlessly with Victron inverters. The battery can communicate precisely where it is in the charge cycle, causing the generator to start only when necessary and telling the systems when it's fully charged.
The closed-loop battery systems that we sell enable the battery to protect itself and maintain itself better than was previously possible with isolated batteries. All your batteries are working together and balanced, maximizing your capacity. When your system is communicating in this way, it's very difficult to damage your batteries by overcharging them. As the batteries age, the system will make the necessary changes to ensure the longest life possible.
If you're preparing to spend more to buy lithium for your off-grid or hybrid system, it's worth trying to get the best value. And that equation has to include the inverter, the solar charge controller, and the batteries.
If you're naturally suspicious, like me, the lack of documentation and real-life, third-party performance data on the flood of new lithium-ion batteries entering the market is concerning (for more on this, look out for our upcoming blog article about how we shopped for a battery to distribute with our Victron product line.)
Our desire is to recommend, with confidence, battery-inverter combinations that offer world-class performance. The two batteries outlined below represent, in our opinion, the best options on the market today:
Pylontech's US3000C, US5000(C) and RT12100
We've been selling Pylontech's US3000C and US5000(C) lithium-iron phosphate (LiFePO4) batteries for the past 2 years, primarily for residential use, and have had zero warranty issues on over 500 batteries sold. And many of these batteries have been installed in less than ideal temperature and humidity scenarios such as crawl spaces and seasonal cabins in locations that experience extreme changes in temperature. Pylontech also makes a 12 Volt 100Ah battery that is ideal for small compartments in boats and RVs.
Coupling these batteries with Victron equipment is the best way to guarantee their performance. Many older systems do not support lithium well, and it's not fair to the batteries to connect them to inverters and solar inputs that don't know what to do. These batteries are designed to be rack-mounted. Six US3000C batteries, for example, will provide over 20kw of usable power.
Related Reading >>> Victron & Pylontech: a Robust Inverter-Battery Combination for Off-grid Energy Systems
BYD's Battery-Box Premium LV
BYD Battery-Box Premium LVL is the number one 48 Volt lithium battery sold in Germany and has an impressive global track record of 250,000 installations and a 6-year track record of positive working experience with Victron inverters. It comes with a nice 15.4kw cabinet, and you can stack two batteries vertically, making for a very compact and nice-looking 30+ kw battery.
It also has tight integration with Victron Energy, and the communication is closed-loop. The BMS has some additional advantages and is external on the BYD, which can offer some advantages for larger systems and can also be monitored remotely on its own.
BYD is a major manufacturer of batteries in the world as well as electric cars. They have an electric bus factory in Los Angeles. Warren Buffet is a major shareholder. All to say: this company is here to stay and is probably the world's most stable vertically integrated battery manufacturer.
We encourage customers shopping for Lithium to consider:
Does the battery manufacturer have an excellent performance history, a global track record of successful installations, and a clear path to process your warranty? There is a glut of companies on the market. Most are battery assemblers, not battery manufacturers.
Do you know that the battery-inverter combination is going to work well together? Just because they are sold together does not mean they work together. There should be existing documentation and software support for that particular combination from both the inverter manufacturer and the battery manufacturer. If not, it's hard to know that the R&D departments know each other at all.
Do they own their technology? Many battery companies don't make their own cells. They also don't make their own battery management system which means they rely on a generic BMS that they didn't program, meaning it is not designed for their battery cells. A failed BMS is as common of a failure point as the cells themselves.
Are you confident you can receive technical support during installation or in the future if you have an issue? Batteries are expensive and can be a challenge to dispose of properly. They should last for a long time, and if they don't, you should be able to get the support you need quickly. The key to ensuring that these systems work well is ensuring that they are set up well from the beginning, which is why Intelligent Controls is Victron AND Pylontech distributor positioned to provide specific guidance to installers and end users with a very high degree of confidence.
With this battery-inverter combination, if there is an issue, it gets squashed quickly because we know how the system should work and can troubleshoot problems remotely.
Looking for guidance on battery options? Send us a note or email me directly at email@example.com
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