Disclaimer: We conducted this study with a real world scenario in mind.
This test was meant to demonstrate the functionality of a real world scenario of a system with AGM versus lithium batteries. We do acknowledge that some customers are aware of temperature and load effects on the AGM battery cutoffs, but a vast majority do not know or do not update their programming to reflect this based on their given circumstances. We have found that a majority of our customers that call in have not adjusted their system parameters and prefer this way.
Our team performed our testing to model system parameters similar to actual customer systems and that would fully preserve the life cycles of an AGM battery to get the most usage out of it.
We put our LiFePO4 batteries head to head with AGM lead acid batteries to compare their output in increasingly cold temperatures. This study was conducted at various temperatures and shows that our LiFePO4 batteries outperform lead acid AGMs batteries at every temperature.
In this study, at room temperature at 80A, our LiFePO4 batteries delivered 191Ah out of 200Ah, where AGM delivered 11.3Ah out of 210Ah available. That means your LiFePO4 battery has 95% more deliverable power at an 80A draw than an AGM battery. Keep reading to find out what happens below freezing and exactly why #LeadisDead.
Lead is Dead: Introduction
The most asked questions about our batteries deal with cold temperature charging.
“Do they still work in cold temperatures?”
“Can I charge my batteries in colder climates?”
Every one of our batteries are built with an internal BMS (battery management system) programmed to preserve the life and health of the battery. If the battery is in a cooler environment, the BMS will trigger and keep the battery from taking a charge as long as the temperature is below 32° F. This is one of the many ways our BMS helps preserve your battery. To learn more, check out our FAQ page.
Many myths surround LiFePO4 batteries, especially when it comes to their operation in cold temperatures. One of our driving missions at Battle Born Batteries is to help educate people on our batteries inside and out. Not only is LiFePO4 chemistry much safer than a standard AGM lead acid battery, but they are much more efficient and deliver the power they promise.
Our team of engineers helped design and run this experiment at our facility to highlight just how well our LiFePO4 batteries work when compared to the standard lead acid AGM battery in colder temperatures.
Note, we presented our results in amp hours as this is the most widely used way to represent battery power.
Check out this video we put together that summarizes this experiment.
Lithium iron phosphate batteries are commonly referred to as LiFePO4 batteries. For consistency, lithium iron phosphate batteries by Battle Born Batteries will be referred to as LiFePO4 batteries. And the Group 31 lead acid AGM batteries will be referred to as AGM batteries.
It is true that LiFePO4 batteries cannot be charged in the cold, but this implies that our batteries do not perform as well as lead acid in the cold. The purpose of this study is to show that all batteries experience a reduction in power at cold temperatures, but that cold temperatures impact AGM batteries much more than they impact LiFePO4 batteries.
At 25° F, a Battle Born battery will no longer accept a charge. This is to preserve the cells in the battery, and the internal BMS will allow a recharge when the temperature is above 32° F. Every single battery that we assemble has this intelligent internal BMS.
Lead acid AGM batteries do not have an internal BMS, meaning they may operate at colder temperatures for a bit, but you risk damaging the entire battery and losing power for good. Damaging a lead acid battery can be very dangerous for you and your rig and should be avoided.
Our mission is to educate people on the benefits of lithium batteries and how they can add value to your experience in a boat, an RV or off grid solar system. That’s why we put these batteries head-to-head in a cold temperature charging battle that will send shock waves through the industry.
The Peukert Effect Explained
Before we get into the study, we need to talk about the Peukert Effect.
The Peukert Effect is a mathematical equation that says: if you have a high current coming out of the battery, you get less energy coming out of the battery.
This study showcases how the cold temperature amplifies the Peukert Effect. For example: the energy that you get for a 20-hour discharge rate out of a lead acid battery is significantly lower than the energy you would get out of a 5-hour discharge rate from the same lead acid battery. Simply put: as you increase the discharge rate, you decrease the capacity.
Peukert’s Law is only accurate if the battery is discharged at a constant rate and constant temperature.
This law does not consider the temperature and age of the battery. This effect is amplified at colder temperatures or with older batteries.
The point of our study was to show the Peukert Effect in action. We used brand new batteries, so our focus for this experiment was purely on temperature.
We tested the performance difference between AGM batteries and LiFePO4 batteries at four different temperature ranges. Even at room temperature (67-72 degrees) our batteries were able to outperform AGM batteries. We started the testing at room temperature, and went all the way down to 13-18° F. Not only did we test the batteries in varying cold temperatures, but also under different loads of charge and discharge.
For this study, we used two newly purchased Group 31 12V AGM batteries, 105Ah each, and two new Battle Born 100Ah 12V LiFePO4 batteries, assembled in our factory here in Sparks, Nevada.
The LiFePO4 batteries and the AGM batteries were tested under a constant current discharge rate.
The batteries were discharged at the industry recommended 50% depth of discharge. The LiFePO4 batteries were discharged down to 11.8V and the AGM lead acid batteries were discharged down to 12.2V.
The batteries were tested at four different temperature ranges:
- 67-72° Fahrenheit (room temperature)
- 33-37° Fahrenheit
- 26-30° Fahrenheit
- 13-18° Fahrenheit
The batteries were tested at four different load ranges within each temperature range: 30A, 50A, and 80A.
We did NOT do the testing of a 10A load as it pulls such a minimal draw, meaning the results were more of baseline or control.
During each test, both sets of voltage and current were continuously recorded. If you’re curious about what equipment we used, check out our white paper.
For each series of tests, the batteries were fully charged at room temperature and were then cooled to the target temperature range. Once the batteries reached the target range, they were discharged and monitored. The chest freezer was outfitted with an electrical relay temperature controller to bypass the chest freezer’s own thermal control.
After this second discharge test, the battery banks were fully charged at room temperature before a new round of tests were conducted.
The results show that at colder temperatures all batteries exhibit some diminished capacity, but that the diminished capacity is much greater in an AGM battery versus a LiFePO4 battery, which only diminished slightly in capacity.
The results of this study demonstrate that even though both AGM and LiFePO4 batteries are affected by low temperature discharges, the LiFePO4 batteries can perform significantly better than the AGM batteries.
Though the battery banks were of comparable Ah size, the deliverable power of the lead acid at the high discharge rates and lower temperatures rendered this battery bank nearly useless.
The LiFePO4 batteries outperformed the AGM batteries in every test we performed. Note, we presented our results in amp hours as this is the most widely used way to represent battery power. See our results below.
67-72° Fahrenheit (room temperature)
While discharging a battery at room temperature on a 30 amp draw is not a huge load, it was important to set a barometer for the test.
- LiFePO4: 206.98Ah out of 200Ah
- AGM: 63.27Ah out of 210Ah
Even though our batteries are rated at 100Ah, sometimes you will get a slightly higher Ah (103Ah for example) out of the battery. Due to the quality control we do, we never send a battery out lower than 100 Ah. In short, 100Ah is the minimum amount of power you’ll get from our BB10012 batteries.
Even at room temperature, lead acid batteries can’t deliver even one third of their promised capacity. This is a regular lead acid battery at regular temperature. LiFePO4 batteries output versus AGM batteries is much higher, even at the baseline temperature!
But check out what happens when we test at 80 amps:
- LiFePO4: 190.81Ah out of 200Ah
- AGM: 11.25Ah out of 210Ah
The AGM lead acid batteries delivered 11.25 amp hours out of 210 promised amp hours. That means about 5% of the battery capacity is usable.
The LiFePO4 battery delivered as much as 17 times more energy than the AGM lead acid batteries. Even with the closest results, LiFePO4 batteries still delivered three times more energy than AGM batteries at this temperature.
The batteries were brought up to a 100% charge to even the playing field and tested again. This time we tested the batteries at 33-37° F, almost freezing but not quite.
Discharged at the same rates, the LiFePO4 batteries still outperformed the AGM batteries at every level.
- LiFePO4: 199.28Ah out of 200Ah
- AGM: 42.02Ah out of 210Ah
At 30A, the LiFePO4 Battle Born Batteries provided 4.8 times more energy than the AGM batteries.
- LiFePO4: 190.7Ah out of 200Ah
- AGM: 11.23Ah out of 210Ah
At 80A, the LiFePO4 batteries provided 17 times more energy. Think of all of the things you could power with that much energy!
LiFePO4 batteries are outputting almost 100% of their promised Ah at this cooler temperature. Versus the AGM batteries, which lose yet another third of their energy at this temperature.
The next range of temperatures is, truthfully, the most controversial range when it comes to cold temperature and lithium batteries.
This is the most heavily discussed range because at 25° F the Battle Born battery will no longer take a charge due to the BMS. And it won’t recharge the battery until it comes above 32° F. This is to protect the battery in these cooler temperatures. Naturally, most of our customers are curious and ask questions about this temperature range specifically.
- LiFePO4: 178.18Ah out of 200Ah
- AGM: 41.23Ah out of 210Ah
At 30A, the AGM batteries deliver some power at this cooler temperature, but it is only a fraction of their promised capacity. Compare this to our LiFePO4 batteries, which deliver four more times the power of an AGM battery at this rate and temperature (not to mention at a fraction of the weight as well).
- LiFePO4: 175.03Ah out of 200Ah
- AGM: 0.38Ah out of 210Ah
During the 80A discharge test, the AGM battery bank delivered less than 1 amp hour of energy before the low–voltage cutoff was reached. By contrast, the LiFePO4 batteries were able to still deliver 175Ah, more than an AGM battery delivers at room temperature.
The AGM batteries were only able to deliver 0.38 amp hours in this temperature range! That’s less than one amp hour. The AGM battery is underperforming significantly at this temperature.
What happens to the batteries when we drop the temperature even lower?
The final test was performed in the 13-18°F range.
At this temperature range, the LiFePO4 battery bank could not be recharged as it is below the allowable charge temperature of 25°F as set by the internal BMS. Meaning no further charge data was collected for the LiFePO4 bank, while the test continued for the AGM battery bank.
At these cold temperatures, most RVs and boats will be experiencing other mechanical or electrical problems. Unless your rig is specifically built to operate in this kind of cold climate, we wouldn’t recommend it.
- LiFePO4: 166.21Ah out of 200Ah
- AGM: 31.94Ah out of 210Ah
The AGM batteries delivered a fraction of their promised capacity again, which is even lower at this colder temperature. The results of the next 80A test are truly jaw-dropping.
- LiFePO4: 154.45Ah out of 200Ah
- AGM: 0.65Ah out of 210Ah
The AGM batteries were still unable to produce even one amp hour of power at 80A. It only delivered 0.65 amp hours, which won’t power much. Granted, it performed slightly better than at the 26-30 range, however, it’s still an underwhelming amount! The AGM batteries deliver small amounts of power at this cold temperature.
Because of the freezing temps, the AGM batteries may show varying and unreliable voltage readouts. Running any batteries at this temp is not recommended.
The Battle Born LiFePO4 batteries on an 80 amp draw were able to deliver 154.45 amp hours. Again, the LiFePO4 batteries deliver more power than the AGM batteries ever do, even at this freezing temperature.
Just because LiFePO4 batteries cannot be charged in the cold does not mean that you can’t use them in the cold!
The Results Discussed
That’s a lot of data to process. Let’s break it down.
We should note that the Peukert Effect is visible in this study, especially for lead acid AGM batteries. As you increase the discharge rate, you decrease the capacity. We have seen this demonstrated directly in our study. The more we increased the discharge rate (along with the temperature changes), the less power the batteries could deliver.
More importantly, look what happens to the AGM lead acid batteries at the coldest temperatures. At 13-18° F, the capacity diminishes from 31.94 amp hours to virtually zero.
The increased resistance at colder temperature is extreme for lead acid batteries.
The point of this study is to demonstrate that even though our lithium iron phosphate batteries have a low temperature cutoff, you cannot extract or put in current into a similarly sized lead acid or AGM system at cold temperatures.
We at Battle Born Batteries are aware that many of our customers want to be able to charge and discharge their batteries readily at very cold temperatures. We’ve come up with multiple solutions.
Our Heating Solutions
For starters, we have our own external heating solution at Battle Born Batteries. You can purchase our external heating wrap and safely heat and keep your battery above freezing. This will allow your battery to charge and discharge at the appropriate capacities. It is important to note, do not use a lead acid heating blanket or a heating pad with LiFePO4, as you may damage the battery.
The Battle Born team has been developing an option for internal hearing for our next generation of batteries. We’ve developed an internally generated heating solution which helps keep the battery just above freezing. The power for this heat comes either from your charger or from the battery itself, ensuring that you can always keep the battery within the appropriate temperature levels for operation. These batteries are coming soon so stay tuned! Follow us on our Instagram and Facebook for special announcements.
Lead is Dead: Conclusion
The myth that AGM batteries perform better than Battle Born LiFePO4 Batteries at cold temperatures is just that – a myth. The data shows that LiFePO4 batteries perform exceptionally at high power and in cold temperatures, especially when compared to AGM batteries.
The LiFePO4 batteries outperformed the AGM batteries in every test performed. Regardless of temperature or power draw, the Battle Born LiFePO4 batteries delivered repeatedly.
Our cold temperature shutoff does not mean that you cannot use your battery in cold temperatures!
The internal BMS is meant to protect your battery – something that AGM batteries have no way of doing. Not allowing a charge at freezing temperatures preserves the LiFePO4 battery so you are still able to use it!
Don’t worry – you’ll still get more energy out of a Battle Born Battery below freezing than you will out of an AGM battery at any temperature. It’s important to remember that we performed our testing to model system parameters similar to actual customer systems and that would fully preserve the life cycles of an AGM battery to get the most usage out of it.
If you would like to read the published white paper, please click here.