Lithium vs AGM Batteries
Today we are going to do a Lithium vs AGM Battery comparison.
To understand this age-old debate, one must understand what the difference is between a Lithium-Ion Battery and an AGM Battery. The three biggest factors between the two are weight, upfront cost, and cycle life. We will cover these topics and much more in this blog post. So let’s understand what the difference is between an AGM battery and a Lithium-Ion battery:
What is an AGM Battery?
AGM stands for “Absorbed Glass Mat” or “Absorbent Glass Mat”. You’ll find most caravans, campers trailers and hybrid campers in Australia come standard with these kinds of batteries. In a standard camper trailer you usually have 1 x 100Ah AGM battery, while some Hybrid Campers will carry up to 3 x 100Ah AGM batteries.
They have become a trusted power source for many RV owners. AGM is named for the woven fiberglass mat that separates the positive and negative electrodes and holds acid absorbed in its fibers. Unlike flooded batteries, AGM is unspillable and requires no maintenance. The manufacturing cost may be higher than a standard “wet” battery, but it delivers a reliable and consistent current when needed. AGM’s have a good cycle capability, and can handle the rough roads and tracks of Australia.
AGM batteries were developed in the 1980s and have become a reliable source of power for many campers.
What is a Lithium-Ion Battery?
Lithium-Ion is also known by the term (LiFePO4) – which stands for Lithium Iron Phosphate or Lithium Ferro Phosphate. These batteries were first commercialized in the late 1990’s and have become the go-to battery solution for many RV owners.
A lithium iron phosphate (LFP) battery is a type of lithium-ion battery that is capable of charging and discharging at high speeds compared to other types of batteries. It is a rechargeable battery consisting of LiFePO4 as its cathode material; hence the name.
Don’t confuse this kind of battery with the Lithium Polymer batteries you find in a camera, remote control car, etc. A Lithium-Ion battery is very different in its chemical composition, performance, and usage types.
Lithium vs AGM Battery Comparison
For this case, our experts at Camper Trailers and Hybrid Campers looked at 100Ah and 200Ah batteries, respectively. We will compare the weights and sizes of each battery, along with Depth of Discharge (DOD), Cycle Lifespan, and Warranty Period. For this comparison we have chosen similar sized batteries in the 100Ah and 200Ah class.
100Ah Class
| AGM | LITHIUM-ION |
| BRAND: CAMEC | BRAND: ENERDRIVE |
| 100Amp Hour SLA AGM Battery | eLITE 12V 100Ah Lithium Battery |
| Weight: 25.5Kg | Weight: 12.5Kg |
| Size: 306mm x 169mm x 210mm (LxWxH) | Size: 310mm x 170mm x 236mm (LxWxH) |
| Warranty: 3 years | Warranty: 5 years |
| DOD: 50% | DOD: 80% |
| Cycles: 500 | Cycles: 2000 |
| $289 | $949 |
200Ah Class
| AGM | LITHIUM-ION |
| BRAND: POWERSONIC | BRAND: ENERDRIVE |
| 12V 215 Amp Hour AGM Battery | ePOWER B-TEC 200Ah Lithium Battery |
| Weight: 62.5Kg | Weight: 25Kg |
| Size: 522mm x 240mm x 218mm (LxWxH) | Size: 505mm x 172.5mm x 265mm (LxWxH) |
| Warranty: 1.5 years | Warranty: 5 years |
| DOD: 50% | DOD: 80% |
| Cycles: 500 | Cycles: 2000 |
| $729 | $2299 |
Details current as at 22/7/2021
Lithium vs AGM Battery comparison - terminology explained
What is battery cycle life (cycles)?
The number of charge/discharge cycles that can be achieved before a battery reaches the end of its useful life. The number of cycles depends on the capacity taken from the battery (a function of discharge rate and depth of discharge), operating temperature and charging method. As a general rule, Lithium-Ion batteries have a cycle count 4 times more than an equivalent size AGM battery, meaning a longer lifetime.
What is Depth of Discharge (DOD)?
The Depth of Discharge is the manufacturer's ideal lowest point of discharge for your battery. In an AGM battery it is usually 50% of the battery capacity, whereas in a Lithium-Ion battery, you can extend your depth of discharge up to 80% of the battery capacity.
If you can discharge your battery to 80% vs 50%, then this gives you more usable power and this could mean an extended stay off-grid. Many RV owners have gone past the manufacturers recommendations of an 80% DOD for Lithium-Ion batteries. There have been reports of DOD figures on Lithium batteries, down as much as 95%.
Does temperature affect a battery's lifespan?
Another factor affecting the lifetime of your battery is how well you maintain it, and more particularly the temperature it’s kept in. Batteries in a hot environment (over 30 deg celcius) may overheat, which shortens the lifetime of the battery. Conversely, very cold temperatures also have a negative impact on the battery. In tough weather conditions, the battery has to work harder. To maximize your battery’s useful life, try to keep it in a relatively mild environment – not too hot and not too cold. Some battery monitors can show you the battery temperature.
How quickly will a lithium battery recharge?
Aside from the weight savings, Lithium batteries also have significantly quicker re-charge vs. AGM batteries. The low resistance in the Lithium cells allow the battery to accept the full output from the charger. With a 30 Amp charger, a 100Ah Lithium battery can be fully charged from flat to full in just over 3 hours vs. 10+ for a 100Ah AGM battery. This is a huge advantage with solar in that every amp that your solar panels produce are going directly into the battery.
What size battery charger should I buy for my battery?
The global consensus for AGM batteries is that you should purchase a battery charger between 10-20% of the battery capacity. For example, if you have a 100Ah AGM battery, consider purchasing a 10-20Ah multi-stage charger. A happy medium of 15Ah would be ideal. When it comes to selecting a battery charger for a Lithium-Ion battery, it is important to use a Lithium-Ion charger. You cannot use a dedicated AGM battery charger for Lithium-Ion batteries. Lithium batteries require a Constant current/Constant voltage (CC/CV) charge type with simple Bulk, Absorption, Float stages. Many lead acid chargers have desulphation and equalisation stages built in, which will pulse high voltages of 15.3-15.8V into the battery.
Generally speaking Lithium batteries don't like being charged at full voltage over a long period of time. One they have reached their full charge, the charger should either disconnect or fall back to float charge, usually 13.6V. Most Lithium battery suppliers suggest a charger rates to 30% of the Lithium Battery capacity, for example, a 30Ah Charger for a 100Ah battery.
What is a battery management system?
A Battery Management System is the central technology hub where all your power inputs, charging, monitoring and electrical protection takes place. The BMS hub can be made up of one device with a display screen or several devices. They are often mounted inside your RV on a board, or mounted in a cabinet. We offer a few BMS options in our Camping Store.
Good quality battery management systems should be able to perform the following tasks:
- Charge your batteries from multiple inputs: solar, vehicle battery and 240V mains power.
- Monitor multiple parameters of your battery bank (voltage, depth of discharge, temperature, etc).
- Monitor water tank levels.
- Provide current draw data when appliances are powered from your battery bank.
BMS Brands to Consider
In Australia, we are home to some of the biggest and brightest BMS manufacturers. We particularly like Enerdrive, RedArc, BMPro, Victron, and Projecta. These trusted brands are used by many RV manufacturers and should be considered when looking for a reliable Battery Management System. A good BMS should be considered in a Lithium vs AGM Battery comparison.
Is an AGM Battery setup cheaper than a Lithium-Ion Battery setup?
The answer depends on how you camp, and your specific situation. In some cases you are better off staying with the AGM battery, while for other people, it’s a Lithium-Ion battery solution all the way. Let’s take a look at these two situations and analyse them in detail:
Situation 1: Weekend use, 4 trips per year with 50Ah usable capacity required per day with mostly lights (i.e. utilising the 20 hour rate of the AGM.)
- AGM – 50Ah usable requires 100Ah capacity as AGM should only be discharged to approximately 50% to preserve its life long term. A 100Ah AGM battery of reasonable quality may cost approximately $300 – 400, have a 1 to 2 year warranty and are rated to 600 cycles and have up to a 12 year float life. With solar or a mains charger keeping the battery full, the battery will only have used 96 cycles over 12 years and therefore still be almost 80% of its original capacity.
- Lithium – 55Ah usable required. The cost of a lithium battery about this size may cost approximately $500 – $1,000 and typically come with a 3 year warranty, be rated to 2,000 cycles and have a 10 year shelf life.
In this situation the lithium batteries offer little advantage over the AGM batteries apart from weight and size.
Situation 2: Daily off-grid use, 288Ah required per day, two days autonomy (two days allowing for no charging sources being available). Large loads are often used such as air conditioning so 48V is beneficial.
- AGM – 4x 360Ah (17.28kWh) (allowing for the 5 hour rate) batteries and 3 battery balancers required. Cost of approximately $3,200 to $4,200. These will last less than 2 years with 365 cycles per year.
- OPzV (often called long-life lead-acid) – 6x 360Ah (17.28kWh) cells required. Cost of approximately $5,000 to $7,000. These will last about 8.2 years with 365 cycles per year.
- Lithium – 32x 80Ah (8.192kWh) cells and a suitable 16 cell BMS required. Cost of approximately $3,100. These will last about 8.2 years with 365 cycles per year.
In this situation the lithium batteries offer significant advantages over the AGM and OPzV batteries.
Our Conclusion
Consider how often you travel, where you travel, and the power consumption you are likely to use. Take into account secondary factors like towing and payload weights, your budget, and the resale value of your RV. For weekenders, stick to the AGM battery option. For those on the open-road for longer parts of the year, a Lithium-Ion upgrade is certainly worth the investment. This is a crucial part of the Lithium vs AGM Battery comparison checklist.
Calculate your power usage using our power usage calculator tool. Once you have determined your average daily usage rate, jot this down and then seek the help of a RV battery specialist so they can match your specific needs to their range. If you are on the lookout for a new camper trailer or hybrid camper, search right here.
Happy camping!
