AGM vs Lithium Campervan Batteries: Which is Better?
Welcome to our guide on the comparison between AGM vs lithium batteries, which help you choose between two battery technologies. Whether your system needs a simple absorbed glass mat (AGM) for affordability and efficiency or high-end lithium-ion power cells to provide the best performance possible.
We will walk through all benefits that each type has!
You’ve decided to go with a dual battery system for your campervan, motorhome, or RV, but you’re not sure what technology is right for you. You’ve come to the correct spot — we’re going to break down the distinctions between the two most popular types so you can make an informed decision.
Of course, having efficient solar panels linked to your battery bank increases the importance of choosing between different sorts of batteries. According to many van lifers, the best batteries are lithium iron phosphate (LiFePO4) and absorbed gas mat (AGM) batteries.
While there are other battery systems, these two batteries are the best choice for most camper van electrical system battery banks.
AGM battery vs lithium
Batteries can be used in various ways, and they come in a wide range of chemical compositions. Although there are several types of batteries on the market today, the two most common battery types are lead-acid and lithium.
AGM Batteries (absorbed glass matt):
These batteries utilize a glass matt rather than a liquid electrode to separate the plates, as the name implies. AGM batteries have excellent long-term storage capacity and are less responsive to overcharging than wet cells.
These batteries do not require separate ventilation since they have sealed valves that keep the gas inside unless severely overcharged. They’re designed for the military, so they’re physically robust and can withstand a wide range of temperatures.
AGM batteries provide longer life and better performance in hotter climates, lower maintenance costs, and fast recharging time. They are less expensive than lithium batteries, though.
AGM batteries do not require to be stored upright to function correctly since to their design. In addition, these batteries need less maintenance. AGMs are known by various names and may be sold as dry cell batteries, non-spillable, or valve-regulated lead-acid.
| AGM PROS | AGM CONS |
|---|---|
| No dedicated ventilation required
Holds charge well Robust (can operate at an angle) No monthly Maintenance Usually higher discharge rate | Shorter lifespan than FLA or Lithium
More sensitive to overcharging depth of discharge is 50% |
Lithium Batteries
Lithium batteries are ideal because they can be discharged and stored to almost nothing without long-term damage. This implies that you can use 90% of the total Ah capacity rather than 50%, the maximum suggested for an AGM.
Lithium batteries can be charged more quickly than AGM batteries because lithium batteries may discharge faster and more deeply. Lithium batteries are the answer to your efficiency and longevity needs! They last longer than any other type, but they also cost more.
Many people make a trade-off when choosing their battery system, favouring something with better performance at an affordable price point.
Lithium batteries have certain disadvantages. They require a charging method that is different from that used with lead-acid batteries. Thus many charging components are ineffective.
Because they cannot be charged below freezing, more temperature control is required for cold regions
| Lithium PROS | Lithium CONS |
|---|---|
| More power for a fraction of the weight
Can operate sideways or tilted Safe, no ventilation required Very low DOD (up to 95%) Faster charge than any other battery type Long-lasting | Expensive up-front
Newer tech leads to fewer options Charge controller needs to be programmed Harder to find or replace |
Which Battery is Better
Let’s get into breaking down which battery type is better than the other.
We will like at
- Cost
- Functionality
- Size
- Weight
- Temperature
- Charging
Cost
Lithium batteries are more expensive to make than AGM batteries, and the cost of Lithium is not decreasing. Because Lithium is a mineral commodity traded on the stock market alongside gold, platinum, and silver, all manufacturers will pay the market price.
Essentially, the production cost of the battery is determined by both the amount and quality used in batteries and internal components. We’re talking about such factors as cell grade and rating, internal Battery Management System, and usable capacity of the battery.
Unfortunately, many of these factors may only be determined after purchasing the battery, making it critical to get the right one and not end up with the sub-par quality that will need to be replaced or repaired.
I’ve limited the costings to a 100AH capacity to understand relative comparison better. Enerdrive B-TEC 100Ah Slim Lithium Battery Review – Is It Really Good?“>Lithium batteries range from around $800 to $2000 per 100Ah.
AGM batteries of the same size range from about $200-$600, depending on the brand and model. As a result, a high-quality
Functionality
Lithium batteries are superior in performance and life cycle compared to AGM batteries. They can be discharged to a lower level safely than their counterparts, resulting in greater actual usable Amps.
Discharging a lead-acid battery below 50% is not advised by most AGM battery makers since the heat generated when charging it back up can harm the cells and plates, which may drastically reduce their life.
On the other hand, Lithiums can be safely discharged to a 100% Depth Of Discharge (DOD) (10.5v), which allows for more usable amps than an AGM’s maximum 50% DOD extends its charging cycle life.
A Lithium battery can have a cycle life ten times greater than an AGM. A Lithium cycled to 50% DOD has a lifespan of 5,000 cycles, whereas an AGM cycles 500 cycles.
This implies that most people can expect to get 10-12 years of life out of a good lithium battery instead of 3-5 years from an AGM.
Size
This is where lithium batteries shine. An equivalent (usable capacity) Lithium battery will take up half the physical space of an AGM battery, which is ideal if you want to conceal it somewhere. Alternatively, you may have double the power for the same area.
Comparing a Victron Lithium battery to an AGM (100Ah)
- Lithium 100Ah (100 Ah useable) – 321x152x197mm .
- Lithium 60Ah (60AH useable) – 286x132x239 mm
- AGM 100Ah (50Ah useable) – 260x186x215mm
Weight
Another benefit of using a Lithium battery is its weight savings. A 105 Ah AGM battery will weigh roughly 28 kg instead of 7.7 kg for a 60Ah Lithium Battery.
Both have similar usable storage capacities. A 165Ah AGM, for example, weighs 53.6kg, while a 100Ah Lithium (with more useable power) weighs 12.8 kg.
Even if you switched out a 105AH AGM for a 100AH Lithium, you’d save 16KG of weight and gain almost 50% extra useable capacity. You’d save 40KG of weight by replacing a 165AH AGM with a 100AH Lithium, but you’d still end up with nearly 20% more usable capacity.
Temperature
AGM and lithium-ion batteries can both be safely maintained in cold weather. A Battery Management System manages the sensitivity of a lithium-ion battery to cold. If a Lithium battery is rated to charge/discharge below a specific temperature, the BMS protects it from harm.
This is a more recent innovation; previously, we avoided Lithium batteries since they would be damaged in below-freezing conditions.
Both batteries can be discharged without problems, and charging may take longer in cold temperatures. AGM by Victron is ready to charge at temperatures below -5°C, while Lithium by Victron can only be charged at temperatures above 0°C.
Charging Speed
Lithiums are also lighter than AGM batteries, with a quicker recharge. The low resistance in the Lithium cells allows the battery to accept the total amount offered by the battery charger.
A 100Ah Lithium battery can be completely charged from flat to complete in less than 3 hours when charging with a 30 Amp charger instead of 10+ hours for a 100Ah AGM. This is a significant benefit with solar energy because every watt of power generated by your solar setup goes straight into the battery.
Before You Buy
Not all Lithium Batteries are the same. In the long term, lithium-ion batteries outperform lead-acid batteries in nearly every way, but they are more of an upfront cost, and there are a few more factors to consider before purchasing one.
If you look online, you’ll find a significant price difference between batteries that are advertised as being comparable in terms of AH capacity.
While the cheaper alternative is appealing, you must do your homework first. Many videos on the internet claim EBAY batteries labelled as 120Ah batteries have a capacity of just 50Ah to 10.5v; therefore, you need to be careful when conducting your research.
Here are a few more factors to consider while comparing Lithium alternatives.
C-Value
This one almost caught us out then designing our electrical system. The C-value is a measurement of the charge/discharge rate of a battery over the course of 1 hour.
A 1C rating indicates that you can pull 100 amps continuously for 60 minutes. A.5C 100Ah battery may safely draw 50 amps from the battery for one hour, while a.2C 100ah battery can handle 20 amps for 60 minutes.
A 1C battery isn’t necessarily superior to a.5C battery. However, it does have distinct limitations on the battery’s performance and usage and BMS (internal battery management system) requirements for maximum continuous discharge.
To prevent the cells from being overcharged and sustaining the longest life cycle of the battery, a BMS should be used in a 1C rated cell x 100Ah battery.
A 50A continuous draw BMS is required for a.5C cell x 100Ah battery. A 100AH capacity can only be drawn safely for two hours with a.5C cell, and the maximum draw you can put on the battery is 50A.
Mismatch BMS
We have heard horror stories from people who bought cheap batteries have seen that the BMS is designed to take up to 100A, but cells inside the battery are only .5C, which means they are only intended for a 50A BMS.
It means that the battery puts stress on the cells to produce current, resulting in decreased performance and life over time.
Tip to check if you have a mismatched BMS. Select the correct charging mode for your battery and then match it with the maximum load stated by the manufacturer.
Start with 50A, and if the voltage remains constant, you’re in good shape. Increase the draw to 100A, and check whether the voltage drops. If it stays steady, there’s no problem.
Your BMS should be rated correctly.
TIP: The only way to tell whether the BMS is matched to the rating of the cells in the battery is to check the output voltage of the charged battery with a Multi-meter and then apply the maximum load stated by the battery manufacturer.
Start with 50A, and the voltage should stay constant. Up the draw to 100A and then see if the voltage drops. If it stays the same, the BMS is matched to the cells. If it falls, then you’ve got a mismatch.
Final Thoughts
Lithium iron phosphate batteries are generally superior in every respect, as long as you choose the battery’s capacity to your requirements and can afford the initial expenditure.
There’s no need to toss your old batteries yet, but it may be a good idea to set some more money away for when the current ones die. It will function longer, be lighter, and generate more power than other versions.
Frequently Asked Questions
Can I replace AGM with lithium?
You can replace lead-acid batteries with lithium in marine and RV applications. You will just need to check your current charge controller. Does it have a charge setting for lithium? If yes, there should be no issues.
Can you charge a lithium battery with an AGM charger?
The best way to charge a LiFePO4 battery is with a lithium iron phosphate battery charger, as you can program it with the appropriate voltage limits. AGM chargers can work. However, it is not recommended and possibly could decrease the battery’s life span.
Are lithium batteries good for solar?
Lithium solar batteries are an excellent choice for solar energy storage. They have a high power to weight ratio and can withstand more charge and discharge cycles than AGM batteries. Its always recommended to charge the batteries with a solar charge controller due to the fluctuating voltages.
