Compiled from field data across the 2025 to 2026 touring seasons
Stand in a campsite anywhere between the Flinders Ranges and Cape Tribulation in any given week of the year, and you will see the same conversation unfold over a camp chair: the caravanner who just swapped two heavy black AGM batteries for a single blue lithium block, talking through the change with someone three vehicles down who is still on the fence. The fence is a reasonable place to be. The two chemistries cost different amounts of money, weigh different amounts on the draw bar, charge in different ways from different sources, and behave differently when the night gets cold. None of that gets resolved by a brochure.
This article is the pillar comparison for an Australian touring audience that has done the research, knows that lithium iron phosphate and absorbent glass mat are the two serious contenders, and now wants to see them set against each other on the variables that actually decide a trip. There is no chemistry advocacy here. There are figures, trade-offs, and honest cases where each option still wins.
Two Chemistries, Two Eras of Deep-Cycle Power
The absorbent glass mat battery, almost always abbreviated as AGM, is a sealed variant of lead-acid. The active material sits on lead plates, suspended in sulphuric acid that is held inside a fibre glass mat. It has been the default deep-cycle option for Australian caravans, four-wheel drives, and camper trailers for the better part of two decades, and most installations sold before about 2022 ship with it as standard.
The lithium iron phosphate battery, abbreviated LiFePO4, is the dominant lithium chemistry in deep-cycle applications because it is thermally stable, tolerates partial state of charge cycling without harm, and pairs with an internal battery management system that protects the cells from the kind of abuse that destroys other lithium chemistries. It has moved from premium curiosity to mainstream option since around 2020, and now occupies roughly the same shelf space as AGM in most reputable retailers.
Both are sold in the same nominal 12V 100Ah label. From that point onward, almost every meaningful number diverges.
Gentrax 12V 100Ah Lithium LiFePO4 Battery
Usable Capacity: The Number That Decides the Trip
The amp-hour figure printed on either battery is a gross rating, not a working rating. The chemistry decides what proportion of it can be reliably pulled out, and the two chemistries land in very different places.
A quality AGM is conventionally rated to a safe working depth of discharge of 50 per cent. Drag it deeper than that on a regular basis, and the lifespan figure on the brochure collapses. So a 100Ah AGM delivers around 600 watt-hours of usable energy on each cycle, or roughly half its rated capacity at 12V nominal.
A LiFePO4 battery, protected by its internal battery management system, runs to a safe working depth of discharge of 100 per cent. A 100Ah LiFePO4, like the VoltX 12V 100Ah Lithium Battery, delivers around 1,200 watt-hours on each cycle. Same label, double the working energy, before any other variable enters the picture.
Here’s what one of our customers said:
“This is my 2nd purchase of this type of battery from Outbax. These 2 are for my caravan, I have a 300amp which is now 3+ years old and still going strong in the 4wd.”
For a typical 60-litre camping fridge averaging 45 watts across a day, that is the difference between roughly thirteen hours of fridge runtime on AGM and slightly over twenty-six hours on LiFePO4 from an identical amp hour label. The figure that lets you stay an extra night in the bush is hidden in the depth of the discharge multiplier, and the AGM is not being cheated. Its chemistry simply cannot tolerate being asked for more.
VoltX 12V 100Ah Lithium LiFePO4 Battery
Cycle Life and the Honest Lifespan Comparison
A cycle is one complete charge and discharge of the battery. Cycle life describes how many times the chemistry can survive before capacity drops to a defined fraction of the original rating, usually 80 per cent.
AGM, at its rated 50 per cent depth of discharge, delivers somewhere between 300 and 500 cycles on a quality product. Run it deeper on a regular basis, and that figure falls steeply. A weekend touring rig might see three or four years of life. A full-time off-grid installation that cycles daily can wear out an AGM in under eighteen months.
LiFePO4 at 100 per cent depth of discharge delivers around 4,000 cycles on quality cells. Run more gently at 80 per cent depth of discharge, and the figure climbs further. In calendar terms, that is most owners’ total ownership of the vehicle the battery is installed in. Lithium routinely outlives the caravan it was bought for.
Two batteries with similar-looking cycle life numbers in different chemistries are not the same product. The depth of discharge condition of the cycle figure was measured as much as the headline figure itself. AGM cycle life is short and quoted under gentle conditions. LiFePO4 cycle life is long and quoted at the deepest possible discharge.
Weight, Towing, and the Numbers Off the Draw Bar
A 12V 100Ah AGM, in a Group 27 case, weighs between 28 and 32 kilograms depending on the manufacturer. A 12V 100Ah LiFePO4, such as the Gentrax 12V 100Ah LiFePO4 Battery of equivalent capacity, weighs between 11 and 14 kilograms. The difference is not marginal. It is more than half the mass of the heavier option every time.
For a single battery installation, the saving is around 17 kilograms. For a dual battery setup, it is 34 kilograms. For a 400Ah bank that uses four 100Ah lithium blocks in place of four AGM, it is over 60 kilograms removed from a battery box that is usually mounted near the rear of the vehicle, where it does the most to upset the tow balance.
The handling benefit is real and noticeable. Caravanners who switch report less sway on long descents, lower nose weight on the coupling, and noticeably easier hitching. That weight saving can also be spent on payload elsewhere, which matters for any rig sitting close to its gross combined mass rating.
VoltX 12V 100Ah Bluetooth Daly Lithium LiFePO4 Battery
Charging: Where the Hidden Costs Hide
Both chemistries charge from the same three sources: a vehicle alternator while driving, a fixed AC charger on mains power, and solar through a charge controller. The voltages and acceptance curves they expect from those sources are not the same, and this is where most of the hidden upgrade cost on a LiFePO4 conversion sits.
AGM tolerates the variable-voltage output of a smart alternator and is generally happy with any reasonable multi-stage charger. The supporting hardware that came with the caravan from the factory is almost always adequate.
LiFePO4 requires a charging profile that holds the bulk voltage near 14.4V and a float voltage closer to 13.6V, and the cells need to be charged through a system that can hold steady against the variable output of a modern smart alternator. In practice, that means most LiFePO4 conversions also require a DC-to-DC charger between the alternator and the lithium bank, and an AC charger and solar controller that are explicitly set to a lithium profile rather than the lead acid default. The supporting hardware adds genuine cost. A serious caravan upgrade often runs $300 to $700 in addition to the battery itself once the charging system is brought up to current Australian standards.
Once the system is sorted, lithium charges around three times faster than the AGM it replaced. A flat 100Ah LiFePO4 will accept a full charge in roughly two hours on a 50A AC charger, where the AGM equivalent might take eight to twelve hours. That charge speed is what allows lithium to recover meaningfully on a single hour of solar around midday in conditions where the AGM bank barely holds its ground.
Temperature Behaviour in Australian Conditions
Both chemistries deliver less of their rated capacity at temperature extremes. The shape of the curve is different.
AGM tolerates cold reasonably well and loses capacity rapidly above 40 degrees Celsius. The Australian summer in any battery box mounted near the rear of a four-wheel drive can easily push the AGM past that point, and the result is a real, measurable reduction in deliverable energy on the same physical battery.
LiFePO4 holds capacity well in heat through its internal battery management system, which intervenes before damage occurs, but it will not charge at temperatures below zero degrees Celsius. For Australian summer touring that is irrelevant. For alpine winter touring in Tasmania or the Snowy Mountains, it is a real operational consideration that can require a heated battery box or a careful charge plan.
For Australian touring across the typical seasonal range, LiFePO4 wins on heat, and AGM wins narrowly on extreme cold. For alpine touring in winter, an AGM is still a defensible choice for that single reason. Everywhere else, the temperature variable runs in lithium’s favour.
VoltX 12V 100Ah Blade Lithium LiFePO4 Battery
The Five-Year Cost Comparison
Sticker price is the first thing every buyer notices and the worst single variable to make a decision on. A 100Ah AGM battery in the current Australian market sits roughly between $250 and $400 for a reputable brand. A 100Ah LiFePO4, such as the VoltX 12V 100Ah Bluetooth Daly Lithium Battery, sits roughly between $700 and $1,200. On day one, lithium looks twice the price.
Across a five-year ownership window, the math shifts. A heavily cycled AGM installation may go through two or three batteries in that period. The LiFePO4 will still be in its first stage, with thousands of cycles of headroom remaining. Once the replacement count is folded in, alongside the hardware cost of the lithium conversion and the working watt-hours each chemistry actually delivers, the per-usable kilowatt-hour cost of lithium typically lands at or below AGM for any application that cycles regularly.
For a low-usage application that genuinely sees only a handful of weekend trips a year, the AGM may still come out cheaper at the five-year mark. For everyone touring more seriously than that, the lithium cost gap closes inside two years and inverts inside three.
Three Cases Where AGM Still Wins
This article is an honest comparison, and the honest answer is that there are still buyer scenarios where AGM is the right call.
- Low-usage applications. A van that gets used three or four weekends a year does not need LiFePO4 to deliver acceptable performance. The premium pays back too slowly to justify the upfront cost.
- Hard budget caps. If the total project budget will not stretch to lithium plus the supporting charging hardware, a properly sized AGM bank with appropriate hardware will outperform an undersized lithium bank with the wrong charger.
- Sub-zero alpine touring. The charging cut-off below zero degrees Celsius is a real operational constraint in winter alpine conditions. AGM keeps charging in those temperatures, which can be the deciding variable for that specific use case.
Outside those three cases, the comparison runs hard in lithium’s direction on every variable that matters to a touring rig.
The Touring Buyer’s Bottom Line
Buy LiFePO4 if you tour regularly, if the fridge runs more than a handful of weekends a year, if weight off the draw bar matters to the rig, or if the project will cycle the battery hard enough to wear out an AGM inside three years. Budget honestly for the supporting charging hardware on top of the battery itself, and the upgrade pays back quickly.
Buy AGM if usage is light, if the budget is tight, if winter alpine touring is a regular use case, or if the existing charging system on the vehicle is recent, healthy, and already configured for lead acid.
Both chemistries earn a place on this market. The buyer who knows their own usage pattern can pick the right one in five minutes.
