Where This Guide Comes From
Every number in this article comes from one source video — 4WD 24-7's head-to-head test of a 105Ah AGM battery against a 100Ah Redarc lithium, where Shauno charged both fully, plugged them into identical 69L fridges, and let them run until one gave up. No spec-sheet math, no marketing figures: two batteries, two fridges, one shed, days of waiting. If you'd rather watch the test before reading the breakdown, the video is right here:
The question the video answers is the one every 4WD and camper owner ends up asking: is a lithium battery really worth five times the price of an AGM? The short answer, after the test, is that lithium wins on nearly every technical point except upfront cost — and the upfront gap shrinks a lot once you spread it over a decade of ownership. Below is the full breakdown, every number taken from the on-camera test.
AGM Still Has Its Place — Here Is the Case For It
AGM batteries are still the default for a reason. They're proven, reliable and reasonably priced, and you can buy them in a huge range of shapes and sizes to fit whatever space you have. They're sealed, so you can mount them inside a vehicle — even on their side — without worrying about acid spills. For a weekend camper on a budget, an AGM genuinely gets the job done.
But the AGM's two big weaknesses are the same two things that matter most in a 12V touring setup. First, weight: the 105Ah AGM in this test weighs 28.4kg — call it 30kg for easy maths. That's a serious chunk of payload in the back of a 4WD. Second, usable capacity: of that 105Ah rating, you realistically only get about 50–60Ah before you risk over-discharging and damaging the internals. Discharging an AGM much past 50% shortens its life every time you do it — the deeper the discharge, the more sulfates form on the plates, and the harder it gets for the battery to fully recharge.
The practical rule for AGM owners: a fully charged AGM reads about 12.8–13V; at roughly 12V it's about 50% discharged and needs charging soon; at 10–10.5V it's dead flat and will never be as good as new again. That's the moment your fridge shuts off and your food is spoiled — exactly what the test below demonstrates.
Lithium: What You're Actually Paying For
Lithium's advantages are, almost point for point, the AGM's disadvantages. The same 100Ah class of lithium weighs just 12.5kg — less than half the AGM's 28.5kg — because there are no lead plates and no heavy electrolyte inside. That weight saving means you can mount lithiums in places you'd never put 30kg of AGM, like high up in a canopy, and it cuts real payload off your vehicle.
You also get to actually use the capacity you bought. Where an AGM's usable energy stops at ~50% depth of discharge, a lithium battery holds a useful voltage almost all the way down — so a 100Ah lithium delivers close to 100Ah of usable energy. Cycle life is on a different scale too: discharge a Redarc 100Ah lithium to 50% and you get roughly 5,000 cycles; even down to 20% you're still over 2,000 cycles. The same AGM at 50% discharge gives about 900 cycles, and only about 300 if you run it flat each time.
The one real disadvantage is cost: a typical AGM runs about $300, while a Redarc lithium like the one tested is $1,500–$1,900 depending on the model. Whether that gap is justified is the question the next sections — and the test — actually answer.
Parameter Comparison Table
These are the headline numbers straight from the video. Cycle figures are manufacturer-stated for the specific batteries tested; weight and capacity were measured on the bench.
| Parameter | 105Ah AGM | 100Ah Lithium (Redarc HD) |
|---|---|---|
| Nominal capacity | 105 Ah | 100 Ah |
| Usable capacity (safe DoD) | ~50–60 Ah (50% rule) | ~100 Ah (near full) |
| Weight | 28.4 kg | 12.5 kg |
| Cycles @ 50% discharge | ~900 | ~5,000 |
| Cycles @ deep discharge | ~300 (100% DoD) | 2,000+ (down to 20%) |
| Max charge current | 25A | 50A |
| Max discharge current | 35A | 100A |
| High-current loads (grinder, inverter) | Struggles past ~30A | Handles 100A output |
| Charger requirement | Any AGM-profile charger | Lithium-compatible charger only |
| Cold-weather charging | No low-temp cutoff | BMS low-temp protection (needed) |
| Typical price | ~$300 | $1,500–$1,900 |
| Typical service life | ~3–5 years | ~10 years (if charged correctly) |
Test 1: Two 69L Fridges, Two and a Half Days
This is the test that matters for campers. Two 69L fridges, both set up identically, both fully charged, each running off one battery — 10 litres of water inside each fridge, target temperature 0°C, no one opening them, in a shed at moderate temperatures. The AGM started at 12.89V; the lithium at 13.8V, which is normal for lithium.
After two and a half days, the AGM's fridge showed an error at 11.15V — over-discharged, at the point where continued use reduces battery life. The fridge on the lithium was still running at 12.9V and kept going for three more days. In real camping conditions — fridge opened constantly, hot car, long trips — you'd expect maybe half that performance from both, but the lithium still delivered roughly double the runtime of the AGM from batteries that were nominally the same size.
That gap isn't magic: it's usable capacity. The AGM stopped being usable at ~50% discharge; the lithium kept delivering useful voltage almost to empty. Same box of energy, but lithium lets you reach it.
Test 2: Heavy-Duty Appliances and Discharge Rate
Runtime is one thing; whether the battery can hold up under a heavy draw is another. The video tests this with an angle grinder, which pulls roughly 40A at startup. The 105Ah AGM, per manufacturer specifications, can only deliver about 30A — so it struggles or cuts out. The 100Ah lithium has a 100A output rating, so it runs the grinder easily, and with headroom to spare for a coffee machine or an induction cooker.
The difference comes down to two things inside the battery: a battery management system (BMS) that manages the cells, and cell construction that moves power efficiently. One caveat from the video worth remembering: not all lithium batteries are made equal. Cheaper lithiums often have lower discharge ratings — a "100Ah" battery that can't actually deliver 100A. Check the C-rate before you buy; the higher the rating, the more power-hungry appliances it can run, and the faster it can charge.
There's also a voltage-curve effect. As any battery drains, voltage drops and current rises to deliver the same power — until voltage gets so low that accessories start shutting off. Lithium holds a higher voltage throughout the whole discharge cycle, so at camp with an inverter running hungry appliances, lithium keeps them running efficiently for longer.
Test 3: Charging Speed — and the Charger You Can't Skip
Charging is where lithium changes your habits. A standard AGM charges at a maximum of 25A and discharges at 35A. The Redarc lithium in this test charges at 50A and discharges at 100A — with a 50A charger, you can fill the entire battery from empty in about two hours.
But there's a non-negotiable: lithium has a different charge profile, so you can't use any old charger. You need a lithium-compatible charger — like Redarc's DC-DC range — or you risk damaging the battery. Every lithium battery also has a BMS that protects against excessive discharge and over-voltage, and will shut the battery down if something is wrong. It's easy to restart, but you should expect it: the BMS is doing its job, protecting the cells inside.
If you're running a hard-mounted solar panel and a quality multi-phase DC-DC charger, you can also keep an AGM topped up and get years more out of it — the video's three practical tips for AGM owners are solar topping-up, a proper multi-stage charger, and a voltmeter so you start recharging at 12.2–12.3V instead of dropping into the 11s.
The 10-Year Cost: Do the Numbers Add Up?
This is the calculation that settles the debate for most people. A $300 AGM realistically lasts about five years (Shauno says his experience is closer to three). Ten years of AGM ownership means at least one replacement — $600 already. And because you only get ~50% usable capacity from an AGM, matching the usable power of one lithium means running two AGMs. Replace those two every five years and over ten years you've bought four AGMs — $1,200 — against one $1,500–$1,900 lithium that lasted the whole decade.
And the lithium still wins on everything else in that same period: ~50kg less weight carried, heavy-duty appliances you couldn't run at all, faster charging, and more time out bush. The math flips harder the longer you keep the vehicle. If you're a young bloke on a budget doing weekend trips, an AGM will genuinely cut it — but if you plan to own the vehicle for years and run a fridge, lights, an induction cooker or an inverter off it, lithium pays for itself.
Three Ways to Build a 12V System
The right answer depends on how you camp. The video walks through three setups worth knowing about before you spend money:
1. Portable (no install). A unit like Redarc's GoBlock packs 100Ah of lithium into a small, liftable case with a built-in charger, cigarette sockets, an Anderson plug for solar, and everything a "fancy" 12V system needs — no install, carry it between the car, the boat and the tent. Best for people who want one system in multiple places.
2. Single lithium in the vehicle. Shauno's own upgrade from two AGMs to one lithium: set-and-forget for ~10 years versus replacing AGMs every three, ~50kg of weight saved, and the second battery's space freed up for storage. One lithium genuinely does the job of two AGMs.
3. Full touring build. Two 100Ah lithiums charged by a 30A DC-DC, a 2,000W pure sine wave inverter, everything managed by a system controller. 200Ah of lithium runs nearly any 12V or even 240V appliance — coffee machine, induction cooker, corded angle grinder — without ever thinking about the battery going flat. Not budget, but if you want to be off-grid for months, this is the setup.
Whichever route fits, the battery chemistry underneath matters more than the badge on the case — and that's worth thinking about early, because every setup above ends at the same question: what cells are actually inside?
Bottom Line: Who Should Switch to Lithium?
On the test bench, the verdict is clean: lithium beats AGM on usable capacity, weight, cycle life, high-current output and charging speed — the only real loss is upfront price. On the campsite, the verdict depends on you: if you camp a few weekends a year on a budget, an AGM is honest value and this test doesn't change that. If you tour seriously, run a fridge around the clock, or want to power anything heavy, the 10-year maths makes lithium the cheaper battery.
One last warning from the video applies to both chemistries: respect the charging rules. AGMs need topping up and proper multi-stage charging; lithiums need a lithium-compatible charger and their BMS handled properly. Batteries don't fail from use — they fail from the wrong charger and the wrong discharge habits.
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What Viewers Are Asking (Top Comments on the Video)
These are the most useful of the video's top comments, with our practical answers. The original creator did not reply to these threads, so the answers below are ours — written the way we'd answer a customer on the shop floor. Thanks-only comments were left out on purpose; these are the ones with actual information in them.
Source video: 4WD 24-7 — "DEEP CYCLE BATTERY COMPARISON - Is Lithium really worth it?" (youtube.com/watch?v=2o7T2F9rFko). Comment excerpts are quoted verbatim from the video's top comments; the original creator did not reply to these threads, so all answers are Dajiu Energy's own. Test figures are transcribed from the video's measurements.