Review: KickAss 120 AH Slim Lithium Battery

Reviewing batteries is tough…. 5 stars if it works, 1 star if it doesn't? But given the scarcity of good information on overland battery systems, I’m going to do my best to break down why the KickAss 120 AH slim lithium battery warrants consideration for your overland build — and for more reasons than it just works.

The backside of the InPowered Adventures module, tucked beneath my Goose Gear drawers. You can see the 120 AH slim lithium battery, DCDC charger, and the connection to my fridge and accessories is all cleanly organized and optimized for off-road adventures.

When I built my first overland battery system, I selected a KickAss 170 AH slim AGM battery. When I reviewed it at the time, I mentioned that one of my quibbles was that I would have preferred lithium, but there were no companies offering slim lithium batteries in the US market yet. I begged KickAss to bring their slim lithium batteries, which were available in Australia, to the US and they listened. So it’s time for an upgrade…

The KickAss 120AH slim lithium battery is smaller, lighter, and higher usable capacity than its AGM battery counterparts, making it an ideal choice for overlanders.

Lithium vs AGM Batteries

I am not an expert in batteries by any means, so I am not going to try and explain the technical differences. But what I do know is practical differences — things that matter to us as overlanders. First, lithium technology is much newer, so they tend to cost more than more traditional battery technology that powered the first Jeeps in 1942. But what comes with that new technology is a handful of benefits that, in my opinion, are worth paying for. Compared to AGM, lithium offers the following advantages.

KickAss provides the above specs for the 120ah slim lithium battery

Ability to use more of the battery capacity

AGM batteries are unable to recharge once they have been drained below a certain voltage, whereas lithium batteries can recover even if they are almost fully depleted. This is why cell phone companies rely on lithium batteries in their phones — imagine being told that you wouldn’t be able to recharge your phone if you drained it below 50%!

In vehicles, that means that a battery with a 200 AH rating probably only has closer to 100 AH of usable battery capacity (numbers approximate). With lithium, a similarly sized battery would offer almost twice as much capacity.

Even though I “downgraded” in battery size from 170 AH with the AGM battery to a 120 AH lithium battery, I actually increased my usable battery capacity.

Lighter weight

AGM batteries are heavy — and there is just no way around that. Lithium technology weighs substantially less. In real terms, the KickAss 170 AH AGM battery tipped the scales at over 100 lbs, whereas the KickAss 120 AH Lithium battery comes in at a sleek 32 lbs. Not only does that make the installation and transportation easier, it also affects vehicle performance, taking substantial weight off the rear axle. Overlanding is a gear intensive activity, and we rarely consider the effect that our gear weight has on our vehicle’s performance. While I’m unlikely to see a 70 lbs reduction of weight show up at the gas pump, I can see from the lines on my rear shocks that the back sits a bit higher than it did before.

Smaller form factor

Rounding out our trio of features is that a lithium battery is just smaller than an AGM counterpart. I went from having an AGM battery that took up the entire tray of the InPowered Adventures module to a battery that left an abundance of extra space for wiring and accessories, making the entire install that much cleaner. And when we’re trying to shove batteries and gear into every nook and cranny and optimize vehicle storage, a smaller form factor is a huge benefit.

To date, I am still not aware of another US offering of a slim lithium battery designed with the capacity needed for overland travel. KickAss really has created a unique and amazing thing with these 5” thick batteries.

KickAss 120 AH Slim Lithium Battery

I was elated when I saw that my friends at KickAss were bringing their slim lithium battery line to the United States; in full transparency, I would have purchased this battery two years ago when I first purchased their batteries and DCDC chargers. But it wasn’t available then, so I have the unique perspective of being able to compare the two systems.

Comparison from a performance standpoint is tough. The fridge turns on when I push the button with both batteries. The lights turn on the same. I never took detailed enough measurements to evaluate if one battery charges faster that the other. But what I can say is that I’m incredibly pleased with the size, weight, and overall functionality of this lithium battery, even if I lack the metrics to quantify any improvement.

Thankfully the KickAss DCDC charge controller that I installed previously is already compatible with lithium, so as soon as I connected the battery to the controller, it lit up and started sending beautiful solar rays into the battery pack. Of course, I still have it connected to my alternator, so I can pack in more charge while driving down the road.

One significant difference between the KickAss lithium and AGM batteries is that the lithium offers integration with apps and smart phones, along with the ability to connect an external monitor. I have purposefully not connected my smart phone to my battery — while the idea of monitoring my battery from my cell phone is novel, it’ll only further drain the battery to enable that connection, and I already have a battery monitor that gives me quick data on performance from the rear of the vehicle.

That said, KickAss does offer a remote display that connects to a weather-sealed connector on the top of the battery in their Australian stores, but that display has yet to swim over to the United States. I would like to see that becomes available, as I currently use a Renogy battery display system to monitor health and performance. It does annoy me when companies offer a feature, but that feature is only accessible to you if you live in a particular market. Hopefully KickAss will stash a few of those controllers in their next container across the Pacific and we can enjoy the benefits of a built in battery monitor without the need to rely on external components….. hint hint?

The KickAss lithium battery includes a connector for attaching an external monitor (see the wire in the middle, left of the image above), but that monitor is not available in the US market as of October 2023.

Installation in the InPowered Adventures Module

Installing the lithium battery was pretty straightforward since I previously built the InPowered Adventures module (click the aforementioned link for a full walk-through). The most challenging part was to remove the 100 lbs monster that was the previous KickAss AGM battery without damaging the delicate wiring. With my wife’s help, we carefully hoisted it out and replaced it with the lithium battery in a matter of seconds. Everything was re-connected exactly as-is — the only difference in this installation is that I had to re-program the DCDC charger to lithium — a process that took less than 10 seconds.

Removing the old 170AH AGM battery from KickAss. You can see how that battery took up almost the entire storage area, making wiring a challenge. The smaller form factor of the lithium battery makes it much easier to work with in tight spaces, like this one.

It requires a bit of yoga to get into these tight spaces, but the benefit of a slim battery is that it tucks into such a small space under my Goose Gear drawers in my Jeep.

Reconnecting all the wiring to the new lithium battery was a breeze. I just had to reset the KickAss DCDC controller to lithium mode, but everything else was the same from my previous installation.

We did have to haul the old AGM battery to the dump, which was not a ton of fun given the weight, but proper disposal of batteries is important, so if you are planning a similar upgrade, make sure you dispose of your old battery correctly.

Verdict

As I said at the onset, it’s hard to review a battery. However, KickAss is continuing to earn high marks with me because of the quality of their products, availability (albeit delayed) of unique battery offerings in overlanding-friendly sizes, and price point. Lithium batteries are not cheap, but KickAss offering a slim lithium battery that can power your overland adventures almost indefinitely (assuming solar and alternator charging) for under $600 is incredibly reasonable. For comparison, Dometic offers a bulky and ill-performing 40 AH lithium battery for $850…. so KickAss is not only very fair in their pricing, but they stand behind their products with excellent customer service and warranty support.

The KickAss batteries integrate seamlessly with the DCDC charge controllers offered from KickAss — making for one easy-to-install and powerful overland power setup.

My only gripes? Other than making the aforementioned battery remote display unit available in the US market, I don’t really have any. But if I am going to complain that KickAss needs to send those units to the US market, then I’d also petition that they make a range of other accessories, like inverters, available to the US market as well. Hopefully those things are on the way soon. In the mean time, hats off to KickAss for continuing to improve their offerings here in the US.

Buy the KickAss 120 AH slim lithium battery from KickAss Products here!