Stihl RMA 448 TC Review

What is the Stihl RMA 448 TC?

Stihl’s flagship cordless mower is a self-propelled, 46cm cut model designed for larger lawns. Dual battery slots and a range of batteries allow you to specify the RMA 448 TC to suit your garden, and it packs in features including Stihl’s single-sided mono handle, large split-to-empty grass bin, and a mulching kit option.

Outstanding build quality, superb cut, class-leading pickup and long run-times saw the RMA 448 TC outperform its specification in every respect. The self-drive is paced perfectly, the lawnmower is super-easy to empty, and the 75mm ‘high’ cut setting is ideal for rough areas and early season.

Our package came with a woefully slow charger, but for a few pounds more you can have an outstanding all-round cordless mower package for the biggest of lawns.

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Stihl RMA 448 TC – Design and features

We love brands with experience, and premium German garden machinery maker Stihl has over 90 years of it. Wheeling out its top-spec cordless lawnmower, the RMA 448 TC, that expertise is abundantly clear. This large, 46cm cut mower simply exudes build quality. Everything fits together with slick precision, set-up and controls are crisp and free of any play, and the features list is extensive.

This £475 ‘naked’ mower runs on Stihl’s 36V AP battery system and features twin battery slots for extended run-time. Only one slot is active though and you will need to manually swap batteries around to use the fresh battery. As tested at £692, our mower came with the entry-level AL 101 charger and a single 6Ah AP 300 battery, promising to cut up to 500m² of lawn on a single charge. A range of battery and charger option are available, however (see below).

Most obviously different from other mowers is the flag-like single-sided Mono Comfort handle. Our immediate thoughts were ‘a bit of a gimmick’, and a concern that the handle would feel a little flexy.

Not so. It’s superbly engineered with no flex or play whatsoever. It folds and opens with consummate ease, and the open-side makes pulling off a full grass box the easiest of any mower on the market. That showed us then.

The machine is built around a robust polymer chassis, double-walled and braced with metal plates on the cutter deck. The wheels run on proper ball bearings, driven across the rear by an independent motor. The 448 TC is a single-speed design, but the pacing of the drive speed transpired to be spot-on.

Stihl says the 46cm blade has been ‘flow-optimised’, designed to best balance cutting, pick-up and run-time. We thought that was just marketing hype, but that notion also came with a slice of humble pie during testing.

Outback, the 55-litre grass box looks huge, but it clips and unclips from the mower with ease. Fins moulded into the box ensure you don’t get dust blown up at you while mowing, and there’s a bin-full indicator flap on the top that folds flat when full. Packed full of well-compacted grass trimmings, the box is quite weighty. Yet the mono handle and split-open design promise to ease the process of emptying.

The large, black carry handle on the main body cleverly houses the release mechanism for the 25-75mm height adjustment. Squeeze the trigger-like switch and the mower pushes up and down with ease. A cutting-height gauge is moulded into the chassis plastic. It’s marked arbitrarily from 1-6 and isn’t the easiest to read, especially when it gets a little dirty. The mower weight is nicely sprung-balanced, so altering the height takes little effort.

Popping up the main cover reveals the dual battery slots, kill key and ECO mode switch. The power pack needs to be placed in the rear-most slot as the forward port is simply a battery carrier for a spare.

The ECO mode promises extended run-time by using variable power, which starts low but ramps up cutting force and blade speed over rough grass. In fact, the RMA 448 TC does that on both settings, although the ECO mode runs less power normally to increase run-time by around 25%.

Up top of the mono-comfort handle is a traditional lock-release button and two robust wire-levers to start the drive and cutting motor independently. Unfortunately, you can’t start the drive motor without the mower blades running. That does mean you can’t simply ‘drive’ the mower back to your shed. Thankfully, the drive disengages when you push the mower, so this is no more onerous than a non-drive model.

Overall attention to build quality and design detail is outstanding throughout. Everything feels solid, slick and superbly well-put-together. After a couple of months with the RMA 448 TC, we really couldn’t fault its design or usability.

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Stihl RMA 448 TC – Batteries, charging and run-time

Our RMA 448 TC package came supplied with a recommended AP 300 battery and AL101 charger combination, although that combo wouldn’t have been our first choice. The single battery doesn’t make full use of the RMA 448 TC’s full twin battery potential,and the charger is woefully, glacially slow for such a large battery. The green charger light flashes for an eternity as the battery’s four segments illuminate at a rate of slower than one per hour.

The AL 101 is Stihl’s entry-level charger for the AK/AP battery range and its low 1.6Ah charging output felt pretty sluggish, even with the smaller AK20 battery we used with other Stihl machinery. Insert the beefy AP 300 battery, and it will take the wrong side of four hours to charge. If you mow the entire lawn and then simply stick the battery on charge ready for next week, that won’t be a problem, so just ignore us.

If you want to use the battery more than once in a day, we’d strongly recommend adding £40 or so to the package price and specifying Stihl’s AL 300 charger instead. That will take an AP 300 battery from exhausted to ready to mow in about 75 minutes.

Need quicker still? For around £90 more, you can specify your package with the fan-cooled charging beast that’s Stihl’s AL 500 Fast Charger. With a 12Ah output, it will recycle the AP 300 battery in less time than it takes to have a coffee and cake stop between mowing sessions… just 35 minutes. All of these chargers can be wall-mounted if you need to save some shelf space.

The AP 300 battery supplied here is a compact, just over 6Ah battery weighing in at 1.8kg. At 36V, it offers a total of 227Wh of power.  That’s a fair chunk of available power, but given the RMA 448 TC has a self-propelled driving motor and a huge 46cm blade, could the battery last for the 450sqm of lawn Stihl’s promises?

Yes. Yes, and a fair bit more in fact! Running on the standard (non ECO) mode, the RMA 448 TC drove around for almost exactly 30 minutes, covering a very healthy 16m-long section of our 40m-wide lawn (not pictured). That was 640m² of open lawn – far exceeding Stihl’s claims for the coverage. Excellent.

Recharged, we tried the same battery using the RMA 448 TC’s ECO mode. There’s precious little difference in its cutting ability over normal, well-kept grass in this mode, and the drive is no slower either. The mower drove us around for a solid 38 minutes in ECO mode, covering well over 750m² of flat, open lawn.

Start navigating your way up and down slopes, around obstacles or through long grass and weeds, and those run-times and cut-areas will decrease of course. Yet the Stihl’s clever power-up when it hits the rough stuff, then dropping back to normal power over easier-to-cut areas, should mean that it isn’t by much.

Add a second AP 300 battery (around £180 – ouch) to the package and the RMA 448 TC’s run-time and cut area doubles although you will have to swap the batteries between slots. Even better, if you also invested in an AL 500 Fast Charger, you could charge one AL 300 in the time it takes to drain the other while mowing.

An RMA 448 TC mower with two AP 300 batteries and an AL 500 Fast Charger would tip the purchase price to over £900, but the combination would offer almost limitless mowing time.

Stihl RMA 448 TC – Handling and performance

We love it when we look back over our testing notes, written over several weeks, and find pages and pages littered with words like ‘great’, ‘excellent’ and ‘outstanding’. Excluding some expletives about the supplied charger, the RMA 448 TC delivered all that and a very neatly mowed lawn besides.

The Mono-Comfort assembly clips seamlessly into one of two positions, giving a couple of handle-heights to choose from. Despite its single-sided design, it’s amazingly solid-feeling and inspires confidence. The main grab handle is easy to grip and the buttons and switch-gear are crisp. Push in the lock-release button, and the wire levers are nicely weighted. Once the blade has started, pushing the rear lever towards the bar gently starts the forward drive. Grab quickly at this lever and the mower lurches forwards, but you soon get the hang of a smooth start that Lewis Hamilton would be proud of.

We aren’t generally fans of machines with a single drive speed – they tend to be a bit too fast or too slow, or can’t be controlled for delicate manoeuvres and U-turns. Thankfully, the RMA 448 TC’s drive speed was described as ‘spot on’ or ‘perfect’ by myself, Jackie and – subsequently – Bryan, the farm’s Estate Manager, who we pulled in for a further opinion.

When you come to do a U-turn or navigate around some obstacle, simply letting go of the rear lever disengages the drive and allows the wheels to spin freely. Since this machine runs on ball-bearing wheels, advanced manoeuvres without the motor are slick and reasonably effortless.

The cut-height adjuster mechanism is inspired and extremely easy to use – more so than many mowers a fraction of the size or weight of the 448. The gauge isn’t the easiest to read, since it’s moulded into the plastic and the ‘pointer’ is on the underside of a metal bar that links front and rear wheel height. Some contrast on the numbers or a more obvious pointer would be welcome, but we’re being very picky on that given the overall ease of adjustment.

The heights themselves are well gauged in approximately 10mm increments. The highest 75mm level is ideal for rough cuts and early season weed chaos, while the lowest 25mm setting will be great for those wanting to mow, say, a billiard table. Neither it nor the 35mm setting have much use here at the farm, but you can’t fault the cut finish or pick-up even at these low settings.

Cut lines were crisp, the mower perambulates in very straight lines (many self-propelled mowers have a bias), and the pickup was faultless.

As we used the RMA 448 TC over the following month, the pickup continued to impress as the mower would lift, chop and eject all sorts of lawn debris into the bin. Grass, leaves, sticks, debris, acorns and even a rubber dog toy all ended up in there. This mower has, frankly, amazing pickup, inspiring Bryan to use it – in his words – ‘like a Dyson’ simply to clean up the lawn even when it didn’t need mowing. Brilliant.

That excellent pickup is thanks to the blade design (oh… it was flow-optimised then), which creates massive lift and fan power to blow the debris into the bin. The result is that grass clippings are seriously compacted into the bin, allowing you to mow for longer between empties.

It makes for a heavy, full bin, but the single-sided mower handle makes it easy to remove, and you simply split the bin in two to empty. The grass box also effectively directs exhaust air downwards towards your feet, rather than at your knees or higher. It appears all but immune to blockages, and has a genuinely functional bag-full indicator.

If you mow regularly and want to explore the moisture and nutrient retention benefits of mulching, Stihl offers an optional mulching kit for the RMA 448 TC. This large plug with moulded-in handle simply pushes into the ejector slot from the rear. You can leave the bin off to save some weight since the sprung flap then further seals the rear of the machine.

We’re big fans of mulching, mostly since it saves a lot of bin-emptying work. The RMA 448 TC doesn’t disappoint here, trimming low lawn growth into very fine clippings.

Despite some serious ‘testing’ test conditions during this review – including flood, drought, a sapling and bramble takeover of the lawn, and dried-out broken ground – the RMA 448 TC worked faultlessly, never failing to impress. We’d spec a different charger than the one supplied with our test package – but otherwise, it is, as our notes suggested, ‘great’, ‘excellent’ and ‘outstanding’ all-round.

Why buy Stihl RMA 448 TC?

Stihl has delivered a truly exceptional cordless mower for the larger lawn – which proves, through outstanding performance, excellent design and fabulous build-quality, that battery mowers are the way ahead. Long run-times, great coverage (up to 750m² with the AP 300 battery), faultless cut and collect performance, and unrivalled ergonomics make this one of the top self-propelled cordless mowers available today.

Get to a Stihl dealer to help you choose the right battery and charger for your garden, and the RMA 448 TC will deliver great results and super-low running costs for years to come.

Verdict

The Stihl is an outstanding cordless mower for the larger lawn, offering truly top-notch features, cut performance, pick up and build quality.