The main reason that I was so bowled over by the Moto Z3 Play for so long was because of the TurboCharge Battery Mod, adding 3,490mAh to the phone's 3,000, giving me a whopping 6,490mAh. I have been drooling over the Moto G8 Power's performance with 5,000mAh giving 3 real-world days between charges. Then there was the 6,000mAh Unihertz Titan. And now, I've swooned at the performance of the 3,885mAh battery in the Pixel 4a 5G - doesn't sound like it's in the same ballpark, but the longevity is staggering.
Samsung have dabbled with 6,000mAh batteries in the M31 range but, like the M51 here, it always felt like they were struggling to get these devices out of the east and into western markets - so I never saw one. This M51 is now being sold by Samsung themselves at least in the UK direct, even if nobody else is doing so outside of India. The other issue for me here is that when testing Samsung devices in the past, I have often felt that for whatever reason (I suspect all the background processes going on) batteries have not performed as well as others do, given the same capacity. So, gauntlet thrown down!
First though, to the usual furniture of my review process - and not forgetting that on the face of it, this is a cracking phone - regardless of battery. The box, then! What's in it? A TPU-shaped box with no TPU in it, just some papers and a pokey-hole tool! Mean! A USB-C to USB-C cable, a "Super Fast Charging" (it says it, on it) 25W power brick, a pair of nasty-looking in-ear-canal wired earphones (I'd rather have had a TPU) and that's it. Smaller box that you'd expect for this size of phone, no doubt they will claim eco-friendly.
As you might expect with not only this giant battery but also the general trend for phones to get bigger (particularly when designed for eastern markets), this phone is large! Though actually to be fair, it's not as big as I had feared it might be. It's not that much bigger than my Nokia 9 PureView - about the same width, a centimetre taller, but certainly significantly fatter. It's 163.9 x 76.3 x 9.5mm and 213g in weight. It's even closer to the size of the Motorola One Zoom, similarly slightly bigger in all directions. But there's something about it in the hand which doesn't make it feel that giant. I can get my finger and thumb around it and some tasks I can actually execute one-handed (before any software tricks). It's very slippery, so a TPU is advised which, sadly, makes it feel significantly bigger.
The back panel is made of plastic and this one here is a shiny shimmering black, dominated by a large oblong camera island top-left which all the trend now. On the right side of the plastic frame is the (very slim but solid-feeling) volume-rocker and beneath that, the capacitive fingerprint scanner with power-button (press-in for click) incorporated. Up-top is just a microphone and on the right, Dual nanoSIM Card Tray with a third slot for microSD. On the bottom there's the USB-C port, central, single mono speaker to the right and 3.5mm audio-out socket to the left. The plastics used feel pretty solid and good enough, for those brave enough to use the phone naked - though be careful as there's also no IP-rating!
The power is the natural starting point then and yes, that 7,000mAh battery inside. I've done my usual tests and the screen-on-reading test was a little disappointing compared to other devices - it returns just over two hours and I was expecting more, given that the 5,000mAh battery of the Moto G8 Power returns 3 hours 10 minutes and the recent new champion, Google Pixel 5 with just over 4,000mAh, 3 hours 20 minutes! So there's something about the screen-drain or background processes I'm guessing here (which I'll come to) as the average daily use test is quite staggering. In my tests, I go through the day, using the phone medium-to-heavy, and get to the end of it with 75% left or more! This makes this a 4 day phone for battery, or at very least 3 even hammering it! As always, your mileage will vary - if you run films and loud music all day then of course, it'll be different. The battery can be charged with the supplied plug from flat to full in under two hours.
Samsung claim up to 34 hours watching video and 182 hours of audio playback time (screen off) which is just over a week! I haven't done any of these extreme tests but I don't doubt them. In my usage over the last weeks, it has been the best performing battery I've ever used on a phone (apart from that 10% test) so going away for a weekend camping without a powerbank is a reality! And there's more - there's no Qi Wireless charging, but there is Reverse Charging by cable, which means that you can pass-through power to another phone or device for when your friends' phones give up! So even if you don't want to use this as your main phone, it's a great backup and powerbank! Wow.
Samsung's Super AMOLED Plus 6.7" 1080p front panel is flat. That's great. We've all had enough of curved screens now. Time to look back and admire the jewellery, but move on. The Gorilla Glass 3 protected screen looks super-bright to me (even before winding it up to 100% manually) and colours, the usual Samsung Saturated but as you'd expect, this can be toned down in settings, warm, cool, vivid, natural and full white-balance controls. Make the screen look how you like. It's great outdoors even in sunshine - no visibility issues here - even before employing the 'high brightness mode' turning it up to 11 on the slider! It's a 20:9 ratio panel which returns 393ppi. It doesn't feel too tall in the hand with the subtle difference from, for example, Sony's 21:9. There's a punch-hole selfie cam at the top of the screen, centralised. Bezels are minimal making this giant 6.7" screen feel like it shouldn't really fit into the chassis. The punch-hole is smartly 'hidden' most of the time, only rearing its head really when viewing media splayed out to fill the whole panel. It's fine. Really. Trust your brain to hide it for you! Viewing angles are also excellent as you turn the phone around.
Driving the phone is a SnapDragon 730G chipset, so no Exynos here. It's a mid-range economic solution which seems to get good press. A good number of recent phones from Realme, Oppo and Xiaomi have been equipped with this and I've not had any complaints on testing. Apparently it has an additional 15% graphics boost over Snapdragon 730 and impressive battery improvements when employed - like it needed that here! Like most smartphones in the mid-range these days, it appears to fly through whatever tasks are presented and even though from previous testing (for my use) I can't see any difference much between SnapDragon and Exynos, it feels somehow more satisfactory to have the former! Supporting the multi-tasking, keeping apps open and running in the background is 6GB RAM. I realise that there's mad hikes in RAM these days, doubling that in some devices (some not even flagships) but as we know, 4GB is really enough for Android - so 6GB comfy! I see no apps closing down without reason as long as you don't let Samsung software do its thing optimising stuff. Again, those kind of battery saving measures are just not needed here.
Talking of the One Zoom, I'm going to compare the audio output of this Samsung with the Motorola as from previous experience I think it might be a close match. They both have a single mono speaker, Samsung firing out the bottom, Moto top. They both have a 3.5mm audio-out socket. Starting with the speaker then, there's not a huge difference in the pair but the Moto edges it on volume and certainly, out of the box, quality. There are some basic controls for each phone (Dolby & Moto Audio Tuned by Dolby) in terms of system-wide adjustment for speaker output but the breadth of these is similar for both. Not a great deal. But the Samsung edges out the Moto as it has a custom manual set of sliders where the Moto is all pre-sets. Both phones' speakers are good room-filling sounds and punch well above their weight for what you'd expect from a single mono speaker. If I had to choose at this point, it would be the Moto. Just.
Plug in a set of headphones and again, there's the ultimate system-wide lack of a true manual custom control for the sound with the Moto as the Samsung moves ahead with fancy equalisation options in excess of the Moto, making the sound output more flexible for the listener. Similarly, whilst the Moto wins the basic speaker test the Samsung clearly wins the headphone test with louder and better quality output. It sounds as though it has a fancy enhanced DAC onboard to me but I can't believe it has or Samsung would be listing the spec and other listings would reference it. It somehow sounds great though, very loud and excellent quality - more so than the Moto. The Moto grabs some points back with the excellent spatial 3D Stereo with headphones but it doesn't quite reach the height of the Samsung. But it's quite close in reality - to all but the audiophile.
We have come to expect bluetooth these days to be staggeringly good and sure enough, tested here with my Huawei FreeBuds 3 both phones sound stunning. No wonder everyone's going bluetooth instead of 3.5mm! In addition to all this, the Samsung has a hearing test with beeps to test the user's hearing and adjusts the output afterwards to suit the particular hearing profile of the user. All clever stuff. Lastly on audio, there's a recording FM Radio (in this UK version) which looks fabulous, locks onto stations well and can be switched to play through the speaker once signal secured via something plugged into the 3.5mm socket.
Speaking of clever software, the M51 comes armed with Android 10 and Samsung's One UI 2.1 overlay. Whether the user likes or dislikes this overlay, nobody can deny that it is exhaustive, smart and some distance from Vanilla Android! As much as I love Android as Google designed it via the use of Pixels, you can't help but be impressed with the depth of features and software supplied here, ensuring that the Samsung user in time won't want to leave the walled-garden! I'm not going to trail through all the One UI and Samsung enhancements here again. To read up on the evolution of changes have a read of this at Wikipedia. A special mention for Always on Display however, as it's so good and exhaustive in terms of choices and layout. Yes, there's loads of them and more from themes and developers out there. Many free, many paid. It's a shame that Edge Lighting isn't a part of this setup which I'm guessing they removed as the panel is flat, not curved. But then that's also true of the Galaxy S10e. Odd. It can't be money - it's their own software and would, presumably have cost nothing to add. Maybe it'll come in an update. In the meantime there's loads of 3rd Party solutions including the recommended NiceLock which adds that and oodles more!
As I write, we slip into November 2020 and the Google Security patches on the phone are present up to August 2020 - so not bang up-to-date certainly but Samsung do have a growing reputation (and claim) that they will keep their newer devices up to date with security and OS. Security to prevent others getting into your phone include the aforementioned side-mounted capacitive fingerprint scanner. This is great working as the main power button when clicked in and FPS when touched and not clicked. Registration is simple and fast and it works first time, every time. So much better than under-screen efforts and into the bargain, can be accessed when the phone is flat on the table/desk. There's also face-unlock which, again, works excellently well when you look at the phone (though you do still have to slide-up to get past the splash-screen).
The array of cameras on that island on the back include the following (deep breath) a 64MP f1.8 main Sony Quad Bayer shooter, 12MP f2.2 wide-angle, 5MP f2.4 macro, 5MP f2.4 depth lens (and a 32MP f2 selfie round the front). There's no optical zoom, nor OIS anywhere in all this lot. The user can manually pinch-to-zoom for digital up to 10x but results are a bit ropey as you'd imagine. Shots are more than usable for most people at 2x zoom or even 3 but it's just a bit of a shame that they didn't include this optically and maybe even drop one of the others. Having said that, the 5MP Macro lens gets the shooter in pretty close and to some degree that might be more useful for some, though not the masses. The Night Mode is pretty dreadful in my tests here - appears to behave in the same way as the Pixel, but the resulting image is terrible. With the Pixel we get a really quite usable shot, with this, nothing. Black cat in a coal cellar at night. The reality is that for most people using this phone for most social media uses and video of their mates for YouTube, it's absolutely fine. It's just the pixel-peepers who won't be interested as there is so much better out there, even for very similar money.
As we dance around all these other specs, it's only one which matters here over any other phone in a similar price or spec band - yes, that battery. It's quite simply the strongest battery in a phone that I've had in my hand and used (from a mainstream manufacturer) which has a trick up the sleeve of reverse-cable charging. It's almost worth having in the glove-box as a back-up phone in case it is also needed to top up your regular phone (or any other device, come to that). But that sells it a bit short, too. For the £329 it costs in the UK, it's also very capable in many other ways.
This is no flagship, with key elements missing from that experience, so no IP-rating, no Qi Charging, no DeX support, no stereo speakers to mention a few, but what it has, it exploits well (and supports with that battery) and many, many people will be very pleased to use this as their primary phone. With Samsung's ongoing commitment to support and updates, it's a compelling option - especially for those who are not going to be too annoyed having to move away from Vanilla Android and into the waiting arms of Samsung. They won't regret this.