Caterpillar CAT S61 phone review

Henri Rantanen 0

I got myself a not-so-shiny, rubberized and heavy new phone, CAT S61 from Caterpillar. Here are my two cents about it for those considering getting one. I have used the device for 3 months now, here are my thoughts:

The good things

Its very rugged

I have accidentally dropped the phone a couple of times in a way that would have destroyed the regular glass-sandwiches.

There is a rim around the display that should stop the screen from hitting the floor, thus protecting it well. I have managed to put a small dent into the aluminum rim, but it its just cosmetic wear.

Rugged design of CAT S61
Rugged design of CAT S61

It’s dual-sim

I have two phone numbers, one for work, one is my own. This enables me to not drag two devices around and works surprisingly well. Only another SIM has to be enabled for mobile data and you can choose which card to use to call and text people. Noted that it is way too easy to use the wrong card to call people, which usually just confuses them.

Note, that you can choose between dual SIM or one SIM plus a memory card. You can not have two SIMs and a memory card.

Integrated FLIR thermal camera

Integrated FLIR thermal imaging camera is a nice add-on to every nerd’s toolbox. It solves arguments like who’s beer is the coldest and helps you find the cats in the dark.

The phone combines images from the thermal sensor and regular camera to create a composite image, that has drawn outlines of the subject. You can also use the included FLIR gallery app to view the regular photo of the thermal image to see what it was all about.

CAT S61 flir thermal image toilet
Thermal image from bathroom. Floor heating cables clearly visible through the tiles.

It also is actually quite a helpful tool that helps you realize things that you otherwise wouldn’t – for example, I’ve identified a leaky window seal and few bad solder-joints with the camera, just by taking a look mostly for fun. Like seeing your warm foot-prints on the floor or determineing that you dont have blood circulation in your mouse-hand.

It’s a tool, but you have to know how to use it effectively. You have to understand reflective surfaces and emissivity in order to take any actual measurements that have values even close to real life.

The smartphone can also take thermal video and time-lapse for those hard-to-debug situations. It can even stream to YouTube live if that is what you desire.

thermal image of soda in the fridge
Always pick the coldest soda in the store! You can easily see what has been just put in to the fridge.

Battery life

I am quite an active user of mobile apps, I use it to navigate, keep my food-diary, compulsively browse Reddit, chat in Telegram, listen to music etc. during the day and the battery lasts easily to the evening. It has not run out on me once.

Processing power

Even tho the tech is “previous gen” technology, it has aged well. I was afraid this would be a deal breaker to use “old hardware” but my fears were misplaced. I currently have installed 93 apps on my phone and I haven’t noticed any performance issues nor the phone heating up in use.

Air quality measurement

This is more of a curiosity for me. The VOC sensor is sensitive enough to send you notification within 10 minutes if somebody opens a can of beer with the device within half a meter’s range. It will make you pay more attention to your surroundings.

Phone will yell at you if you hang around in areas where solvents are handled, for example if there is fresh paint. It will not measure CO2 though, which is a shame.

CAT S61 air quality sensor
CAT S61 air quality sensor

The joke of you getting a complaint to your Android smartwatch if you pass gas with the phone in your pocket gets old quite quickly tho.

It’s waterproof

I was planning to use it in the public swimming hall as lap-timer to record my progress but so far I haven’t found any apps that would work nicely for that purpose. Supposedly you can take photos under water with it but I haven’t tested it.

Miscellaneous good mentionable

  • The phone came with a screen protector installed right out of the box.
  • The included charger is fast, even tho it makes the device heat up quite a bit
  • The little orange configurable button on the side should be a norm in all phones.
  • Design of the phone is a real head-turner, people ask about it
  • Display is good enough, not unneccessary pixels to suck up processing power.
CAT S61's programmable orange button
CAT S61’s glorious programmable orange button

The bad things

Missing fingerprint sensor

Oh my god this took a while to get used to. Coming from Honor 8, I had used the fingerprint lock to banking apps, lockscreen and basically everything that allows it. It’s a huge convenience and Ive missed this since I moved to S61.

Visible Light Camera

The main camera of the CAT S61 is terrible. You can use it to document stuff and use it to take notes for example, but if you are looking to publish beautiful photos on Instagram, this ain’t your tool. It has all the basic camera functionality and would have been acceptable 5 years ago, but not today.

The camera is good for what its intended for, drawing lines in the thermal images to make them more clear to read. Without this feature the thermal images would just be a coloured blur.

Sample image straight from phone (click to open)

The smartphone is BIG and heavy

The most common comment I have gotten from people who have handled the phone has been “well this feels like a tool” or they have described it as a weapon. It might just ruin your pants if you slip it in the pocket of your skinny jeans.

Being a ruggedised smartphone this should not be a problem unless you drop the phone on your leg or something, it will make a dent.

User interface

I have failed to answer many important phone-calls because I ended up clicking the red phone key while getting the phone out of my pocket.

Water-seals are annoying

When you plug the phone to charge or want to attach headphones, you have to use your fingernails to dig out the little protection flaps that cover the ports. These are attached to the phone even when open, they fold over and might prevent some more bulky cables from being used.

The hard-plastic part of the bottom charge port water seal came off after half a year of use.

CAT S61 headphone jack water and dust seal
CAT S61 headphone jack water/dust seal

Clicky buttons feel mushy

Navigation buttons under the display have been made with hardware switches, it’s quite a fresh breath of air in the smartphone market to bring out mechanics. Buttons are good as they work with gloves etc. but they feel quite mushy, are loud and take some getting used to.

There is no satisfying click

Mushy buttons of Caterpillar CAT S61
Mushy buttons of Caterpillar CAT S61

LASER rangefinder is quite slow to use

You can use the phone’s built-in LASER to measure distances up to 8 m. It works with the camera of the phone and calculates the distance from the photo, basically where the dot is. This process is quite slow and does not replace a roller measure.

Whenever I have needed to measure something, the accuracy of the phone measurement has not been enough (cm precision) when I usually need the measurement within few millimeters.

CAT S61 Range finding feature
CAT S61 Range finding feature

The red > 1mW LASER beam is reasonably bright and works super-well for biological cats. With this phone, you will always have one with you.
LASER I mean, not a cat. Even thought the back of the device says CAT.

It’s not rootable

At the moment of writing this article (29.1.2019), this might be a good thing if you want to keep your mobile payment apps like Google Pay in working order, but it is poison if you want to do stuff like edit Android’s own hosts-file to block Facebook from tracking you.

At 29.1.2019 Caterpillar CAT S61 is not rootable.

No accessories

I have magnetic phone holder in my car that has a metallic sticker you glue into your phone. With regular phones you can easily slip those between the phone and the cover, in this one this is not an option.

The back-side is rubberized, so the sticker probably would not stay nor it would not look good. The phone is rather heavy and needs a sturdy grip mechanism to mount it properly. I don’t think this would me anyway mountable to the vent-fins in the car without wrecking them on the nearest pothole.

The phone is so “rare” and mechanically weird, that there is basically no accessories for it. No custom cases, no charge docks etc.

Bad mentionables

  • Stop telling me about LASER-safety every time I start a milliwatt class LASER
  • FLIR apps take forever to load
  • FLIR app sometimes fails to load correcly, visuals work but thermal imaging does not. Took couple of reboots to fix.


Main reasons for me would be the poor main camera and the inability to root the phone and missing fingerprint sensor.

Caterpillar CAT S61 works for me now, would not buy again.

Henri Rantanen, 2019

Sure, it is rather a cheap way to get into thermal imaging, but you can get USB-add on to your regular-people phone.

Build quality is good, software hasn’t had any major issues and it works as you’d expect any Android to work.

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