E600, E500, E400 Cheap ECG smartwatches w. breast strap

I bought this cheap E600 smart watch out of curiosity of what a breast strap can do.

I bought the smartwatch including a breast strap, stickers, and extra band, and you can get that less tax including shipping “as an early bird” offer for $21 from here That special price has gone, other sell it for $31. (I stupidly paid $49 from another seller – silly me, at the least I was not that much of a sucker that I paid $284).

The watch alone is available for $23 (including shipping, less taxes).

 

E600, E610, E500, E400, …

This watch exists with the same internals in a number of variations, varying in shapes, displays and buttons.

E600 E610 E500 E400
Width 26.0mm ~26mm ~38mm ~45mm
Total case height 50.5mm ~50mm ~54mm ~49mm
Display dimensions, diagonal 1.47″ 1.47″ 1.92″ ø1.39″
Display dimensions (mm) 17.7mm × x32.9mm 17.7mm × 32.9mm 31.5mm × 37.2mm ø35.3mm
Display pixels (mm) 172 × x320 172 × 320 240 × 284 ø360
Display DPI 247 247 193 259
Thickness less protrusion ~11.6mm ~11.6mm ~12mm ~11mm
Thickness incl protrusion 13.95mm ~14.2mm ? ?
Thickness with breast strap 21.0mm ~21.0mm ? ?
Control beyond touch none! none! yes, one (rotary?) Yes, two

The E610 dimensions, are estimates as almost identical to the E600, less the left side electrode removed, and the right shortened.
(I have ordered the E500 and E400 also, so will revise info above when I get them)

The lack of real buttons on the E600 (E610) is bad when used on a breast strap, as you can not disable touch…. (That is why I ordered the others too…)

It seem the that the E600 has been (or is being) superseded by a E610 with identical specs, slightly different sides (less the left side electrode removed, and the right shortened), and less smooth transition between case and band. The right side of the E600 is not a real button.

Here to rendering images with exaggerated displays (not real photos)

But I guess they in ads can claim the E610 as shorter, excluding the arms, but that is just marketing BS, it is really the same size, and they have NOT upgraded the display to AMOLED..

I think the E400/E500 in similar ways  same ways are upgraded to E420/E530. The info on the various models are a little ‘flaky’ so not quite sure what is correct, and what perhaps have been updated internally too.

I am unsure if the ET580/E481 are further upgrades or competitors. They come with amoled, and different chips, and does not seem to be supporting breast band. So I think competitor is the most likely. The ad material also seems substantially different.

 

E600 Exterior

It does not feel as cheap as it actually is (!), but it is not signalling premium exclusivity either… The back is just plastic.

Here a few real-life images. With the first the same as the ad-image above….

Note that I have the brightness set at just 4 of 12 on the watch, but had the background light in the room cranked up high, so the display is far from as bad as the images here could indicate. The reading angle should be fairly straight on to have a good image though, some +/- 45° perhaps. It has been grey and rainy for days, so have not tested the outdoor legibility. There are no ambient light sensor to regulate (AFAIK). Here with full light and straight on (ambient light cranked up at same high level)

The band attachment is quite well thought trough! It can go in any direction from straight down around a 4½cm wide very small wrist, to flat out for as large as you can get a band! And this is done without it looking ‘odd’ at any angle.

So in that aspect is can suit a large range of different arm-sizes. (Strictly it can even go narrower than straight down, but that is rather academic…)

The band uses a standard 20mm pin attachment, so there are zillions of alternatives to match personal taste out there.

The sensor block (17.6mm x 24.1mm x 2.6mm), is so big that it really is the shape of the back rather than a “protrusion” seen on most, and talking about how much less thick the device is outside makes little sense. It is so big that the edges of the house is hoovering over the arm.

So it is not that it is particularly wearable, and it feels really clumsy compared to my T8 on the other arm (yes wearing both while testing), and the shirt certainly easily got caught

compare that to the T8:

 

The E600 got no physical buttons. No microphone nor speaker. No NFC nor GPS.

They are focussing on the health aspect. So not a complaint, just a fact.

You can read notifications and control music though.

The display is simple TFT, so no AOD as it is not AMOLED, e-ink or lcd.

 

Specs

Here from one source, I have not been able to find out the manufacturer… But it MIGHT be Shenzhen Shengye Technology Co.

Hardware Parameters
CPU GR5515
RAM 128 MbFLASH
Display 1.47-inch 172 x 320 HD touch screen (E600 only)
Touch Panel Full Touch Screen
ECG chip TYHX3220
PPG chip SFH2201
Blood oxygen GH3220 RF analog front-end+ SFH2201
G-sensor Rohm KXTJ3-1057
BT Version 5.1
Battery 160mAh Lithium Polymer Battery
Stand-by Time: 30Days
Typical Use Time: 7Days
Certificates: TO BE DONE
GPS No
Vibration Motor Support
Speaker No
Microphone No
Structive Components Parameters
Middle Frame Zinc Alloy
Middle Frame Color Default Black Color
Back Case PC+ABS
Straps Silicone,Leather
Button 1 Buttons
Charging Structure Magnetic Pins Charing
Waterproof Level IP68
Function Parameters
Watch Languages Available in Russian, Hungarian, Turkish, German, Italian, Czech, Slovak, Japanese, French, Polish, Persian, simplified Chinese, traditional Chinese, English, Portuguese, Spanish, Vietnamese, Arabic, Korean
APP Languages Chinese (simplified and Traditional), Korean, Japanese, English, German, French, Italian, Spanish, Portuguese (Portuguese), Russian, Hungarian, Turkish, Indonesian, Polish, Czech, Greek, Swedish
Sport Modes Multiple motion mode.
Health Functions Intelligent ECG blood glucose health watch, ECG, chest patch real-time ECG analysis, ECG monitoring, non-invasive blood glucose, heart rate monitoring, blood pressure monitoring, blood oxygen monitoring, exercise record. Sleep monitoring,
Other Functions 1.39-inch 360*360 HD touch screen (E400 only!)
multi-exercise mode, custom dial, online multi-dial,call and message reminder, ultra low power consumption and long endurance.Metal alloy case, silent alarm clock, remote photo, music control, sitting reminder, drink water reminder, weather display, countdown, shake to take photos, mobile phone search.
BT Push Information Twitter, Facebook, Gmail, WhatApp, Messenger, QQ, WeChat, News, Texts etc.
APP Name H Band

It seem the that the E600 has been or is being superseded by a E610 with identical specs (AFAIK), slightly different sides, and less smooth transition between case and band. It still is not a button, but only an electrode on one of the sides. And the same ‘soft button’ for home.

But I guess they in ads can claim the E610 as shorter, excluding the arms, but that is just marketing BS, it is really the same size, and they have NOT even upgraded the display to AMOLED…

 

Battery & Stamina

The “low power consumption design” shall be taken with a pinch of salt, to say the least.

The initial days with all monitoring ON and dozens of ECG-tests, I think the stamina was about 2-3 days. I see NO indications with a percentage, just an icon, in either the app (two places) or on the watch. While charging is it also just an icon, so a little hard to really tell how fast it discharges. It charges with just 0.05mA , and at the end to as little as 0.0375, 0.025mA, and finally 0.0125mA!!

I charged it fully. And with all sensors on, it did an AutoOff after 5 days and 7 hours, BUT it began stopping recordings after precisely 4 days, some ran a few hours extra(??).

So the conclusion is FOUR DAYS sharp. And that is with all sensors active, BUT no manual ECG or exercises.
It charged the first about 750% in 1½ hour at the ‘full’ 0.05A. And shortly after that it starts reducing, to 0.0375A.

After two hours (less two minutes) it says “Charging complete” briefly, but still pulls 0.0375A then 0.025A and finally 0.0125A

All in all a FULL charge to it pulling less than 0.01A. took three hours (perhaps less a few minutes).

All in all quite underwhelming in the power handling!!

 

Breast strap

I struggled quite a bit with the breast strap as the images in the manual and the listing are self contradicting, and thus wrong!

You can unfortunately physically attach the watch in either way on the plastic plate, but the orientation matters, and the orientation of the band in the images was wrong too!
The watch should be attached to the plate with the home ‘button’ towards the small text “ECG” (the side with one electrode). And when worn, this end should be away from the heart. That is the end with two electrodes towards the heart. It shall be worn quite high, above nipples height (they have hinted that slightly in image 04 below).
Here I tried to correct the image from the ad, by rotating/mirroring various elements!!! (marked what I did with green arrows.)

(The same four images are in the small manual that came with the band)

It is fairly easy to swap usage between wrist band and breast strap usage.
Very surprisingly the the breast-strap is NOT for ECG measurements only!!
Despite they can not use the optical sensor, so you can wear it at the breast and have it do all the other health stuff too!!

Despite what the images indicate, you do NOT need to remove the band ends. Here I clicked it onto the plastic plate

Obviously if you are not wearing some shirt or T-shirt over you will have the two band ends dangling, here the plate clicked on the band mounted.

If you want to use the strap for ECG-testing only, it requires you to be at rest anyway (measuring while moving not supported, and reports as sinus arrhythmia), so in that case the dangling ends are not really an issue, and much to prefer over fiddling with detaching and re-attaching the two ends of the band every time IMHO.

If you want to use it primarily with the breast strap and not on the wrist, you obviously should detach the band.

Mounted it sticks out about 2cm from the back of the band, and though that may sound a bit much, you actually do not notice it when wearing a normal casual shirt. (or a shirt and a tie). If you are wearing something tight like a T-shirt I guess it will be visible and look a bit odd though, if worn when not exercising.

Especially with this usage it is lacking an option to select to temporarily disable the touch and display, so there is a risk of inadvertent interaction (and waste of battery).

If you place it a bit lower on the breast you will get a more clear R pulse but a less clear T and P pulse (see below ECG section for letters)

Here the back with the three conductive lanes (click to enlarge..)

 

Health functions offered

It offers the following monitoring, that can be selected on/off individually, but monitoring is at a fixed 5min interval for (almost) everything.

Monitoring 24/7:

  • Heart Rate (every 1 minute)
  • Blood Pressure
  • Blood Glucoserubbish, see later.
  • Body&Skin Temperature

During sleep:

  • Sleep quality (Duration, Awake, Preparation time, REM, Light and Deep, falling a sleep efficiency, sleep efficiency)  – most rubbish see later
  • SpO2 (OAAHS: Apnea, Respiratory rate, Hypoxia time, cardiac load, range of sleeping activity)
  • HRV

On demand

  • ECG and PTT, finger held (01), Hand held (02), breast strap(03) or stickers(04) – numbers see above image
  • SpO2 (in addition to the optional during sleep)
  • (the four options from monitoring 24/7)

And apart from that the usual sport and exercise stuff that I do not care about.

See next sections for implementation.

So it offers way way more info than my T8, even when just worn on the wrist!!!

 

Sports

It also offers monitoring steps, distance and  calories as well as a number of workout stuff I do not care about.

 

The App

The app is “H band” in the android Market (And I think at the fruit store too), and I found it a little tedious at first, getting things to work, but it offers a lot of data and analysis, for anyone interested once things are working.

Obviously the quality is no better than the measurements, and I do not take it too seriously.

e.g. a sneeze during an ECG, was recorded as Sinus arrhythmia…

Should I show all the screenshots from within the app, it would be scores!

But here some (as usual click to enlarge)

 

Sleep

The Sleep graphs looks like they are very detailed at first glance

.. but actually it is just pure garbage!!! As can be seen from this example for the next day I added to this post.
The extremely short duration of almost all of each claimed type of sleep is a hint that something is just utterly wrong, and looks almost random.
It also missed that I woke up shortly. I know for sure I did at the least once. The T8 claims twice, cold be correct.

You can turn off the Sleep monitoring, but this will also turn of the HRV, that (like the SpO2) is only active while it detect you as asleep.

It works equally bad worn on the wrist or breast.

 

Heart rate

I have no real comparison for most of it but the plain heart rate I can compare with the T8 while the E600 is on the wrist.

I have not tried to dig into the details, but it looks fairly the same, with a steep drop as I went to bed roughly 00:30. The odd straight green line on the E600, is because it (incorrectly) just connect the dots over a period where the watch was off (14:33-16:08), if I click for individual minute measurements). Not a big bug though.

 

Blood  Glucose

The curves got three daily peak, worn on wrist or breast strap, but as it is EXTREMELY rare that I have three daily meal, and the meals I have can be at rather random time of day. It also vary from anywhere between 00 and 03 when I go to bed, and more often later than that than sooner… So I will have to conclude that this is just UTTER NONSENSE!!!

See this, click too enlarge.

The strange ‘missing’ evening top on 2024-02-10, and later completely missing, is at the time I let it drain completely and it shut down various measurements asynchronously, so that is a tolerable glitch, we just have to remember to charge it frequent enough.

 

Blood Pressure

I found this text on this:

Research has shown that pulse transit time (PTT), which is the time delay between the electrocardiogram (ECG) signal and the signal from a photoplethysmogram (PPG) sensor, can be used to estimate systolic blood pressure (SBP) and diastolic blood pressure (DBP) without the need for a cuff

Pretty amazing that it can be done, but now I at the least know how…….

 

ECG and PTT

Taking an ECG you are supposed to relax and avoid eating a few hours before. But of course I tried to stress-test that, to see how it reacted…
First I took two successive tests fairly relaxed, with a pulse around 65. I then took another test still sitting and lifting an about 20kg load on one foot, raising the heart rate to 90, but still everything fine. I then tried the load moved to the other foot, and that raised the pulse to 102, and the ECG correctly concluded “sinus tachycardia”, as over 100.
But the output seems fairly consistent, as long as you sit still during ECG measurements. Of course the conclusion of an ECG recording is wrong when taken during exercise… But for those with more understanding of these things than me, there might still be interesting information to pull from the offered graphs-reports during or after some exercising.

 

It is quite clear that if the sampling rate were higher, the details would have been better here. When a peak is much less than its neighbours I highly doubt that it is my heart not producing the peaks at about roughly the same size, and it is clear that when the pulses are narrowed to 90 and then 102 bpm, it struggles even more with getting the peaks in a consistent height. With a sampling frequency of 512Hz, it got 480 samlings per beat at 64bpm, but are at 301 at 102bpm, so obviously harder to get the sharp shapes right. But If the scale is the same, it is clear that ‘more is going on’ between the main pulses when the pulse increases, and I guess that is what could be expected, so I think it is doing an OK job. At the least a lot more consistent than I expected for the price!

Tried to take an ECG while wearing on the right wrist and using two fingers (method 01 in early image above), and similar on the left wrist later, and though the amplitudes are low, it can get something (I added the splash texts), I really did not expect that to work.

And this obviously is much quicker to do than mount a breast strap first, so could be interesting, to quickly record anything odd you observe is going on.
If you got very dry fingers you may need to moist them first, to get anything at all. (Note that on the right hand the image is ‘mirrored’ with the main peaks going down, a bit odd they do not detect that and mirror it for us)

With the terminology from figure 6 stolen from here, it is quite clear that the handheld at best get the R, and a vague idea of P an T, and the rest more or less drowns in noise. With the breast strap it gets all fairly distinctively. Whether the software is able to reasonably correct pull/estimate all 11 from each pulse in the data used for the plots is then a different question.

If the battery is below some threshold, perhaps 25%(??), any attempts to take an ECG are just ignored!! After pressing start, it just stops again with no error message, and redisplay the start button. If you go to the main display, it is not so low that it displays the battery icon in red. (That is deeper, maybe 10 or 20 %?)

A PTT is started from the watch, and kan be seen under ECG in the app, where recording can be started, and ended after at the least 6 minutes.

A tiny bug in the App is that should not try to do a ECG or PTT cross midnight, I guess it stores each sample with time only, and the app is not clever enough to handle that displaying the graphs.

 

Watch faces

There are a handful of fixed watch-faces, and you can download one(!), from less than fifty.

 

Bug in showing time!

When you turn on the display to have a brief look, then it often for a fraction of a second shows the time it LAST had the display on. If you are in a rush to catch a train or similar and just have a quick glance, you might end up being mislead here! I have seen other brands with the same silly bug, how anyone could ever have had the idea to display the time before updating is beyond me, it is just so utterly stupid. For some reason it seems to go for dials showing seconds only.  I have been tricked by this on a watch before, but luckily did not miss anything important.

 

Conclusion

Well I guess you can say that you get what you pay for… And in some aspects more than I expected.
I must say that I’m impressed of the details presented in the app. So if used with better hardware it might give better output.
Two functions should be just ignored though!!! The Blood Glucose seems out of touch with any reality! The Sleep-handling of the E600 seems really bad in the details, though it seems to do an OK job detecting the overall sleep period start/end (and thus length).

The E600 seems centered on the heart-measurements, and though I have no real reference measurement, except more or less verifying the heart rate. The ECG output at rest seems fairly consistent, and matches what I can count manually or se with other smart watches.

So the overall verdict must be: Good value for the money! just ignore Blood Glucose and sleep details.