NEW Brymen Bluetooth BM787BT Multimeter

[BILLPOD]

Thank you for the distance test on your $50 phone.   I haven't done any open air distance testing, but I'm sure my $80 BLU 61S couldn't have done as well.  Indoors, the walls and floors do have an impact on distance, but my 6 ft. max. is in the same room with nothing between meter and phone.  I'll have to try Mother's phone, but prying it from her hands is another difficult challenge.   I'll try a used phone off Ebay and see what I get.    I love your dog; she is a real sweety.   Thanks very much for your help, Joe.

[joeqsmith]

Glad to help. 

[joeqsmith]

Dave's hiding the battery life testing for the BM787BT under his review of a UNI-T meter.   I asked Brymen about the spikes.  Sounds like they try to put it into sleep mode as much as possible to save battery life.   " BLE power consumption in Active mode is much more than in Sleeping mode and introduce those current spikes.  "

https://youtu.be/dv3kIiqOQOw?t=1819

[EEVblog]

Apple shoe phone test:

[mlord]

Thank you for the distance test on your $50 phone.   I haven't done any open air distance testing, but I'm sure my $80 BLU 61S couldn't have done as well.

The BLU G64 has Bluetooth/BLE 5.0, whereas the older BLU 61S has Bluetooth/BLE 4.2.
There's a 4X range improvement with 5.0 compared to 4.2.

That may explain why the BLU 61S isn't doing very well with distance.

[joeqsmith]

Apple shoe phone test:

It would be very interesting to see if you can replicate that 10x fault with that iPhone. 

I mentioned that you could use Wireshark with that Adafruit BLE radio to sniff the traffic.  It turns out that it does not support the larger MTU sizes required by Brymen, or at least I could not figure out how to make it work.   Not having the proper tools to debug it,  about all I can do is run it. 

***
One other thing that may be helpful... When running their application, it shows the min and max readings.   I only check the test a few times during the day and have never seen the max display anything odd.  Have you?

[EEVblog]

Was testing last night but the battery pack and phoen died, so lost everything.
The iOS app stops logging and prompts to save data if the phone goes out of range. That's annoying, what if there is a short interruption? I'd rather have a bit of lost NULL data in that case than the logging stop.

[joeqsmith]

The iOS app stops logging and prompts to save data if the phone goes out of range.

The older version of the application lost everything when the connection drops.  At least now it allows you to save it.  I am not sure how they handle disconnects now. 

I keep the phones plugged in when running these longer tests.   Currently both are at about 1.5 days.  The peak readings are still at 1k.

[joeqsmith]

I did open circuit the meter during the test.  The max went to OL as expected and remained that until I decided to restart it today.   I would expect if it glitched, we would see the max level reflect it, but also, I have never seen the 10x spikes in the plots while collecting data. 

[EEVblog]

Today I was logging at home on the iPhone, phone upstairs, meter downstairs, was logging fine for hours until I was standing there watching it when I switched on the room light and the meter stopped logging and asked me to save the data. Not sure if the light was a coincidence or a cause, but it was within seconds of the event.
It would then not reconnect at all to the meter regardless of how close I got. I had to restart the bluetooth on the meter before it would reconnect again.

[joeqsmith]

Do you feel the original version of the application more robust as far as the recovery?  When I could get my phone to connect, if the connection was lost, it was pretty much game over.  I posted about that here:

https://www.eevblog.com/forum/testgear/hear-kitty-kitty-kitty-nope-not-that-kind-of-cat/msg5886596/#msg5886596

The most recent version of my software waits up to 4 seconds for meter to send the data.   If nothing comes back, I keep the port open but turn off the notification (stops data collection).   I then check if the meter is advertising.   If it is, I resend the password and notifier, then restart the collection.  If the meter is not advertising, it waits until it does or until I stop the collection.  When I was trying to sort out how to recover from a disconnect, Brymen had told me that I would need to resend the password. 

I had tried temperature, battery voltage, sweeping the resistance over a small range, and using my spark gap transmitters to create some RFI.  None of these effected the link.   
https://www.eevblog.com/forum/testgear/new-brymen-bluetooth-bm787bt-multimeter/msg5916858/#msg5916858

But having the meter sitting right next to the phone, with nothing in the lab running (little RFI) and no traffic, then the phone disconnects.   

[EEVblog]

iPhone data logged all night, stopped it to save and got a "Extreme Memory Usage" warning, but it let me save the data anyway. But then it went into a doom loop and repeated the sam thing again, and again, saving each time and never exiting.
It looked like the multipe files were there and it said syncing to iCloud, but I look an hour later and the files are not on my iCloud.

[joeqsmith]

When I used my wife's iPhone, I don't think I actually saved any data.  With the Androids, I have not had a problem saving local outside of it can take several minutes to save several days of data.   Doesn't the iPhone allow saving it to local? 

I have about 2.5 days now with their updates.  The one phone was reset after I forced the open circuit, but the other has been running non-stop.  Both show a min/max of 1k.  I plan to keep a closer track of the min/max until the meters disconnect.   There may be a clue.

[EEVblog]

Doesn't the iPhone allow saving it to local? 

Yes it does, but the iCloud lets me easily access it from the lab.

[joeqsmith]

I noticed how often updates/patches are pushed.  I have no idea if this causes a problem during the data collection.  Two of the phones have no sim card, and the other has no plan.  I disable networking during these longer tests to minimize the number of variables we are dealing with. 

[EEVblog]

Another Extreme Memory Usage warning after a few hours last night. The iPhone app looks troublesome on my iPhone 11 Pro.

[tautech]

Another Extreme Memory Usage warning after a few hours last night. The iPhone app looks troublesome on my iPhone 11 Pro.

I imagine the IOS version is more important for bug diagnosis than the iPhone model #. 

[joeqsmith]

My wife's is an iPhone 12 Pro Max.  One this long term test completes, I'll try it out overnight.

[EEVblog]

Another Extreme Memory Usage warning after a few hours last night. The iPhone app looks troublesome on my iPhone 11 Pro.

I imagine the IOS version is more important for bug diagnosis than the iPhone model #. 

It's the latest 18.whatever

[tautech]

Another Extreme Memory Usage warning after a few hours last night. The iPhone app looks troublesome on my iPhone 11 Pro.

I imagine the IOS version is more important for bug diagnosis than the iPhone model #. 

It's the latest 18.whatever

That Apple broke some of their own functionality with recent IOS updates and it took a further 2 or 3 updates to fix their shit so some consistency on the IOS version that you report any logging issues to Brymen might be a good idea.
On 18.5 here......

[joeqsmith]

When I checked, both meters were powered off.  Sadly, the one charger was unable to keep up with the phone and it also powered down.  This caused it to loose all that data.   

1)Slow down of the application while logging
2)Phone dropping the connection at random (not battery, low signal or outside RF interference)
3)Unable to reconnect after a connection was made (requires restarting the application)
4)Recorded data is 10x higher than actual and outside of meters range *1
5)If phone powers off due to low battery, data is lost *2

*1 This last round of testing, using both meters for 4 days, the problem did not replicate with the latest updates from 7/11/25. 

*2 I am not sure why they don't ask for the file name first, then stream it to NVRAM rather than keeping the data in RAM. 

[joeqsmith]

Another day of logging complete.  The cheap phone did not come with a charger and I have changed over to a 2.5A one.  Seems to be keeping up.

I had looked at the data from the previous run and there were no 10x faults.  The only disturbance was when I open circuited the leads.   My plan is to run these two meters for the entire week.   

[EEVblog]

Apple logging overnight, went to save, and then the app shut down losing everything. iOS 18.5

[joeqsmith]

Can you use it to log over any length of time and save?  Say 10 minutes?   

Does the iPhone slow down like I have demonstrated with the Android?   With it appearing that they keep everything in RAM while logging, does your iPhone run out, or does the OS start swapping to NVRAM?   

***
Also, have you turned off the wireless networking, cell phone carrier ... to make sure that nothing was going on in the background?   

My plan is to just run the wife's phone as is and see what happens but that's for a latter date after I finish this round of testing. 

[iMo]

With android I've been using this BT terminal on my dedicated vintage Sammy S6 for logging .csv data off my 34401A:
https://play.google.com/store/apps/details?id=de.kai_morich.serial_bluetooth_terminal&hl=us
Logging works also in background and when the phone "sleeps" as well. Many settings..