Tronsmart Mega Pro 60 – battery design fail

What are the symptoms?

After a year or two (but not heavy usage – mostly lying around) speaker was unable to charge to 100% (also charging never finished) and Bluetooth showed at best 90%. Immediately after charging disconnect, it dropped to 60% or even less. While playing, it could barely withstand 30min of playback.

Wild guess would be the battery issue – I’ve assumed that manufacturer used some crappy lithium cells and that how it ended. I can’t confirm or deny this now – since definitely, by how they where charged, it damaged them a bit  – but they seems to be around 2500mAh, so decent.

So what is/was wrong?

Speaker have four 18650 lion cells, grouped by two. This gives around 7,4-8V total. Contrary, to what I’ve supposed before dissembling it, it had 2S lion protection board installed (on the first battery pack, under the shrinking tape) but it’s missing balancing feature. So one pair was charged to 4,4V and another was 3,3V. BMS (let’s call it this way for now) was cutting charging off (overcharge protection of one pair), but never reached top voltage (so charger IC was still trying to charge it – it’s a separate component on the main board – not on BMS). The other pair was all the time undercharge and quickly dropped to undervoltage protection, that’s why speaker could only play 30min or less.

In theory, if the cells are equal quality and used proportionally – this unbalancing could not have happened or took much longer time. But usually designers do some shortcuts (this is often in power cells for hand held devices – drills etc) and sometime power the low current BMS electronics with only one pair of batteries – because it’s easier – pushing cells to imbalance (I’ve seen this behavior in few Parkside and Makita devices). This is just an example – but it shows the idea.


Tronsmart Mega Pro - new BMS
Tronsmart Mega Pro – new BMS

So what it takes to fix the issue, is to use BMS with cell balancing and replace broken cells. In my case one of four cells where totally broken (unable to fully charge and was loosing charge).

I’ve used HX-2S-JH20 BMS board – plenty of those on Aliexpress for few bucks – because I had it at hand.

Oh and I forgot to mention – I have two of those speakers, and both face the same issue – so it’s not a fluke 🙂

PhotoTrap V2

ESP32-Cam based photo trap

So, we meet again – with esp32-cam board 😉 . My first encounter was rather disappointing. I’ve tried to used it for streaming, and the image was poor quality (OV2640) and what is more troublesome, the board itself was unstable.

Recently I had a need, for some kind of Photo Trap – to see what animals are finding food (that we left for them) close to my land. It could be moose or some kind of deer. Of course I could buy one, but where is the fun in it – and it would be probably much worst. The one I saw was old type, powered with four AA batteries etc. but it had also cellular modem used to send MMS with picture 🙁 in 21 century.

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Agregat prądotwórczy Smart (sm-01-3300inv) 3kW – krótka recenzja

Kilka moich spostrzeżeń na temat niniejszego agregatu. Szukałem czegoś relatywnie taniego i z sensownej jakości prądem na wyjściu. Szukałem czegoś powyżej 2,5kW by zasilić piłę (lub inne narzędzia w garażu).

Oczywiście najbardziej cieszył bym się z jakiejś porządnej Yamahy lub Hondy, a już zupełnie z dobrej instalacji fotowoltaicznej i akumulatorów LiFePo4, ale.. no nie ma warunków 🙂

Tak czy siak, Yamaha to dużo ponad 4kpln a taki Smart “tylko” 1,6kpln.

  • Generator działa – to pierwszy plus :), przetestowałem go na silnikach szczotkowych o mocy do 2000W – daje rade.
  • Przetestowałem całkowite, chwilowe obciążenie ciut ponad 3,5kW – piła, wyciąg, grzanie olejowe i ładowanie akumulatorów – było ok.
  • Działają zasilacze (laptop, modem, kamera), piły i kompresory – zarówno na silnikach szczotkowych jak i indukcyjnych.
  • Niestety wahania napięcia są wystarczająco duże, by było dostrzegalne miganie oświetlenia diodowego (jarzeniowe – mniej).
  • Jedyne co nie potrafiło pracować na nim w warsztacie, to przełączniki Sonoff (zwykłe S26 i x4) – ciągły reset, próbowałem zwiększyć im kondensatory na 5V – nie pomogło Okazuje się ze jednak działaja – mój błąd w konfiguracji.

Jakość sinusa jest przyzwoita (ale daleka od “sieciowego” czy z inwertera sinus), wypełnienie i okres również – poniżej zdjęcie z oscyloskopu.

Parametry prądu z agregatu

Update – 29.01.2021

Po kilku miesiącach użytkowania mogę zdecydowanie polecić urządzenie. Przepracował powyżej 100h i wszystko jest w najlepszym porządku. Trzeba regularnie wymieniać olej i czyścić świecę – inaczej zdarza mu się zgasnąć. Ale do tej pory robiłem to 3 razy.

Głównie używam go w trybie Eco – przy obciążeniu ok 1kW. Ale przy pile i wyciągu czy kompresorze trzeba wyłączyć Eco (co niestety wiąże się ze spacerem do agregatu 😉 ).

Jedyne co bym poprawił to dodał jakiś autorestart samego generatora prądu. Bo jeśli przeciąży się agregat (głównie w trybie Eco – w normalnym nie udało mi się, ale też nie próbowałem), to niestety silnik pracuje dalej ale generator się rozłącza. W efekcie jedyny sposób na wznowienie pracy to restart całego agregatu, a to trochę upierdliwe.

Kankun smart plug OpenWRT upgrade

During recent cleanups of all my IoTs devices, I wanted to disable Kankun reporting to company servers (I’ve moved everything to customs firmwares like Tasmota or Espurna with House Assistant to manage it – so I don’t want any third parties) and also it seemed to be a good idea to upgrade OpenWRT on it.

If you haven’t seen this type of smart plugs it’s a little nifty device. Comparing to recent Sonoff type smart plugs – that utilize esp8266 (that I like a lot and use with all type of other projects – but mostly ESP32 now) – this plug has Atheros AR9330 rev 1 chipset with full OpenWRT Linux on it. If you want to do more, than just on/off operations it’s just perfect device.

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PIDKiln v1.2 update

I’ve just created v1.1 release of PIDKiln, and bumped development version to v1.2.

Most significant change in release 1.1 are:

  • replaced MAX31855 library with another one – it’s much cleaner and easier to modify
  • much better MAX31855 error handling, both with thermocouple and MAX31855 itself
  • introduced network logging with syslog protocol – so you can watch all debug information on remote host
  • all logging settings are now in Preferences
  • compressed local JS, and created separate Preference setting to allow remote downloading of JS scripts (Internet connection required – recommended to use)

And I have also (after some 1.2 changes) first, real Kiln test run.

With two termocouples and power meters.

Source like always on GitHub.

Candle cnc 1.2b on Linux

If you would like to test latest (yet already quite old) Candle on Linux machine, you could face the same problems as I did – so few tips how to make it work.

I still think UGS platform is a better choice in many cases – but sometimes Candle may be necessity (I have found problem with UGS and Fusion 360 gcode files)..

Anyway, you may face this kind of compilation errors and configuration problems with latest 1.2b source code: Continue Reading

PIDKiln 0.9 – update

It’s time to make it look better, I don’t dare to say good :). So I’ve printed a case with all holes required, and now I’m soldering everything up.

I thought about creating dedicated PCB for it, but it probably would require double side one, and so far I’ve been only making one side PCB on my CNC mill. Other problem I’ve seen was the WiFi antenna on TTGO board. With single PCB for all components, It would be shielded either by PCB or LCD or wires. This board does not have external antenna connector (some other does). So I’ve decided I’ll put ESP32 board separately and at 90deg angle close to the plastic case. This way signal should be not blocked anyway. Continue Reading