Author Archives: mirek

Mega power bank (93000mAh)

Friend of mine  wanted really big power bank for his camping. So I made one. I bought brand new Xiaomi Mi 18W Fast Charge Power Bank 10000mAh and took it apart. After removing original cell, whole powerbank was cut by hacksaw. Cutted part nicely fits to 3D printed enclosure. With help of my trusty spot welder I made 1S30P from recycled 3.1Ah Li-Ion cells. Resulting battery is 3.6V/93Ah (330Wh) nominal. It will take some time to charge.. 🙂 For faster charging there is XT60 connector embedded in the case.

C1 Chaser FPV build

Got myself C1 Chaser wing. Built for DJI Digital FPV system. My intention was to buikld it as clean as possible.

  • C1 Chaser kit
  • FC: Matek F405-WING
  • DJI Digital FPV system
  • 30A BlHeli32 ESC
  • Emax analog servos
  • Dualsky XM2830EA-8 motor with 7×5 prop
  • 4S1P 4Ah made from 21700 LG cells.
  • OpenLRS at 868MHz with inegrated balun for dipole antenna
  • INAV 2.5.1
  • EDIT: All Up Weight is 837g

Everything buried inside a foam was carefully CNC milled.

Finished plane:

Photos from build:


Recently, I have acquired a few professional radios used in taxi service for a good price. Radios are very well made, very rugged and probably very reliable. They are VHF only. Service manual with full schematics and programming software is available.

After searching Internet back and forth for some information and software i have finally gathered all I need and I will share it here.

Programming cable

Original cable is supposed to be ICOM OPC-592. By looking at the schematic I realized it is simple one wire TTL-UART. In the past I hacked together same interface for Alinco DJ-X30 scanner. Here is the schematic:

If you do not have this “FTDI” interface, I would recommend buying one with Silabs CP2101 chipset. That one is least problematic. FTDI and Prolific are often fake chips and driver refuse to work with those.

My ugly hack cable:

If some wants ready made cable, leave a comment and I can make it for you.

Programming (cloning) software

Deep down on the web there was installation files available for download. I believe this software was sold by ICOM, but it is more that 15years old (and still works well on Windows 10). I think no one will be offended if I mirror it here. I consider this abandon-ware.

Do not ask me how to program X or Y, I still do not know. There are many options related to trunk operation in professional segment and I have almost no clue. I was able to program channels to get to my repeater and open VHF channels.

Download the software CS-F1600 CD-221501-003

Service manual

ICOM service manuals do not stop to amaze me. One can learn so much by studying their block diagrams and schematics. It is invaluable to have it. I also own very old ICOM IC-240 from late 70’s and with help of service manual I was able to fix it and make new VFO unit for it!

IC-F1610 Service Manual



New battery for ebike, part 2

Main positive and negative conductors are made of copper strips cut from sheet. Strip ends go trough fiberglass part where end are folded back to secure the strips in place.

Detail of balance wires and connector. Output cable is already soldered on copper tabs.

Whole battery


Battery housing. Intelligent BMS and all the wiring in place.

Plywood separating battery and BMS space

Cushioning of battery compartment with foam. There is fiberglass “floor” (with blue foam).

Battery fits tightly and does not move with lid on.

New battery for ebike, part 1

This is the temporary battery. 12S / 7700mAh. Battery is a few years old but still can give 250Wh of energy. I did over 200km on this one. Range with this one is between 10km to 20km depending on speed and pedaling. It is made from two old 6S Li-Po donated by Vladimir L. Thank you!

New battery is Li-Ion 12S 8P made of Samsung INR18650-30Q cells. There is 96 of them. I used plastic trays and paper stickers for + pole as additional safety isolation as the included plastic spacer in battery can potentially melt during welding causing short.


Welding was done by my trusty Spot Welder.


Next step is to get amperes out of battery. There is always problem of getting output current from end of battery of this kind. Nickel strip is itself not enough to carry big currents. I got myself 0.5mm copper plate. I used my CNC to  mill copper comb which is soldered to ends of nickel strips. Negative pole is simple. The stub is for soldering thick cable. Positive side includes custom made fuse holder.


That’s it for today. Battery still needs all wires soldered and some basic isolation. Last step will be to replace temporary battery with this one and enjoy range between 30km to 90km depending on how hard I will be on throttle.




Ebike update: chain works, new handlebars and electric brake

Got myself half twist throttle. Old thumb lever is now used as brake. It is much more comfortable. Electric braking works great! Thanks to enormous direct drive hub motor, braking force is huge. Only very steep hills cannot be braked with this alone. Slowing down before turn can be almost always done with ebrake. Brake pads will probably last eternity. Braking does charge battery, but recovered energy is insignificant in long run.

VESC speed controller manages braking in very clever way. When speed is high enough, it PWMs motor phases to actually boost BEMF voltage higher than battery – current flows to battery. When RPMs are too low, it just shorts phase wires and all the current flows inside motor phases. In this mode which engages at ~6km/h motor is hard to turn.

This bike has non-standard steering stem of 21.2mm diameter for 22mm handlebars. No standard part of today’s era fits. 🙁 Clamp for handlebars is 22mm. So I needed to find tall handlebars (but no ape hangers) for 22mm clamp. After a lot of searching I finally bought handlebars for Simson Enduro 50cc motorcycle. Little heavy but very solid with shiny chrome. On the left there is heavy duty cell phone holder from RAM-MOUNT. I love it and also use it on motorcycle.

I got myself the biggest and most comfortable seat available in the store. Also new seat tube with clamp. Old one is incompatible. End of ass pain.

I managed to fit freewheel on motor and now I am able to pedal. Nice and slow pedaling saves me about 100W of power. And provides backup in case of drive failure. From ~6 test rides, nothing faulted yet. I am playing with idea to make it fix gear. That would save cables and levers on handlebars for other stuff. And less to go wrong. With motor I never needed to shift anyway.

I bought new tires, suitable for ebikes. Schwalbe Marathon Plus Tour. Not exactly cheap but they work well. Even for light offroad. Rolling resistance is lower.


A lot of other stuff needs to be sorted out. But I love this machine. With tall handlebars I can finally ride it without pain. Riding position is very natural and comfortable.

Li-Ion spot welder

Almost two years ago I decided to build spot welder for batteries. After researching my options I choose construction by Albert van Dalen

It is microwave transformer based, controlled by arduino. It switches primary side with two big-ass thyristors. It also does peak detection of sine wave, to turn on welding exactly when phase voltage is highest. It uses double pulse method. Read his article. I think this is best free construction you can build.

I bought Sunkko welding tweezers. But those are crap. I dissembled them and created two independent swing arms. Arms are long enough for very big battery. Pushing force is adjusted by hand. There is a pedal input to keep both hands for welding.

I measured current trough secondary side with Rogowski probe. It was not during welding, but output was connected firmly together. Over 1200A, nice 🙂

And here is some examples of batteries made with this one:

And this one is done with my spot welder by friend of mine whom I borrowed it.

OpenLRS Tx v1.5

Just another version of OpenLRSng Tx.

  • Open source
  • RFM23BP powered from own adjustable supply
  • Full power of 28.5dBm (700mW).
  • Improved cooling by soldering RFM module to big uninterrupted ground-plane from bottom
  • Atmega328 at 16MHz  powered from 5V, no EEPROM issues as with 3.3V@16MHz
  • True voltage level converters between SPI of RFM and AVR
  • Ready for LCFN-490 filter (with one track cut)
  • Without filter 2nd harmonic at -5dBm, 3rd harmonic -3dBm
  • PPM input buffered and protected (for old radios)
  • Power switch onboard
  • Uses BOARD_TYPE 4 hardware connections
  • Fits in nice aluminum box from Fischer electronics

KOLRSHPTX15 Eagle 6.4.0 files