Hybrid BLDC ESC & GX25 ECU

I have advanced my thinking about the power train. More specifically the details for the board that will handle generator stage has converged somewhat. This is the current idea:

• Use Brushless DC (BLDC) motor as both starter and generator connected to Honda GX25 motor.
• Build a simple DIY ESC circuit that when powered will rotate the BLDC shaft to start the GX25 (working as a starter motor).
• Build a rectifier circuit that when engaged to BLDC will make it generate power for charging batteries and giving the robot an extra power boost in the hour of need.
• Build an ECU circuit with inputs for tachometer, voltmeter, ammeter and outputs for throttle servo and mechanical relays that allows engaging/disengaging the ignition, ESC and rectifier circuits on demand.

GX25 BLDC generator

The basic API for the circuit should look something like this:

• Low-level
• Start engine
• Stop engine
• Set throttle
• Set charging
• High-level
• Start generator only when battery is low and/or power drain is high
• Adjust throttle to accommodate load
• Detect, alert and manage overheating
• Detect, alert and manage low-fuel
• Manage motor warm-up under different ambient temperatures.

How this circuit will communicate with central command and what will happen when communication breaks down is still to be decided.

Generator update

I have been stuck with progress for some time on the generator. It turns out alternators are hard to come by for free/cheaps. While i continue to look for alternators i have turned my attention to the "other end" of the motor, where I will be fitting the starter motor in place of the recoil starter.

After initial investigation, i made a makeshift tool to remove the wheel attached to the shaft that the recoil starter grabs durin a pull, and verified that the shaft is right way threaded M6 (5mm ⊙) with 1.0mm threads.

I have purchased two one way bearings of ebay and the plan is to make a 10mm ⊙ adapter with M6 hole to fit on the shaft and then slide on a one way bearing which in turn will be driven by a small electric motor somehow. Not sure how yet, i need to get some experience with one way bearings first. Peculiar thigs they are in deed, and from what i have read the can sometimes be fickle.

CNC Mill and Honda GX25 engine ordered

I had previously decided to make my own CNC Mill as part of this project. That was before I got money on my hands, and before I found a great offer on a used CNC Mill.

EMCO F1P-CNC Mill (to the right )with matching
EMCO tronic M1 controller (to the left).
Image shamelessly copied of the internet.

I have ordered it, and it will be arriving at my apartment in a week. It is an old "EMCO F1P" with a matching control/monitor unit "M1". Mor details will follow as I "unbox" it.

I also bought a Honda GX25 mini 4-stroke 1-cylinder petrol engine. If you have seen the post about power and electronics you will know that I intended to use a generator on board to provide longer range.

The engine arrived just 1 day after I ordered it, the unboxing of which will follow in a later post.