Wiring

Sensible Wiring

One of the things that annoys me about EM's design is the wiring.  It has very long wire runs, excess wire length, and too many connectors.  Mecatechno has done a much better job (but it's still not up to Japanese standards).  

The power wiring is about as short as would be practical to make it.  Red and black connectors are used for the battery (which has been removed for photography).  Battery connectors are Amass AS150.  These are 7mm connectors rated for 150 A continuously.   The motor connectors are Amass XT150 and are 6mm in diameter.

Wiring Diagram

I can't take credit for the wiring diagram.  It was drawn by a friend and Dragonfly owner.  I did give it a good going over, and it all looks quite reasonable.

It's much better thought-out than EM's scheme.

A high-quality replacement for the 200A, 58VDC fuse appears to be manufactured by Littelfuse as part number 142.5631.6202. 

Display Module

The display module shows the battery voltage, estimated battery state of charge, and ambient temperature in degrees C.  

The display itself is manufactured by Drok.  I was unable to find the exact model Mecatecno used, but Drok's 200507 is quite similar.  A search for that model number will produce the instruction manual.  I found the calibration on the unit I have to be imperfect.  It read about 0.3 volts high almost everywhere. 

It's possible to perform a new calibration yourself, but this requires a precise 20.00 volt reference. 

The unit draws 10.3 mA while operating and can be switched off. 

The display also indicates ambient temperature.  I suppose this was considered important because Li-Ion cells should not be charged below freezing.  I think it would be more interesting to see the temperature of the motor housing.

The sensor itself cannot be seen in the adjacent photo.  It is a thermsitor at the end of the cable that has been wrapped around the display. Because the sensor is a thermsitor (as opposed to a thermocouple), the cable could be lengthened with regular copper wire.