© 2017 Ian Watts

  • Ian Watts

Electrics : Tidy Up & Modifications

It now came time to turn my attention to the original / as-fitted electrics, to sort them out and tidy them up. Once again, like the strip down, this was pretty straight forward.

Unfortunately, the Chinese used a 'strip, twist, solder and tape' method of making joints within the wiring loom. They also had multiple earth / ground connections (using the 'strip, twist, solder and tape' method) which in turn connected at both ends of a common (green) wire to the chassis with other, sporadic, interconnections in between. None too neat or pleasant to work with and definitely not simple to fault find. The cause of the original intermittent spark did become apparent though - just a little too late for this ol' scoot !!

All the 'strip, twist, solder and tape' -type joints were removed and each item was individually removed or, if absolutely necessary to remain, tidied up. In all cases (there's not a lot of current involved here and it's all 12V) the earth cables were directed back aft to a common earth bolt.

Once the cable loom had been opened up it became possible to begin removing cables; the battery cables first, then the ignition and charge system (c/w CDI and regulator)...

At the end of an hour all that was left was lighting, ignition, side-stand down, fuel gauge, low oil, starter and kill switch cabling and floor was littered with no-longer required cable ends. The now removed 'twist & tape' cables had either been removed or had the pigtail removed (replaced with a dedicated cable) and heat shrunk over for long-term protection.


The 'kill' switch was modified (with an additional cable) from connecting the low-tension side of the spark / ignition system to earth (thereby killing the spark) to being a pass through switch intended as an interlock for the controller/motor HV relays. An additional plug / socket was required for the extra cable and the cable pair was hen routed aft towards the intended controller location (area vacated by original fuel tank).


The momentary 'starter' switch cable was re-tasked to be a Reverse switch. So the cable was renewed (the original wasn't long enough) and directed aft, toward the intended Controller position - the space vacated by the old fuel tank.

The black/white cable was the original Starter. It was removed from the original connector and re-sited within a new 2 pole connector block. The other (pink) cable is the new kill switch cable. Both cables were routed from the right hand cluster to the controller area.


The fuel gauge cable was isolated as was the low oil level cable. These will be re-tasked later.

The idea is (once the scoot is 'up and running') to re-task the :

[1] low oil (red) warning lamp to be a low Voltage lamp (something like, 72V battery pack below 65--ish Volts)

[2] the fuel gauge cable (full scale deflection at 0V / connected to ground / earth) to indicate battery pack voltage and, therefore, a kind of battery level indicator. An AVR Tiny will be used to pulse the gauge at a preset rate depending upon the battery voltage it detects (thereby adjusting gauge needle deflection)... Crude... but I don't like unused controls / gauges and it would be a helpful indicator whilst employing the existing panel gauge. An improvement would most definitely be to switch out the programming of the AVR to be a coulomb counter and, therefore, make it MUCH for useful SoC indicator... we'll see... both are later-date projects...

I would prefer to keep the HV battery voltage as 'contained' / local to the controller as possible and, to achieve, this have a made a small 12V Li-Ion pack (Panasonic 18650 cells again) which will be charged by the DCDC convertor and used to 'power' the ignition switch, via the modified 'kill' switch, and thereby energise the Controller <Enable> line and two (one HV/72V and one LV/12V) relays / contactors or, in my case SSRs (solid state relays). The idea here is :

[1] high voltage (72V) ONLY exists within the battery / controller area - it does not 'wander' around the scoot.

[2] low voltage (12V) exists in two forms : [a] 12V Li-Ion for the ignition switch / controller enable and contactor circuits and [b] 12V DCDC convertor for all other scoot lighting, horn etc electrics.

[3] the Li-Ion pack will be connected to the DCDC convertor via a diode arrangement so that the convertor maintains the Li-Ion pack BUT the Li-Ion pack does NOT power any part of the scoot except the ignition / controller enable circuit.

All lights have been switched out for low-power LEDS, including the head light (VASTLY improved over the original headlight). The only challenge here was the standard method of earthing the indicators was 'novel' in that the Chinese manufacturer used the instrument panel indicator 'On' tell-tale as a ground for the active indicators. Due to the extremely low power required by LEDs, this simply meant that ALL indicators flash when either direction is selected. The way I chose to work around this was to trace the two, left/right, indicator cables at the panel tell-tale and insert standard 1N4001 diodes into each. This way one indicator direction cannot back-feed the other. Hey-presto - all LEDs including panel lights work as expected. To boot, the horn works too !

Finally the new 'loom' was routed through some braided sleeving with cables exiting at their required points along the route. Much neater.

Now onto the main EV electrics !!!