72V… Up and running at last (mostly)!

I awoke yesterday morning to the call of the delivery guy from Northwest Scooters. He’d brought with him the replacement for the topbox that was damaged in transit, plus the new battery I needed for the upgrade, and the various nuts and bolts that I’d requested. Just a couple of days previously I’d received the new controller, and the cheap spare I also ordered arrived later that same day.

I was also in for a little bonus. Terry had thrown in an extra battery. It looked a little stained round the connector, like it had been zapped, but checked out okay, reading as almost fully charged (even more charged than the prettier, brand new battery that came with it, in fact).

There’s an issue with my controller that I ordered from China though. It came with absolutely no documentation, and what little I was emailed in response to my request for some told me nothing that I didn’t already know, made no mention of all the extra connectors, and – most importantly – didn’t detail regen braking, which I’m especially keen on getting working. Ian of the Electric Motoring Forum however, has kindly offered to do a deal on the better-documented e-crazyman unit that he is re-conditioning as part exchange for my unit. He can then use my unit as his spare (providing  it works, of course!)

Now I had everything I needed for the upgrade…


Since I already had to replace the topbox with its replacement, I thought I might as well take off its mounting bracket too, so that the side panels – as well as the seat – could be removed to give easy access to every part of the bike.

The New Battery Bank

The first thing I had to do was enlarge the existing hole in the underseat space to accommodate the sixth battery. This done, I tested it for fit and made two little notches along the edge of the hole to feed cables through from the battery bank below.

I’d already upgraded the battery bank wiring to use the 170A welding cable as recommended by Mike & Ian. As part of the 72V upgrade I wanted to extend this all the way to the controller’s power connector. I added a cable I’d made up the night before, running the thicker cable from the master negative of the battery bank to the Anderson connector.

Top Left to Right you can see the Negative Lead running to the Anderson Connector (Controller removed, here)

I also ran a positive line of the new cable from the ON/OFF side of the breaker switch to the Anderson. This would power the new controller.  The ceramic block would no longer be needed, as power to the controller would be taken from this new line instead. That done, I removed the old controller, disconnecting the three phase-wires from the six-way junction box, unplugging the hall sensor connector, brake connector and throttle connector, then disconnecting the main black/red feed wires from their terminals on the ceramic block.

Next I put the seat back in place and wired in the two extra batteries to the underseat space. Then I removed the ceramic block and cut off the ends of the wires at the loom, sealing them with insulation tape.

The Anderson connector, with the positive about to be connected to the breaker switch ( N.B: The lead going into the breaker really shouldn’t be exposed like that, and needs fixing)

The wires that formerly served the ceramic block have been cut off at the top of the loom (the length within the loom is spared as it serves the ignition feed)

The Adapter

Finally it was time to test the 72V-12V adaptor I’d built from Mike’s specifications (my own guide here). I connected the adapter into the loom connector that used to serve the old 48V adapter, switched on the breaker switch and turned on the ignition.

When the battery meter didn’t spring to life like it usually does, my heart sank, but a loud “beeep!!” when I hit the horn demonstrated that all was indeed well with the 12V circuit. The headlights came to life when I switched them on, and I breathed a sigh of relief that I wasn’t going to have to go running crying to anyone on the Electric Vehicle Forum just yet. The little green light on the adaptor was also on, though dimly (reflecting the lower voltage than the 110V it was originally manufactured for).

A few moments later it dawned on me why the battery monitor hadn’t come on: That unit runs off the high voltage circuit mediated by the controller. No controller, no battery meter. So it was on to the next stage: Replacing the old controller with the 72V unit.

The Phase Wires

At first I was delighted about the fact that the phase wires already had solid ring connectors connected to them (the e-crazyman controller comes with bullet connectors, that have to be changed). But when I was about to bolt them to the 3-way connector block that interfaced them to the motor wiring, I found that the bolts wouldn’t go through – the holes in the connectors were fractionally too small.

Rather than go though the hassle of replacing perfectly good ring connectors, I had a plan: Instead, I would just bore out the extra mm  of hole I needed with a drill. This, however, is a very delicate operation which really needs a vice to securely hold the ring connector while it is bored out. Holding it with pliars as I ran the drill – albeit at at low speed – nearly ended in disaster when the bit jammed on the sides of the hole and wound most of the length of the phase wire round the drill bit before mercifully coming to rest a couple of inches short of the controller case. Mercifully the only damage (apart from a slight twisting on the yellow phase wire) was a small graze which I gingerly covered in some white insulation tape, hoping Ian wouldn’t judge me too harshly for such abuse.

After this, I proceeded far more carefully, gripping the ring connector between my thickest pair of pliars, and ever so gently easing the drill softly against the hole, letting it lightly grind off the surplus width of the connector until it was safely through. The results was a very snug fit for the bolt, but that’s just what you want for important bits of wiring like this.

Once the ring connectors were ready, I mounted the new controller and connected the Bl/Gr/Y phase wires to the big 6-point connector block that the old phase wires had just come out of. The six-way Hall sensor connector on the new controller  was exactly the same as it had been on the old controller (Bl/Gr/Y/Bl/R). So I connected this onto its respective connector  on the loom.

Next came the throttle. In place of the old R/Gy/Bk 3-way connector, the new controller had a R/Gr/Bk 3-way that was identified in the meagre documentation  as “Turning” (presumably a Chinese attempt to describe the throttle). I connected this to the white striped R/Gr/Bl throttle connector on the loom.

The Brake and Throttle Connectors, as connected to the old 48V Controller

Finally I connected the R/Bk terminals of the Anderson block to the R/Bk power cables for the controller. The plastic 3-way connector on the controller power cable (one pin empty) was no good, so I just took the R/Bk spade terminals out in preparation for rigging a makeshift connection.

The Controller Power Cables (Left)

At the time I was unsure whether to fit the remaining side of my Anderson connector to the controller power cables, as I didn’t know if the cables could benefit from being upgraded first. So in the mean time, I used small, leftover sections of the welding cable jacket (that I’d cut off to add the connectors) to fashion a  connection. I fitted these snuggly inside the end of the anderson connectors to make a good, albeit temporary connection with the spade connectors on the controller power cables…

The makeshift Power Connection (N.B. Be very careful with exposed bits of live connector like this! – they were later masked off with insulation tape)

All that was left was the stray red wire, and the brake wire. Ian said they should go to the 2-way on the loom that was plugged into the Violet/Red connector from the old unit. Unfortunately these connectors were completely incompatible, so I fashioned a workaround based on the 2-way connector from the old unit. I cut it off and crimped a female spade connector onto the red-wire that would connect firmly to the spade on the controller’s (small) power feed wire. Then I crimped a spade to the violet wire that would connect to the white, brake wire’s female connector. This was just a quick-fix until I got round to getting a fresh 2-way connector so I could wire it up properly.

The temporary Brake/Power-feed Connector

I’d already switched everything on to test the motor on its centre-stand once I’d hooked up the power cables, but nothing happened. So I thought I’d have more luck now I’d connected up the final two wires. Unfortunately, still nothing happened, and I checked voltages to make sure the 72V+ was getting through to the controller. It was, but an odd residual voltage I was getting from the controller wire sent me on a wild goose chase that involved removing all the connections again to find out where the voltage was coming from. It turned out these were just residual current from the controller’s gargantuan capacitor, so I put it all back together again.

Continuing to have no joy, I posted an SOS on the Electric Motoring Forum to see if Ian or Mike could help me figure out what was up. Ian kindly PMed me with his mobile number to offer some tech support and the problem was quickly traced to the same one he had had with his own upgrade, – two of the wires on the throttle control cable were reversed. Once I’d picked open the connector and switched the wires over, the motor jumped to life with no further trouble. (Thanks, Ian!).

So finally it was time to put everything back together again. There was one small snag with the new 72V-12V power adaptor though: The 72V-12V Adaptor wouldn’t reach the connector on the loom from where I wanted it positioned beside the batteries in the underseat compartment, so I had to settle for just sitting it on top of the batteries for the test run. Later I’d make up an extension lead with a three-way connector to reach the extra distance.

Once I’d put everything back together again and secured all the connections, I was finally ready for my test-drive!

Two problems did show up in testing however: Firstly the indicators aren’t working properly, which is odd. They don’t blink, they just come on solid, and the warning blinker lights on the instrument panel don’t come on at all. I also discovered that the brakes or the sidestand (both on the same circuit) would not cut off the throttle, even though the brake connector (white) is properly wired in.

I’m going to look into these issues before I write up the report on my test-drive. Watch this space!…

2 Responses to 72V… Up and running at last (mostly)!

  1. wong elana says:

    wow very informative step by step installing electricity on scoota

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