As I was going away for a week’s holiday last week but not leaving till the Monday, I decided it was high time I did some of the maintenance I’ve been putting off for far too long. This involved the 175A cable upgrade I’ve had the bits for since last November, and maybe a bit of investigation into what I’ve often referred to as my “throttle problem”, which in some cases in the bad weather has manifested itself as a complete loss of power for a number of seconds. It always recovers, but I’m sure you can imagine how frustrating and unnerving it can be not knowing if you are going to suddenly lose power, especially if you have someone following very closely.
So over the weekend before going away, I started taking things apart, safe in the knowledge that if I didn’t get it finished I still had a day to get it all back together after my holiday before the inevitable return to work. I disconnected all the battery cables and removed the controller, and started making up the link cables with the new 175A cable.
Taking a break for a cup of tea, I decided to open up the controller to see if I could see anything out of the ordinary. A first scan showed all the cables apparently in place and soldered correctly, but looking over it a bit closer I suddenly noticed a dry joint! For those not familiar with this term, it is basically where a component has little or no solder on one of its legs, resulting in intermittent contact and thus unreliable performance. It turns out that the particular component would cause exactly the problem I have previously described, which is sudden loss of power without warning, and in a very extreme case could have blown up the controller completely!
So a quick application of solder to the offending contact, reassemble the controller and it was back to the cabling job. As predicted I ran out of time to complete this, so I had to leave it until after the holiday.
On my return I finished putting the new cables together, and reassembled everything, only to find that the ignition switch had no effect. In my reluctance to disturb too many of the existing cables I had bypassed them where they go through the loom, not realising that the takeoff for the ignition switch is somewhere down there! So I insulated the bottom of the old cables at the bottom of the loom, and reconnected them at the top (although they were now a *very* tight fit in the connector at the top along with the new, very thick, cable).
All back together again, and I took it for a quick test round the block. What a difference! I can now roll on the throttle gently and get consistent drive, and the motor sounds generally quieter and smoother at low speeds. Riding to work the next day showed speeds comparable to or greater than those I have had to date, and not a hint of hesitation or cutting out.
I wasn’t too confident about having the cables jammed into the old connector, so this weekend I fitted what’s known as an “Anderson connector” in place of the old ceramic block, which has a much larger hole for the cables to fit into, so I now feel confident that none of the cables are going to work loose.
The cable upgrade now means that I am in a better position for my next intended upgrade, which I alluded to in my last post. This involves an uprated controller board and FETs, and now includes a higher wattage motor as although my existing motor would probably handle the higher currents involved, the weedy cables feeding it almost certainly wouldn’t, so there should be a motor with my name on it winging its way from China soon, I hope.
This upgrade will not affect the top speed of the scooter, as I will still be running at 72V and as I think I have said in the past, speed is a function of voltage, and acceleration a function of current. So the upgrade should result in greatly enhanced acceleration, which I have found to be a source of frustration on occasions, as my existing controller has what they call “soft start” which deliberately limits the current when pulling away from a standstill. It’s frustrating to the point that I find myself pushing the scooter forward with my feet just to get it going sometimes!
So my next post will probably be after I have completed this upgrade – more when I have it!
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