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Monday, November 9, 2009

Welcome To The Wired Side

While I was fixing a couple of wiring issues that have come up, another thing I've done in the last several days, a bit at a time, is to change some of the wiring from the ugly harness remains and oddball bits and pieces to some multi-wire cables, and to alter the battery/circuit-breaker/current-meter hookups.

I used to have the battery/cb/cm setup like this:

Ammeter neg lead (to controller B+ input)
Ammeter pos lead
Top of circuit breaker
Bottom of CB
Pos of top batt
Neg of top batt
Pos of middle batt
neg of middle batt
Pos of bottom batt (Pos of lighting system)
Neg of bottom batt (Neg of lighting system, controller B- input)

Lighting system has it's own switches for power, doesn't go thru main power switch/CB.

Problem with this setup is that there's no way to monitor the current used up by lighting, nor any way to globally cut off power to everything on the bike in case of emergency.

So now it's like this:

Pos of top batt (to controller B+ input)
Neg of top batt
Pos of middle batt
neg of middle batt
Pos of bottom batt (Pos of lighting system)
Neg of bottom batt
Ammeter neg lead
Ammeter pos lead
Top of circuit breaker
Bottom of CB (Neg of lighting system, B- of motor controller)

This way the lighting is protected and switched by the breaker, so no one can just turn on the lights by accident and leave them on while I'm away from the bike (well, they can if they flip the breaker back on, but the breaker is not visible without messing further with the bike than a casual "what does this do?" flick of a switch).

Also, the lighting is monitored by the ammeter now, so I can get an idea of the *total* current drain happening at any instant.

Further, since the lighting (due to the incandescent scooter turn signals) has the bike frame at pack ground, it was previously not possible to "isolate" the pack from the bike, but now it is, since the pack ground is the breaker end now. If I get a wiring short from some positive level (motor or lighting) to the frame, flipping the breaker will stop current flow. If it's high enough, that'll trip the breaker on it's own, but otherwise I can manually do it.

I'm still working on replacing *all* of the hokey harnesses with the multiconductor cable, but expect to have that done in the next week or two, time permitting. If I pre-made the new harness as a drop-in replacement, I could've done it all at once, I suppose, but otherwise I must only do as much as I can finish quickly, else I will leave something non-functional that I need to safely ride the bike when I next go out!


Test and shopping ride today: at an average of around 14MPH cruising speed, with at least a couple of dozen full stops and starts, I easily got 12 miles today, with plenty of power to spare (batteries still at 11.4V each with a 2A load on them). I rode in next-to-highest gear all the time except the last mile or so when I had the pods so heavily loaded with about 80 pounds of groceries and stuff that I didn't want to strain the mechanical parts of the drivetrain (I heard creaking as I tried to start in high gear!).

But even with it in an "inefficient" high gear for startups, I *still* got that range out of it, so if I "hypermile" it I could probably get another 20-30%, by ensuring I always startup from low gears and shift only when it will not draw as much current (the points of which I still have to determine for sure).

Max level motor-only speed was 21.3, better than before (same path for most of the trip, just not as far). It's probably better today because I redid the pack wiring and soldered the meter connections I'd previously only had twisted on before. Didn't *feel* any different in performance. I can't think of any other reason it'd be different in speed.

Previously I had a suspicion that maybe the reason I wasn't getting anything beyond 20MPH with the larger motor sprocket (which calculated out ought to give 23-24MPH top speed) was that perhaps the derailer was not fully shifting to the highest gear (smallest sprocket) under load. Meaning, it would shift to it but while under load maybe was pulling up onto the next biggest one, then when load let off went back to that sprocket, because it was always there if I checked by stopping while in that gear, and when tested on the "test stand" at home.

So I verified on-road under load that the motor is using the smallest sprocket, by shifting into that gear first, locking the derailer adjustment screws, and starting up from that gear from a stop and accellerating to 20.9MPH in about 21 seconds or so, with out-of-range current draw most of the time until reaching speed, then it stayed around 10-11A. No different really than before, for speed; not up to what was calculated.

I suspect it's drawing more now because it can? Less resistance at the now-soldered connections? The change in where the meter and breaker are should make no difference to the current path.

I also had cleaned and re-oiled all the chains and stuff Saturday, without taking them off, but today I had problems with the motor chain coming off repeatedly, despite how tight it is. Only under acceleration in high gear, whether or not I even have my feet on the pedals. I'm going to have to trim the motor end off the hub a bit and use spacers at the bolt end, so I can force alignment of the chains--that is certainly why it happens.

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