Drum Roll
Now, nearly a year after the bearings failed on my 36 volt system, a rebuilt 48 Volt system is up and running. I am now using the external Golden Motor "Cruise Controller" (some of you will remember my disastrous experience with the now discontinued 48V "Zhidong" regen controller) with good results and the 48V 1000W hub mounted in a 20" spoked wheel.
I had a heck of time "synching" my wheel to the Zhidong controller. It had different instructions than other GM controllers and this was NOT made clear from the outset. After exhaustive diagnostics all agreed that it was motor which was at fault and GM China sent a new motor to GM USA in Aridzona. I sent them my old wheel and they sent me the new one. The first one was properly centered while the second had a rim offset by at least an inch. After several hours with a spoke wrench and dial guage, I was able to move it most, but not all, of the way. It is still off by an eighth of an inch or so. I wish I still had the first one!
Both wheels were significantly rounder than my 2007 36V wheel. The double walled rim is nice but makes fitting a tube difficult and fitting a pump (in the 20" model at least) impossible. I need to find a 90 bend valve. The bike shop told me to go to the trailer store but I did not make it there before they closed. The spoke nipples are #13 on the round universal spoke wrench. I could not find a single-size wrench that fit. I used mini-vice grips with the 36V as they were somewhere between bike and motor bike size that I could not find. The nuts and washers supplied with the wheels were not of the highest quality and I replaced them with locally bought or machined parts. I ran out of nipple thread before I could get the rim centered. This is my only complaint about the wheel other than it sure would be nice if it came with the 90 schrader valve.
The Cruise Controller is a dream. I was concerned about its ability to sink heat. Mounting holes on all four corners would be nice as would matching motor wires. The controller comes with short 6 inch leads that convert the controller connections to the wheel connections and the throttle and brake etc. This arrangement works but puts an additional connector in the circuit which is an additional place for corrosion and failure.
It has reverse and cruise control which I scoffed at at first but find useful as I can peddle harder when both hands are firmly on the bars. It has a horn that might work in a bucolic setting but is way to quiet for the city. And it has auto-synch and can run without Hall Effect sensors. Oh, and don't forget the "regen" braking. I don't think this is generating much juice but its a damn nice brake. My two criticisms are: 1) the switched brake handles that come with the kit are scary, and 2) its all or nothing. It would be nice to have several steps so you could actually coast down a hill with a little bit of brake. I have to pulse it to keep going and that sends a shock through the head tube that can't be good for forks and heads.
I have 40 10AH NiMH "D" cells in series. They are sandwiched endwise between two sheets of half inch plastic with 1/4 holes the diameters of the cells drilled in them. The cells are separated by a finger's width and mounted so that the breeze blows over them. This design was inspired by a visit to the Honda Insight junk yard in Eaglerock, CA.
I had two 36 volt packs in parallel in the first build and was concerned that 10AH would be enough. But it for my 10 mile up hill run from the bottom of the valley where the railroad tracks go through to the million dollar houses in the foothills. I think its a 1200 foot climb. The last few hundred yards is ridiculously steep (like get off and push steep) and after 10 miles of climbing I still had 40 Volts at full load. I know this because it appears that GM is shipping all controllers with a cut off voltage set for 24V operation and I was paranoid so I strapped a cheap Harbor-Freight DVM to my defunct bike computer. The motor is not as fast as I was expecting but it is fast enough and seems to be more efficient than the 36V
I know my cutoff is supposed to be 39 volts but is that at load or open circuit? My charger has a discharge mode that takes it down to 38.9 V across an open circuit. My open circuit voltages are still in the mid-forties at the end of my loop but it did drop to 38 under full load up a hill. Is this too low?
So unless someone has a clamp on two-piece die to extend spoke threads, I have moved the wheel as far as I can that way and need to start playing with axle shims if I am to center it and keep my rear tire from going sideways down the road. Other than that, I think I am done, unless I can find a suspension shock that will work.
Here are some pictures.
