Good to know. There's another incentive to keep the old controller.
Hacking shunts out of a programmable controller is a pretty brutal last resort -- not a first line of attack. Once you butcher the controller you no longer have calibration and the programming utility profiles will no longer apply. Working back to being able to program it is a PITA.
The gear reduction is 5:1 but that's irrelevant. Put the thing on a truing stand, hook up the controller and run it flat out. You can measure the rpm and so will know the Kv and hence the wind - the most popular are 8T and 10T. From there you go to the ebikes.ca simulator and figure out what controller current and battery you need to do what you want. Not really any guesswork or on-the-road experimentation involved. Remember that regardless of the wind, all MACs have about the same hill-climbing power - the higher turn count motors will just have a lower top speed. So - since hill-climbing depends on torque (phase amps), it's the controller that determines that ability.
This is spot on, although to be clear, it's the clutch not the gears that can be damaged. This is why EM3EV used to have caveats on the old site about using the 12FET on a MAC - their standard choice was a 9FET. The new site is tidied up and a lot of the info is gone or hard to find.motomech wrote: ↑Jan 24, 2018 10:49 amA 40 Amp max. controller is not necessarily too much for a Mac.
... the thing more likely to effect day to day riding, is how the controller engages the motor. A "hard-hitting" controller, like a 40 Amp Infineon, can result in "gear hammering"and a touchy throttle, creating a need to "tame the throttle",...
You might be right, but at this point he can't even really walk yet. He needs a feet forward bike that can run adequately without any pedal input at all. But I also want to set him up on a drag-free bike so in time he can ride it without motor power as appropriate. I have a bike that's doable for feet forward riding position, and it's a heavy cruiser. This kit I had sitting around already seemed to check all the boxes, but it will require a big and costly battery.
Does it become more efficient with a load on it, or does this amount to a 250W penalty whenever the motor is running?
The loss is clearly rpm-related but the bike can never achieve that unloaded speed on the road. I don't really understand (and haven't thought about) the reasons for the high unloaded current, but I can tell you that I often run with PAS adding only a very very modest 60W or so at meandering bike path speeds. The motor is not a power hog or grossly inefficient if that's what you are asking.
That's probably a V2 motor which cam in a 'Speed' and 'Torque' models. Both are in the ebikes.ca simulator. You just need to go and play around with some configurations. At 48V with a 26" wheel those two motors will do about 30mph and 24mph respectively for any controller over about 25A. Any Amps over that amount are not going to give speed but will give acceleration and hill-climbing power.
I think not. This motor is light by DD standards - even compared to the common 9C clones. This motor will have good getaway torque so your friend won't have to work to get going and up to speed.
A quick look at the EM3EV site shows a 48V shark pack + charge for under $400 and a 9 FET programmable controller with bar mounted power selector switch and programming cable for under a hundred. This gets you a wimpier controller that you can program to match the battery. You can play with getting a 36V battery that will give a bit more current than the 48V (More P, less S) but you want to pick a motor unloaded speed that's about 125% of your target max. (And of course there's that annoying shipping from China that's not to be overlooked....)
I guess you subliminally knew how fast it will go, this guy gets 35 to 38 mph w/ a 52 V battery and the 2500 Watt kit (What you have).But if the result is a 35mph bike, that's not good.
There's no way on earth that the V2 spd will go that fast. I get about 40mph at 66V with two motors on my bike - almost exactly what the simulator predicts so I know the simulator Kv is correct.
Could it really be this fast? Could it be that "rare" V3 you refered to?I have findings about this BMC motor and controller. First off, they worked together fine once I crimped a JST on the controller Hall leads and faked up a battery connector for my 48V Shark pack.
This motor is stupid fast. Full unloaded speed on my 13S battery was about 700rpm. !!!
I didn't really believe it at first, so I used a variety of strobe apps and tone generators to verify what I was hearing. I put a zip tie on the spokes that could pluck the workbench as the wheel spun, and I made a video that I can send to you. I was getting very close to 11.80 hz (708 rpm) from the wheel while viewing the label with a couple of different strobe apps.
Anyway, best indications are a hub kV of about 13.
Yep, that sounds like it. This is a way fast motor. The regular V2 Spd wind was an 8T and the V3 was a 6T.motomech wrote: ↑Feb 09, 2018 4:15 pmteklektik-Chalo and I are talking about swapping motors.
He has been busy and has tested the BMC, here is his report;Could it really be this fast? Could it be that "rare" V3 you refered to?I have findings about this BMC motor and controller.
Anyway, best indications are a hub kV of about 13.