RTIII wrote: ↑
Mar 03 2018 4:20pm
Hmmm... What about solving the "instant start PAS" requirement, that seems to require some measured rotation, by having some sort of extra magnet mechanically go past the sensor? ...I'm guessing from your other comments you're not excited about this because it's not automatic.
If it isn't completely pedal controlled, there's no point, because if I have to use my hands at all, then I'd just use the throttles, and just ghost pedal, or whatever--that would be MUCH simpler and more reliable than the several potential points of failure including TorquePAS sensor, CA, settings, extra interconnecting wiring, etc.
The main advantage to the PAS version is that I can have hands-free operation, for those times my hands just randomly go numb (it's not a bike thing, it's a nerve thing and just happens sometimes for no predictable cause/timing/conditions/etc. Sometimes it's just one hand, sometimes it's both; I can still move my hands then but I can't feel them so unless I watch what I'm doing I can't tell what that is for certain, and on the road it's dangerous to watch my hands and not the road/etc. How long they stay numb is also random, usually it's pretty short, but it can last for minutes or an hour or more).
It also allows me to be legal if they should ever pass an update to the law here that requires it (presently it doesn't limit anything except speed to <20MPH).
...How does it get the rotation information, from the PAS / torque sensor assembly or from a magnet mounted on a wheel?
The TDCM sensor has all of it integrated. There's a manual for it on the ebikes.ca product pages, though it's not clearly explanatory as there are several versions.
Basically the torque sensor outputs a voltage range based on the torque input, which is detected via tension on the chain vs the cranks. It does detect both cranks (others like THUN only detect the left crank), but it sees two to three times higher torque on the left than the right, probably just how the sensor is placed inside vs the twisting of the crankshaft, etc. In my case this is actually good, because my left leg is perhaps half as capable as my right (before the hurting starts seriously), so it probably comes out even.
Then it has a 12-pole "regular" PAS sensor that outputs pulses the CA counts, and between the two kinds of sensor it can also detect the direction of rotation.
A sensor with a higher number of poles (the CA supports up to 24) would have a faster response, but would still require a certain amount of rotation of pedals to get started--and the point of the motors is to not require me to hurt my joints further by pedalling from a stop with no assist--the very hardest part of the job.
Seems to me the dual requirement of torque plus rotation is likely a deal-breaker for you if the extra-magnet doesn't do it for you. Oh! WHAT ABOUT... if you used the _release_ of an e-brake handle to trip a dirt cheap relay that could act as a short-lived electro-magnet next to the speed sensor? The only trick is keeping the pulse time short lived so it wasn't going off but once and briefly... Not entirely sure how you'd do that but maybe this gets you thinking. Or, what about putting a magnet on ever spoke?
Anything that requires my hands negates the usefulness of PAS at all.
Magnets on spokes or anything else that requires any movement of the trike is useless, because it means I have to get the trike started moving by pedal power alone, which means hurting myself (and risking injury with really heavy loads or on a slope) to get it started. That's the whole point of the motors, so I don't have to do that.
(I have pretty low gearing, that in 1st goes about 1mph at about 60 crank rpm, but for me, that's not enough to do this by myself regularly; it's only meant as an emergency thing in case of complete power system failure. The unloaded trike I can pedal on the flats in lowest gear, for a while, but starting it from a stop hurts my knees a bit even then, and doing that over and over every commute would leave me exhausted, and possibly unable to walk around at work all day (even with my cane). I can't imagine trying to do it with a heavy load).
At present the only thing I've figured out that's practical is to have an op-amp or transistor circuit external to the CA that takes the analog torque sensor output voltage change, and converts taht into a throttle signal to input into the CA. This can be in parallel to having the sensor input into the PAS input of the CA, and can have some sort of sensor (speed, etc) that shuts it off once the trike is moving enough for the CA to begin applying a throttle signal based on the actual TorquePAS / rotation of the cranks.
This is a relatively simple circuit I can throw together with parts I probably already have in junk around here (old audio stuff, for instance). But I'm hoping there's a solution within the CA itself (I just don't think there is, unless Grin has a custom / beta version that does this).
... BTW, I'm about to wire up a dual-use of my e-brake switches. They're officially for cutting out the electric motor, but I'm going to use them for that plus as a brake-light signal source.
I use a separate ebrake lever for the brake lights, but you can easily use a 5v relay or a simple open-collector transistor switching circuit to have them also switch brake lights that run on a different voltage. I used to do that on DayGlo Avenger, which only had a front brake and rear brake lever for the mechanical rim brakes, and the ebrake switch for geared (and later DD w/regen) motor cutoff.
Note too that I love the changes you've been making overall - the trike looks a hell of a lot better of late, and I think the fenders are cool.
The idea is to make it look pretty nice, as kind of an ebike (etrike) ambassador since it gets so much attention wherever I go. The disadvantage is it can make it more of a theft target, but completely custom and unique as it is, it would be easy to spot if it was stolen and ridden anywhere--and pointless to steal just to cut up for parts.
Also, the nicer it looks, the less I get the "hey it's a homeless guy on a bike" thing from some people, and the more respect I get on the roads. (at least, from those that don't hate everything that isn't them cuz you MIGHT make them take a few seconds longer to get somewhere).
As for the new battery arangement, you already know a lot of your requirements; I'd focus on keeping the leads short, the connection ends all very close together with one larger compartment underneath, accessed from the back, with highly sloped sheet metal on the front face for impact protection (with air vent louvers if available) and then separate enclosures within the larger enclosure. This will help keep water out but still have the benefit of isolation, and yet provide for the monitoring access that you discussed. It can also be done in a light-weight way. I'm thinking of dead computer equipment as your source materials - dirt cheap to free and maybe having bracketry that could be helpful. ...Those batteries look like they'd fit in larger disk drive bays, perhaps?
They might fit in 5.25" drive bays, but computer cases are far too large / deep to mount under the trike. The bays themselves are detachable on some cases but they're not long enough by themselves to cover the cells or secure them. So...no reason to use the bays.
I have a couple of old tower cases that are probably heavy enough gauge steel to bend/cut/weld into tough cases for the cells/modules. But I also have such steel from retail fixtures (couple of 4-5 foot long 2-3 foot wide pieces already in red), and from at least one old window A/C unit, etc. So not really any shortage of that.
Regarding design...because of hte layout under the trike it isn't flat enough to just bolt on a simple box to hold it all; the box has to fit around things in a way that still leaves me access to those things (chain, etc) without removing the box.
I'm not really worried about impacts--if there's anything that would hit the cell boxes, they'd hit other things on the trike too, and break other stuff. I just avoid anything that might remotely cause such damage. If there's debris like that on the road I can't avoid, well, it's just as likely to take stuff out with or without protection.
It's more complex to make separate boxes for the modules to go in differnet areas, but it enables me to use two of the deeper areas I couldn't put them in otherwise, just behind the seatbox, forward of the transfer axle. Two boxes for eight cells each there, and a third box for 12 more (28 total) (or 16 more if I include the lighting 4s1p pack in there) behind those on the other side of the transfer axle. It is also more separation of cells in case of fire, which while extremely unlikely isn't ever impossible. And it makes swapout of entire modules easier if I have to do it, cuz the'll be smaller and lighter than the almost 40-pound block I have in teh seatbox at present.
Cell monitoring isn't really necessary, just something I would really like to have available. I pretty much only do it randomly just in the interests of "science"
to post up here on ES, as the batteries age. I've had nearly no problems with these cells, and am not really worried about their balance.
Oh, before I sign off for the moment, why is it again you want the new front fork?
There's a few reasons.
--Experiment with a geared hubmotor powerful enough to actually be able to move the trike in a large (26") wheel. Cant' do that on the rear; they're 20" (probably actually 22" with the tires I've got on there), and I'm pretty sure it'd work back there in the smaller diameter wheels. But I only have rear geared hubs in the "1000w" range. (one Ezee v1, one Fusin lastmodel). So neither one can fit in any front fork I already have. I'd have to build one to do that, which I'd been planning to do for additional other reasons (I'll go into that later).
The idea of the motor is as a backup, and extra power I wouldn't be using under normal circumstances, but could use for extra start-from-a-stop power with heavy loads like a trailer full of stuff. If it works on the trike, it'd also work on the trailer itself. (but I'd have to rebuild the trailer frame to put a rear-geared hub on there; it's made for narrower front wheels).
-- The suspension fork (Suntour XCV) has wiggle between the stanchions and lowers during braking, which can contribute to loss of traction and create a skid where there wouldn't be one otherwise. This fatbike fork is a non-suspension fork, so it won't have that wiggle. Personally I prefer having the suspension, but I'd give that up for safer braking (especially with a load under adverse conditions).
And, what's with the need for a 20 MPH speed limiting feature? Can't you limit it yourself without need for the controller to enforce it?
Sure--I do it all the time. In fact, years back I decided specifically against having any limiting hardware and doing it myself just so that I wouldn't ever be limited in a situation that required sudden acceleration past that limit (rare, but potentially fatal if I can't).
But as I think I said in the posts about that, it means putting my attention on the speedo and not on the road, and having to do that in (stupid) traffic in a shopping mall area (my commute is mostly thru a big one) adds just that much more risk to every trip. Mostly, I know how fast I am by the sound of hte motors, but as the load changes when I am on some of the very very slight downslopes of the road, the sound can seem the same when in fact I'm a MPH or two above the 20MPH limit.
(if I was in a car, just about no LEO would bother about that, if it was a road speed limit. But this isn't a road speed limit, it's in the definition of what a bicycle is and isn't, and some LEOs can be very hard about this--not usually here in Phoenix or even in the valley, but in Tucson it's been common enough, and there's nothing to stop anyone from choosing to enforce the law at any moment anywhere).
I'll still need the ability to override that limit in an emergency (when a collision is imminent if I do not accelerate out of the way, and braking will not prevent it), probably with a button that sits right at the WOT position of the throttles, so I can push it with either (or both) thumbs, and bypass the CA (this could be almost as simple as shorting across the CA's throttle input and output pins...though not quite).
I used that ability to accelerate out of the way twice today on the way to work. If I hadn't bypassed the CA completely before I reached the first one (because it still limits power at startup even though it should not be), I'd've been hit by someone changing lanes right into me, with traffic right behind me that I'd be hit by if I slammed on my brakes. The second one was someone pulling out of a driveway as I was *just* about to pass it, again with traffic right behind me, and to my left, so nowhere to go but forward.
Normally it's only once every so often, maybe every few weeks or months, or even less often. I don't need it much, or for more than a second in most cases, two or three at the most that I recall, but if I didn't have it, I'd've been hit or rammed off the road by the side of a truck or car (or bus) many times over.
Or I'd just have to ride on the sidewalks everywhere, and be stuck at walking speed at best for most of my commute, assuming I could even get past pedestrians / etc going the other way. (probably not, with the trike, and definitely not with the trailer--Yogi's Mk IV is too wide to even stay on many sidewalks--the wheels would be at both edges, and even the Mk III is basically just as wide as the trike). And assuming some car or truck didnt' just hit me as they go in and out of driveways without looking. (which is my primary reason for never using any sidewalks unless I have no other safe choice, and riding on the roads in the first place).