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Thursday, December 31, 2009

2QD Still In Progress, Now Using Curtis 1204-410 Controller

Since I have had so very little time to work on anything recently, I haven't finished the 2QD controller repairs or the physical repairs to the bike (wheel, chain).

The major problems were just the power output section (bottom two MOSFETs blown, gate resistors burned open as they were designed to). But one minor problem that kept anything from working right was a 9.1V zener diode that was only allowing 1.45V! So there was no internal power supply to run the entire comparator and feedback/control section, which is the majority of the controller.

I fixed that by replacing the zener with a 5.6 and a 4.1 in series, which while higher than the original still allows it to work. This got the main section working again, and now I just need to finish the power section as described a couple of posts back. I have wanted to use a different case for a while, so now is my chance.

Since it is taking a while to figure out and then make the holders for the FETs to line them up and keep them tightly against the case inside, and to polish the aluminum and the FETs for flatness and smoothness (for better heat transfer, since I have to use thermally conductive / electrically insulative pads, too), I decided to take a quick look again at the Curtis 1204-410 I have had for a few months with little time to troubleshoot.

I let it sit on the bench powered on (but not doing anything as it doesn't respond to input), for a while, and suddenly it started working, the motor attached to it began slowly spinning (the throtle was just a regular pot set to barely on). Apparently once it got warm enough (from me having the oven on to warm up the room), a connection was made well enough to start working.

There are six interconnect wires between the Curtis logic board and it's power board. Two carry B+ and two ground, and the other two carry signals. One is the PWM output to the FETs, and the other looks like a feedback from the FETs as it is time-shifted just a tiny bit late (which I can barely see at all with my old 531A), but identical to the PWM waveform.

The solder joints on them must've been flexed or vibrated enough to crack them, so they would only make connections good enough to work when warm or hot. Over 85F, anyway. Under that, they might work and might not. I reflowed the solder and now they always work.

Since it's a 36-48V 225A controller for brushed PMDC motors, it can be used in place of the 2QD, so for now I put it on CrazyBike2 and verified it works with the bike. I can use it until I finish the 2QD rehousing.

Now I need to build a new rear wheel, move the chain and some shifters and stuff from one of the spare bikes I got for parts from someone for Christmas, and finalize the new throttle control setup, and CB2 will be ready to ride more than just for tests.

I also cobbled together this temporary throttle lever and mounting, for using a powerchair's spring-return throttle on CB2.

The spring is so strong that without a pretty long lever, I cannot keep it pressed down for very long. Sorry the pic is so dark, but the flash keeps shining off the metal and the camera autodarkens the rest of it to compensate. :(

The aluminum bars are just end-pieces, uncut, off the rackmount fan enclosure from the same old studio-type Sony VTR the gray transistors from the last post are from. I'll probably wind up modifying a brake lever setup to use for this instead, as it will already be designed to clamp to the handlebar, and it has a long pivot arm.

Optionally, I considered using a lever-style shifter, but it is more complicated to set up for this, and it is also a much shorter lever.

UPS And PC Power Supply Parts Bonanza

A bit of salvaging of some old computer power supplies and UPSs (most of which were found in alleys or roadside on bulk trash days, over the last few months, but sat "intact" until now due to lack of time) netted me several pounds of parts (not counting the toroids or transformers!), including the stuff shown in the pics below.

Bunches of small value caps, diodes, zeners, transistors, mounting screws, heatsinks and clips (and thermal pads), and lots of resistors not yet taken off the boards (not in pic), several TL431A and some LM317

Some very old 100V+ Vce type transistors in PNP and NPN, off some boards from a Sony VTR (I never saw the VTR, just the boards)

They'll be used to replace some lower voltage 2222's on my 2QD so I can up it to 48V+ usability.

Bunches of small signal transistors, 50V Vce types, a bit better than the 2222 but not much.

A few beefy dual-diode (common cathode) units, one of them up to 40V at 50A!

Also about three times that many smaller TO220 versions of these, mostly in the 40V 3A range. All can be used with heatsinks to parallel unequally-charged battery packs in a pinch.

Of course, there are lots of large caps, too, in low and high voltages, and many form factors.

MOSFETs; lots of them, too, though mostly lower-voltage types, and generally fairly high RDSon.

Some IC's, too. Optoisolators, LM339 and LM324 chips, other single or double op-amp chips, some logic chips (74x series), some "house branded" chips in the UPSs which probably means they're ROMs or pre-programmed MCUs. Some standard PWM SMPS control chips, might be adaptable as controller chips.

Transformers, connectors, toroids, cables, wire, heatsinks, switches, LEDs, etc. Fans, too, but the fans are all defective. They might have usable hall sensors in them, though, as long as I don't need linear sensors (they're more likley to be switching types).

Most of the desoldering was done by carefully using a very small propane torch to heat the thru-hole lead areas, while gently tapping the PCB on the bench (outside, so any fumes would not suffocate me). Some things required a solder-sucker and regular soldering iron.

I should be able to build up my other 2QD controller out of what's there, plus have plenty left over for other projects for a while to come, such as a BLDC controller.

There are LOTS of electronics that have all this stuff salvageable if you have time to do it. I generally spend only a minute or two at a time, over days or weeks, and end up with what looks like "Christmas at the parts store". :) Even if only half the parts worked when done, it'd have saved me enough money it'd stil be worth it.

Sunday, December 27, 2009

Christmas Bikes For Parts

I wasn't expecting any presents this year, but I ended up with a few. Those NiMH packs in the previous post were a couple, and these two bikes as well. Pardon the stuff on the floor; Hachi was assimilating a bunch of junk mail just before I got home and I'd not had time to clean up the little tiny bits leftover. :-)

The first is a Huffy "Nevada". It's about the same as all the other Huffys I've had or seen, though at least this one has *indexed* lever shifters. Since they are for 3-ring and 6-ring, which I currently have on CrazyBike2, I'll probably move the shifters to CB2 in place of the ones I have (of which the rear one is an 8-speed so doesn't line up with the 6-ring cassette I have now).

It's a 26" wheel bike, with typical steel hubs but aluminum rims. Don't know what spoke type. Brakes are a center pull type I haven't seen before, but appear to work the same as some of the better OTS units I've got. Tires are knobby but not greatly so, and made more in a rounded fashion, so they ride a little better than most of the knobbys I have.

Cargo rack is cheap steel, and would not actually hold much in the way of cargo without wobbling or bending. Well, *relatively* much, given that I expect to be able to haul at least 40 pounds on any bike I ride, preferably up to 100 pounds.

One-piece cranks aren't useful, as I have lots of those. Overall this bike might just stay like it is as an emergency bike, for when experiments in progress on others aren't working or not completed enough to ride.

The other is more useful for parts, and is a Magna "Great Divide".

Like the Huffy it's a department-store 26" hardtail. But unlike the Huffy it has a front suspension fork. It also has square-taper cranks/BB, which is the type I need for jackshafts, and for the easily-changeable chainring sets I'd like to use.

It has grip-shifters, which I like on MTB style bars, but which don't work well for the downturned bars used on CB2, nor are they the safest thing to use with any ebike that has a twistgrip throttle (which I don't use now partly for that reason).

It also uses center-pull brakes, but a different style that is one I have seen, using the same mounting studs that linear side-pull brakes do. These are useful on any bike that has these studs, which many modern bikes, both cheap and high-end, do.

Has the same basic steel hubs and aluminum rims the Huffy does; tires are not as good though.

I have some ideas forming about using the above frame as part of a new version of CrazyBike2, but as a trike. One version of the idea is a tadpole, the other a delta. Since this is a 26" frame, I'm thinking of using a 26" rear wheel, and two 26" wheelchair wheels I currently have on that flatbed trailer right now. They have tubeless foam tires right now, but I'd change those to regular bike tires. Optionally, I could use a pair of 20" wheels meant for single-ended axle mounting. Either way, I'd make this into a full-suspension trike, if it's the tadpole version.

If I do it as a delta, I'd probably only have front suspension, unless I can figure out a way to make the rear wheels independently suspended. And independently driven, rather than a single axle.

It's much easier to build and drive the tadpole, especially as a full suspension. I just have to find all the right parts.

Friday, December 25, 2009

2QD Repairs, Modifications, Thoughts, Part 2, Used NiMH Packs

Some pics of the modification/repair in progress.

This is the old Jensen inverter case:

The three long caps "below" it are the ones from the UPS. The smaller one to their right is the one I originally had on the 2QD, and it has been getting hot with generous motor use.

An end view of the box with all the controller parts loosely fit inside it (except for MOSFETs)

The two large holes on this end used to house the AC outlets on the inverter. The switch on the right is one I've had laying around unused for around 15 or 20 years; bought at Radio Shack for some forgotten purpose. ;) It has an orange LED in it that will be used at VERY low brightness (20K resistor) to tell me if the controller is powered on and the throttle connected, and not open-circuit.

With the case open, you can see the general fit of parts. The three caps with the main power supply wires feeding between them will fit on one end/side. The MOSFETs will be clamped to the left side, and hand-wired to the PCB.

The PCB will fit in as seen above, and is cut down from it's original length to do so.

Another shot of the layout.

The 2QD PCB freshly cut.

It is separated just at the gate resistors for the lower leg of the half-bridge, as that is the length needed to fit inside the Jensen case.

The MOSFET end can be used as-is to keep the MOSFETs together, and easy to mount to the wall of the case.

They do still have to be electrically insulated from the case, as their heatsinks are electrically active and different parts of the circuit.

I am not sure when I will finish it and get CrazyBike2 back on the road for the 30 miles it needs to get to 1000 miles, as time is a scarce commodity right now.

To add to my growing collection of power sources, a couple of NiMH packs arrived tonight:

USPS kind of squished the package but didn't damage the contents.

They did put a nice notice about the oopsie, under the shrink wrap plastic they put on to hold it together.

The packs themselves:

The white one is a Sanforce 24V pack. The green one is a 36V pack from a Giant Suede.

I know that the 24V pack was damaged a bit by a thermal issue during charging, so it reportedly now has voltage sag if more than 7A is drawn from it, even at full charge. It's made of 10 super-F cells of 13Ah each. It's charging rate is 1/10C, for 16 hours. Don't know the original discharge rating, but now it's about 0.5C.

The 36V pack's original specs were 12 pounds, 9Ah, rechargeable in 4 hours (so charging at about 4.5A or 0.5C), and originally drove a 240W hub motor. Don't know what it's discharge rating is.

I dont' have a NiMH charger, so will have to use the Sorenson and careful monitoring for now.

I'm considering putting them in series for a 60V pack, then modding a 2QD for that high a voltage operation, and putting them on DayGlo Avenger along with one of the various motors I have around here, with appropriate reduction system. There's a 1/3HP 100VDC weedeater motor I might try, or perhaps a couple of my radiator fan motors in series. Have to see how things work out with CB2 first.

Wednesday, December 23, 2009

2QD Repairs, Modifications, Thoughts

The repair of the controller has turned into a modification session, too. So it is taking considerably longer than I originally expected or intended.

I'm upping it to 48V capability, changing out a few transistors and whatnot, as well as installing the whole thing into a better case that will provide heatsinking over it's whole surface. The case used to be for a Jensen 300W car AC inverter that doesn't output anything, which I gave up on fixing for now (I can always rehouse it later).

The extruded aluminum case is not very large but is big enough to hold the 2QD board with the power end cut off, 3 very tall low-ESR caps (75V 1500uF each) off that giant UPS board instead of the dinky one I could fit on the 2QD PCB, so much better power filtering, and plenty of surface area to bolt multiple MOSFETs to. Plus I can seal it up for watertightness and still vent all the heat outward, unlike the plastic PacTec project box I had it in before, with the tiny heatsink out the end of it.

I'm still waffling back and forth on whether to just use the TO220 style FDP038AN06 FETs I already use, or the higher-power-handling but higher RDSon TO264 style NTY100N10 FETs I used so well for so long on the original rebuilt ScootNGo controller.

Either way, I have to hand-wire the FETs to the control PCB, as there is no way to fit the whole PCB in there in a way that lets me bolt the FETs directly to the casing, without removing the FETs from the PCB. So I cut the entire end of it off from the gate resistors on, and will just run wires to each FET and then bolt them to the inside of the case, using insulating pads to keep them electrically isolated between the upper and lower halves of the halfbridge.

The case also has a spot for an automotive blade fuse. I am not using it now, but I may wire it in later, once I have an easy way to set a limit for the current on the 2QD. Right now the 2QD limits current via a voltage drop measured across the MOSFETs, so it depends on their RDSon. Since the RDSon of the MOSFETs I am using now is so low, around 3.5mOhms (actually half that since I've got parallel pairs), the current limit is apparently very high. Beyond 153 Amps, at least.

There is a current limit fine adjust resistor, and it's coarse adjust next to it, so I just have to figure out the circuit so I can work out what potentiometer I can install there to give me a good range of limitation I can use, for as low as 5A to as high as 50A (more if I have MOSFETs installed that can handle that). Then I can also use this to test for various different limitations, such as batteries that can't supply as much current, like my Li-Ion and a pair of well-used NiMH packs someone on ES is sending me (which might put out 7A on a good day).

Also so I can test for how well it performs at the actual legal max of 750W. ;)

I've also been charging all the SLAs I have around here for the last week or more. Some of the UPS ones simply won't charge well, but I am still letting them trickle charge in hopes they might recover at least a bit. I think that with the two newer ones that came in that most recent powerchair case, I will have 7 good ones in the 17Ah range, and 2 not very good ones, and one dead one. Plus the three 31Ah U1s I'd started with but changed out due to weight when I got the 17Ah UPS batteries. One U1 seems a little weaker than the other two.

I haven't done a full discharge test on any of them yet, but will do that using the Turnigy meter to get an idea of how many Ah I can realistically expect out of each one, including the three already on the bike.

Tuesday, December 15, 2009

Blown MOSFETs Due To Chain Jam, Possible BMS Arrives for Li-Ion Pack

I have been having balanced karma of late--every time something really good happens, something equally bad compensates.

Yesterday on the way home from work the bike's rear chain (regular bike drivetrain part) somehow derailed and got tangled up, which actually pulled the entire right end of the rear axle and the derailer bolted to it off the dropouts and bent the rim up against the chainstay on the other side (the left end stayed bolted in), and then everything jammed and both bottom-leg MOSFETs blew.

The power meter registered over 3500 watts peak, 153 amps peak, which is a more than any of it is rated for--the MOSFETs I installed in my 2QD are only rated at 80A continuous, and can handle ~150A for *maybe* a second absolute max, with sufficient cooling (which they don't have in my setup, by any means). So it's no surprise they blew up.

All that only took about half a second as I was accelerating away from an intersection, crossing two lanes to get to a left turn I have to make to get home without going down a very busy stretch of road.

Then I had to drag the bike across the rest of the lane (while cars that weren't yet coming when this all started kept trying to go around me instead of letting me get out of their way!), up onto the concrete median, and spend an HOUR with traffic roaring by me, while untangling the chain enough to get the wheel off, unbend the rim and true it enough to get it able to roll. Then I had to take out around 6" of chain due to bent and broken links, and set it up to run only in lower gear in front since it was now too short for the big ring. Plus I had to take the motor chain off, since my pedals are linked to it and it is nigh impossible to pedal the bike without the motor running otherwise.

After that it was a heck of a ride home, at about 9MPH, which is just above the unstable speed of the bike, and I was totally worn out when I got home (and then had to go to a different job as handyman for someone else).

I didn't have the camera with me to take pics of the chain/etc, but wow, it was awful looking. It looked like someone had hit my rear wheel from behind and then stepped on it sideways, but it was just from being yanked so hard by the chain as it tangled.

The frame and dropouts all appear intact, but the wheel was seriously messed up. I will need to take it completely apart, restraighten the rim, and then re-lace it to get it back to anything close to really true.

The derailer cage was slightly bent but not badly, but the bolt that secures it to the little shaped nut that recesses into the dropout behind the axle had sheared thru as it was all pulled out. I am just lucky that I carry spare nuts/bolts in the toolkit, one of which happens to be the same thread pitch and diameter as that bolt--it is a bolt from a rackmount kit--it's so long that it prevents use of the highest (smallest) sprocket on the rear cassette, but as I had to pedal with no assist there was no way I was going to be shifting up that high anyway.

I guess the good news is that I *could* fix the problem on the road well enough to get home.

Here's some pics of the controller with toasty MOSFETs, before repair. I still haven't had time to go back and fix it yet; just replacing the MOSFETs and gate resistors (whcih also burned open as they are supposed to) didn't fix it. I'm too tired to try more now, after another day of work. Tomorrow and the next day I have to go help do a roof and some other things, so I won't be able to do it then, either. Fri and Sat I'm working again, so I don't know when I will find the time to finish troubleshooting it. Maybe Sunday. Should be easy, when I have time and am not too worn out to concentrate. (writing this post has taken several tries).

A close up of the damaged area. The discoloration around the screw on one MOSFET is actually the melted remains of the plastic insulator's still not shorted to the heatsink, but that insulator is totally destroyed from the heat.

This blown LiFePO4 BMS (sent by an Endless Sphere forum member) arrived today:

All that is known about it's problem is that a puff of magic smoke escaped from it somewhere, but not specifically where. With luck it's the MOSFETs, as those I have around here already.

Once I find and fix the blown part(s), then if I can figure out how to change it's HVC and LVC voltages to match those of my Li-Ion cells, I can use it as a BMS for my custom-built pack.

First, I just need to invent a time-machine that gives me extra time to do everything and still get enough rest....

Monday, December 14, 2009

More Batteries, More Boxes, More Chargers.

Recently donated was another pair of old wheelchair batteries in their box with a charger. All of these are useful, as the batteries are the same size as my 12V 17Ah, but they are 20Ah. The box is an interestingly useful shape, split to lock in over a central electrical connection, but in this case it is wide enough to fit over a top tube! The charger is a 4A 24V charger almost identical to the 3A charger I already have.

First, there is the possibility now to hook up both chargers like this:

if I change the pack to a 48V using four SLAs instead of the three I currently use. I was planning on that anyway, with the fourth to go in the rear triangle once the suspension is done. This would let me simply plug in wherever, and charge up the batteries unattended with the automatic chargers' own 3-stage normal charging, instead of the two ways I do it now.

At home, for overnight charging, I set the big heavy Sorenson for 44.5V and max current, then plug it into the pack in place of the motor controller.

On longer trips where I can recharge along the way, I carry the 3A 24V charger, which is only a couple of pounds, along with an Anderson that has a jumper wire across it. Since it only charges two at a time, I unplug one battery and plug in the jumper in it's place, then plug the charger in place of the motor controller. Every 30 minutes to two hours, I move the jumper to a different battery connection, so that all three get a part of a charge cycle. It is not optimal by any means, but it extends my range some.

Thew new stuff:

The new batteries are 20Ah,

But it is the same size and about the same wieght as the 17Ah:

The battery box opened up

and the handle on it's top is removable.

If I cut out the part where the charger connector went (an XLR), up to the bottom lip of the cover, then put an upside-down "U" of aluminum sheet in there to help restiffen the case, the box can be placed across the top of the top tube just behind the headstock, at the front of the bike.

This would put about 30 pounds up there, so it will definitely change the way it handles, and will probably take out most of the shock absorption the shock fork gives me now.

If I used this box I would put the fourth battery plus the rearmost of the three existing ones in this, moving much more weight up front to balance the bike, which would help especially when I am going to carry cargo.

However, I could also make it so these are optional batteries only used for additional range. To do this, I would keep all three existing batteries where they are, and add two new ones in this, plus a third new one in the rear triangle. All three new ones would be wired in parallel with the existing ones, as a second 36V string. A mostly-removable wire harness would need to be made that leaves extra Andersons hanging at front and back always on the bike for the other batteries to just plug into, so that I could add or remove the extra ones quickly as needed.

This would still leave me with the problem of charging them, as there would still be sets of three. However, they can be charged in pairs at least, so an automatically-rotating charger is possible but would involve heavy-duty relays/contactors or cabling (which would also be required to auto-rotate as I currently do manually, as motor power would have to flow thru some parts of the current system).

So, to charge them in pairs like this, I could simply use a timer that every 10 to 30 minutes or so would switch from the first pair to the second to the third and back to the first, switching a set of high-power relays in at least one case, though low-power could be used for the other two pairs.

For the "bottom" pair in each triplet, simply switching a low-power relay on across each one pair to engage the charger would work.

For the "top" battery in each triplet, it is harder, as they cannot directly be connected in series. First their parallel-ish connection (both positives wired together) must be changed to series (positive of one to negative of second, opposite pos/neg then connected to the charger).

That one requires a heavy duty contactor to open between the positives of each battery and the rest of the bike. Then a second (low-power) contactor to close that connects the batteries in series, and also to the charger.

The heavy-duty contactor is the issue, as it must be able to handle 100+ Amp surges during motor operation (though it does not ever have to make/break during load).

So it is much easier to go to 48V and get only one extra battery's worth of power, for now. At least until I get the Li-Ion packs finished (they are not yet started for lack of a BMS).

Friday, December 11, 2009

More Power Usage Data

The day after the trip in the last post, I took another trip in that general direction, the 11-mile-one-way trip where I recharge at the destination.

The first leg of the trip was 11.298 miles, about 48 minutes time actually moving (VeloAce does not count total time, only time in motion), with end odometer reading 942.3 miles.

It used up 9.059Ah, 328.8Wh, for around 36.3Wh/mile.

Peak amps was 77.57A, 29V pack sag, 37.59V pack end voltage, and 2437W peak.

Recharge at destination gave back about 9.4Ah.

Return leg was same distance, same trip time, using 9.28Ah, 327Wh, 2402W peak, 36.48V pack end voltage, 27.27V sag. End odometer was 953.6 miles.

I forgot to write down the data from my grocery run the next day, which was about 2 miles.

My trip to and from work the next day, around 5 miles total, with no recharge until returning home was 960.8 miles odometer total for 151Wh, 4.379Ah, (30Wh/mile). 97.5A peak, 2915W peak.

I think this peak is happening because I often end up at some point on the trip to work suddenly being cut off by traffic pulling out of parking lots, etc, onto the street, even though I'm right there (they do it to other cars, too), so I have to slow dramatically down or even outright stop, and then I'm in a high gear since I had no time to shift back down. Accelerating in high gear takes a lot more startup current for longer periods, so I try never to need to do this.

Acceleration once I can implement a more severe current limit on the motor is going to be pretty wimpy. :-(

Wednesday, December 9, 2009

Power Usage and Traffic Patterns

After the repair in the last post, I took off all the suspension stuff to take a trip and pickup some stuff posted on, about 8 miles away from the house. Round trip of around 16 miles should be no problem as long as I help by pedalling and don't go too fast, so I'll have plenty of power to get back with a little to spare.

It didn't quite work out that way, though, as there were almost 3 miles of detours. Twice on the way there I ran into construction that wasn't going on when I last was in the area, where large areas of streets were blocked off that I needed to go thru to get to where I would cross to the next area.

Because of the layout of the city, there are often places where the grid of streets does not continue normally--it is broken up by parks, walled-in apartment complexes and housing areas (that have only one or two inlet/outlet roads, and seemingly never in the direction I must pass thru), and acoustic walls on some streets that have a lot of traffic next to residential areas. Those walls have few breaks for roads or paths so it can be tough to get around them without significant detours.

I plan my trips so that I won't encounter any of those areas, wherever possible, but when I'm forced to detour I may end up having to go around more than just the original detour area because of these other large "blockages". Sometimes I may be able to get around them a shorter way by going on a major road instead, but those roads (due to the traffic constraints of these blockages, primarily) are usually quite congested with traffic at 45 to 50 MPH (even when they are marked 40 or less), and are usually only two narrowish lanes each way, with no room for a bicycle to ride to the right of traffic--I'd have to ride *in* traffic, and would almost certainly
cause someone enough frustration along the way that they'd do something irrational and stupid, and both of us would regret it (assuming I lived to do so).

So I go the long way around when forced. If it is not that far on one of those major roads, and there are gaps in traffic, I may be able to get most or all of the way around before traffic catches up, but that is unusual. If it's really short, 1/8 mile or less, I'll walk the bike on the sidewalk, if there is one. Almost never is it that short.

Thus I end up with detours such as that tonight, using up more power than anticipated. This time it was a serious problem, as I had a car battery and some other stuff to haul back with me, and needed the power to move it all. I'd also planned to stop for some other things along the way, but ended up not being able to due to time (had to ride MUCH slower than usual, around 9 to 10MPH for most of the trip after the first detour, so I could save power).

All in all, the trip was 19.069 miles, and took 2 hours and 5 minutes of actual travel time, not counting several long stops I made on the last 1/4 of the trip to let the batteries rest and get a little more power. I'd guess it actually took more like 3 and a half hours, all told.

I did hit 20.0 MPH at one point in the trip, probably on the downhill of one of the canal tunnels. 9.1MPH was the average, though. The odometer hit 931.0 miles as I pulled up into the driveway.

When I left, the batteries were at 40.5V resting, and 34.9V resting when I got back. 31.0V under half load, and 28V if I put it at full throttle, with almost no pull. The lowest voltage noted by the meter was 23.77V! Hopefully I haven't damaged the pack too badly.

I used 14.239Ah on the trip for the motor (not counting lights or turn signals, which are still not wired thru the meter. I'd guesstimate around 1Ah more for the lights, since I did not turn them off during any part of the trip, even the stops, and they take around a third of an amp including the laptop ac adapter and the intermittent use of the turn signals and brake light.

I probably could have gotten more power from the batteries in warmer weather; it was around 50F when I left a bit after sunset, and it was not much above 40F by the time I got back. Three hours later as I post this, it's just at the edge of freezing outside, at 33F. I keep the bike inside so the batteries don't get really cold, but it's often down to 50F in that back room once it gets this cold outside.

The batteries did not feel warm at all during any part of the ride, but I can't tell their internal temperature. Even feeling the post terminals just felt as cold as the rest of the bike. I kind of wish I had had the DMM with the thermal probe with me, but I didn't.

494.3Wh total, for an average of 29.52Wh/Mile. Still in the same ballpark as the short trip measurements with and without a load.

64.89A was the peak this time around, although I did not notice when it happened exactly, it was sometime in the first third of the trip, and was probably climbing the hill out of the canal tunnel. That gives about 2KW peak power usage.

Now I know a lot more about the numbers to watch for during a longer trip, and my range in the "cold".

I am now recharging the pack thru the meter to see what amount of power it takes to restore it to "full". It's about 60F back there right now; the batteries don't feel warm (the charger only outputs 1.8A absolute max, and 1.5A nominal max).

Suspension Not Quite Going According To Plan

Having tried a few variations of the last idea in this post
I ended up breaking the frame with an incredibly stupid attempt, because I tested it without putting any support between the stays:

As you can see, that left me very unhappy.

On the righthand stay is the prior attempt, which was not long enough; I decided to try one a little farther forward and longer, but being farther forward it had zero support from the dropouts and just crushed the tube as soon as I put the suspension together and let the bike's weight on it, and pushed down just a little.

The repair required replacing some of the tubing. Fortunately I had a frame already being parted out with some tubing just larger than what I had to replace, so it could be slipped over the damaged area and welded on.

I cut out the damaged area first, then straightened the dropouts and other stays.

Then I cut off a piece from the other frame large enough to completely cover the removed area plus as much as I could get from it. I left the curved end on because it comes close to matching the curve on the back of the stay to be fixed.

I left the brake stud on there as a way to manipulate the tubing while I did the repair; it will be removed later once I am sure I'm done.

I slipped it over the front of the stay first, then aligned the stays and slipped it over the back end.

so it ends up like this:

Once alignment was certain, with a wheel in the dropouts instead of the triangle above, I welded it in place. It seems as strong as ever, but I am sure it is not quite as good as it used to be.

Now I have a better plan for doing this, based on this idea:
but modified to be adjustable, based on Drunkskunk's seatpost idea:

So that the cut-off part of the seattube will end up rewelded pointing forward, so a shortened seatpost can be clamped in as an adjuster for the ride height.

Now, I still have to work out the chainline issues, as the chain currently wants to pass directly thru the space the pivot BB occupies. I must install something to force it to go around that, yet still shift across it for gear changes.

I have a nylon or teflon cutting board that I may try to cut a strip from that will be used to deflect the chain across, and clamp it to the BB. It will wear, and it will add noise, but it should let me test the feasibility of the suspension while I think up other ways to get the chain around it (eventually redesigning the rear end to eliminate the problem).

Friday, December 4, 2009

Dualie Wheels, Mk II

I've discussed dualie wheels for the rear before, so that I can have more support back there, and less worry about a blown tire or tube, broken spokes, rims, etc. It's less of a worry once I have rear suspension, but the concern for a blown tire still exists, since as heavy as the bike is it is difficult to fix on the road. Less so if I use the suspension system I'm doing now, where the dropouts are fully behind the cargo pods, so I can at least get to them easily, but still not easy to do.

So I'm considering building a whole wheel from scratch, using the bearings and tube from this:
to make the axle, and welding up a hub, spokes, etc from there.

It's just small enough diameter that I can still fit the threaded part off of a regular hub (minus the bearing cups) over it with clearance, if that part is a bolt-on cover over the bearings.

Then I'd weld up a tube to fit between the bearings, weld on some flanges I can drill out for spokes and for bolting on the freewheel threading off a hub on the right side, and directly bolt on a sprocket on the left side (for motor use).

The flanges would be probably around 6" in diameter, so that I have plenty of clearance for spokes to be replaced without taking the wheel apart (unlike most bike hubs, where you have to take the freewheel or cassette off of it first, since it always seems to be drive-side spokes that break).

That also allows for many more spokes than usual, so I could use 72 spokes, 36 per rim, and have them fully supported. I might choose to not even weld them together, so that they are "independently suspended" as it were, with the spokes.

The rim would otherwise be the dual-rim welded with spacers as suggested by Scrapyard Don above.

It's difficult to imagine from what I am saying, I'm sure, but I have a fairly clear idea of how I'd do it, if I can find all the right parts in my junk pile. I'll try to come up with some sketches at some point.

Adding Rear Suspension to CrazyBike2

I've got several options for doing this, and this is just the first attempt, doing it the "easy way", that lets me revert back to the original at any point, without cutting into the original rear triangle. There are certainly better ways of doing it, but because of the cargo pods, they all require severe modification of the whole rear end that would preclude going back if it doesn't work out.

*This* method allows me to even undo it when I'm on the road, if something breaks unfixably on a longer test trip, though that would be pretty annoying and take at least an hour to do.

It starts with the 24" rear triangle originally slated for the unfinished ReCycle, and bolts it's crankshaft/BB to the dropouts of the CrazyBike2's rear triangle, in place of the wheel. The wheel now goes into the new triangle.

Then a shock with coil-over spring, origin unknown but possibly motorcross bike, bolts to the top of the new rear triangle, pointing forward to align with the top of the original rear triangle/toptube to keep all the pushing forces along a strong line. Below is a simple example of how it might work, bearing in mind that CB2's rear triangle is much less tall than the bike frame on the right.

This adds about a foot to the length of the bike, and about 15 pounds (so much for making it lighter) but it appears to be the easiest first try.

First up is finding a way to compress the spring enough to get a large plate on the shock to hold it in. Neither of these thrift store finds had that plate; it was probably part of the vehicle they came from.

I didn't have a large enough washer or other plate just laying around, but I did have a strong steel tile-cutting blade, too worn to cut anymore but still strong, so that has become the first temporary spring-retention plate. It's not very thick, so I suspect it won't survive all that long in real use, but it will allow me to perform some tests without manufacturing something for a shock I might not even end up using.

So I zip-tied the spring on each side and carefully compressed it just enough to be able to assemble the shock, always keeping everything parallel to my body so nothing could hit me if the zip ties broke. I also made sure none of the dogs could get into the room I was in, so they wouldn't be in danger--they tend to show up at the worst possible time if something is going wrong (before I even start cursing ;-) )

Once compressed suitably, it was easy to screw it all together, then tighten the jam nut against the pivot ring's nut so it can't work it's way loose later.

Next up was a simple way to mount it to the rear triangle for a test:

...a couple of pieces of 1/4" plate steel from a big old desk chair, from the L bracket that holds the seat back to the base, spot welded to the rear triangle at it's strongest point where the stays meet the seat tube. I can easily cut them off and move them elsewhere should the need arise (and it turns out it does, later in the post).

First bolted to the shock to keep them lined up, then clamped in place to the tube.

Then spot welded at each corner.

That's the basic alignment, and approximate position under load, at a guess.

It sticks up a lot more than I would like, so even with the wheel out of the way, it'll be too far up to lay cargo across the pods. :-(

It would be perfect if it were like this:

But that's only prior to loading, with the handy-dandy adjustable-ride-height mechanism.
The front mounting point for the shock is adjustable, to give me about two inches of adjust range, for altering rear end height when loaded if it is necessary. I did this by cutting a strong hard steel plate off the bottom of that same desk chair as above to weld to the square-tubing that supports the cargo pods and seat, as that is the strongest point on this section of the bike.

The silver part is the steering tube from a discarded Razor kick scooter, along with it's "fork". I bored a hole in the plate large enough for the tube to fit thru, with the "fork" end pointing rearwards. I threaded the top nut for the tube on it's "rear" end, behind the plate, and the locknut on the "front" end in front of the plate. Those are what let me adjust it's length, and secure it to the bike. It will not be easily adjustable on the road, as it is under the seat; it is only there so I can change the ride height if I anticipate needing to do so before a particular trip.

The preloading will be done by a tub-balancing-support cable off an old washing machine which will restrict how far the bike can pop back up after I get off of it, which will normally be sagging loose during the ride, so it will only ever have a load on it when it's not being ridden. It's main purpose is to keep the chain from ever having to rub on the frame, and so I can see what the bike is like when I am not on it, plus not having to climb up so high onto the seat. :) The shock itself doesn't have a preload method built in.

This is what the whole bike looks like now, without the preload yet, so it's a lot higher off the ground that it will be.

The spring compresses about 2/3 of it's length with me on it, leaving a bit for bumps and whatnot. If I have much cargo in the pods, it will compress most of the rest of the way, unfortunately, requiring a different leverage method for the spring to use it properly. I'm mostly doing it this way now so I can easily undo it, and because this method is easy to build and test.

This is the rear view, again no preload yet.

A closer view partly from the top/rear, where you can see the extra derailer used only for it's tensioner, at the original dropouts. It's there solely to take up the slack as the triangle moves back down, and provide enough extra chain that I don't need to worry about the actual rear derailer jamming due to chain overtension when I'm on big ring front plus big ring rear on the occasions that must happen.

Now, chainlines I'm still working out, so stuff may change as I do this. In theory with the spring preloaded by cable, the chain should pass normally thru both triangles to the rear wheel. That might not work perfectly thru the gear range at the back, so I might need to add a guide wheel to get around the stays. Hope not, but....

A close up shot of the ride height adjuster.

In first testing, I already had a problem (of course). The steel plate the whole thing goes thru under the seat is great when pushing against it, but apparently not in pulling.

I didn't take a pic of it, but when I sat on the seat and started bouncing up and down to see what would happen (before I put this thing on the road), at full compression the angle of the shock is just above and down onto the front pivot point. That forced the pivot to pull on the plate rather than push against it, and the whole assembly sort of folded down into the empty original rear triangle. Easy enough to bend back up once I got enough leverage, but it certainly suprised me (and shouldn't have).

So I'll need to do some rethinking on this. I have a 1/4" steel bar that I put under the pivot point across the square tubing for the cargo rails, and this prevented it from happening again, but I don't want to add essentially another pound just for that--plus eventually that might bend, too. A thicker plate for the pivot to bolt into would help, too, but again, it's just more weight. There should be a better solution.

I could move the rear pivot point downward closer to the BB, so it is always pushing upward against that plate, or even better against a pivot point that is part of the cargo pod rails. That would actually counter the weight of cargo in the pods pushing down on them, and if the pivot point joins the rails horizontally it will also stiffen that part of the frame.

Chainline currently does not come out right, so having to rework this is actually helpful. I might wind up putting a large sprocket (to reduce noise) on a jackshaft in front of the rear wheel, between the cargo pods, to keep the top of the chainline clear of both sets of stays even during pivoting.

Another idea DrunkSkunk from the Endless Sphere forums had is to use a seatpost in the seat tube, and attach the rear pivot point to *that* instead of my contraption from the Razor/chair up front. Then I could move the seat post up and down for ride height adjustment, and if I use a quick-release seatpost clamp, that'd be very easy to adjust.

The same problem I have with the first arrangement comes in here, though, where the shock is in the way of laying cargo across the pods--something I would like to be able to do, and could not do with the tire there.

If I move the front pivot point to somewhere within the dropout area of the original rear triangle, then I can have both the new adjustment method and be able to use the top of the pods for cargo, too. I just have to put the bottom connection point on in a way that won't interfere with putting the bike back together the way it was, if none of this works out.

It'd look something like this, I think:

where purple is the original frame, brown is the load-bearing cargo rails, orange is the new triangle, gray is the seatpost, and red/black is the shock and spring.