Search all of my sites with Google

Wednesday, August 26, 2009

2QD Rehoused, Brake Lever Motor Cutoff, Etc.

I didnt' get anywhere yet on the pedal freewheel, because something is sort of nagging at me about it but I can't figure out what yet. Safer not to start it till I do.

So today I just did a few cleanup things, such as putting the 2QD in a smaller case (the one I had was just so big that there's no good spot on the bike for it).

I also decided to test it out with 2 pairs of smaller TO220 Fairchiled MOSFETs as described in a previous post, instead of the NTY100N10 on each leg of the half bridge. They'll be much lower RDSon this way, so should stay cool even with a small heatsink, with the airflow I can generate near the rear wheel. I have a few of them from various things, so we'll see how they work out. If they blow up due to voltage issues, I'll put the others back on instead.

So there's what it looks like now, with the four smaller MOSFETs directly board-mounted, bolted to a heatsink pulled out of a dead PC power supply. It's small, but may be fully sufficient, since the other ones barely even got warm from operation on their heatsinks. Even if this one gets fairly hot, it should still be safe to run for testing for a while.

I wanted to use an old modem case that was made of aluminum, but I can't find the thing now.

But I remembered I had some similar-sized old Pactec enclosures I got from TriTek many years ago (they're not around anymore), when I was still a student at DeVry. All I can remember is that they were part of some super-deal of a grab-bag sale, and I thought I would use them all up quickly, but only ever used a couple.

I guess I've had these laying around for almost 20 years now, time to finally use one of them again. :) I drilled a hole *exactly* the same size as the OD of the main cap, since it's a lot taller than the case. I actually want that cap out in the air, because it gets more than warm doing it's work, and if it can be cooled a bit by airflow it will last longer.

Halfway installed into the case, you can see the directly-soldered on motor and battery wires, which lead to connectors outside the case. The throttle plug I didn't use an external connector for (not enough time today to dig around for one), so it's run right from the throttle/key up on the bars down into the case, and plugged into the 3-pin header on the PCB (uses the same connector as a PC case fan). When I have more time, I will cut the connector/wires off a dead case fan, desolder the connector for a fan from a dead motherboard, then make an extension cable that will stay as part of the controller with the external connector available for the throttle. Then I can take it off easily when I want to service it or whatever.

This is the fully enclosed 2QD hooked up to the bike, but not mounted yet.

The cap looks dumb but it should stay cooler, and wouldn't have fit in any other enclosure I had, anyway, except the one that's too large to fit on the bike properly.

It now fits neatly under the seat/cargopod crossbars. It's just ziptied for now, but I'll use a radiator hose clamp once I find one large enough in my junk.

It runs fine like this so far, though it does get warmer. I went around the block and it held up ok. We'll see about a longer trip tomorrow when I go to work. I'll just head out early enough that I have time to just pedal if it blows up or something. :-) I'm way too tired to go out and test it on the road right now--I'd probably crash.

One more thing you can see in this pic if you know what you're looking for is the lighting wiring.

The white wires to the black UPS battery in the tray go to the lighting system. I finally decided that the extra 7-14 pounds I was carrying in the one or two smaller SLAs is too much, and just hooked it up to this part of the traction pack for now. It makes a difference to the bike feel, not a lot but definitely noticeable not to have the other weight there.

While I was at it, I found one radiator hose clamp large enough to go around the battery that's on the cargo rack, but I forgot to take a pic of it. It's now secure enough I have no worries about it bouncing off during a ride anymore. Still gotta find some for the two on the white racks.

Also thinking about moving the cargo rack battery down to the midships area where the controller box used to be, where the two bike frames meet above the motor. Not sure it's quite big enough space, though. If it is, it'd improve the handling even more.

Another part of detail cleanup was to add the brake cutoff for the controller. All it is is a N.O. reed switch (under the foam tape sandwich protecting it, horizontally near it's bottom edge), wired in series with the throttle V+ wire (just like the keyswitch is).
Then a magnet off an old CompUSA name badge holder on the side of the head of a stripped-head bike-accessory screw.

I had to have some way to hold the magnet "upright" so it's field would activate the reed switch, and the smallest bit of steel I had just laying around that didn't have sharp edges I'd have to file was that screw (and others like it). I ziptied one end of the screw, played around with the positioning until squeezing the brake lever just enough to begin engaging the brakes also cut out the motor. Once it was adjusted I added Gorilla Glue with little moisture around it to secure it in place, then the zip tie can come off with no worries about losing it on the road.

That screw doesn't just give the magnet a handy place to stick upright, it also is doing something to shape the field, because without it, I can't get the reed switch to reliably operate for *on* unless the magnet is so close that pulling the brake lever doens't give enough distance to go beyond the hysteresis point of the reed switch and let it turn *off*. With the screw, it works at a nominal distance just fine.

A third thing I actually added a few days ago but forgot about was this little door-holder.

I dont' know what it was originally from, as I found it laying on the ground. It's got two little clips, one on each end, and a weakish long spring between them. I simply clipped one end to a hole already in the top cover, and the other to an existing slot in the side cover, and the tension of it holds the cover open no matter which way the bike leans when parked (it rests on the edge of a cargo pod, since I never put the kickstand back on), even when it's really windy.

It also helps hold it closed, although i don't particularly understand why.

Since it was there, I also took a pic of the repaired Sorenson power supply that I use to finalize the battery charge now that I have to swap the real charger around from pair to pair (it being for 24v and me now having a 36V pack).

It's current limited, so I can set it for 14.4-15.0V (per the battery's label for cycle use) and charge for a while first at the full 1.5A it can handle, then cut it down to half and then 1/4 of that current, as each battery gets closer to full charge (13.6V unloaded after sitting an hour or so off charger).

Kludgy and operator-dependent, but it works for now and only takes a moment to setup and change around, every so often.

I was trying to figure out how much power I am using in my 5-mile work trips, but I'm not exactly sure. The 24V charger (nominally a 3A charger) charges the first pair (A & B) for about an hour and a half at 2amps fading down to .25amps somewhere along the way (I tried to stay and watch it but got pulled away by the dogs every time so far). Then the uncharged one (C) plus one of the first pair (A) are hooked up and it charges for around 20-30 minutes at 2A, then quickly fades out to nothing, leaving C barely recharged and A closer to fully charged. Move it to C & B, same thing, maybe a few minutes less at 2A.

Moving around in pairs like that I let it top off as much as it can, but only takes a minute or less for the 2A charge to stop whenever A or B are in the loop.

So I use the Sorenson to finish charging C, which by itself sucks the 1.5A for maybe 30-40 minutes or more (again, got pulled away by the dogs), and then the battery voltage starts to catch up to the setting on the Sorenson and current drops way down to around 300mA or less, where it tends to stay until I disconnect it.

Unfortunately, with all that shuffling around, I'm not sure how to calculate what power I'm actually putting back into the pack!

1 comment:

  1. That capacitor protruding is good, considering the alternative of less efficient use of space on our small vehicles.

    I found your information on batteries useful. Lately, I have been leaving mine on charge at 13.6V all the time. My bike uses just a single 12V lead acid. It has boost to up to 48V built in the controller/charger.


Alternate suggestions or improvements to anything that's been posted is very welcome, and extreme detail is preferred to brevity.

Keep in mind that unless you leave an email address in your comment, I haven't any way to reply to you except to reply to your comment here. That means if you want a reply, you'll have to come back to *this* blog entry and it's comments to see my reply to you, unless you leave some method of contact within your comment.