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).

Low-Speed Stabilizers, Mk I-a Alpha

A few days ago, I started on this alpha idea for the stabilizers, but I forgot to post about it.

I have a couple of very similar kick scooters, with various little defects. One given to me and I think the other was maybe $5 at Deseret Industries thrift store, a couple of years ago.

They come apart very similarly, into a pile of components that's pretty much the same:

One has easy quick-release-skewer type assembly for all of it, and one uses allen-head bolts and Jesus-clips, which I happen to have the tool for this size, making removal much easier (and safer).

The part that I wanted out of it is the entire steering tube and "fork", with wheel, which also includes the pivot point for folding.

I don't need the handlebar tube, as that's not how it'll be raised/lowered. It'll be self-steering as casters, turn around backwards from the way the scooter uses it.

The pic above shows a wheel from each one, but since they're slightly different sizes I'll put a pair of the same wheels onto the two different forks, most likely. That's about where and how they'll look, just wide enough to hold the bike up by itself, but not quite as wide as the bike is. Just outside the cargo pod rails, under the seat, is how they'll fold up:

That puts them about the same distance as my feet on the pedals, as seen below:

I haven't worked out the lowering/raising mechanism nor the actual pivot axle, but the above pics are the bike standing on it's own with them holding it up, just temporarily bolted to the cargo pod rail (too weak to actually do the job on the road; will probably use dropouts instead), and sitting so the edge of the top of the steering tube is catching on the bottom edge of the cargo pod rail, thus supporting the bike.

With a stiff axle pivot, and a latching mechanism, these should work fine as an alpha test to see if it is worth pursuing further.

The battery fairy does wheels, too:

They're not super-soft, but they are slightly compressible urethane casters with good bearings, and fairly light with plastic hubs. Also are larger diameter (about 4-5"), and over an inch and a half wide. That should roll much better on pavement than the kick scooter wheels, should the idea prove out good enough to continue development.

If I use these for the stabilizer wheels, then I would probably make a stub axle bolted into a single tube that simply pivots on a titanium wheelchair bolt from the dropouts, for each side. Then the two tubes would be welded in an "H" with the bar very low down, and one of the tubes much longer than the other, so I can reach down and use it as a lever to lower and engage the wheels or raise them.

The wheel pivot for caster I am still considering, but probably a second axle with bearing that joins the wheel section of tube with the pivot section of tube, inside the tube diameter.

I might even be able to bolt it all together instead of welding, using pieces of old aluminum crutches, of which I have a few in poor shape (for crutches, but not for materials).

Low-Speed Stabilizers Idea

I've been inspired by another bit of one of AussieJester's projects--stabilizer wheels to let him ride at slower speeds, as well as a stable stand to hold the bike upright when stopped. Last time I was able to nearly directly take the idea and run with it almost just like he already used it (the brake-arm chain tensioner), but this time it'll have to be quite different in execution.

Because my motor would never handle the power needed to climb hills at speeds over 8 or 9MPH, and neither will my legs, I have the bike geared so I could crawl up a hill to do it. However, the bike isn't *stable* at the very low speeds (1-3MPH) that I could climb long hills at, so I would be unable to help the motor by pedalling, as I'd have to keep balancing the bike by touching the ground all the time with my feet.

So I need stabilizer wheels (or a trike design, which is the works but not possible yet) for really low speeds. I also need them to not both touch the ground at the same time, since in Arizona, a bicycle is only a bicycle under the law if it is three or less wheels in contact with the ground. As long as I keep only three of them touching, I'm safe from any legal hassles (it's already wierd-looking enough, I can imagine some problems with misunderstandings already, if someone looking for a reason to issue somebody a ticket that day picked on me).

Since I'd be riding potentially a mile or two up some hills like this, I don't want to use solid wheels, so I'm looking for a busted dolly that has good inflatable-type tires, 6" to 8", even if they have plastic hubs, as long as they have bearings in them. I have the old electric scooter wheels but the hubs are big and clunky; I think they're 10" wheels and would ride nice, but those hubs...plus the tires are relatively narrow, and wouldn't give as much shock cushion on bumps and stuff, but the dolly wheels would, since they're usually 2-3" wide.

I don't have any sort of actuators that'll do this kind of work, so it'll be just a manual lever along the center frame I reach down and pull, along the lines of the emergency-brake lever in the middle console of some cars.

The pic below shows about where they would go, and how they'd raise/lower.

Basically, the swivel point would be at the former rear dropouts of the Magna frame I'm using for the front half of the bike. They're dropouts, so they are strong enough to take the strain, even though I no longer have the seat stays that went down to them that you can see in this pic of an older revision of the bike (the batteries now rigidly fill part of the space between the top tube and the base of the bottom triangle/diamond formed by the chainstays).

The handle would go up and around the battery area, to clear them and the cabling, on the left side (even though it's the right side in this pic), so I could keep my hand on the throttle and shifter if need be.

Both wheels would be joined at that dropout, and angle out kind of like yours, so that there would be around 1/4", maybe 1/8" on either side below one wheel when the other was on the ground, without me on the bike. With me (and posssibly cargo) on the bike, it'd be less to nearly (but not) none, depending on front/rear tire pressure and front shock load. They'd pivot together as I move the one handle.

Not yet sure how I latch them in place; possibly some sort of mechanical detent device on the frame that the handle "snaps" into at full extension, with a harddisk magnet or three to hold the system in retraction when not in use.

One problem I have to deal with using midships stabilizers like this is that they probably will have to be casters--they must be able to turn with the bike, or else I could end up with the one on the ground causing sideways resistance to any turns, lane changes, etc.

If I'm lucky, they'll work as solid axles, not needing any steering/caster pivots, so they'll be built that way first. But I foresee the likelihood Murphy will smack me around for doing that, and make me build casters instead. ;-)