Kabbage Commuter No. 2

[Kabbage]

Well, it's been 13 months since I broke my humerous falling off a skateboard, and so unable to ride the bike - I went in for surgery last week to have the arm 'mended' and they got around to looking at the X-Ray and saying 'well hell, it looks like it is acutally healing now - so no surgery for you'.

So I'm back commuting on the Avanti! How much better is that than the train? Lots, let me tell you.

Anyway, also time to start bike No. 2, to try a few new things, relative to the Avanti.

This time I'm starting with a 700c commuter, a Scott Sub...



Mine's a sort of Sub20/30 bastard child made with leftover parts, apparently, but that's fine, it's got hydraulic discs which is nice, but I mainly got it because it's a really nice matt black. Always wanted a matt back bike ever since Robocop...

It actually had some ridiculous bright orange rims on it (which I suspect is one reason they were selling it cheap - no one else wanted it) - the number of spokes didn't match the motor, so I've had both wheels re-shod into some black Mavic 700C rims with black spokes.

Ahh, the motor! Actually, Kepler's recent weight weenie Super Commuter build got me thinking about downsizing the motor as much as possible, so I got a little 250W Bafang SWXH geared motor from BenMoore.

I'll be running it off a 48V 10Ah custom Headway 38120 battery pack (more on that later!), which I plan to build long and thin like Full-throttle's, to put it 'in the triangle', but without using one of them fugly bags. It will be running through a 20A controller at about 750W or so, I guess.

In keeping with my 3-speed setup on the Avanti, I've decided to remove the rear derailer and controls, and go singlespeed on the rear, with the three chainrings providing gearing up front. I had got a nice Paul Melvin chain tensioner to replace the derailer, but it's turned out to not have enough dimensional flexibility, shall we say, to enable a reasonable chainline. More on that once I get the bike for real this week, hopefully.

Ok, back to the battery; These suckers arrived from evassemble today;

View attachment 2



So now all I've got to do is build it. As I said above, planning a long skinny battery like Full-throttle's. So it's 16S in four rows of four, joined like this....



So here's my first question... What's the best way to join these together in a space-effective manner? Is it possible to join with a short section of flexible wire soldered to the ends of the batteries? (I deliberately got the batteries without the screw fittings). Or is it possible to put in some sort of copper joiner, and then squeeze some solder in from the edge? (sounds like fun...).

Thoughts?

 

[Bill Nye the science guy]

I solder my nimh batteries together with 12 gauge stranded wire. use a soldering iron with a big tip that can store alot of heat energy then tin up the tip/ the wire/ tin up the battery terminal then join the two together. takes alot of heat fast to tin the battery because they dissipate alot of heat though the rest of the battery and you just want to heat it, solder it and let it cool without heating up the battery too much.

maybe someone else has something better.

 

[Kabbage]

So here's a picture of the real thing, which I picked up today....



and closeup of the rear wheel

View attachment 1

Here is the planned location of the battery; four of these suckers....

 

[Rollodo]

1. You may have difficulty joining 4 banks of these together in that triangle and still remain a slim package - wrapping them around the top tube may be a better option.

2. Sooner or later, you will have to balance those anyway. I know it's Headways, but I know it's not NiMH either. Think it through before connecting them together.

A word on these batteries - I don't know how much you paid for these new (err, I hope they're new?), but the folks in the Used section have some Headways with very little cycles and serious discounts - it's a hunt, but give that a look anyway.

 

[ken1645]

. I had got a nice Paul Melvin chain tensioner to replace the derailer, but it's turned out to not have enough dimensional flexibility, shall we say, to enable a reasonable chainline.

Couldn't you just remove some of the chain links to make the chain tight?

 

[Rollodo]

Couldn't you just remove some of the chain links to make the chain tight?

Sometimes, it actually makes more sense to get a tensioner - last time I had to remove and put the chain back together, it was a complete and utter nightmare.

 

[Kabbage]

. I had got a nice Paul Melvin chain tensioner to replace the derailer, but it's turned out to not have enough dimensional flexibility, shall we say, to enable a reasonable chainline.

Couldn't you just remove some of the chain links to make the chain tight?

I'm running three speed on the front chainrings, so need a tensioner.

 

[Kabbage]

OK, so it's been a little while coming, but I've finally started on the battery;



full-throttle gave me some nickel plate, which I'm cutting into approx. 10mm x 25mm tabs, which I bend in the middle. I can then tin the terminals of the batteries, and the tab, and then do the heat quickly with the soldering iron between both the tab and the battery terminal, and then jamb-together as quickly as possible method. Seems to work OK.

The two batteries on the left of middle stick out a little bit beyond the others, to enable it to be screwed down through the spine, onto the drink bottle holder screws.

Hope they're strong enough, some of the weight will be sitting on the downtube anyway, so it's really a locational issue, more than full load bearing... That's what I tell myself.

The spine (below) is a 16mm aluminium tube. $8 for 3.5m, who knew it was so cheap?

 

[headwind]

Hope they're strong enough, some of the weight will be sitting on the downtube anyway, so it's really a locational issue, more than full load bearing... That's what I tell myself.

The downtube will support the mass, but keep in mind the drink bottle holder mounts will be subject to lateral and shock loads.

 

[Kabbage]

Finally got some time to press on with my battery;

with the main four cell runs finished. BMS wires are a shocker to work around...







So that's it, my 16S 10Ah headway LiFePO4. Running 48V (about 55V off the charger).

Fixed to the bike via the aluminium spine with a 50mm M5 bolt (Phillips head) into the drink bracket fixings, and a 90mm socket head M5 bolt into the top fixing. seems pretty stable so far.

 

[Kabbage]

Here's a picture of my mostly finished bike;

View attachment 3

There's still no lights or throttle on it here, soon. And the cables aren't managed properly yet either. Just want to get it in a state where it is rideable, to make sure it all works...

I 'managed' all the BMS and other battery cables with the help of some hot-melt glue onto the battery itself, and then wrapped it in gaffer tape (inspired by full-throttle).

View attachment 2



Here's a detail of the controller, attached with the 90mm M5 bolt into the top drink bottle holder mounting point.



The little hump on top of the battery in front of the controller is the BMS. It's quite large.

I aimed to make it look OK, but don't seem to have done as nicely as full-throttle has with my taping skills. Might have to get the sewing machine out like AdrianSM... but probably worse than taping skills, so we'll see how that goes.

 

[Kabbage]

Scott Commuter First Ride Thoughts:

Took the new beastie for a spin tonight, here's my first thoughts....

Firstly, the little bafang appeared to be *really* loud. Like, nasty, but particularly under load when starting off - at full bore it is fine. I thought I might have copped a dodgey one, since Kepler has also noted that his first one was quite loud, but it appears to have got much better with a lap or five around the block - maybe just needed some grease to get thrown around it.

I'm running it off 50V with a 20A controller with no limiting - and I'm going cut back, so no CA to monitor or limit anything. So who knows how much it's getting really, perhaps it's hitting 1000W? I went around the block a few times, and none of the battery, controller or motor are getting hot (just warm, perhaps?).

I was originally running it with the halls connected, but because it was running rough to start, I disconnected the halls and tried it 'sensorless' (since the new ebikes.ca controllers autodetect either sensored or sensorless). It seemed to run pretty much exactly the same, so I have left the halls disconnected for now. (Any tips on what to do there??). I tested with an old hall sensored thumb throttle, but have switched it to my Button Throttle, which works sweet.

In terms of power and speed - it's obviously not the same as the Crystalyte HS3540 on my Avanti, but, I'm still surprised how well the little 250W Bafang SWXH goes - it is entirely serviceable, probably running in the low-mid 30kmh range, with adequate acceleration (ie much better than pedal power alone).

So it'll be fun to trial this one for a while against the Avanti/Crystalyte setup, and I'll probably eventually go back to the Avanti/Bafang BPM, if it turns out not to be cactus from my pothole incident.

At this stage, I haven't gone that far, but don't find that the lack of front suspension is a killer yet either. another thing to keep an eye on...

There you go. I'll update once I get the lights on, and cables managed/waterproofed properly.

 

[Kabbage]

... here's my first thoughts....

OK, second thoughts time. I had a few issues with the controller turning off randomly. Turns out one of my Anderson plug terminations was cactus, so that appears to be solved.

Also, I discovered that the motor runs much quieter when using the Hall sensors, rather than running it sensorless (which this new ebikes.ca controller can do).

I've now ridden it to work a few times - although it is definitely slower than my Avanti with the big Crystalyte, by the time you get stopped a few traffic lights on the trip, it doesn't work out appreciably slower door-to-door. Funny how that works out.

The torque is actually pretty good, and it handles the small hills on my route to work pretty well. Since I don't have a CA on this bike (I even chopped off the CA cables on the controller!), I have no idea how much instantaneous power I'm drawing, or the overall efficiency. Nevertheless, I have a 20A controller, and 50V 16S LiFePO4 battery, so it's probably in the 700-1000W range at times. My 10Ah battery handles the 14km commute round trip no worries, and charges in less than an hour - so I reckon I am using only 4Ah or thereabouts for the trip.

Neither the controller or the motor is getting overly hot. The motor is definitely 'warm' when you touch it, but I certainly wouldn't describe it as hot.

The pushbutton throttle is working perfectly. I'd never go back to a thumb throttle now.

cheers!

 

[headwind]

Nice one. Having ridden both bikes, Kabbage Commuter #2 is definitely much nicer handling than the (early Porsche 911-esque) Avanti.

Also impressive that the tiny 250W hub motor is pumping out 1000W no problems.