Back in the Saddle, 'Bent Mid-drive project!!

[amberwolf]

If you have no regen braking, and the motor chain freewheels when not driven by the motor, then maybe make sure the CA is really set to zero current. Otherwise, any "negative" current it reads (evne mistakenly) is taken as regen.

[LI-ghtcycle]

If you have no regen braking, and the motor chain freewheels when not driven by the motor, then maybe make sure the CA is really set to zero current. Otherwise, any "negative" current it reads (evne mistakenly) is taken as regen.

Oh, good point, perhaps I should calibrate to "zero amps" and then I won't see the negative amps showing, I don't have a freewheel at the motor, it is always turning when ever I pedal, with power or not, however I have seen negative amps (very very low) even when it's just sitting still and I imagine it's just fluctuation, but I don't want it to skew the AH's available.

Thanks AW!

[amberwolf]

If it's always turning with pedals, then you do actually have regen, even if you don't use it for braking. Anytime you pedal without using the motor, or happen to pedal faster than the motor is turning under power, you will get a bit of regen from it. Or rather, you *can*, as long as the motor puts out enough voltage for the controller to feed back to the battery.

[LI-ghtcycle]

Hmmm ok kewl, that makes sense, but I think I still might zero the amps since it will from time to time show something like 0.03 negative amps just sitting still.

[LI-ghtcycle]

Ok, I'm too lazy to take screen shots, but today was a perfect day to test things out on a normal med. range commute for me!

I went to church in the morning, and back, which is pretty flat no major climbs very light usage to keep things up to speed, and racked up about 3 miles.

Then I decided since the weather is going to be pretty nasty the rest of the week, I better take advantage of it, and went to REI in portland, so I added another 39 miles to the clock.

I was again pleasantly surprised, the motor has quieted down considerably (is there a break-in period for a motor?) and since I'm not going to the ultra high-speed RPM's on the road as in no-load testing, it's virtually the same amount of noise as my 9C which is next to nothing.

Here are the stats in total for today's trip!

Total Miles: 42

Average Speed: 13 MPH

Watts Per Mile: 8.7

One other thing to note, I stepped it up once again today, using the power to get up to 20 MPH on the flats, and 15 MPH on the more hilly sections, and maintained that speed with moderate pedaling, and then maintaining said speed with minimal power, usually around 5 AMPS draw or less on the flat, closer to 10 AMPS on the minor hills, and no more than 15 - 20 AMPS constant on the steep hills, and only for short bursts (1/4 or 1/2 mile at a time) while constantly monitoring the temp of both the controller & motor with my hand, and only on the steepest of parts of the 2 mile long hill (10% approx.) here in Oregon City did I have to forgo the use of the motor for the last 2-3 blocks since my gearing is at 15 MPH minimum gearing, and I need it geared for more like 7 MPH.

The good news is that with gearing even as tall as it is, I am able to take on 5% hills all day long at about 7 - 8 MPH with out a complaint from controller or motor, and just getting the motor warm, not really hot.

The motor did get hot on some of the short bursts above 6%, but would quickly cool back down once I backed off the speed a bit, and lowered the amp draw considerably.

This shows great promise, and since this motor is rating to use between 24 - 60V, I first optimize gearing for the current 12S 45V pack, and if it doesn't give me as much torque as I like, I will try 20S with the same pack and adjusted gearing for the higher RPM.

As much strength as I am seeing now, I suspect that 12S will be plenty, but If I can get more torque for the same watts at 74V, why not!

[StudEbiker]

Fantastic news Li-ghtcycle!! Your build is making me very anxious to get all the kinks sorted out on the Bike E. Your efficiency numbers are impressive. I don't have your light handedness on the throttle I guess, but hopefully I will be able to get somewhere close to those numbers. I would be VERY happy if I did! Anyway, congrats on an awesome build!

[LI-ghtcycle]

Fantastic news Li-ghtcycle!! Your build is making me very anxious to get all the kinks sorted out on the Bike E. Your efficiency numbers are impressive. I don't have your light handedness on the throttle I guess, but hopefully I will be able to get somewhere close to those numbers. I would be VERY happy if I did! Anyway, congrats on an awesome build!

Thanks man! To be fair, I got a pretty good work-out today too, once I get the gearing sorted, and the motor is more in cadence with my pedaling, it should be less strenuous, but realistically, until I get another 12 AH's of LiPo, I'm being extra careful, and I'm wanting to be flexible in case I decide to use 20S instead for greater torque & efficiency.

The beauty of pairing the RPM/V with-in the range of comfortable pedaling, is you can tell when you have a good gear ratio for the motor since it will work well for yourself too.

Right now, I either have to use my largest chain ring or just recognize that I will be spinning the pedals pretty fast when the motor is in a good gear especially for climbing hills.

[LI-ghtcycle]

Ok, so after a lot of consideration, I went back to my original final drive plan from a previous build, #25 chain.

Nothing else gives me the flexibility with such small high tooth count yet relatively small diameter of sprockets and allows me to keep my simple single stage reduction design.

I have talked with Staton Inc, and it looks like they will make me a custom 17T #25 sprocket for the motor with 14mm keyed bore, and I have a 95T sprocket to have welded onto my spare freewheel adapter (might be able to have that part done locally, just need to open up the 1/2 in ID sprocket to 1 1/2 or what ever the size needed is and have it welded).

https://sdp-si.com/eStore/

https://sdp-si.com/eStore/PartDetail.asp?Opener=Group&PartID=3930&GroupID=586



I will still have to contend with a larger sprocket interfering with the derailleur acting as tensioner, but I really should find a better solution anyway, the derailleur doesn't stay put and needs some adjustment from time to time.

[LI-ghtcycle]

Oh, I just realized I don't have any recent pics of bike for you all to see it in finished form (well it's never really finished right? ) here ya go!



(I'm still working on that aero-belly and beard! )

[LI-ghtcycle]

Here are some more pics:









I just had a thought!

If I reduce to 8S, or 31V, I can then solve my gearing issues, and at least test to see if it puts things where they need to be for getting final drive RPM more sensible for pedaling speeds!

Now I just need to figure out how to re-program my controller.

[LI-ghtcycle]

Ok! I got the controller reprogrammed for 8S (Big Thank You to Lyen! ), and now I have had a chance to do some real testing!!

I'm REALLY Impressed with this motor!!

I'm running this thing at 32V, 30A, 960W and it's just as strong as it was at 47V!!

I haven't gone on a long hill, but I went up the super steep 5-7% mini-valley of a road a couple blocks away, and slowed the bike down to just 10 MPH at the bottom of the valley, and then got it up to 15 MPH and held that with med pedaling and a very strong pulling motor, and it didn't get even WARM!!

I'm noticing that I am of course not quite as efficient as I was at higher voltage (now 9.7 Wh/Mi. at 32V VS 8.7 Wh/Mi. ) but it's pulling strong and confirming that my new gearing ratio is going to be spot-on!

[StudEbiker]

Awesome man! I am really loving the simplicity of your set-up. You've heard of the K.I.S.S. method right? On my Bike E build I feel like I've come up with my own method. The K.I.D.D. method, keep it difficult dummy.

[LI-ghtcycle]

Awesome man! I am really loving the simplicity of your set-up. You've heard of the K.I.S.S. method right? On my Bike E build I feel like I've come up with my own method. The K.I.D.D. method, keep it difficult dummy.

ROFLOL!! KIDD!! I Love it!!

Thanks man!

Don't be so hard on yourself, we are all learning here, I specifically set out in this instance to make it as basic as possible even at the cost of some efficiency, and so far, it seems to be even working out to still be pretty efficient too.

I have yet to take it up a long hill, but I think it will still perform admirably. I'm even more excited however to get my new batteries, sprockets and see how much more efficient it runs at 14S, and with the right gearing, it should allow for even a no-pedal climb of these same hills, which is my ultimate goal.

[amberwolf]

The K.I.D.D. method, keep it difficult dummy.

I knew there had to be a catchphrase for how I do things...now you've invented it.

[LI-ghtcycle]

Well, I am happy to say that at 32V this motor is JUST as efficient as it has been at 47V!

I went for a short trip in the sun today after working around the house, about 7 miles on less than 2 AH!!

It came to 8.7 Wh/Mi. and an average speed of 16 MPH, and a top speed of 32 MPH!!

All this on 32V!!! (8S LiPo )

This is with the same six 4S, 6AH Turnigy Nano Tech bricks configured now in 2s 3P for a 33V 18 AH pack, but for some reason, running it as a 33V 18AH pack instead of 49V 12AH pack keeps the cells better balanced, even though I am pulling almost identical watts!

There is virtually no voltage sag either, I guess 3P is the secret sauce in this equation.

And my batteries are charging up much faster and staying in balance and not taking a huge amount of time like before.

[AussieJester]

(I'm still working on that aero-belly and beard! )

hehe...I was going to ask too

Nice looking ride, good to put a face to the name to


KiM

[LI-ghtcycle]

(I'm still working on that aero-belly and beard! )

hehe...I was going to ask too

Nice looking ride, good to put a face to the name to


KiM

Thanks!

Same to you Kim, I wish I had a video cam, I would spin the motor and let you hear it sing!

I'm gonna have to get a stretched frame built with the help of my neighbor and see what I can get out of this motor with 24S soon!!

I'm thinking something along the lines of what Drewjet built as a test mule, and then eventually something more of a CF design to be a best of both worlds between 'bent and a DF bike.

[StudEbiker]

I wish I had a video cam, I would spin the motor and let you hear it sing!

Does your still camera have a video mode? Almost all of them do.

[LI-ghtcycle]

I wish I had a video cam, I would spin the motor and let you hear it sing!

Does your still camera have a video mode? Almost all of them do.

Yes it does, but since the last windows up-date it's really weird, I can't seem to figure out how to load a video anymore, it's only like 20 sec. though.

[LI-ghtcycle]

More goodies!

Just got these today!



Man, that 95 tooth looks like a buzz saw!

I was so excited I rushed it to my machinist, Brad at City Machine in Oregon City, and he's such a kewl guy that he's gonna squeeze it in when he gets a spare moment or two, and I will be bringing the bike in on Friday to mic the shaft on the motor to make sure it's done exactly to size, and then the college will have to make the key-way once he has taken the 10MM D bore out to 14MM.

The 95 tooth wheel sprocket will be bored out to the size of the NuVinci freewheel adapter and then my welder will tack it onto the sprocket for me!

I'm going to eventually have him make me some better mounting blocks too out of billet aluminum so that I don't have to worry about the thin steel square tube eventually cutting into the paint.

[LI-ghtcycle]

Ok so I was having "too much fun" last night blasting along on my way home from bible class and suddenly I heard "CRACK!" when I was on the throttle, I was sure I had just snapped the poor drive chain (it's just BMX chain, nothing heavy duty) and at first I thought it might have been something worse because I lost my pedal power too!

Fortunately, it wasn't anything serious, just my letting things get too loose and when the drive chain got free it smacked the pedal chain over too and it jammed between the frame & freewheel. Fortunately, the freewheels I use are narrow enough that they don't get jammed even when something is right up against them, so no harm done, and today I decided to make a chain tensioner.

I had already started on one earlier and had used a old derailleur for the job, but I was inspired by the fixed one on our old-school tandem bicycle, and decided to make my own version.



Found this nifty little bike rack bracket and it's going to be perfect for my purpose!



Just bent up one end to bolt down, and it's looking and sounding pretty good on no-load testing, gonna get a test in later tonight between rain showers.





Here is a rubber caster wheel from the hardware store that I turned down on my drill press to use as a roller.





For the axle, I used one from the wheel of a roller blade, and the bushings from the wheel I put into the modified caster wheel now roller.





I made the head of the bolt axle's head narrower to fit inside the bracket to lock it into place for tightening.



I then shortened the axle and re-tapped threads for the bolt to use, this way I have a shoulder to tighten against with out tightening up the roller.

(more pics to come)

[LI-ghtcycle]

More pics, tensioner:





I'm pretty happy with it.

It's a bit loud when you just pedaling (I'm guessing since the tension is on the non-motor tension side), but becomes very quiet when the motor is running.

This is just temporary until I have the #25 sprockets & chain, and then I will have to adjust it.

[LI-ghtcycle]

More sprockets!





Here is the 95T sprocket, expertly broached! The NuVinci freewheel adapter fits so snug it's going to be a cinch to have it welded!

Once it's welded, it will looks much like these one from Staton Inc:

[StudEbiker]

That's awesome! If the jackshaft setup on the Bike E craps out again, I'll definitely be looking at going with a setup like yours. The Bike E is back together and ready for testing again with the auto-shifting CVP. Will have some reports tomorrow.

[LI-ghtcycle]

That's awesome! If the jackshaft setup on the Bike E craps out again, I'll definitely be looking at going with a setup like yours. The Bike E is back together and ready for testing again with the auto-shifting CVP. Will have some reports tomorrow.

Kewl man! Get some numbers on efficiency too if you can.