StefEbike for my wonderful disabled wife

[E-HP]

Speed	Lynx	Wh/mile	StefEbike	Wh/mile	Prancing Pony	Wh/mile
10			115		11.5	115		11.5
15			325		21.7	325		21.7
20	335	16.8	600		30.0	590		29.5
25	675	27.0	950		38.0	960		38.4
30	725	24.2	1425 @ 29	47.5	1560		52.0
35

Any idea what makes the recumbent use less energy per mile at 30 mph than at 25 mph? Seems like an unexpected result.

 

[thundercamel]

It just goes to show that I need to redo my recumbent testing. It was too windy yesterday, and it's very hard to guess an average watching the watt meter bounce around while trying to hold the throttle and speed steady.

 

[neptronix]

Speed	Lynx	Wh/mile	StefEbike	Wh/mile	Prancing Pony	Wh/mile
10			115		11.5	115		11.5
15			325		21.7	325		21.7
20	335	16.8	600		30.0	590		29.5
25	675	27.0	950		38.0	960		38.4
30	725	24.2	1425 @ 29	47.5	1560		52.0
35

Holy smokes, that recumbent slices through the air like a ginsu knife compared to the others.

 

[wturber]

Any idea what makes the recumbent use less energy per mile at 30 mph than at 25 mph? Seems like an unexpected result.

I strongly suspect either an outright error in measurement, recording, methodology or control of environment. I don't trust those results.

 

[thundercamel]

After two years of great reliability, the StefEbike battery is giving me a problem now. Battery group 11 is draining at about five hundredths of a volt per day. I've unplugged the BMS, recharged that group to match the rest, and will monitor for a few days, but I have a feeling that the balance resistor for group 11 is stuck in circuit. Before unplugging the BMS, I tried feeling what I believe are the balance resistors labeled 151 on the right hand side, but couldn't feel any warmth.

There was some heat coming from the two larger transistors just left of the balance resistors (near the date code). A google search shows that ZT5551 (CZT5551) is a bipolar NPN transistor, so I don't think they're necessarily bad, but the heat would indicate that the BMS might be the source of the power drain. If the BMS does prove to be the source of the problem, it would be nice to repair it rather than spend another $50 to replace it.

This picture is from the BMS in my bike, and the BMS in question is the same model but revision 1.3 instead.

Front side of the board, just in case

 

[neptronix]

What kind of battery are you rockin"? i am always skeptical of BMSes for the reasons you highlighted. Yet, a cell group could be draining on it's own because it's gone funky. It can be hard to tell..

The most telling would be a measure of voltage of each group at ~10% SOC after the pack has been discharged from a full balance charge. I personally will only use a BMS that has the ability to tell you what's going on with this stuff, which is why EM3EV's packs are the only ones i'll buy.

I'd rather go back to a BMSless setup though once i get back on my feet ( literally ) :lol:

 

[thundercamel]

I made my own batteries, which I'm pretty sure you knew, but I know there's a lot on your mind
Both use a JBD smart BMS, which I assume is similar to what EM3EV uses. I am so glad they now offer a smart BMS option, by the way. The smart BMS is what made me aware of the problem, and it shows while charging that it's trying to balance every other cell group except group 11. It doesn't think group 11 has it's balance resistor in circuit, but after 22 hours of having the BMS disconnected group 11 hasn't dropped in voltage like it was.

I could just buy another BMS, but with 15 balance circuits on board to compare against, I'm probing for any differences with group 11. If the problem lies with the microcontroller, then $50 for a new one it is. Maybe this power cycle will fix the problem, eh? At least I don't need to tear into the pack to replace a cell!

 

[thundercamel]

The power cycle may have fixed the BMS. I disconnected the 11th balance wire, which is connected to the positive end of cell group 11, and placing my meter in series shows no current flowing through that wire. It's only the positive side of cell group 11, but current would have to flow through both sides to complete the circuit that was draining group 11.

 

[thundercamel]

There's still something going on with this BMS, but I haven't nailed it down yet. While charging I used one of the balance wires to monitor a -30mA current when group 12 is balancing, and a 30mA current when group 11 is balancing, but haven't caught it drawing 30mA when it's not supposed to yet. Currently doing a longer than 25 hour test with the BMS disconnected again, just to for sure rule that out.

 

[neptronix]

Hopefully 25 hours is enough time to isolate the problem..
..unfortunately a weak cell group could be the culprit too :/

Hopefully it's not the hard problem!!

 

[thundercamel]

That possibility of a weak cell group is what I'm re-testing now, by leaving the BMS disconnected for several days. Last time I left it for 25 hours before I needed the bike for a group ride. So far, all the voltages are staying right in line. :thumb:

 

[thundercamel]

So my journey on Sunday turned out to be the most adventurous bike trip I've ever had, that's for sure! The Des Plains River was 3 feet over normal levels, which would have been perfect until it rained all day Saturday. This brought the levels up to 5.25 feet over normal! Made it through with determination though.

[youtube]w0A7fuOLNhA[/youtube]

EDIT: replaced video with a higher quality version

 

[neptronix]

Oh dear! did you drain the hub motor after that ride?

 

[rowbiker]

Made it through with determination though.

I think you had more than determination going for you!

Living 1.5 blocks from the Mississippi, with lots of great trails along the river, I get lots of opportunities to do what you did. I'll tackle up-to-axle depths with a non-electric recumbent 'high racer', on which you can even keep your feet dry. BUT, on an e-bike, I have NEVER attempted doing this. It was encouraging to see that it *could* be done. Of course, I'm still too chickenshit to try it even after watching you guys do it.

I think all of us are very curious to find out if either of your bikes suffered any consequences within the following days/weeks of this exposure to water. Thanks for posting!

 

[thundercamel]

My motor did have some hall sensor/position glitches at the end of that ride, and it did have a small puddle underneath it on the car ride home. I've been sick this whole week, so between work and kids I've just been going to bed early every day. Right when they got home I strapped a magnetic 200w oil pan heater to the side of my motor for several days, in the hopes of evaporating whatever water was left. Shifted it to the StefEbike motor for several days as well. Both motors are working fine, though I may peek inside at some point.

The bottom corner of the StefEbike battery had some humidity, including inside the smart BMS bluetooth module. I cleaned all that up and let a space heater dry out the battery for a few hours.

 

[thundercamel]

This is a sample of 360 video footage from the beginning of the year. We should have used the camera more! I think the format does a better job of feeling like you were there, since you can look wherever you want.

[youtube]XeLD6lq_2pY[/youtube]

 

[E-HP]

This is a sample of 360 video footage from the beginning of the year. We should have used the camera more! I think the format does a better job of feeling like you were there, since you can look wherever you want.

Pretty cool! So looking at the shadows, it looks like the camera is mounted on some kind of rod and positioned above the bike to get the right perspective, correct?

 

[thundercamel]

Yes, he had a telescoping pole it was mounted on. I'm not sure if mounting it on my helmet would block out a lot of the downward view. If I'm going to look dorky anyway, I could raise it up a bit on a pole.

 

[thundercamel]

So last year I was still searching for a better suspension fork that would fit on my recumbent bike. I had originally done most of my research on the HP-Velotechnik Streetmachine Gte bike, and that comes with a Spinner Grind2 (20?) fork that offers a heavy duty spring for loads over 100kg. I found the fork on Spinner's website, and they offer it with a 1" stem that I need! Couldn't find any for sale with the 1" stem, and without much expectation I clicked the Inquiry button on their website. Lo and behold, they emailed me offering a custom built fork for just $135! I thought I was going to have to convert to a threadless headset, but they also offered to thread the steerer tube with the needed 140mm length for no extra charge! I also specified gloss black and the heavy duty spring no problem. Then I asked how to pay, with visa or paypal? No, they only accept a wire transfer to their bank account in Taiwan via swift or telex (whatever that means).

This was bizarre for me, and I had never once done a money transfer before, and it seemed kinda risky. My dealings with Spinner had all seemed legitimate so far, and $135 wasn't too much to risk. Western Union only had an $11 fee, but when I chose Taiwan they only had an option to send money to an individual there, not a bank account. Moneygram's website didn't even seem to be working. I eventually had my credit union complete the transfer, but their fee was a bitter $45!

Well it worked out in the end, and the fork is great! I had to grind/file down the crown race seat from 27mm to 26.4mm AGAIN since the fork followed the 1" J.I.S. standard instead of the 1" ISO standard, but at least I didn't have to convert to threadless. I'm glad I got the heavy duty spring, and I think it only bottomed out once on my first big ride. The bike is cushy and now feels like it has actual suspension, thought I'm not sure if the rear does any actual dampening. I will swap that out for a $30 DNM unit at some point. Next up is another hydraulic disc brake on the front now that I have a mount, and that will also require swapping out the brifters that don't work very well anyway, even though they're Shimano Deore XT.

 

[thundercamel]

Well, Neptronix was right, which shouldn't surprise me. I thought for sure any water in my hub motor would have drained/cooked off from my heater after that flooded trip I did last year. Nope. I finally opened the hub to look into the hall sensor errors I'm getting this year, and some water came out.

The little circuit board that the hall sensors are wired to seems to have lost whatever layer of traces is on the back. I added my own tiny wires to re-connect everything, but one sensor is stuck putting out 2.3 volts. I'm going to check out the circuitry more tomorrow before I look into ordering sensors, because I really don't want to do the chore of replacing one of those...

Also my Park Tools FR-1.3 stripped trying to remove my freewheel this time. There was never much engagement with those teeth! Think they'll do a warranty replacement?

 

[pwd]

... Designing an arrangement with the hexagon pattern was fun!

Quick question. When you were assembling your battery pack, did you use any sort of adhesive etc.. between the cells and the black cell holders?

 

[thundercamel]

Yes I did There's a link to it on the first post of this thread, for $6.99, and I found that type by the suggestion of someone's thread on Endless Sphere. Just two strips of glue down the length of each holder. If the left side of the battery was 0% and the right side was 100%, then I did a strip at 25% and a strip at 75%.

I wanted the battery to be solid, and in case I ever get a bad cell (which I might actually have), I've seen people slide the metal cell out of the original heat shrink, and slide a new one in. Anyone ever heard of an 18650 cell suddenly start to very slowly discharge by itself? So far it hasn't been a problem that BMS balancing can't easily fix, and I'm still investigating.

 

[pwd]

Thanks. Good luck with the hall sensors.

 

[thundercamel]

The Prancing Pony lives!! The 5 volt in leg on sensor A had become disconnected for whatever reason. Solder did NOT want to stick to that leg, even when I tried cleaning it with flux. I ended up bending it into a little hook, and hooking a little jumper wire around that, and encasing the hooks in solder In hindsight, that might have been related to the back side traces not working Tuesday, but whatever; it all works now. Feels great to have this bike back again!

Since I've been stuck in my house so much, I've been ordering all sorts of parts for my bikes. I started putting a Tektro HD-290M disc brake on the Lynx, but the 850(?)mm hose it comes with is not nearly long enough for those handlebars. I don't feel like re-assembling the V-brakes and old shifter, so I'm just leaving it half finished until the Tektro hose and bleed kit comes in.

Seeing the 160mm brake disc on the 20" wheel makes me think the lame A10.11 pads it comes with will be more effective since the wheel spins faster with the smaller circumference. 160/20=8, and for the 26 inch wheel on the upright bike 160/26=6.15. I planned to eventually upgrade to 203mm rotors, so why not now? 203/26=7.8, so almost the same ratio as the 20" wheel. I found this cool rotor plus adapter kit, so that's coming soon, plus some parts for the StefEbike!

 

[thundercamel]

I'm posting this bit about brake pads separately in the hopes that it will show up in google search results. Right now, searching E10.11 vs. B01S barely confirms that they are interchangeable, and I haven't seen any opinion stating which one is better. Well let me state: Shimano B01S are the pads that I've been looking for. This was my progression below:

1. The Flying Wheels 70mm V-Brake pads are what I had before upgrading the front forks on my three bikes. They're decent pads, and I still use them on the rear wheel of each bike.

2. BlueSunshine MTB BB8 Mechanical Disc Brake set - Total joke. These instructions allowed me to get them aligned where they wouldn't rub at all, and I cleaned the disc with brake clean spray before usage. I tried bedding them in and confirmed they got nice and hot, but in the end I could probably stop faster by dragging my shoes on the ground. The calipers themselves functioned alright, but at some point pulling the lever tighter doesn't result in an increase in friction, which is a sure sign the pad material just isn't good enough. I also don't like how these (and most mechanical calipers) only have one "piston" and require pushing the rotor into the other brake pad.

3. Tektro A10.11 Metal Ceramic Compound pads came with two of my Tektro HD-M290 Auriga Hydraulic Disc Brake kits - I did try seriously bedding these, but only after they were submerged in water on one trip. Brake pads should be able to handle getting wet. Both before and after they only ever provided as much friction as the V-brakes they replaced, which I still have on the rear wheel to compare with. This is not an upgrade. I may test the unused set of A10.11 pads sometime, but don't expect they'll perform any better.

The HD-M290 calipers are excellent however, and having opposed pistons are definitely the way to go. I like that Tektro features a reusable pin to hold the pads in place, unlike Shimano who uses a disposable cotter pin. I do wish there were 3 or 4 finger levers available for the same price as these to make room for ebike throttles.

4. Tektro E10.11 Organic Compound pads came with an unused take off HD-M290 brake I got from eBay. These are finally an upgrade compared to the V-brakes that are still on the rear of my bikes, and they are currently installed in the front of my upright bike. After a second round of bedding these pads, I've concluded that they always require a lot of pressure, and only provide good levels of friction once they get warm. I'll leave them till they wear thin, but won't be buying them again.

5. Shimano B01S Resin (organic) pads - FINALLY, these pads can do a good emergency stop, like most cars can do. They didn't really need to be bedded in, just used a few times to machine themselves smooth with the brake rotor. They feel good under normal biking conditions as well, with easy modulation and no squealing. Only the silly BlueSunshine brakes squealed at all for me so far, with regards to the disc brakes. Some reviews say these pads wear out quickly, but we'll see how that goes. They're installed on my wife's StefEbike 26" with 203mm rotor, and my Lynx recumbent 20" with 160mm rotor, and both work great! They don't require much pressure, and have good initial bite even when cold.