Kinni's E-bike questions and stuffs

[jkbrigman]

Lipo runs great hot. So don't worry about ambient temps in the 100's. If your ride is making it really hot, you need more ah. Toasty warm is fine though. Cooling is important to your controller though.

Guess I sounded bitchy the other day. The single most persistent mistruth about hub motors is that slow windings have more torque. But they sure feel that way to the rider, and are often sold as the torque model.

Not more torque, just less stall. Bet it felt good to have a motor eh!

dogman - don't stop. I appreciate vigorous defense of the facts. I'll send you a box of sweet 'n low. My remarks were speculative, and therefore not helpful. You drove home the point that I need to do some modeling work on the 2810 and collect some data. I'd like very much to submit enough data on the motor to get it listed on the sim - I don't like "faking" the motor on the sim, it makes it look worse-performing than it really is.

For "low speed" ebikes (under 35mph) I'd have to say I really like the 2810 - you just have to feed it 18S LiPo to make it be awesome. But I have to add (to both you and Kinni), I'm convinced that everything - motor, controller and batteries - all run cooler at high voltage/low-ish current than a similar setup at medium/low voltage and high-ish current. That results in lower losses, better efficiency. It cost me more money to build to 18S "72v", but I'm very happy with the results - I've run the setup hard without appreciable heat production. I'm sure your "dirt bike research" bears that out.

JKB

[Kinni420]

wanted to mention my battery charge today (cycle 14). Used 3.7 Ah of the packs. Here's stats on each pack at start of charge, length and mAh

Pack 1:
start voltage Time taken mAh
1: 3.72 55:11 3708
2: 3.72
3: 3.73
4: 3.74
5: 3.74
6: 3.71
Max Variance: .03 V

Pack 2:
start voltage Time taken mAh
1: 3.75 55:29 3716
2: 3.74
3: 3.75
4: 3.75
5: 3.75
6: 3.54
Max Variance: .21 V (this doesn't seem a lot but compared to every other cell in all three batteries (.04v max) it looks wrong.) Wish i could get a nice discharge graph to check. need to get the stuff neptronix told me about (some halogens etc.)

Pack : 3
start voltage Time taken mAh
1: 3.74 52:17 3716
2: 3.74
3: 3.73
4: 3.74
5: 3.73
6: 3.73
Max Variance: .01 V (actually .008v. I think this is my best pack.)

I'm still afraid to start bulk charging with that funky pack, but I have the time to balance everything nicely until I get a parallel balance harness.

I was asking about airflow around the batteries since I kind of packed them very well for shock absorption and didn't leave much room for airflow. Thanks Dogman.

Not more torque, just less stall.

sounds like more power to me! I couldn't stall that bike on the short trail I climbed. With a little math and a bad topographic map, I figure about a 7% slope for .8 miles or so. One of these days Ill have 18s2p and those short rides can be a lot longer!

getting 2 more batteries on Thursday from USA warehouse. 1 to replace the bad one (if I have to send it back) and 1 for a backup in-case anything else goes wrong. (maybe 24s1p? Muahaha! ) I can afford a third in the middle of april (along with the falcon EV bag, mine wont fit more than 4 batteries nicely ) and Ill be up to 18s2p. Time to buy more wire, bullet plugs and bananas! Speaking of which, one of my 4mm bullet connectors is being pissy on my charge harness (the sockets fit very loose over the connectors and I keep getting "connection break" errors if I use it.

question here. When parallel charging, I can up the Amps on the charge to 10 (the max on the 106B+)which would make it 2/3C charge rate right?

The 2810 cruises for me VERY well from around 19 to 25 mph(depending on slope) but makes a weird squeaking noise at around 16-17 mph. Id assume this is normal and perhaps related to resonance? Anyhow, 25 is plenty fast enough for me with the traffic around here but a little extra boost would be nice for those off-road adventures. Been seriously thinking about an X5 hehe.

[jkbrigman]

wanted to mention my battery charge today (cycle 14). Used 3.7 Ah of the packs. Here's stats on each pack at start of charge, length and mAh

The 2810 cruises for me VERY well from around 19 to 25 mph(depending on slope) but makes a weird squeaking noise at around 16-17 mph. Id assume this is normal and perhaps related to resonance? Anyhow, 25 is plenty fat enough for me with the traffic around here but a little extra boost would be nice for those off-road adventures. Been seriously thinking about an X5 hehe.

K;
I get that same "sqeaking" noise. I thought it was the controller dipping down into an audible range, but it could be the motor too, I can't tell which since my controller and motor are right next to each other. There's also an odd "rattle" that sounds like the rotating field slipping past the magnets. God Bless You Mr. Tesla.

My experience bears out yours about cruising speed - seems to be very happy at 19-25mph. I can goose mine to 30mph above 70v but I fear death from the front wheel.

You had some beautiful data there. All generated through logview?

JKB

[Kinni420]

Most of the information was done from the cell monitoring option on the charger. I could have gotten more accurate voltages from log-view (and I do use it whenever I'm at home due to that funky cell 6) but I figured 100ths of a volt were good enough to post. Its not the Space Shuttle .

I might try to get an audio of that squeak, and it definitely comes from the rear (unless my hearing is going) I actually enjoy the fact that the wheel makes noise at all times. Sounds like a really quiet dirt bike Also turns heads.

What does a big hair rock band from the 80's have to do with e-bikes? I don't know Tesla's theories on magnetic fields lol.

BTW: I'd fear death just climbing on that contraption of yours! It reminds me of something like trying to ski with a lawn chair attached.

[jkbrigman]

Most of the information was done from the cell monitoring option on the charger. I could have gotten more accurate voltages from log-view (and I do use it whenever I'm at home due to that funky cell 6) but I figured 100ths of a volt were good enough to post. Its not the Space Shuttle .

I might try to get an audio of that squeak, and it definitely comes from the rear (unless my hearing is going) I actually enjoy the fact that the wheel makes noise at all times. Sounds like a really quiet dirt bike Also turns heads.

What does a big hair rock band from the 80's have to do with e-bikes? I don't know Tesla's theories on magnetic fields lol.

BTW: I'd fear death just climbing on that contraption of yours! It reminds me of something like trying to ski with a lawn chair attached.

I worry about the fact that it makes noise and I hope it's not delamination of the iron armature core. Aside from that, though, I love the different sounds at different levels of current. You can "hear" when it's sucking power or when it's not. I'm wondering now if it's just the 2810 or if all the 9c motors do this?

Tesla: http://en.wikipedia.org/wiki/Nikola_Tesla. I have a sermon on the subject I'll not preach at this time. Seems to me a thread here on E-S would be appropriate, however.

re: Fearing Death - You are far wiser than me on that count. I had to get on the thing and ride it 30 miles at 30mph to realize the problem when I started hearing the front spokes "pinging" and realized there's far more weight on that front wheel than I first imagined.

To use a biblical turn of phrase, I will return to the recumbent in the fullness of time. For now, it's time for me to join the brethren who "ride upright".

JKB

[Kinni420]

wheel pinging. from my experience, the only time Ive EVER heard a wheel ping is just after getting the wheel trued WELL. The spokes tend to stretch slightly and rub against each other causing that sound. freaked me out the first time I heard it but never been an issue. With all the weight added to the rear of my upright, Ive only added about 4 total pounds to the front. hmm

[jkbrigman]

wheel pinging. from my experience, the only time Ive EVER heard a wheel ping is just after getting the wheel trued WELL. The spokes tend to stretch slightly and rub against each other causing that sound. freaked me out the first time I heard it but never been an issue. With all the weight added to the rear of my upright, Ive only added about 4 total pounds to the front. hmm

You're right. The wheel has maybe 60 miles on it. It's "old", but not been ridden much.

[dogman]

Motor wheel spokes do tend to talk a lot. By about 50 miles they have usually stretched. Don't overtighten, but do snug loose spokes up.

If that doesn't quiet the squeak, it could be a very light rub of the freewheel on the hub cover. This is easy to confirm, pedaling so the freewheel doesn't spin would stop the squeak.

[Kinni420]

enjoy

[neptronix]

Hey, Golden, Co is not so bad lookin

Glad you got your build up. Dude, that bike is ripe for a falconEV bag, just sayin... ;D

[Kinni420]

I agree with you on that falcon bag. Rent comin up. couple more weeks for 2p and teh bag

[Kinni420]

ive done a bunch of testing while riding the bike and I find its actually more efficient at higher speeds.

14 mph 700w avg
23 mph 350 w avg

crazy to be getting more mileage out of more speed

I cant get off this damn thing LOL

[neptronix]

That doesn't seem right... are you using a multi-speed switch, or are the lower speeds occurring while climbing a hill or accelerating?

[jkbrigman]

ive done a bunch of testing while riding the bike and I find its actually more efficient at higher speeds.
14 mph 700w avg
23 mph 350 w avg
crazy to be getting more mileage out of more speed - I cant get off this damn thing LOL

I find the same thing "for the same throttle setting" and I don't think that's wrong. I expected it, and that's what the simulator predicts. I can maintain 21-23 mph using 240-270W on the recumbent. The power I need is used to maintain forward motion over the frictional losses plus wind resistance. (and BTW: I'm running 80-90 PSI in my tires)

At the higher speed, the motor generates more back-EMF, so less current flow, less power used and less available torque. In fact, if you watch on a 2810 you'll ALWAYS burn more power at low speed unless you really "feather" the throttle back. You can see this reflected in the curves on the ebikes.ca simulator. I don't care which motor you pick, the torque curve goes down and reaches zero. Power consumption rises to a maximum, then decreases, as you reach the maximum available voltage and speed of the motor.

In the sim, these curves go all the way to zero. On my recumbent, I "enjoyed" this fact when I was pedaling my ass off to keep the bike at or above 20mph. A 250W motor would have been fine to keep me at 22-23mph on flat land. At higher speeds, as you apply more throttle, the power consumption spikes, but as the motor "catches up" with it's own rotating field, power consumption once again drops. (I'd love to see motor voltage plotted on the simulator. )

Same is true, say, when you're going down a hill and picking up speed on your own. True, you're converting potential to kinetic energy, and so the motor doesn't "have to" supply power, but that's not the only effect in play. The motor is spinning faster and generating higher back EMF as you move the coils through the PM field.

Say you're going close to the motor's maximum speed, like in your video when you go pas the radar sign (31MPH, awesome!)

You'll see it's not possible to push the motor any further with 72V. It won't take any power from the controller at all. The "cogging" of an unloaded motor generates power itself and at high speed, as the motor generates enough back-EMF to push current back through the controller, you can't go any faster.

That's the same reason the motor's max speed is in proportion to the higher voltage we apply. If I want any more than about 32mph, I gotta go above 18S. I've been wondering about making a 22S (96v) LiPo brick and see what happens with the motor. (I THINK our 25A IFRB controllers can handle that without failing...now I know what my next test should be! )

Another thing I've noticed: even though our 2810 motors aren't in the simulator, the curves for the 2808 look awfully close to the performance I'm seeing with the 2810 on a 26" wheel.

Hey, tell me: (since you're running 72VDC also) - my controller and batteries don't get hot, or even warm, when I ride. Is that what you are seeing?

JKB

[Beachcruzer]

JKB, just this afternoon I was thinking the same thing about building a 22s pack to run with Method's kit. Then I picked up my kid's crayon and did some 'calculations' in the margins of her coloring book. A 24s pack charged to 4.0 volts per cell also gives 96 volts and would presumably, probably be safe for that controller. If you already have the 6s lipo packs (as I do) that would be a simpler solution, and still leave room to charge to 100 volts if you're feeling lucky.

[jkbrigman]

JKB, just this afternoon I was thinking the same thing about building a 22s pack to run with Method's kit. Then I picked up my kid's crayon and did some 'calculations' in the margins of her coloring book. A 24s pack charged to 4.0 volts per cell also gives 96 volts and would presumably, probably be safe for that controller. If you already have the 6s lipo packs (as I do) that would be a simpler solution, and still leave room to charge to 100 volts if you're feeling lucky.

I'm with you on that. I tried the 4-brick LiPo (24S) and it was sparkling. I documented it in my Recumbent Commuter thread, where the legions of Recumbent Police are beating me up because I think it's dangerous to go 30mph or more on a short wheelbase recumbent.

[Beachcruzer]

Recumbent police brutality is really getting out of hand these days. Fight the power!

I'm about to start a build with one of Methods 2810 kits, so I've been following your build. Great bike, but I'm a little sketched out by the thought of riding a recumbent in traffic.

[jkbrigman]

Recumbent police brutality is really getting out of hand these days. Fight the power!

I'm about to start a build with one of Methods 2810 kits, so I've been following your build. Great bike, but I'm a little sketched out by the thought of riding a recumbent in traffic.

wait - you are doing upright, not recumbent, right?

Yes, the Recumbent Police are taking out their nightsticks and letting me have it for kicking them in the jesus. They better watch out - I'll pull a Justin on them and convert an Xtracycle. Take THAT, Recumbent Police!

I'm very happy with the 2810. dogman is right - you just can't kill the darn thing. Good torque, very efficient. It seems to be a nice compromise between power and efficiency, and the thing never heats up on me. ONLY PROBLEM is that you gotta feed that baby 72V to get it to do anything. I've not even tried less than 72V.

I'm going to start a new thread where I move the parts over from the recumbent to the upright bike. I'm ordering a FalconEV bag for the upright today. I anticipate it will be a very short thread - I want to build a bike that's as plain-vanilla as it gets. I have to be able to cruise at 30mph or more, so I MIGHT have to go up to 24S to get that kind of speed on an upright.

JKB

[Kinni420]

a warning here on the Cycle Analyst and wet weather riding!!!

Today it was rain/snow mix for my ride to work. I had full faith in the bike set up and rode the 5.6 miles to work. At my 9:30 coffee break I decided to ride to the store to get a pack of cigarettes, flicked on the power switch and BAM! My CA lit up all black and the wheel wouldn't turn.

Somewhere I had read that it was ok to use this unit in "light rain". Sure it was a rain/snow mix and what I would call "light" but (quote) "if the unit developed a haze inside the glass, take it apart and let it air dry" I did so. There was a nice little bit of caulking around the perimeter of the unit for weatherizing.

While I was letting it dry out I noticed that the area where the wires come out, there's 6 wide open holes! All that facing into the wind! I got out my can of rubber cement and plugged up all the holes. CA dried out and bike worked perfectly.

Batteries and harness were dry as a bone in my nice little bag. Controller didnt seem to mind the wheel spray (pretty fierce this morning in that sleet mix).

please send me some better luck. In the past 4 days Ive broken at least 3 ribs, got stung by a wasp, missed a day of work, was late to work today and got the riot act, and had to freeze my ass off for 11+ miles.

regardless, got 14.1 Wh/mile, 2.6 Ah used for 11.9 miles. Riding pretty slow cuz every bump I hit makes me want to pass out from the pain

video filming is on hold till I can handle standing in the saddle again.

I read somewhere on this forum someone asking Methods about running 24s on these motors and controllers. Methods said that "as long as you watch the heat" 24s would be fine. Im actually thinking of dialing back my CA to 25A instead of 40A unless Im off-roading as I really dont need 2900 W of acceleration on my commute. Easy enough to change if I need it.

[Beachcruzer]

Kinni I broke some ribs about 6 weeks ago, the net result of which has been spending way more time and money on ebikes. Time I would normally spend surfing is spent staring at my bikes and dreaming up new things to do to them, soldering harnesses, ordering ebike stuff online, and asking noob questions on the forum. So I feel for you, and your wallet which is about to get hammered by new bike acquisitions.

Love your video. Great production values, and you can tell you had fun making it.

I'm going to be on the Method's 2810 bandwagon with you and JKB. Plan right now is a Specialized Big Hit FSR downhill bike with 6 x 10 9c and 24s lipo in a front-mounted Pelican case, a la Oatnet. Also have a Worksman Newsboy cruiser that's screaming for a hi-torque rear motor, but have to take things slow. Need to recover from these ribs soon so I can split ebike time with a less-expensive hobby!

[jkbrigman]

Holy crapoly guys - I hope both of you get a visit from the rib fairy and start feeling great soon.

Beachcruzer, I love my 2810, and it runs just happy on 24S LiPo. So does the controller.

Kinni -thank you very much for the sad parable of the CA in the weather. I will heed your word to the wise!

JKB

[Kinni420]

unfortunately, Ive probably spent 2 years of my total life with cracked/busted ribs from my old snowboarding days. Ribs are probably the slowest recovery injury out there

[Kinni420]

SO! reporting back in after 6 months of constant commuting! recent updates:

1) ribs are fully healed but still ache a bit if I work too hard. 99% recovery.

2) almost 200 cycles on the batteries. Battery #2 Cell #6 is dying. After a ride last week I did a quick monitor before charging. Cells 1-5 were at 3.6V each Cell 6 was at 2.9V!!!!!! Im only getting about 3 Ah out of the 5Ah packs now and Im pretty sure its this battery causing this. Im ordering a replacement battery tomorrow (Good thing HK gave me credit on this runt battery. $7 shipped from US warehouse.) Any ideas/thoughts on this issue?

3) I'm trying to get out of having to pull the batteries from the bike every time I charge them. Doing this has resulted in several broken connections in the balance leads and even the 4mm bullet connectors. I have a great place in my new garage to pull this off but I have some questions. Sure I could just create a 3x parallel charge lead, purchase a 6x parallel balance cable (Id build my own but I cant find a female JST-XH connector for the life of me) and a JST-XH extenstion but this still requires unplugging the discharge harness from the batteries themselves.

Lets look at what I have:

3x 6s turnigy 5000 mAh in series (18s)
iCharger 106B+

Can i charge in series with this charger? Im still pretty fuzzy on series charging.

My main plan here is balance every 5th or so charge, requiring me to hook up that balance charge lead i was talking about but still not removing the batteries from the bike. Normal charging would be done in series through the anderson powerpole connector that currenttly attaches my discharge harness to my controller.

Any and all help is greatly appreciated. Links, diagrams etc are great too!

Kinni

[docnjoj]

Sure I could just create a 3x parallel charge lead, purchase a 6x parallel balance cable (Id build my own but I cant find a female JST-XH connector for the life of me) and a JST-XH extenstion but this still requires unplugging the discharge harness from the batteries themselves.

Try EPbuddy.
otherDoc

[Kinni420]

Try EPbuddy.

sold out