Kinni's E-bike questions and stuffs

[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

[docnjoj]

Try EPbuddy.

sold out

Gotta call him because not all stock is always up on the computer.
otherDoc

[Kinni420]

new battery is on its way...hope its not another dud like the one Im replacing.

football sunday! 3 hours till kick off.....go niners!

[Kinni420]

stupid question I know but i need to ask it.

running 18s atm. plan on going 2p soon. since im running 3 6s batteries, is it ok to pop in a 2s battery in series with those 6s to make a 20s? Or do they all have to be the same size batteries (like going 4x 5s)? I sure would like the extra voltage for more speed on the wife kit and repurchasing a ton of batteries would be expensive.

along with that, the controller im using, methods 40A modified, would it be able to handle that extra voltage? he did say it had 100v caps in it on the website.

[jkbrigman]

stupid question I know but i need to ask it.

running 18s atm. plan on going 2p soon. since im running 3 6s batteries, is it ok to pop in a 2s battery in series with those 6s to make a 20s? Or do they all have to be the same size batteries (like going 4x 5s)? I sure would like the extra voltage for more speed on the wife kit and repurchasing a ton of batteries would be expensive.

along with that, the controller im using, methods 40A modified, would it be able to handle that extra voltage? he did say it had 100v caps in it on the website.

Chris - I did a successful 10 mile test ride previously (on the recumbent) using 24s of cells - 94v - and I couldn't tell any problems with the controller or motor at that voltage. I've seen other threads here on E-S where guys talk about doing exactly what you describe: bumping up the voltage by adding a 2s or 3s brick to the rest of their 6s bricks.

IMHO, I believe what you propose will work just fine.

I would switch to 24s myself but I already bought two bulk chargers at 74v, which won't work with 18s.

JKB