Building a Kona Ute cargo/commuter bike

[miuan]

Well I got no reply from ping or raf242 so far, which led me into further e-speculation.
As Drunkskunk pointed out, the motor starts working miracles once you plug a higher voltage in, and 6*10 motor has almost exactly half the speed of a 5 winding (superfast 2805) 9C motor.
So I simulated the 2805 motor with a 700c wheel, 72V pack and 20A controller. I hope some of you already tried 9C at 72V, so you can confirm my findings.
It looks very promising for my bike. The best aspect of this is that cruising at 80+ efficiency AND enough power available is possible from 25 to 50kph, and speed is only dependent on throttle setting and pedal input. The motor would only start being inefficient in really slow and super steep climbs, but also here it is more efficient than it was at 48V simulation. See the attached pic for various throttle settings.

So I would have a choice of speed AND power, without much need to compromise either. I would only need to get the slower motor, which is out of stock now. A 7*9 may however also do the trick, if a little too fast. Getting a 72V pack charged evenly and buying a controller that can do 72V may be a bigger challenge, but not impossible. I think the power at this voltage is ample, so I could get eway even with a 15-17A controller. Any thoughts?

 

[dogman dan]

1. You must have money.

2. If you really want the high power get a crystalyte 5305. Why? because at voltages above 48, or high watts however you get there, you will need a motor that can take all the heat that will be made.

So the recomendation becomes 72v, 30-50 amp controller, and 72v 20 ah of headway batteries. You will have about 60 amps continuous avaliable. It won''t be stealth, though, it will be a small motorcycle. If you crave the power, that's about the max before you start moving on to converted motorcycles. $2,000 for the batteries alone.

If you went with 72v 20 amp controller, then you could go with 10 ah of headways, for about $1,000. You would still have a substantial bike, with 30 amps continuous avaliable for hills.

Bear in mind, with that much power you can have great fun smoking tires and doing wheelies. Motors can be killed in just a few minuites with that much power avaliable doing stunts.



It's really fun to play witht the simulator isn't it? But a lot less bike for a lot less money will do what you need. I stand by my recomendation of a 9x7 motor ,22 amp controller, and 48v 20 ah or 48v 15 ah pingbattery to do what you need. ( 35 kph for 40 k)

By all means though, buy a lot more bike and battery if you want it, and have the money. I have no doubt the bike will be fun. But then you may want get into what I've ended up with, one practical bike for daily travel, and another, or several others that you tinker around with for fun. Once you own a good high c rate battery then you can fairly cheaply have multiple bikes that run on it. Say 9x7 36v front hub cargo bike, and 6x10 72v off road fun bike. Or 5305 clyte 72v fun bike. Or to really fly, the 5 turn 9 c at 72v. Two 36v 10 ah headway packs used as 36v 20 ah or 72v 10 ah.

 

[miuan]

I'm not that much into e-biking really. Also I'm not planning multiple conversions yet, and this bike is an ideal platform for that purpose. Sturdy, stable, stealth and pedals well. An efficient AND fast bike will be good. Since my commute is short enough, I can do it fairly fast without draining the battery, yet have a bike that serves well on longer runs and lower speeds (up to 30kph) if I tame the throttle .

For even faster riding, I have a motorcycle. But if I sould have a 72V battery, I would divide it into 2 batteries for the said reason - my girlfrient may get envious so a cute Bafang could do the job for her.

More importantly, I don't need more power than my previously intended 48V setup provided. So I'll actually be perfectly fine with a 72 * 15A controller, lowering the CA wattage by 25% from my previous graphs. That is 1200W max, and should be OK for a 205 sized 9C motor, right? I mean, as long as the wattage is ~ the same as at 48V/27A, I shouldn't be afraid of higher voltage, as the motor damage only occurs when heat can't dissipate fast enough. I may even go to a 60V/20A setup and a 7*9 motor that is in stock now, plus there is a chance the stock controller will work. Do I get it?

 

[dogman dan]

Sure, but the stock controller is likely to be limited to 48v. And don't forget that going from 48v to higher voltage is going to make the battery much more expensive. Get the 9 count motor if it's top speed is fast enough for you at 48v. Then you could get more battery, and higher voltage controller later.

 

[miuan]

And don't forget that going from 48v to higher voltage is going to make the battery much more expensive.

It's not all that bad.
While still waiting for Ping and Ev-components to reply, I also realized that BMSBattery has 38120 Headway cells in stock, and Jack can make a 24S/10Ah pack for me for 434 USD + 260 USD shipping, (or a 20Ah one for 830 USD) including bleeding BMS. While the price looks cool, shipping is rather expensive so I'll rather wait for others. I also found some cheap LiPo's here. With two of these, I could have a 6.5kg 72/12 battery. The only problem I see with this setup is I would need a new controller. Anyone tried these?

Get the 9 count motor if it's top speed is fast enough for you at 48v. Then you could get more battery, and higher voltage controller later.

I may eventually give up and settle with proven 48V setup, but it's clear from the simulator that 72V with 7*9 motor will have better overall power/efficiency range. It would cost me more for the new controller, which may be 50-200 USD. After I get answers from Ping and EVC, things may clear up a little.

 

[miuan]

OK, so I pulled the trigger and ordered 22 Turnigy 5S1P 3Ah 20C LiPo packs. The plan is to make it a 3*5S/7P 21Ah pack and keep one pack for spare cells. BMS and charger will come from BMSBattery.
Now to the battery type. I frankly think that I won't need more than 80 charges per year. That is 5 years battery life, especially when the 20C pack will be discharged at max. 1.5C.
I also got the proprietary JST-XH charge/balance wiring to be able to connect the packs to BMS or replace them if needed without any soldering. I can thus also check voltage of each cell quickly with a digital tester like this one.
Also ordered the 28"/48V/800W discless 9C rear motor kit and the backlit Turnigy watt meter. Now I only have to wait.

 

[PeteCress]

9c noise is nothing to fear - unless you are worried about your ability to sneak up on cats.

On a scale of 1-10 (where 1 = total silence) can anybody compare 9C's noise to eZee's noise?

EDIT: I've answered my own question.

9C = 2
eZee= 4.

Bottom line - for me, who is about as neurotic about noise as anybody can get, both are acceptable; with the 9C having an edge in stealth on a quiet bike path.

 

[miuan]

So I have done my first 120km on my 2807 9c motor. I have to say it works really well. The complete vehicle weighs about 40kg so it is quite bulky, but I can cope.
My max. speed with pedaling is about 60-65 kph fully charged (62V), good weather conditions, and declines to 40-50 kph when things go worse. Exactly what I wanted, and ideal for city roads. Many thanks to ebike.ca simulator and you ES members for giving me correct advice.
As for my power consumption, at city speeds about 45-50 kph, I go about 3 km/Ah = 20Wh/km. I live in a city but my route is pretty fluent.
My stock thumb throttle starts to give me some trouble though. In some cases, the controller does not react to the throttle at all, but in a couple seconds all is OK again. Not sure if some electric spray lube helps, or it is a controller issue, but all in all, it is a great motor.

 

[miuan]

450km done so far. The Turnigy packs required some balancing but nothing major. They are paralleled by balance leads (7 in a row), no issues there. Usually they will develop an imbalance of ~20mV every 100-150km riding, which is acceptable as I charge to 4.17V anyway and a RC balancer gets it back in couple hours' time. The throttle is OK again, it was probably just a brake lever not releasing the shutoff switch properly. The 63V/12A charger I got from BMSBattery holds up well too, I just put a diode in series to lower the CV phase voltage to ~62.5V, it runs fine and is also very fast, I'm able to charge during morning shower / breakfast to minimize full-charge storage time. Using the bike for anything the car did before except longer routes, I am super stoked. Hope to get many miles this year. Thanks to Hyena and other ES users for advice on the build.

 

[adam78]

450km done so far. The Turnigy packs required some balancing but nothing major. They are paralleled by balance leads (7 in a row), no issues there. Usually they will develop an imbalance of ~20mV every 100-150km riding, which is acceptable as I charge to 4.17V anyway and a RC balancer gets it back in couple hours' time. The throttle is OK again, it was probably just a brake lever not releasing the shutoff switch properly. The 63V/12A charger I got from BMSBattery holds up well too, I just put a diode in series to lower the CV phase voltage to ~62.5V, it runs fine and is also very fast, I'm able to charge during morning shower / breakfast to minimize full-charge storage time. Using the bike for anything the car did before except longer routes, I am super stoked. Hope to get many miles this year. Thanks to Hyena and other ES users for advice on the build.

any pictures of you Kona? where did you install your batteries, etc? Also, can you let me know where you got your Kona for 500EUR? I live in Czech Republic...
Thanks
Adam

 

[miuan]

Hi Adam, I was busy this evening installing some new stuff on the bike, so no more shots today and possible this week as well (traveling for a weekend soon) but drop me a message on icq 81.96.98.98 and I'll come back asap.
Updates today:
26in front wheel in order to fit a proper suspension fork. Most 28" forks won't handle a 203mm disc rotor and neither did the original Kona fork, which got its brake tabs bent.
10watt halogen light front + 1watt red LED rear, both 12V. power sourced via a standard 220V/12V wall socket pulse supply from a broken scanner, that works OK with 60V DC too
I had 5 x 12V leds in series before (4 front, 1 rear) but now it looks much better with a single front light.
2 small side bags on the right. Now it takes up to 40kg of grocery loads.
Battery is now resting on the wooden deck right behind the saddle, can be also hidden in any of the bags in case of bad weather.
I damaged my celllogs, so I'm left with a single slow RC bleed balancer, but it's OK, the cells are quite stable and never get out of balance fast. I try not to fully discharge the battery though.
Planning to install road cranks with 39/52 gearing. The 48/36/26 that I have now is still too slow. At speeds over 55kph, sustained pedaling requires too much rpm.
I bought the bike at closeout in Kaktus Bike, Bratislava. If I should build it again from scratch, I'd prefer a 26" frame alone as I had to swap most components anyway. Also, a more sturdy steel frame could be beneficial for long-term durability.