Kona Kahuna build - 1000 mile review

[patrickza]

Ive been using the stock ampedbikes kit torque arms. They are not long but they work and usually line up with the holes already built into the frame for paniers/racks.

As far as the frames go, The Kona Kikapu, which is almost the same bike as the kahuna has held up really well. I was also skeptical. I check my axle tightness before each ride. I figure that if the bike is meant to accommodate heavier individuals >200lbs, then I should be relatively safe strapping on 20-30 pounds of components being 170lbs myself. Im sure the wheeling doesn't help but

I also tried using plastic for my case. patrickza: disolving some of the plastic into the "glue" is a great idea. Wish I tried it myself! would have had better results.
great build!

Thanks for the info, hopefully I have the same result. As for building out of plastic, I read about a guy who built a boat for his kids entirely our of ABS, so that was where I heard of the technique. Worth a read if you plan ondoing minor plastic building: http://www.duckworksmagazine.com/07/designs/plastic/index.htm

 

[michaelplogue]

it's a homebuilt box. I'm not the handiest guy but I do like to try things myself. I bought a very large sheet of 3mm ABS plastic...

Wow! that's really nicely made, and a fantastic method of 'welding.' Initially, I thought it was welded steel that had been painted grey - and then I saw the battery studs looking like they were ready to come into contact with the 'metal.' My initial post was going to warn you about potential shorts......until I read your follow-up post...

Very nicely done - Kudos!

.

 

[docnjoj]

That is one classy battery box, patrickza! Any chance of more photos from different angles. I need to replace my Frankenbox with something a bit better looking. What thickness ABS did you use? Thanks in advance.
otherDoc
edit: Whoops, just saw the 3mm thickness!

 

[patrickza]

That is one classy battery box, patrickza! Any chance of more photos from different angles. I need to replace my Frankenbox with something a bit better looking. What thickness ABS did you use? Thanks in advance.
otherDoc
edit: Whoops, just saw the 3mm thickness!

Thanks, yeah they sell it as 3mm, but it looks more like 3.5 to me. Here's some pics I took when I was building it. My box had a few weird angles, I think a rectangular box would have been a piece of cake. The plastic is strong. I could stand on my box on it's side no problem. I also modified a plastic vacuum sealer to turn it into a plastic bender. It worked quite well, but I had better results cutting and glueing so I didn't use it at all.

 

[dnmun]

looks great, duane told me about ABS and i am gonna build something similar, like deecanio did too, and bob mccree on his original nicad pack build. and they all fit.

be gentle torquing the axle nut, they don't have as much thread as a regular bolt and can strip pretty easy, use the torque arm to hold it in place, you can't tighten enuff to overcome the torque anyway, especially with that much power.

add a second nut/locknut to the first if you can find space on the end of the axle to compensate for losing some of the threads inside.

 

[docnjoj]

Thanks, partickza for the extra photos! I am inspired to fully enclose my Fatpacks in my triangle under the seat. I think the huge Ping will just simply be too big for my purposes.
otherDoc

 

[patrickza]

IT RIDES!

So finished all the connections, plugged everything into place lifted the (very heavy) rear wheel and gave the throttle a quick turn. I was so shocked, it worked! None of my projects ever work first time round, woohoooo. I must say, I feel like I've learnt more in the past couple of weeks here than I have in the 7 since I got my degree...

Anyway I got a million zip ties, tied all the cables out of the way and carried the heavy beast down the three floors to the ground. Took about a 5km ride around the neighborhood grinning like a fool and feeling like a kid.

Carried her up the three flights of stairs again, I have a feeling I'll be building a few more muscles soon. Anyway, plugged in the charger, and just saw the green light appear. I do have one problem though, so it's not perfect. After the charge (which stopped at 80.4v according to the cycle analyst) I switched on the cycle analyst to see the voltage. Lifted the rear and gave it a spin then turned off again. Went back a little later and turned on the cycle analyst and the light comes on, but nothing displays on the screen. Also when I spin the rear wheel with the cycle analyst plugged in it goes much slower then when I do the same with it unplugged. Any ideas?

Here's a few more pictures:

 

[snowranger]

Very nice build. I was wondering how you lock the bike up though.

 

[patrickza]

Ok I got some advice from voicecoils about the cycle analyst and the screen has come back to life after soldering in a new resistor. The backlight is still flickering but I can live with that for now.

Next up I'll need to start thinking of a cover...

Very nice build. I was wondering how you lock the bike up though.

Thanks, yeah i thought about locking up methods for a while. The crime rate in South Africa is pretty bad. I'll mostly be taking the bike in with me when I go to the office etc, but there is also a gap between the shock and the seatpost for locking things up.

 

[snowranger]

You could also run a cable to your front wheel too.

 

[GreenKnight]

Yep looks like a nice bike. If you do run out of space you can consider putting a few of you triple cell units either behind and under the saddle or in front of the of the handle bars. Where or what are the triple containers from?

As for for the adhesive I would go with the silicon rubber. Its strong enough to hold things together, doesn't conduct and can be cut with a sharp knife if you need to disassemble.

 

[patrickza]

Thanks, partickza for the extra photos! I am inspired to fully enclose my Fatpacks in my triangle under the seat. I think the huge Ping will just simply be too big for my purposes.
otherDoc

I agree, you should get going docnoj! Looks like a good candidate for some ABS building. It's a fun material for working with too. You should be able to knock together something in two evenings. Where the thought will come in is how you open and close it. I made the inner triangle just fit the frame, then put a double layer around the left edge, and built the right triangle cover 3.5mm wider so it slides on. You'd probably make a top cover which lifts off to gain access to the cells.

Where or what are the triple containers from?

They're not really containers. it's 0.8mm double sided tape in between cells with duct tape around it. Then I connected the cells using copper braid I salvaged from some cable. The edges of the copper braid would fray a little so I dipped the end few mm into my ABS acetone mixture and let dry, then repeated again. They came out so strong that the copper would break before the cables frayed.

 

[patrickza]

So just got back from my second ride I'm still grinning from ear to ear. Took it to show my grandparents, they're both in their 80s but like seeing new ideas. My grandfather used to be quite a tinkerer when he was younger so he was really into it.

Ok so stats for the ride were as follows, I haven't calibrated the cycle analyst apart from setting the wheel circumference:
Distance 30.8km
Starting voltage: 80.4v
Ending voltage: 78.8v
Lowest I saw under heavy load towards the end of the ride: 69v
Cycle analyst reported 4.6ah used.
Top speed: +-55km/h on the flat.

I'll hook up the multimeter to try get it calibrated this week sometime, Justin said the rshunt could be anywhere between 1 and 2 mOhms.

 

[patrickza]

Well the white stood out quite a lot. The street vendors here love the bike, I get tons of thumbs up wherever I ride. Anyway I was feeling decidedly under duct taped, so in following with the inspirational doctorbass, my case has been duct taped up. I think it looks better, but also it will protect the plastic from the sun in the upcoming summer months.

A quick update on my stats, I've done 170km since finishing the bike. I'm taking it easy on the batteries for the first while so I tend to only go uphill at 20mph while pedaling along lightly. So far my cycle analyst says I've used up 26ah however it needs to be calibrated. Using Justin's technique of seeing what the highest average amperage is and comparing that with the controller peak it looks like I'm over reading by about 30%. This means the 170km's have been at a cost of +-18ah, not bad going. My average wh/mile is about 20 so I should make my 30km round trip commute on one charge. Only done it once so far and I charged at the destination.

I'm still waiting for a second charger to arrive from ecitypower, I might mount this one to a seatpost rack for on-board charging.

Here's my duct-plastered bike:

 

[michaelplogue]

Here's my duct-plastered bike:

NOOOOOOOOOOO!!!!!!!!!!

That's just frigin' criminal! How could you do that to such a beautiful build?


.

 

[patrickza]

Here's my duct-plastered bike:

NOOOOOOOOOOO!!!!!!!!!!
That's just frigin' criminal! How could you do that to such a beautiful build?
.

Lol, it had to be done... and I must say it looks way better in person than in the picture. But don't worry, it's not over yet, the duct tape is just to protect the plastic from UV, there's still a cover coming as soon as I learn how to sew. I'm thinking matt black lycra, would that be better?

Here's another picture from a little further away. It looks like it's been painted grey to the naked eye, I prefer it. The camera and flash make it look much worse.

 

[jag]

Using Justin's technique of seeing what the highest average amperage is and comparing that with the controller peak it looks like I'm over reading by about 30%.

FYI: The shunts in the controllers aren't very accurate. In my Crystalyte controller the shunt is off by 14%.

You would bet a more accurate calibration by buying an inexpensive digital multimeter with a 10A range, then just run the bike
with the rear in the air at some speed just below 10A on the DMM. Adjust CA to read same.

 

[jag]

inexpensive digital multimeter with a 10A range,

Just wanted to emphasize inexpensive means $5-10. I've found them wherever I've been, 35 yuan in China, 5 Euro in France, CAD 5.55 in Canada. It's the type with a transistor tester also. Comes in different cases, but probably has the same circuit inside. The one I bought in France was particularly nice and small at only 2x3". I buy them and when I have to many I give them to friends. Join the multimeter for everyone movement!

 

[patrickza]

Ok so after following some advice from the Doc (http://endless-sphere.com/forums/viewtopic.php?f=2&t=12080&start=0) it seems like the default setting for the new crystalye controllers is for medium power. I shorted out the speed setting pins and set it to max power and gave it a go.

All I can say is wow. No load speed is up from 55.7km/h to 71.9km/h! Got dressed really warmly (it was 10:30pm in winter), carry bike downstairs and whoa, it's like a completely different animal. Before when I was at 40km/h and opened up it slowly started climbing, now at 40 it's still pulling 3kw! Tucked in on a flat road and I hit 50, 55, 60 then slowly got to 65km/h! That's just over 40mph

I love it, I just don't know if I have the responsibility needed for the great power :lol:

Oh well, it'll just cost me about $0.01 extra when I charge, reasonable trade-off I think.

 

[icecube57]

Welcome to the club. I just barely got in myself. I miss the good ole days of 48v. Once i hit the low 30mph it starts to taper down in to the low teens on the amps. WOT in the higher voltages. You are going to see a constant 40A draw with no dip in sight.

 

[nightowlgk]

I'm psyched. American Plastics Corp. is 12 miles from me!!

http://www.americanplasticscorp.com/index.html

I'm going to get some ABS sheet and try your method. They will even cut while you wait.

 

[patrickza]

I'm psyched. American Plastics Corp. is 12 miles from me!!

http://www.americanplasticscorp.com/index.html

I'm going to get some ABS sheet and try your method. They will even cut while you wait.

Cool, try get the black, apparently it has the lowest UV degradation with ABS, and buy a bottle of ABS glue from them. It glues fast but not so strong, then use disolved abs in acetone to make the joins strong. And of course show us what you've done!

 

[patrickza]

So today was the day I crossed the 1000 mile mark. I did it in style too, cycled all the way to my folks in the next city 50km away. Left a charger there last week so I could charge for the trip back. Also forgot to wear sunblock, and for you guys on the northern side of the equator, I have to tell you that the hole in the ozone layer is very real... I've spent a week on the beach in LA and barely got a tan, same thing when I was in Belgium, but an hour in the sun in South Africa or Australia and you're literally fried...

Anyway, so here are the stats:
Cycles: 73
Total AH 248
Total Km 1700

And on to the review...

When I decided I wanted an electric bike, I had a few goals in mind.
-Top speed of 50km/h: easily exceeded, my top speed is 65km/h.
-Range of 30km: also exceeded, I comfortably do 50km. I seem to average 10-12wh/km = 16-20wh/mile. It seems really efficient, but I guess it's because I pedal, and mostly only do 20mph.
-Battery, 72v in triangle: It is.
-Weight of um well I need to be able to carry it down 3 flights of stairs: I manage, barely.
-Full suspension: It is.
-Must look cool: I think it does, but looks are relative.
-Must work as simply as my cellphone, ie. I want to plug one plug in to charge, and flip one switch to turn it on: I can.
-Tough enough to go single track riding: Probably can, I don't do jumps even though it should be able to. Dirt roads are no problem though.

So all the basics have been met, now what has gone wrong?

Well for 600 miles I had one low cell. It was causing cutouts at 3.5AH. This was really annoying, and in my attempts to fix it I think I might have permanently damaged my first BMS. Victoria was kind enough to replace it though, and I bought a few extra cells too. After switching the BMS and the low cell everything worked perfectly. After a run all cells are within 0.01v of each other. This made me much happier, now I can go on a long ride and not wonder when the pack will cutout. The other issue was caused by you guys. Yes you, always telling me how tight my axle nuts had to be and so I partially stripped one... It's still working, but I had to use a new nut and remove the washer. It does make me a little nervous about removing and replacing the rear wheel now, I'll have to get it re-threaded at some stage.

Anything I'd do differently?

Well if I had to go back to the pre-ordering stage I'd go for a 5306 rather than my 5305. I really don't need to go 65km/h, 55km/h would be more than enough, I'd be marginally more efficient, and a little more torque never hurt anyone... Unless they have a front hub I guess

Other than that I would have made my battery box easier to get into. At the moment if I want to open and close my battery case I need to cut about 20 cable ties. Doing that and re-tying them is a PITA. And I used to do it a lot when I had those battery issues for the first 600 miles, since then I haven't opened the case so maybe it's not such a big issue anymore.

Changes I've made since I first got the bike running:
-I've added my own toggle switch to go between L M and H settings. I spend most of my time in medium, go to high to show off, or when I need to go 60+ for whatever reason, and low I use when inexperienced bikers or non motorcyclists ask for a test ride.
-My original BMS box couldn't be opened, I cut the top off it and added a new lid which velcros on. Now I can open it to get cell readings, or if it's hot while I'm charging.
-Put on an avid juicy 3.5 with 8" rotor. I thought I'd like this but I don't. I prefer the feel of cable brakes. I'll be ordering a pair of avid bb7s soon.

So there you have it. Overall I'm really happy. The bike does my 30km round trip commute on one charge no problem, it's fun to ride. Handles well due to the good weight distribution, and makes people think I'm clever (hey I'm not going to argue)! It's been very reliable, when I turn the switch, it runs. Every time. Not even any punctures thanks to my tyre liners. I have been told by women I show it to that it's really geeky and won't score me any points with the ladies

What have I got planned for next? Well I would love a stealth electric bike. With a 24s pack of the new 20AH a123 cells. And a 5405 motor in a 24" wheel... Not going to happen though, I could never carry a 55kg+ bike up my stairs. Maybe one day when I've moved into a place with a garage... I'd also love to build a car. A lightweight aerodynamic kit of sorts, 2 seats, with an AC motor and 20kwh's of headway cells would be nice. Again, I'll need a bigger house, and wallet!

 

[patrickza]

Some upgrades have just arrived...

A pair of Avid BB7s. My juicy 3's have done the job but I really prefer the feel of cable brakes. Maybe I'm weird. Another advantage is the bb7 is narrower on the hub side, s it fits in with a little more leeway. With my old brakes I literally had a milimeter between the hub and caliper.

Also got some jagwire ripcord brake cables and housings. Apparently it makes a world of difference, then the third eye bar mirror which I think could be a life saver and lastly a new headlight, the Aurora AK-P7-5 HA-III SSC P7-C. Fantastic light for cycling, the beam is perfect and it's seriously bright. I'll let you know how these all work out soon.

 

[Mark_A_W]

LOL, I'm just changing from BB7s to Juicy7s :lol:


Yes, the BB7s fit better and you can remove the inner red adjustment knob for even more space.


The BB7s are powerful, but my Juicy7s are more so. Also, they move both pads, rather than bend the disc over like mechanicals.

But, I had to space my disc and then make a custom adapter for the Juicy7s.