Total Newb building a Kona Kikapu

[ReeseEngineering]

Hello,
I am new to the forum, but I have been reading up
the last few weeks on all the good info here.
Just to get it out there, I have a BS in Mechanical Engineering,
live in Calif. (SB county) and am very mechanically hands-on.
(I own and operate a small machining/welding shop)

However I am not quite so electrically knowledgeable.
I couldn't design my own circuit board, but I can troubleshoot
and fix pre-1980 automobile electrical problems, I have a ton
of electrical support equipment (various supplies, meters, and
a scope), and I can solder like a pro.

About 5 years ago I built a gas-powered hard-tail bike
with a Honda 4-stroke GX35 friction drive centrifugal clutch.
I have put about 2000 miles on it and it has good and bad points.
Good on-road for short (<4 mile) distances.
Good price to convert (about $400)
Bad off road, bad center of gravity, bad for tires,
bad if you want to be quiet (passing other cyclists).
I've also learned a lot in the process.

Now I want to build a motorized mountain bike.
I have 3 mountain bikes, but chose my Kona Kikapu for this endeavor
based on other people’s success and available space in the frame.
(Other choices were Gary Fisher Joshua Z0 and Specialized FSR)
I have been looking around at what it will take to do this
project and I am willing to spend the money to do it right.

My goals are:
- Durability off road (motor and electronics need to handle
serious vibrations, dust, and occasional mud, but minimal
water) I can hot-glue board components if needed.
- Around 27 - 30MPH top speed on-road on the flat MTB tires.
(If it goes faster than that... ok, but I probably won't take it up that high)
- I want enough power to go up dirt fire roads and dirt hills at a decent clip.
- about 10 mile range at first, and I'm willing to pedal too.
Expandable to 20 miles later if needed.
- regen brake (feasible with most controllers I have seen)
- keep the electronics (Motor, 2 batteries, and C.A. unit) under $2000, less if possible.
- take consideration of weight (possibly start with low voltage,
low Ah, and upgrade as necessary)

I *think* I need to be looking at a 72V system, but this is where
my electronics skills lag. This is also where I have been confused
about the choices out there for Motors, Controllers, Batteries, etc.
and, most importantly: where to purchase them.
I have no problem piece-mailing this together, as long as I understand
what I am actually doing and not fry something expensive (or myself)
in the process. I’m not afraid to void any warranties as long as I
(kinda) know what I am doing.

I am leaning towards the 9C 2807 motor from ebikes.ca but they
are currently sold out. ok I can wait, but maybe there is something
better for my application? 2806? 2808?
I do understand the 06 07 08 winding idea.
06 is less windings per pole but can take you faster relative to 07 or 08

I'm not sure if ebikes.ca even sells a 2808, but I have seen
them online somewhere. I was going to use "good" spokes
and a "good" wheel on whatever motor I decide to get.

I know I want to get the Cycle Analyst, but I may have
to custom wire it to whatever controller I need.
Ok, no big deal as long as I know it will actually
work before I go and buy something incompatible.
This is where the bulk of my questions come from
regarding batteries and controllers.

I think I have determined that Infineon controllers are "the way to go".
But which one do I need for my application?
35A? 40A? 45A? 9FET? 12FET? 18FET?
I understand basic power relationships, voltage, amperage, wattage etc.
I have used the simulator at ebikes.ca with various motor,
controller, battery configs. But I am confused why higher-amp
controllers yield lower speed for the same given battery and
motor combo? I am more interested in Torque because I think
that will be key to off-road performance. I typically equated
higher Torque to more Amps, instead of higher voltage,
but maybe I am way off-base here.

Is there a specific controller to get that offers me the flexibility
of using, say, 36V or 48V at first and then re-configuring the same
controller to 72V later if I want/need to?
Where do I even get one of these controllers?
ebikes.ca? Ebay? E-crazyman?
Eyourmomgoestocollege.com?

Coupled with that, what batteries should I be considering or avoiding?
I *think* I want to use LiFePO4 batteries, but maybe LiMh?
Should I be weary of “Ping” batteries on Ebay?
I have seen others using them with success.
What should I be looking for in terms of capacity? 10Ah? 15Ah?
How do they get higher capacity?
More cells in a battery pack or just bigger cells in a pack?
Does higher capacity mean longer range?

What other options are there for “good” LiFePO4 batteries?
Should I consider “making” my own battery from some kit or something?

Can I just hook two LiFePO4 36V batteries in Series and get my 72V?
Can I start with one 36V battery and a 45A controller and then upgrade to 72V later?
Will a brand new 36V battery and a used 36V battery hooked in series
make a bad combo for 72V down the road?

Whew. I think that's it. :?

Any help would be greatly appreciated.
I will post a link to photos as soon as things start getting serious.

Reese

 

[neptronix]

Welcome to the forums!

Too many questions in one post though, buddy!
You may want to check out the ebike photos & video sections on here to see what has been done before. There are plenty of logs of excellent builds, and should serve as some inspiration and guidance.

 

[Philistine]

I think I have determined that Infineon controllers are "the way to go".
But which one do I need for my application?
35A? 40A? 45A? 9FET? 12FET? 18FET?
I understand basic power relationships, voltage, amperage, wattage etc.
I have used the simulator at ebikes.ca with various motor,
controller, battery configs. But I am confused why higher-amp
controllers yield lower speed for the same given battery and
motor combo? I am more interested in Torque because I think
that will be key to off-road performance. I typically equated
higher Torque to more Amps, instead of higher voltage,
but maybe I am way off-base here.

Is there a specific controller to get that offers me the flexibility
of using, say, 36V or 48V at first and then re-configuring the same
controller to 72V later if I want/need to?
Where do I even get one of these controllers?
ebikes.ca? Ebay? E-crazyman?
Eyourmomgoestocollege.com?

Personally if I were you, I would go with either a 12 Fet or 18 Fet controller from ES member Lyen (he uses infineons) (the 18 Fet is bigger, but can handle more current). If you message him, he will give you his prices. Unless you are going to run monster amps or a high speed motor wind, then the 12 Fet should be fine. Get it with the programming cable installed, and with the cycle analyst DP plug in it. Then get a Cycle analyst DP (that stands for direct plug in, not the other DP).

That way you can program your controller with different amps as you like. I run a Lyen 12 Fet on all the voltages you mentioned @ 40 amps battery and it is fine. The only time it wasn't fine was when I used it on a X5303 (a high speed wind) and it melted the phase wires on the controller. But if you are running a lower speed/higher torque wind, then the 12 Fet should be fine for you. By getting a programmable controller you can change the configuration of your controller settings when you like. Having the Cycle analyst DP plug in, will allow you to also limit amp draw on the controller on the fly (through the CA).

Lyen is a great guy and gives a great service. Send him a PM.

The reason that higher amps doesn't give more speed, is increasing amps just increases the current (ie, it will increase the wattage, and thus will increase torque), but top speed is a function of the kv, and hence higher volts means a higher top speed - increasing the current (amps) will increase power (watts) but not top speed.

Cheers, Phil.

EDIT: to try and give you my recommended configuration given your many questions, I will try to give a quick summary, If you follow the standard path of most ebike "overvolters", you will probably start on lifepo4, then quickly move to the freebase of batteries - Lipo. You will start saying that 48V is enough, then quickly realise that life is too short to mess around, and you will end up running 20S or 24S (84 or 100vhot). So yes, prepare for justifying to yourself that 72v is necessary.

In terms of motor, if you want an alround ebike hub, good for overvolting and not necessarily used for pulling heavy loads or going up steep hills, then yes, the 9x7 9C or the 8x8 9C is good, but I would personally go with one of the new Crystallite HS35 or HT35 motors. In my opinion it is worth spending the extra compared to a 9C - there is ES member Illia/EbikesSF in the for sale section sellingt these - make sure you buy a sensored one if you do (a sensorless motor will only run on a sensorless controller). Then get a Lyen 12Fet or 18Fet. Then my advice is go straight to Lipo if you have the cash and are serious, then get a Hyperion 1420i charger. Lipo is another whole topic though - do your homework.

Hope that is of some help, ask an info loaded question, get a info loaded answer.....

 

[dogman dan]

You DONT want a 2807 or 2806 motor for that kind of bike. You'll fry it for sure, and it won't give you good low speed throttle controll on the tricky parts where you need a fine touch going slower.

You DO want a 2810 or even 2812 winding 9 continent. Rear hub motor for dang sure. Currently avaliable here.
http://endless-sphere.com/forums/viewtopic.php?f=31&t=26603

To get the 2812 you'd have to lace a new rim onto the 20" rim motor, or like I did, buy both 2810 and a 2812. Then just swap the windings out to put a 2812 into the 26" rim.

A 2810 motor on mere 48v will go 20 mph, and climb 15% fast enough to not fry the motor. At 72v they will have the speed you want. Go easy though, at 3000 watts you can melt a motor fast going up really steep hills. I am currently running a tiny 9 fet 72v 20 amp controller on my dirt rider and climbing hills fine, yet with only 1500 watts I'm not melting down motors. That's while riding in todays weather, above 100F too!

The othe good choices for your needs are the larger size gearmotors, such as the Mac from cellman, or BMC's from various retailers that are USA located. I think the dd motor sheds heat better though, so that's why I like the 9 c myself. But for dd, you gotta have the slooooow winding to get up those hills cool. The gearmotors do have one big advantage, a 48v battery is all you need for those ones.

I can't say anything about the HT motor from clyte. I just don't have the data to know if the HT model is really slow enough for this kind of riding. I suspect not. Motors that only go 15 mph on 36v are a hard to sell item. I bet it's a similar wind to a 2808 9c. Good for 10% grades for sure, but I ride grades 4x steeper than that all the time with my 2812.

This will all fit well under your 2k budget, even with two motors bought, and a 72v 10 ah lipo battery and charger setup.

Pic of my dirtbike, a bit out of date, but close enough. There is a thread on it, in the pics section. You tube vids of the rides, at Dogman5018.

 

[ReeseEngineering]

Thank you for the replies and good recommendations.
(sorry for 100 questions in my original post)
I am on my way on this project, and learning a lot as I go.
I will give updates as things progress, with photos.
But now it is time to start gearing-up for the 4th of July weekend.

ReeseEngineering

 

[pdf]

Reese,

I think I just built your bike, maybe. I used a 2810 on a 26 in Giant Boulder MTB, with 72v 5 Ahr of LiPO and a direct plug in CA. I bought an 18FET controller from Lyen and I recommend it. The whole she-bang was dead simple and I am a hack. The 2810 came in a rim already (got it from an ES member who bought out somebody and had bunches). The most time consuming part was cutting off and soldering on connectors to mate everything together. I'd advise buying enough silcon insulated 12 gauge wire and using 4 mm bullet connectors on all the power wires. Get enough shrink wrap of the correct size and color also. I got mine from EP Buddy but I think Hobby King sells also.

Have no complaints with the controller or anything really. The controller is programable and 72V ready. At 72v, the 2810 will do around 25 mph, maybe a bit more, so it is in your range. I've never seen it pull more than 20, maybe 25 amps at this voltage, but that is a lot of power. We have had no problems whatsoever, but if you are going to run continuously at 15% grades in the heat for miles and miles, I don't know if the motor will shed the heat quickly enough. For super tough duty I've been told the slow wind 5000 series C-lytes can't be beat but they are much heavier. The way we use it ("we" is my son and I) is for a mile or two of low grade (less than 10%) and short, steep sections (less than 100 yds of 20%). Not enough to even get it warm, but my son is only around 100 lbs.

If you can ride a few ebikes in conditions you expect to encounter, it will be very helpful. I did a lot of shopping around, although I had to drive several hundred miles to try an ebike. It was worth it. Pics below of my "stable". The Giant is on the right, obviously. On $2000, you have a lot of options that will do what you want. It might be hard to find bikes to test, but do it if you can. You will know what to expect for a similar system.

 

[torker]

Good on the 4th of July celebrations starting I run 2 2810 motors as well. One is in a 26 inch rim and it runs about 19 mph. on 10s lipo =42 volts hot. I run my other 9C 2810 in a 20 inch rim and it runs approx. 23 mph. on 15s = 63 v hot off the charger. I modded the shunt on a stock 9 fet Infineon and the 20 inch setup really rocks.. I would love to try the 2812 in a 26 inch like Dogman runs. I can only imagine how sweet it is under 20 mph. at 72 v As you run slower windings and up the voltage they become very linear on the throttle response. And, All ya gotta do is up the voltage to get the speed up Welcome to the fray !!

Just saw PDFs response. Right on the money about shedding heat at lower speeds/ steeper grades. Another reason to consider a 2812 or limit to 72 v and 20 amps .. The slower 2812 winding will be a lot more forgiving on the fireroads.

 

[dogman dan]

Looks like the 2812 winding is gone now. But methods still has some 2810's I believe. When they are gone, then it will be just the HT clyte for choices. 5304's may no longer be avaliable in the USA as far as I can tell.

 

[ReeseEngineering]

After about a year I finally got this thing together.
Ended up going with 6 LiPo packs. 3 in series x2 parallel banks = 97 volts, ~18 Ah

I took it out today for it's initial run from my house to a friend's house and back.
12 miles round trip. Average speed 15mph, max 40mph, 45 minutes travel time
I'm down to 92.5 volts, so could probably go there and back again.
It was all on-road, so I figure maybe 12~15 mile range on dirt trails / average offroad.
(No huge hill climbs, and pedal when it is appropriate)

It is hard to resist the urge to pin the throttle all the time.
The highest I saw on the CA was 5200W yikes!

Notes:
The initial power-on killed my main (30A) power switch - locked it in the "ON" position.
So I had to use the fuse as my power disconnect.
When I connect power from the batteries to the controller it creates a BIG spark.
Question: Is there any way around this? Soft-start?

More to come.

Jack

 

[Punx0r]

Have a search for "precharge resistor"

 

[ReeseEngineering]

Yep. Precharge resistor did the trick. Thanks Punx0r for the search suggestion!

I added a 10 Watt 100 Ohm Wirewound Ceramic from Radio Shack
and a small SPST toggle switch to energize the controller.
I was also able to disassemble and rework the spot-welded main switch,
so it is back in action.

The next step is to try a 1/2 grip twist throttle instead of the
current thumb-throttle configuration. Applying the throttle is
too jerky as-is. The full-grip throttle was also difficult to control.
3rd time's the charm?
We will see.