Underdog`s Projects

[underdog]

Hello again good folks of the Sphere. I got bitten... And now I cant stop building!

Tree projects going on at the moment, and thought it would be good with some feedback from the pro`s. Especially on my dual motor cruiser build. Maybe someone has some experience from similar setup? The idea is to have a small 250/350w geared hub mid-mounted for 0-10/15 kph, and then let the DD (9c-copy) fronthub take over 10-60 kph. I have broken my front dropouts two times when accelerating from zero, when just using the DD hub. Once without torque arms (asked for it, I know), and once with `em.

Had to throw it together with parts laying around at home to get the feel for the frame geometry, and take a cruise in the sun.

Actual build:

Front motor. 9C-clone from CNE. Drilled some holes in it 13cm^2 intake on one side, and 14cm^2 airvents on the other. Thinking of making some small fins from the center en out on the inside of the covers to stir up some airflow in/out with the rotation. Should work...(?)

Inntake:

Airvents:

Also started making the battery compartment. Bought some carbon/kevlar fabric at hobbyking together with the lipo`s:

For the mid drive, I have a 350W rated geared motor capable of 300rpm @ 36v. Not sure how to do the power for this one, since the other motor, and my batterypack, runs 74 volts. I was thinking of a DC-DC converter, but not sure if I can source one that is capable of up to 12A without costing millions, or weighing tonns... Maybe a 36V 3Ah pack piggy-charging from the main pack via a DC-DC converter would be easier? The mid-motor will only be used at "takeoff" anyways? Ideas and experiences is much apprecieated

Cheers

 

[underdog]

Dual motor setup put on ice for now, and 9C moved to the back. Maybe adding a Zelena Vozila "hillclimber" 800w hub in the front over time.


Electric setup:

Charger: EMC-400, 84V3A (ca. 100min full charge).
Battery: 20S2P 5000mAh 20C Turnigy LiPo, 740Wh pack, with bleed-type BMS.
Controller: Infineon IRFB4110 40A controller.
Motor: 9C-Clone, 30mm stator.
Cables: Turnigy 8awg pure silicone 200c wires
Dashboard: Cycle Analyst v3

Auxiliary battery: 4S1P 5000mAh 20C Turnigy LiPo
Front lights: 27w multi-LED
Rear lights: 3w LED

 

[underdog]

Teaser-pic.

My wheel-guy had serious problems trying to tru the motor in the wheel. We found out that the width of the motor spoke-flanges was exacly the same at the width between the right and left holes in the 80mm rims. So they did not become very stable (side to side). I will have to find some wide rims with all holes in the center, so the spokes becomes more treangular for stability. Looking at Some 250 motorbike rims, but cant seem to figure out the best solution of spokes....

 

[underdog]

I know this shold not be in the bike-section. But its really not worthy of a new thread

Poor Man`s "Scrapheap" Electric Longboard

1x Old Landyathz deck
1x Old Bear truck
2x Old wheels and bearings
1x Old 9C front hub
1x Old "kiddycart"-tyre
1x Old steel front forks
1x Infineon IRFB4110 Controller
4x Turnigy 5000mAh 4S LiPo`s

 

[underdog]

Todays topic: Packbuilding

Finally the rest of LiPo`s showed up

Since this battery is getting a BMS and I want everything as tidy as possible, I chose to solder it all up and shrinkwrap the parallels to each other. Soldered the 2 12AWG cables from the packs together to a single 8AWG silicone/copper Turnigy cable. Never used any Turnigy products before this, but the quality looks really good for the price.

For some reason the charger got more and more inaccurate over time. After charging the 3 first packs, the charger began to over-shoot the target 4,2v on every cell. The first ones was perfect, but at the last packs it stoped at 4,23-4,25 on all the cells. Is this normal behavior for a low-cost charger?

 

[underdog]

Pack almost done...

75!! solderings on it so far on it. Just another 20 to go on the bms-wires. (Message to self: Soldering two 12 gauge wires in to one 8 gauge is PAIN). Screw-type Headways looks soooo good right now!

 

[fechter]

Nice looking builds :wink:

What kind of BMS is that?

 

[underdog]

Nice looking builds :wink:

What kind of BMS is that?

Thank you

Its a BesTech Power Model HCX-D131 for 74V 20S Li-polymer 80A working current. Not sure if I can recommend it yet though.. I have tested it with a 20s 5000mAh Li-Po pack before. But then it shut down under load (at about 25A). But I am guessing that was from a broken lipo-cell that kept bothering the balance. My guess is that that verry cell dropped to much when I got past 50% throttle. (...Or so I hope!)

 

[GiantEV]

For some reason the charger got more and more inaccurate over time. After charging the 3 first packs, the charger began to over-shoot the target 4,2v on every cell. The first ones was perfect, but at the last packs it stoped at 4,23-4,25 on all the cells. Is this normal behavior for a low-cost charger?

There are lots of clones of those chargers being sold. Have you checked if yours is genuine or not? If it's a clone then that could explain the inconsistencies you're seeing, which is common for many of the clones out there.

 

[underdog]

First testdrive today! This thing kicks ass It was raining, and brakes still needs a bleed and service, so could not test it full out, but I was surprised with how fast 84 volts @ only 40A accelerate. And the long and low frame geometry and massive tyres really gives much more grip than a normal ebike. Was cruising along doing about 40 kph, and the bike tried to slip out in front of me when giving more throttle...

*happy*

 

[underdog]

Transportation and e-bike meet at the park.

Mett another cool home-buiilt frame cruiser too..

 

[underdog]

Just testdrived a customerbike that is technicly almost finished. First time I have used the em3ev MAC. 24" in the front and 26" in the back. Used the upgraded MAC 12T configuration, 6 FET infineon and a 48V 20Ah LiMn pack. And I have to say, its one of the coolest bikes I have ridden in a looong time. Agile as a snake. Topspeed 38kph :lol: (sorry `bout the bad picture as always)

 

[underdog]

Since I tried the 12T MAC motor on the "post-service" bike, I have been looking into the posibility of running a higher voltage setup of this motor on my own bike. But I can find a couple of concerns by doing so, and not much documented tests from others...

I understand that hotrodding a geared motor puts lots of stress on components like gears, and not to mention heat buildup. By my experience amps is a lot more common killer than volts, when it comes to heat-damage. The upgraded em3ev version boosts a temp sensor, so I think this factor can be some what superviced, and controlled. Running a 48v (nom.) setup with this motor gives me a real life speed of about 38 kph. So a simplified calculation gives me a topspeed of about 58 kph using a 74v pack and controller. Does anybody have any experience with running these or similar motors at this speed?

The max freespinning rpm on 74 volts would be just above 400 rpm. Since it is a 12T motor, with such a slow wound, will this voltage put extra strain on the controller in terms of a much higher "phase-change-rate" than in a DD motor? Is the controller fast enough to handle this over time without damage?

I have to say this is tempting, having a spare motor, a Infineon 12 fet 4110 and a 74v lipo pack extra... But should I ??

 

[underdog]

I have not been to happy with the 74V lipo pack I built earlier in the respect of safety, and ease of mount and removal on my bike. So I have been trying to come up with an idea of how to make the pack more safe, and more servicable. Tape and shrinkwrap does not feel totaly flame-proof... This is just an idea that I came up with during insomnia... I have yet to find the right solution for fast and easy mount and de-mount on the bike, but i have some ideas. The idea is to let the pack hang over the main-tube over the triangle, with some smart fast fixtures... Any input with similar solutions would be greatly appreciated

 

[underdog]

I have neglected to update anything for a long time. Waited for something modified enough

Just completed building this badboy for a good friend of mine. Its a Gary Fisher Cake 1 frame, with BB7 200mm disks, manitou swinger in the back and 130mm Splice in the front. Running 24" 9C-clone motor, Infineon 12Fet 3077 @ 30A and a custom 51,8V 10Ah LiPo pack with a 40/12A BMS from em3ev. For stealth-reassons the pack is to be used in a backpack.

I left some room in terms of controller and battery capabilities, since I know he will be "begging for more" really soon. Then I can just hotrod the 9C with some vents and maybe upgraded phase-wires in to the stator, and run 40A. It does about 50kph+ at the moment, but acelerates like a champ

 

[underdog]

Happy to report that my long awaited new workshop is now opened. Some cool bikes are comming to life these days. Here is a couple of the works in progress...