Mongoose CX 450 Builds

[EvoBikeShop]

Honestly if your not less then 170lbs, i wouldnt suggest running the 13t cause the motor kinda strains with no pedaling. Hmm not sure what would be the best way to add a second motor. Why not just add a 250w geared hub (328rpm) in the front?


EBS

Yeah, I am 200 lbs, hoping to get to 185 soon, but still... LOL. When planning for more speed and durability, I was just thinking of adding the second brushed motor (and controller) just for the cool factor Ths visual impact and twin gear whines would be pretty cool. If I was adding a hub motor I would just add a big one and ditch the little brushed motor.

Fair enough. Hmm you could easily do dual currie's on 13t. Maybe you could mount another motor under the factory one. Use 24in rims for hight.


EBS

 

[EvoBikeShop]

Ok, so the most my pack is going to give me is 41v

 

[EvoBikeShop]

Top speed is 30.93 at 41v. Now to put it back to 24v (28v hot off charger) for now. I figure the best setup would be 10s and 20ah (to get some distance), 24in rims, 9t motor sprocket and 16t freewheel. Its a whole lot of fun at 30mph, especially seeing the faces of other people on the road.


EBS

 

[EvoBikeShop]

Too bad I'm going to be consentrating on my carbon bamboo bike.


EBS

 

[e-biker]

your build looks so fun I had to get my old currie 450 out an install it on a cheap wally world mongoose frame with a 2007 ezip controller 10 ah of 12 lipo. It is not something I am gonna commute on but it is fun to ride around the neighborhood with my 10 year old daughter and her friends, the other day while riding with her one of her friends wanted to ride mine so I let take it for a spin it was fun to see the grin on his face he is now addicted to the grin .

 

[EvoBikeShop]

It really is a blast to ride. May end up keeping it and modding it out some more. I would really like to upgrade to 24''ers and run it on 36v but regear it to top out at about 25mph so I dont strain the motor too much. Ive been practicing wheeling it and I'm getting better. Not sure what I'm going to do.


EBS

 

[maurtis]

I did a dual motored experiment with my CX, ended up going back to single motor for reliability and simplicity's sake. And the dual motors sucked down power quickly, even while just using a single controller. I gave up on the project before going to a second controller

BTW, EBS, I ordered my new MY1018Z from monsterscooterparts and when run in single motor (stock) form, it was 4 MPH slower than my stock motor! I verified this with my GPS, 24 MPH with the new motor. Swapped my old motor back in, 28 MPH. I may have been shipped a dud, just an FYI. I opened it up to verify it was a straight cut geared MY1018 and not a helical cut XYD in disguise, and it was straight cut just like the stock motor.

The short version of the build, ordered an eZip/iZip mounting plate for the rear axle and a new MY1018. Due to the mounting position of the rear motor, the top chain run had to be lowered or it would not clear the rear brakes. I could not find a suitable chain roller so I make one out of two radius bearings mounted together. Were I to do it again, I would have either used a turned down skateboard wheel, or a motorcycle chain roller...

The first chain roller I made was out of aluminum bar stock, since that is what I had on hand and it was too late to go to the hardware store. It was a miserable failure, LOL.

After about 10 seconds in the backyard:

The next one was made out of 3/16" steel and the top mounted to my rear 3/8" footpeg bolt and the bottom clamped to the swingarm, nice and solid:

Just for the test run I was running the stock controller with the output paralleled to the motors. The plan was to get the kinks worked out then go to two controllers. This was before I knew the new motor was slower than the old one.

Acceleration from 0-5 MPH felt stronger, mid range acceleration felt about the same, and the top end was 2 MPH slower, now I know why. On the top end I only had one motor pulling and it was fighting extra drag in the system. For the first half of the ride the motors did feel cooler than the single stock motor would, but on the way back they felt considerably warmer. It turns out the bearing that I used for the chain roller failed, so the last half of the trip the motors were dragging the chain over it... oops.

So for now I am sticking with the stock setup with one motor, and keeping the new motor shelved for either another project or when this one smokes. After I do a faster hub build, I will probably revisit modifying this bike into a light duty offroader. But for now, I will keep her as reliably as possible at 36V to be my daily neighborhood runabout

 

[EvoBikeShop]

Sorry to hear that it didnt work, maybe with a better motor would. Did you check the grease on the new motor? It might be too old and its holding the motor back.


EBS

 

[dustyearlobe]

did you check the amps draw ? if your controller will only supply say 15amps to one motor it will stillonly supply 15amps to two and I suspect the lead motor would pull most of that at full load leaving not a lot for the drag motor

 

[DrkAngel]

Just noticed this thread ... sorry.

A few tips:
Polarized film helps make voltage LEDs readable in daylight.

Heat is the enemy!
Damaging motor heat is much more a result of heavy throttle at the lower, more inefficient, rpms.
Full throttle cruising at 30 mph might produce 1/4 the damaging heat as 15mph up a slight hill.
From a dead stop, an eZip, MY1018Z @ 36v, motor might produce, (37V x 35A = 1295w), ~1295w of damaging heat.
At a dead stop, initial efficiency is 0%.
Efficiency does increase, hitting 50%, (at 40% of no load speed), near 15mph, or 650w of power and 650w of damaging heat.
At near 80% of no load speed (top speed?) efficiency increases to ~75% and amps decrease to ~15-20A.
(37V x 15A = 555w) x.75 = 415w of power + 140w of damaging heat or ...
(37V x 20A = 740w) x.75 = 555w of power + 185w of damaging heat.
Reasonable throttle and pedal assist, especially from a dead stop, can substantially moderate damaging heat production.
I've run an eZip at 37V for 5 years and ~4000 miles, but due to awareness and moderated throttle usage ... with no over heat failures (37V 20.6Ah recycled laptop LiCo in eZip oem pack) See - Homemade Battery Packs

Efficiency range shifts with partial throttle usage!
75% efficiency attainable at any speed, with restricted throttle!
I recommend pedal assist with a gradual throttle increase until cruising speed attained.

And am tempted and confident in attempting a 44.4V MAGNUM battery pack.

Begin coasting well before you want to stop!
A well tuned bike will maintain good speed for a considerable distance!
(Low roll friction tires
good pressure
wheels "trued"
brakes adjusted
etc.)

Various eZip re-gearing methods - consolidated.

Various re-Volting mods.

 

[EvoBikeShop]

Hey drkangel,

Thanks for your input, it is a greatly appriciated addition to this thread.

I myself always pedal until I reach the speed where pedaling becomes pointless. I also try to coast as much as possible.
Again thanks for the info.


EBS

 

[maurtis]

Thanks for the tip on the polarized film for viewing the LEDs, I will have to give that a try... and thanks for the heat info. I do try to pedal from stops, but find myself getting lazier and lazier, lol.

As far as the new motor goes, I did pop it open before I even ran it to make sure it had straight cut gears and noticed the grease inside was a decent amount and still fresh, so I did not touch it.

When I try the dual motor setup again later, I will be sure to have watt meters on each motor.

 

[DrkAngel]

Thanks for the tip on the polarized film for viewing the LEDs, I will have to give that a try... and thanks for the heat info. I do try to pedal from stops, but find myself getting lazier and lazier, lol.

As far as the new motor goes, I did pop it open before I even ran it to make sure it had straight cut gears and noticed the grease inside was a decent amount and still fresh, so I did not touch it.

When I try the dual motor setup again later, I will be sure to have watt meters on each motor.

I believe you original motor should be a 24V 450w MY1018z.
Make sure you did not get a 36v 450w or a 24v 250w.
Either might display the problems you noticed.

24V 450w motor running at 36v = 675w output
36V 450w motor running at 36v = 450w output
24V 250w motor running at 36v = 375w output

 

[EvoBikeShop]

Wow 1350w combined would make the cx fly.


EBS

 

[maurtis]

I have been thinking about installing headlights for a while now, not for night time visibility but just to be a little more conspicuous during the day, a little something extra to help others on the road know that this is not a regular bike and to pay attention.

We had a set of cheapo chinese LED running lights that we were planning to install on my son's go-kart and never got around to, so I repurposed them They are not very bright, but better than nothing. They actually light up the road pretty well at night if I ever get caught out after dark, but since the light is unfocused it is not all that kind to other people on the road.

The original plan was to get a small 12V SLA to run them, but I realized I had two 7.2V nicads from another project lying around! Since I was afraid the extra voltage might fry the cheap LEDs (15.8v hot), I picked up two 12V 1A voltage regulators from Radio Shack and wired them in between the rocker switch and the lights.

The batteries are mounted with body molding tape, one on each side of the frame:

And also secured with zip ties:

I also found a nice little handlebar bag for my phone from Target, it allows you to use the touchscreen through the plastic, so works well for using my phone as a speedo/odo:

AND... FINALLY... I hit 30!!! Hot off the charger, full tuck, cool day, nice long straight, w00t! I actually hit 31 on a downhill straight section of road, but the 30 was on a flat.

With this setup, 27 - 28 MPH comes pretty easily but anything over that you have to fight for, LOL. I think at 10s I would hit 30 without eating the bars.

 

[EvoBikeShop]

Looks cool and congrats on hitting 30! On another note I sold my cx and carbon electric bike, as I am moving back out west. But when i get settled in and have the cash, i will start building a 2wd high speed lightweight carbon fs bike. I look forward to seeing more updates of your bike maurtis. Ebiking is too addicting for me not to build another. I will be starting a new thread when I start the new build.


EBS

 

[maurtis]

Good luck on the move, EBS! I look forward to your next build, sounds like you have some big plans for it.

 

[EvoBikeShop]

Thank you maurtis. And yes i do!

 

[Idontwanttopedal]

Look farward to seeing your next build

 

[EvoBikeShop]

Thanks man. I am missing my mongoose already lol!

 

[Mongoosed]

Hi new to E-bikes and just bought a CX for $40. It was in pretty decent shape but batteries were toast. I had some 12V batteries from a UPS so I wired them up and it works. Now originally I bought this just to go camping but being the speed freak I need to go faster!! I'm guessing with some pedaling I get up to 12MPH and would like to be in the 20MPH range without compromising acceleration. Saying that and not looking to spend a bunch of money, is this even possible? Anyone have some quick easy tips to achieve this? Again I am a noob at this and barely understand the operation of the controller, throttle, 24V Vs 36V. Am I better off ditching this bike and looking elsewhere? My only experience with electric vehicles is throwing a 18V lithium drill battery in my kids 12V power wheels. Man did that thing fly!! Did about 8MPH with much better acceleration. Surprisingly enough rode for around 15 minutes with no noticeable damage to the motors but I'm sure they were a bit warm. Had to switch back to the 12V as mom was not too pleased to see her son peeling out and taking off like a rocket. Thanks in advance for any help in my quest.

 

[maurtis]

Welcome Goose! Most 12V Power Wheels handle 18V no problem. We had my son's PW Escalade at 18V for about a year before we gave it to a friend of ours. My wife would even ride in it with my son. They have had it for about a year with almost daily use and still going strong. I did have 2 computer fans wired in, though, one for each motor. Probably not necessary, but just playing it safe. I had plans on eventually going with faster wind motors and 24V with a scooter controller and hall effect throttle pedal, but my son outgrew it and moved on to en electric motorcycle and go-kart. The PW was so much fun to work on, too!

If you want to get the CX to 20 MPH easily, you can either go to 36V or stick with 24V and swap out the rear freewheel from the stock 20T to a smaller 16T. Either should get you to about 20 MPH. Going to 36V you keep the same acceleration, which is good. Sticking with 24V and going with the smaller sprocket you gain top speed but lose acceleration.

 

[maurtis]

Added barend mirrors today. I used the same Third Eye barend mirrors that I used on my old motorcycle, cheapish at $10 each at Amazon and a snap to install: http://www.amazon.com/Third-Eye-Bar-Bicycle-Mirror/dp/B001600YZ4

 

[wingtip]

Hey guys I thought I would throw this first build up here and sort of introduce myself. I've been lurking for a long time and have been riding electric bikes for a lot longer. So far always factory built and including: an early currie freedom with the brushless USPD style drive and powered by lead from around 1999, actually a great ebike, much better than the low end stuff Currie makes now. Two LiMn powered "thompson" branded electric bikes from china from around 2005, both victims of their low end BMS aka "battery murdering systems" and general low quality components. A currie Via Lento RMB hub powered lead pig that needs a new battery from 2007 and finally an A2B hybrid that is currently getting well used.

Clearly I've been bitten by the electric bug and have started various builds including some small scooters that I've completed but this is my first bike build using one of the mongoose BSO toys that seem to pop up on Craigslist now and then that can be bought for $20 as a starting point.


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Procedure so far as follows:

Bike stripped,
lubed pivots,
rebuilt headset,
rebuilt bottom bracket,
new old used 52t crankset from the bike graveyard (aka backyard),
rear motor side freewheel replaced with old used 99t currie sprocket from my pile of old currie scooters,
front fork replaced with slightly less junky "mozo" department store fork (in need of another if this thing is ever to handle good),
craptastic shock replaced equally crapalicous shock just slightly longer to compensate for longer fork
motor replaced with currie style brushed motor in home-made mount 11t pinion (surplus currie motor purchased from All-Electronics and labeled as 450watt),
frame trimmed and seat tube welded to original flat steel seat supports,
new old seatpost, seat bars and stem from the graveyard.


I was kinda going for this urban hooligan type of thing with this, something that was kinda slow and that I would feel comfortable hopping curbs on and such. I've only pedaled it so far and I actually kinda like the way it rides unpowered. Now I need to figure out some batteries. Unfortunately I have a bunch of good lead lying around so I'm more than likely gonna start with that for now.

 

[wingtip]

I mounted some lead on the ghetto goose and got it going. Of course it's a complete dog but is perfectly rideable as is. It tops out at about 17 or so mph but it sure takes its time getting there with me on board. The gearing feels about right but its no hill climber, that's for sure. I spin out at top speed on level ground with the motor assisting so the single speed pedal gearing is about right. (Chalo would be pleased, I can actually contribute to the motion of this electric BSO.)
I still motor past pretty much every other cyclist I encounter (unless of course we are on a downhill...). Overall the thing is pretty fun to putter around on. So far I've put about 40 miles on it
As you can see from the side view, the seat post angle is not right. I'm gonna give it a bit more angle and use a shorter, bmx style stem and bars. I tried to emulate the seating position of some of my bikes but theres too much weight over the front end. It also needs new tires, these suck. If i can make it handle a bit better, which i think is definitely doable, it could definitely use some more power. for now I'm gonna stick with the lead in all of its saggy 24 volt glory, it works and was almost free, and I have about a dozen or so working 24v SLA chargers... On the other hand the motor has got to go. I'm gonna keep my eyes open for a trashed ezip 750 or 900 scooter on Craigslist for cheap and snag the motor off that, all in keeping with my lowbrow, ghetto build theme. So far all in I've probably got something like $50 into it.

No idea how much energy its consuming, all I have is a kill-a-watt meter and some DMMs.

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