48V 1000W DD Merax Electric Bike Project

Joined
Apr 10, 2017
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276
Location
Duluth, MN
I am now working on building a second electric bike. It will have any improvements over the original bike I built. It will have disc brakes vs rim brakes, front suspension vs none, mountain bike vs cruiser, 21 speed vs 7 speed, 48v 1000w vs 36v 500w
 
Optimized-WP_20170418_13_37_11_Pro.jpgHere is the motor kit. It also has some improvements other then being much more powerful, it has an lcd display that tells you your speed, battery life in many more increments then three, power to motor and total mileage.
 
$_3 (31).jpgAnother improvement is the battery. I got one I can put in the middle of the frame versus a rear rack mounted one. It is a 48v 15Ah battery. I am not going to be going very far and I might get a second battery.
 
untitled (2).pngI also got this DC-DC step down converter to plug in my headlight and phone. It steps down the 12v headlight connector to 5v and has a USB port. So I can plug in many different accessories.
 
***Update*** The rear derailer snapped after just a block and a half. I have ordered a new one to replace it. I also see another soon-too-fail component. The crankset arms are made of a type of plastic. I would order a new set immediately, but I don't have the extra money right now. The disc brakes are super nice though. Waaaaay better then the rim brakes I have on my other electric bike.
 
I took the advice on leaving the controller out in the air for better cooling. I managed to mount it rather easily to a rear rack I had laying around. Now all I have to do is mount the battery.
 
I also like how the bike frame had screw holes tapped into it just behind the seat. That.made mounting the rack easy. Also, I am still waiting for the headlight to be delivered. And rear view mirrors
 
As it turns out, the battery was a little bit too lengthy to fit in my bike. Not surprising really since the bike I have now was a last minute change of plans. So I took the battery itself out of the metal housing and found it will still fit, but I need something to secure it to the frame. So I ordered a triangle shaped battery bag. My bike is out of service for a while anyways due to the broken derailer. That should be here next week.
 
Optimized-WP_20170421_17_33_10_Pro.jpg
I am working on mounting the battery. Since the battery did not fit while in its shell, I carefully removed it and cut off the plugs and capped the wires from the BMS of the battery. I did not want $320 to go up in flames. I have ordered a triangle battery bag to put it in.
 
That looks like a tight fit for the battery. You may want to add some rubber padding of some sort to help with vibration while riding to avoid any wear on the battery or the triangle bag. Good luck with the rest of your build.
 
pwd said:
That looks like a tight fit for the battery. You may want to add some rubber padding of some sort to help with vibration while riding to avoid any wear on the battery or the triangle bag. Good luck with the rest of your build.
I will sure try it. I am open to whatever works.
 
Optimized-WP_20170422_12_37_41_Pro.jpg On the charger I had some trouble with the color coding on the wires, but thanks to google, I got it figured out. If only all wiring was Red and Black color coding.
 
The battery charger does not work sadly. I had to order a new one. It has a red/green status light and neither turned on when I plugged in the charger. The battery works great though.
 
I took the bike for a test drive and it is much faster then my last bike. I put close to 7 miles on it. I decided to call it quits because the battery is at 3/4 full, and I have no charger right now. I am waiting for the replacement to be delivered. Will take 3-4 days to ship and 15-45 business days to get to the USA from China. I wish the charger that came with the battery would have worked.
Code:
 
https://www.amazon.com/gp/aw/d/B01N5O18B1/ref=oh_aui_i_d_old_o0_img?ie=UTF8&psc=1

Here is a link to the Amazon listing of the bike I bought. Please note that you will want to replace the crappy plastic rear derailer and the plastic crankset.
 
Here is my slapped together mockup for my test runs. I am working on finding a more permanent way to mount the battery then having it wrapped in foam and duct tape then secured by zip ties.
 

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The top speed of my bike is 37.6 MPH without load. The highest I have gotten is 34 while riding on flat ground and 40 down hill. It is very fun. I love the look on the face of drivers when I am behind them on my way to work. :twisted:
 
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