New Bike Build Questions & Opinions (Hub Motor)

[Derekj118]

Hey guys, this is my first post

. I am starting a new build with a new 26' Black Magic Vector ( Magic Pie 5 ) kit from Luna paired with a 52v 13.5ah Shark Pack with Panasonic GA cells mounted on the frame. I will eventually be purchasing a 52v Mighty Mini Cube Pack with Panasonic PF cells ( 6ah for extended range mounted on a rack ).
My bike now is a 26' hardtail Northrock XC6 ( Cheapo Frame ) with front suspension and a suspension seatpost. The motor is a MP3 Vector with torque arm combined with a 48V 10AH LiFePO4 Aluminum Cased Battery from GoldenMotor.CA . The battery has definitely done its job and lasted me a while, however I am finally starting to see some power loss and less range. Plus I hate the weight and bulkiness of the battery. My first question is regarding the frame. The frame is aluminum and everything I have read, stresses the importance of steel for high powered motors. I know the MP5 isnt necessarily high powered compared to some other motors out there, but I will be maxed out on the settings for speed and %100 regen on the brakes. The torque arm I use now is a universal arm fitted directly to the frame without any brackets needed. I have also purchased a large ( okay freakin huge! ) Crystalyte torque arm that I can use if needed, or they could be used together. The bike rides incredibly well, even at full speeds. It is also rather comfortable because the front fork suspension is decent paired with a good seat and suspension seatpost. I wanted to know your opinions on whether I should pursue purchasing a new bike for the build, or replacing many of the components on the current bike? I have a very low budget for the frame/bike itself ($150-$200). I could buy a cheap new bike, a decent used bike, or replace the shifters, freewheel, chain, derailleurs, and cables in the current bike. Please let me know in your opinion what you think is the best direction to take. Steel frame, aluminum, front suspension or full suspension, etc.. All thoughts and ideas are welcomed. Thanks for the help guys and let me know if anyone has additional questions! I posted up some pics of my current bike with the old motor and battery to give a better reference to evaluate.

 

[George S.]

I have an MP5 from Luna that I put on a Trek 820. The Trek was new, under $400, steel frame. The front susp fork helps quite a bit, more that I expected. That's all I use, not seat susp. I have a Grin rear torque arm which I think is good with the steel frame. Anything over 500 watts is 'high power', not what the bike was built for.

Only thing I will point out. I started with LiPo batteries in a handlebar bag. No BMS with these batteries at all. I got massive regenerative braking, almost too much. When I went with the Luna Mini Pack, the 30Q's, the regen stopped. I figured it was the BMS in the pack clamping something. I never pursued it because my riding is pretty low stress and the brakes are OK. I don't go very fast. Something you might ask about.

I worry about brakes, not the other stuff. I like a decent front suspension fork, good grips, and a comfort bar, which aren't much money. For high speeds, good hydraulic disks are the way to go, along with good tires. Maybe you can set up the regen to work, which makes a difference. I assume GM Canada configures their packs for regen.

 

[Derekj118]

I have read mixed information regarding the regenerative braking capabilities of the luna packs and/or the internal BMS. I have seen a few people claim to have some sucess with the regen, while many have also claimed that they lost regen braking completely when they switched batteries. Do you have any accurate information regarding as to the reasons for this? I would like to know because it will moderately effect my range. Also, even if the regenerative braking does not function, or works inefficiently, does that mean that I will lose motor braking function? My current setup now is a ratio of about 90% motor braking and %10 disc brakes so this is a very important detail.

 

[George S.]

I got regen with a set of LiPos and a Chinese Lifepo. I lost it with the 30q mini and the Luna 48V Shark (NCRB version). So neither Luna pack I have gives regen. Luna uses a lot of different BMS boards, so some might work. You'd have to find a pack/BMS that does work. An email to Luna would be a place to start.

 

[Derekj118]

Thanks George. I just reached out to Gary at Luna, so hopefully he will have some info or suggestions about the BMS and pack. I went with a 52v Shark (GA version); so in your opinion it is the BMS that restricts or stops the regen and not the cell type or chemistry?

 

[George S.]

The BMS is configured for the cells. Full regen is a stress. I'm not sure how it should be set up to prevent hurting the cells. I don't know if they need a specific pack/BMS for the MP5 or not. There are a couple of people on the GM Canada forum who know quite a bit about the regen, but that's it. Unfortunately, some of the Magic Pie features just don't get fully implemented. I tweaked the settings in the Bluetooth app to see if I could get the regen to work, but nothing happened. See what they say.