You are knowledgeable Bengy and the kind of input this forum needs to raise the bar of tech available for custom ebike builds. Thanks for sharing your perspective. You know more about battery design options surrounding that carbon frame with integrated battery than I. I have seen a few stock builds of this frameset like Rob's that are running 840wh of unknown Li-Ion cell quality which to me is too small a battery to power the M620 Bafang motor.
If one can reliably package a 14s 21700 4p, a reliable 1000whr battery can be created as you correctly state which puts one in the game with the M620. I run this exact size battery with a BBSHD and it is a very good combination to run a lot of power through the motor for a sustained period to have some fun out for romp or go 50 miles if riding conservatively on a full charge. More battery capacity for a 1500-2K watt mid drive motor is better of course.
Can you provide the links to the battery options you speak of for this frame? I am curious what kind of 3D printed enclosure fits into that downtube?...and what the best path may be for that particular frame to fit a battery...or... perhaps run a parallel piggyback battery on top of the downtube in tandem for dual batteries you mention. Weight in my view should always be at the forefront for a build such as this because you want some level of agility for a bike of this ilk. So maybe a battery in aggregate of 1200-1300wh range would be the sweet spot.
Andy is an interesting man. A creative genius of sorts who seems to get embroiled in controversy because of the risk he takes. He probably would do better in America where men of his nature are allowed more free reign to create and invent with less restriction. Andy has also gone through a lot of personal issues...too many problems to site. I love his genius and his nature. If I knew him, I am sure we would be very good friends because I understand him on some level.
I hope you share your build Bengy with the forum here. Would love to see what direction you take it in the context of the battery in particular which is the heart or lungs of any custom build.
Thanks again for setting the record straight about the options for that frame. I stand corrected on the options available I was unaware of.
PS. I somewhat lean more in the following direction which is similar to what Andy built. But that said, again as you know it comes down to horses for courses. With a high volume tire, I am fine with a hardtail with is lower cost, lower weight and less complexity and maintenance. Because I live in a concrete jungle and my off-roading days are largely behind me, a hardtail for me just makes sense. I like the overall feel of a hardtail...with a bit of trail and wheelbase to really smooth out undulating stretches at higher speed. As to the carbon bike discussed with integrated battery, I don't like to toil with the demanding nature of fitting cells inside of a downtube for somebody's sense of a correct aesthetic. The following looks fine. But in sum for me, this is ultimately why I always default back to a solid production late model mtb frame...a 29'er has very good compliancy...with a BBSHD which is pretty plug and play. Further I am ambivalent about torque sensing because of calibration issues and cadence sensing tends to be a bit more reliable and get what you get when you have the ability to program assist which is a great feature of BBSxx motors as you know. To me, ultimately battery size rules the day when you have enough motor to travel the speed you like. An undersized battery on a M620 isn't something I want to invest my money in. I would ride an XL frame on the following bike and maybe able to squeeze a 20amp-hr shark battery comprised of 14s 21700 4p on this frame which would be a fun combination I believe...but again, really don't need a dually:
Thanks for the kind words
. I actually have a 45a bbshd hardtail right now as my current ebike, with a 52v 832wh battery myself
so I know the want for more range or battery capacity. I will have to find the post talking about the 14s4p case, I know it was a user (or two different users) that had posted about them and I'm 99% sure one mentioned that they would give out the files for others to use. It was either on the emtb forums or one of the m620 motor groups on facebook.
I think the best route would be this 3d printed case, I believe you have to remove the original case mounts to make enough space but you don't have to do any permanent modifications to the frame. I will also link a users post about doing some mods to the frame to fit 14s5p (but in a e23, same frame but larger swingarm for fat tires). The information on the 14s8p 18650 1400wh battery is lacking, the user posted two photos and didn't really describe anything about it other than the cells, amount, and that it was in two pieces to make inserting into the frame possible. I actually talked to his friend? on fb where it was said that he had to "modify the inside of the frame a lot" and that it wasn't recommended. That's the annoying part of the frame, not a lot of information available online to the overall dimensions so hard to know for sure what can be done battery wise unless you have one on hand. I agree weight should always be a high concern with a bike like this, but personally I don't mind sacrificing weight for capability, or at least I don't for my area which is flat so the extra weight isn't really felt. I will put some links at the bottom you should checkout. I also highly recommend checking out the m620 motor groups on fb if you can, lots of good people and information on not just the motor but bikes it goes on. I've seen the frame you link on their as well.
I agree, Andy's content has basically been awesome in the diy ebike scene. I hope he can sort out any more personal issues and hopefully bring out more ebike content, but I know he's somewhat shifting to other hobby's as well.
I would love to but unfortunately I don't believe I will end up doing a build, at least with the m620 motor. It's not that I want to, oh the contrary. I really could see myself pushing what is known on the dengfu frame with the dual battery which I would 100% do if I did a m620 build. (side note, while I do think the seroxat frame Andy uses is better for the diy battery, I really want the clean offroad beast that looks like a off the shelf build not diy that the e22 offers). Something about the e22 really calls to me unlike the other frames. I also wanted to push the bounds of what is known for the m620 more power wise. As you know Andy did do 72v, but before he detuned the power due to overcurrent errors (due to running sensorless) he was "only" doing 96pa and 60ba. Due to the somewhat new information that is very unknown to most of how to get hall outputs from the magnet sensor using the stock controller board not a lot of people have even tried aftermarket controllers for the m620 and I couldn't find anyone showing off using this method, only a short video showing how. I was planning on using a flipsky 75100 to do 120pa and 60ba, a little more than Andy (he later lower pa to 80 due to the errors) but then the 75200 was rumored and later released. That small vesc can do 150a constant at 72v or peaks into the 200-300a range. So the ultimate goal shifted to 200pa (bbshd ludi v2 does 150pa so I don't have any real concerns the motor can't take the power) and 70ba or somewhere around those numbers. This as far as I know would be the most powerful m620 build online, as again the phaserunner is the only external controller I've ever seen used with the m620, and again its 96a max. So very exciting stuff with that much power and going into the unknown for these motors.
So then you might ask why am I not going to go through with the build, well it's very simple, Money. A build like this even after sourcing used suspension and wheel set is going to cost me at least $4000 likely more as I'm sure I forgot stuff in my google sheets list. Now for what I would be getting its not completely unreasonable but for me personally I can't justify that. I'm looking at getting another motorcycle after selling mine a year ago and that's very close to what I could be spending. And I'm in talks with a user on purchasing a hub motor and controller for a very good price. Even after all the parts I will need and doing it on a hardtail I'm going to be under $1500, which although isn't full suspension will be more powerful and better suited for my 85% concrete riding and 15% offroad green trails with no inclines. Not to mention the extra hassle that is getting the m620 on a external controller, making a highly custom battery for the frame, figuring out how to mount the controller externally etc. And I have concerns on heat cause in Texas my 52v 45a bbshd does get quite warm already. If I didn't already have a bbshd bike, the hookup on this hub motor set, or high expectations of power / battery capacity I 100% would be looking at spending the extra to do the m620 with motor frame, so much cleaner, capable and not much more (my bbshd ht was $2500ish, a m620 e22 stock would be around $3000 with similar specs). So that's why I always try to mention it to users that are considering build a ebike.
If are aren't super interested in the full suspension I know they make frames for the m620 without it, that way you don't need to spend or have the extra hassle of it. I do want to mention that although Andy's frame is marketed or named with 27.5in it does fit 29in tires, I've seen it done before in the fb groups, I'm also a fan of 29in so that's what I would use as well. As for torque sensing I haven't had the pleasure to use it before so I wasn't to sure about the reliability. I do know that if you make sure to get a uart m620 you can still mess with the ability to program the assist and stuff, although bafang is fazing out the uart motors you can still find them. I think you probably will be able to fit 20ah in that frame, I actually have seen a post with that frame claiming larger ah, but not with a hard case though like the sharks.
Dengfu e22 emtbforums battery thread list links: https://www.emtbforums.com/community/threads/dengfu-e22-battery-thread.29926/
3d printed cell case(user talked more about it previously but this post best shows it off): https://www.emtbforums.com/community/threads/dengfu-e22-frame-thread.26880/post-422106
I also highly recommended going through that whole thread if you want to learn more about the Dengfu frame.
Endless-sphere user Daxxie e23 build with 14s5p 21700: https://endless-sphere.com/forums/viewtopic.php?t=113569
Post about that frame you linked where user Greeno talks about his two batterys one 24ah and one 34ah at the bottom: https://endless-sphere.com/forums/viewtopic.php?t=113569
Endless-sphere user Tomblarom shows off a picture of Andy's frame with a large custom batter, I've seen it before on fb and iirc a company custom made the case and it was 52v 28ah? Can't find any more info on it: https://endless-sphere.com/forums/viewtopic.php?p=1650325
14s8p 18650 build in the e22:https://www.emtbforums.com/community/threads/dengfu-e22-frame-thread.26880/page-6#post-394932
Dual battery cad design for the e22: https://electricbikereview.com/forums/threads/hydra-batterie-question.46676/page-4