temon10
Well-known member
This frame is for m510 not M820. I have this frame
Bafang m820
- Thread starter Vsoria
- Start date
TCFlowClyde
Active member
CEF50 720 Wh in-house battery. Uses the more efficient/higher capacity 21700 cells to save weight over the old school 18650 cells.
Weight sliming mid-powered under 42 lbs?
-M820 approx 1 pound off bigger M600 cousin using magnesium.
-Approx 1/2 lb off from 21700 cell battery.
-Approx 3-4 lbs reducing battery
cradle/hardware/no key lock and reduced carbon layup needed to support battery cutout.
-Frame Total = -5.5-6.5 lbs shaved off?
I guess the lighter componentry and carbon wheelset reduces it another 1-2 lbs.
-Frame w/componentry = 6.5-8.5 lbs shedded off.
Weight sliming mid-powered under 42 lbs?
-M820 approx 1 pound off bigger M600 cousin using magnesium.
-Approx 1/2 lb off from 21700 cell battery.
-Approx 3-4 lbs reducing battery
cradle/hardware/no key lock and reduced carbon layup needed to support battery cutout.
-Frame Total = -5.5-6.5 lbs shaved off?
I guess the lighter componentry and carbon wheelset reduces it another 1-2 lbs.
-Frame w/componentry = 6.5-8.5 lbs shedded off.
thaeber
Well-known member
720 Wh battery means 10S4P = 40 pcs. 3,6V 5000 mAh 21700 cells, 70g each = 2.800 g for the cells only. Plus wiring / BMS / housing assumption is appr. 3,2 - 3,3 kg for the battery. The M820 motor is quoted 2,3kg, the M510 is 2,9kg, the M600 is 3,9kg. So You save roughly a kilo on the battery vs. the 840 Wh Dengfu battery, and 1,6 kg on the motor. Appr. 1,9 kg on the frame (if the weight is correct at 2,4 kg vs. my E10 frame in size L at 4,3 kg), summing up to 4,5 kg over the Dengfu E10 with M600 and 3,5 kg with M510.
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TCFlowClyde
Active member
Perfect! Great summation and weight breakdown. So, for me on 51ish lb M600 LC004 rig, I'll save 9-10 lb legitimately for the new frame! Sweet agility here I come!
BTW the US really needs to go full metric!
Now here's to hoping that somehow Bafang reversed engineered the Shimano EP8 RS to be even quieter and with less freespin resistance when 820 motor is turned off!
The 600 drags heavily in freespin and creates that "Am I towing an anchor behind me?" range-anxiety feeling. As most know, this is the Achilles Heal of most of the full-powered motors in general, but a nice feature of the lighter-powered ones.I assume that these are probables given the early reviews of the Forestal Siryon EonDrive (aka Posh M820 or Beastie EonDrive?
). Forestal claims 50 dB at 60Nm and frictionless, "drag-free" drivetrain (confirmed by a recent WorldWideCyclery.com reviewer who test road it for 3 months)."Shhhhh"
Forestal Siryon Review - The Best Blend Of Weight, Power & Fun [Video]
Forestal E Bikes Bikes are coming in hot and are looking good!. With the Siryon and Cyon, Forestal is crushing it when it comes to performance from a lightweight motor and battery system. With their own proprietary EonDrive Motor and Aurora Battery, they have been able to pack in 60 nm of torque...
www.worldwidecyclery.com
Thanks.
thaeber
Well-known member
When I was looking for a frame for the v810, I communicated with Jean at this link. There was no new frame on Ali baba before, so I wrote Jin. Jean told me everything and showed me. I liked talking to her. You can use this link to write to JinThis frame is for m510 not M820. I have this frame
You forgot to add 1 kg to the weight of the battery. This is the housing and fasteners. This battery is 3.8 kg. Dengfu 4.2.
thaeber
Well-known member
I added 0,5 kg for the wiring, BMS, housing. No fastener for my understanding, because the battery is „not removable“. Just my guess, I think 1 kg is way too much.
Waynemarlow
E*POWAH Master
Note the weight of this 21700 800Wh battery. Sorry but the 18650 batteries still have the best density and power to weight ratio, the 21700 series have a larger radius and thus leave greater gaps between the cells.
thaeber
Well-known member
Hmmm…the 21700 cells are slightly better at 71 mAh/g then the 18650 at 70 mAh/g. Almost no difference. The 18650 are still a very good choice, robust, technically mature, cheap, available. Depending on the room/volume available and the battery configuration You need it could be the best option.
Looking at the Dengfu 840 Wh battery using 13S5P configuration 18650 cells, and a weight of 4 kg, this is a great powerpack.
I recently saw the specs of a LG 21700 cell with 5800 mAh. If this is correct, and the C-rating is matching Ebike requirements, this would definitely change the game.
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thaeber
Well-known member
This one:
TCFlowClyde
Active member
I'm a total noob here on battery builds. But planning on building a 970Wh 21700 cell soft pack for my LCES004 like a few other 04 owners.
My basic understanding is that the 21700 cells generally have up 15-25% energy density efficiency increase over the 18650 cells depending on the available space of the frame downtube?
As the cost the 21700 cells decrease and their availability increase...typically a better choice for more juice at lighter weight for many slimmer E-mtb downtubes designs?
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Waynemarlow
E*POWAH Master
That’s a pretty impressive cell, easily handle our current at 3P and if run at 52volts will give a pretty good 900Wh’s for just over a 3kg battery.
I wonder how long it will be till the diy guys like us can actually buy them though
thaeber
Well-known member
The advantage of the common 21700 / 5000 mA vs the 18650 / 3500 mA is minimal from the energy density point of view: 255 Wh/kg vs 253 Wh/kg. This is almost nothing. Therefore, to use one ore the other cell format, is more driven by space and required battery configuration, imho..
thaeber
Well-known member
To make it more clear: The 18650 cell weight is ~50g, the 21700 is ~70g.
TCFlowClyde
Active member
In a nutshell: all variables constant....for the same sized box, 21700s will yield fewer cells and greater capacity than 18650s, therefore greater Wh, and probably a lighter battery?
Crude break-down: More bang for the money, in a lighter package (slimmer frame and smaller Nm motor), hence why the mid-powered E-mtbs can shave off lbs/kgs, even with a big 720Wh battery
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thaeber
Well-known member
Not necessarily - depending on the box format it can be more efficient to use the 18650 cells.
TCFlowClyde
Active member
thaeber
Well-known member
Exactly. With today’s available 21700 cells there is almost no advantage above the today’s 18650 cell (the video shows 257 Wh/kg vs 252 Wh/kg). The future cell they state 302 Wh/kg. Thats a big improvement, but not for today, unfortunately.
thaeber
Well-known member
This announcment is more then 1 year old, and the cells are still not available yet:
batteriesnews.com
Gotion High-Tech Announces a Nickel-Rich Li-Ion Battery Cell With 302 Wh/kg - Batteries News
Gotion High-Tech announces a nickel-rich li-ion battery cell with 302 Wh/kg. Guoxuan High-Tech usually gets headlines thanks to its
batteriesnews.com
Waynemarlow
E*POWAH Master
Isn’t this discussion of wanting a big battery sort of defeating the whole reason for a lightweight lower powered bike ? Batteries are heavy, more so than any other part of the bike and to fit a larger battery you will need larger down tubes and larger components, meaning more weight.......even with a big 720Wh battery
Far better to aim for about a 450Wh 2P battery which should fulfil most people’s 2 -3 hours of riding and add a water bottle type add on for those wanting longer rides. My EZesty FAZUA seems to suit this quite nicely and I simply carry a spare battery on any longer rides. My only grumble is that I never use fully both batteries and if I could fit 1/2 a battery as a water bottle, then that’s the next level up of convenience.
downunderdallas
Member
Yes the new ride 60 with a 210Wh range extender to give 640Wh overall would be ideal. A lot of rides I could get away with 430Wh and 90+% 640Wh would suffice. I guess if you really wanted ultimate flexibility you could get a second 430Wh.
thaeber
Well-known member
Totally agree. We‘ve somehow lost track on the thread purpose, the M820. My bad. For me, I‘m thinking about getting this CEF50 frame with the 740 (720?) Wh battery, targeting +-20 kg for the complete bike. Expecting to be able to keep up with any full fat ebike, speed and range. But a more playful bike, like the best compromise out of both worlds. I‘m only struggling with the missing option to remove/change the battery. Today, for the epic full day rides with my buddies, we all have a 2nd battery with us or in the car. At least a range extender option would be great in my opinion.
TCFlowClyde
Active member
In a nutshell: all variables constant....for the same sized box, 21700s will yield fewer cells and greater capacity than 18650s, therefore greater Wh, and probably a lighter battery?
Crude break-down: More bang for the money, in a lighter package (slimmer frame and smaller Nm motor), hence why the mid-powered E-mtbs can shave off lbs/kgs, even with a big 720Wh battery
Sorry, it's not how I interpret it.
TCFlowClyde
Active member
If I was using the Fazua60 system. I would want the forthcoming Transiton Relay with the trailside removable battery and backpack a spare.
I'm a heavier rider. Sure it's another 1.5-2 lbs. But worth it for my riding needs.
TCFlowClyde
Active member
The motor-drop removable (for frame integrated) 720Wh battery is the only reason I was willing to try the M820 on the CEF50. Bottom-line, I'm a heavier rider that consumes battery.
The 820 is also coming in with a higher 75 Nm (95 Nm peak with super-turbo mode, I don't know peak Ws yet) tune if Bafang is accurate in their description. So, given that the 820 is likely going to eat more battery that can't be easily removed, I thought 720Wh was a decent option. Plus, it's cheaper than the Siryon w/EonDrive referenced next.
In contrast, the Forestal EonDrive, a 60Nm tune (aka Posh820), and has the integrated, the motor-drop battery (aurora 360 Wh), will have the range extender. I would prefer a trail-side swapable battery. I would backpack it like the Transition Relay's removable battery...being a heavyweight rider.
Sure the CEF50 720 battery (versus the 410 Wh version) 1.5x bumps the Wh capacity, and adds another pound + or so overall. I'm gambling I'll need it for 75Nm torque increase and my heavy load. Especially, since the CEF50 manufacturer isn't really thinking about developing a range extender as an option when I inquired last.
Again, just fits my needs for 40lb+, mid-powered plus (75Nm) rig with an integrated, bigger 720Wh juice-box, and with no ranger extender options for the smaller 410 Wh iteration. My logic, for my needs. Your's may differ!
The 820 is also coming in with a higher 75 Nm (95 Nm peak with super-turbo mode, I don't know peak Ws yet) tune if Bafang is accurate in their description. So, given that the 820 is likely going to eat more battery that can't be easily removed, I thought 720Wh was a decent option. Plus, it's cheaper than the Siryon w/EonDrive referenced next.
In contrast, the Forestal EonDrive, a 60Nm tune (aka Posh820), and has the integrated, the motor-drop battery (aurora 360 Wh), will have the range extender. I would prefer a trail-side swapable battery. I would backpack it like the Transition Relay's removable battery...being a heavyweight rider.
Sure the CEF50 720 battery (versus the 410 Wh version) 1.5x bumps the Wh capacity, and adds another pound + or so overall. I'm gambling I'll need it for 75Nm torque increase and my heavy load. Especially, since the CEF50 manufacturer isn't really thinking about developing a range extender as an option when I inquired last.
Again, just fits my needs for 40lb+, mid-powered plus (75Nm) rig with an integrated, bigger 720Wh juice-box, and with no ranger extender options for the smaller 410 Wh iteration. My logic, for my needs. Your's may differ!
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