Dave's 80:1 RC mid drive kit build log

Wow! I love the freewheel adapter and the new tension arm, those were kind of a weak spot in the old design (tiny bearings lives a short and dirty life and the freewheel was only removable in theory after a few thousand miles). The gold cooling fins also look great, just hope everything can handle a a mud bath or two.. Overall everything just looks much more ready for punishment. Any info on possible upgrade path?

Congrats Dave, looks awesome!

Is it possible to order a couple NEWER chain tensioners to fit the previous model?

Do you have pics available of the new spider/chain ring carrier? And is it backwards compatible? Will it require different spacing for the motor freewheel to accommodate the new outside position of the chairing compared to the older model?

Alternatively can it still be used with the driven changing on the inner position?

Looks great Dave!

Does your second gen system come with the Cycle Analyst as the first gen did? Thanks.

Upgrade path, yep. I'm offering first gen customers 40% off the new hardware. The intention is you'd move the existing engine/ESC into the new gearbox (it's easy or send it to me and I'll do it for super cheap). That $300 discount can be applied to a brand new kit as well. The upgrade would include new gearbox, motor freewheel+adapter, mounting hardware, chain tensioner, BB spindle and spider (since the chainline moved slightly). Upgrades for the 3210 engine are $495, 3220 upgrade is $545.

Overall the kit is same as before, throttle input to the CA which outputs digital pulse to ESC based on battery shunt measurement. CA included in the kit. I can omit any component from the kit people already have to save a little bit.

The spring tensioner is an 8mm diameter shoulders screw with M6 threads, so it could be used on the old mounting plates. The plates are aluminum so drilling and tapping is easy (could use a bolt on the backside instead of tapping the plate). The spring will need a small (1/16") hole drilled as well. I'll sell these individually but you'll have to line them up and install them yourself, $20. I could quickly alter the length of the arm as well, right now it's 40mm center of pivot to center of jockey wheel.

Spider/chanrings are super simple. It's difficult to get a good picture.



The mounting plate sits flush against the outside face of the BB shell, it's 6.35mm thick (1/4"). Center of derailleur chainring on the inner position is 5.5mm off the face of the plate (12mm outboard of BB face, about where it should be). The spider is on the inside of the FW flange, derailleur ring on the inside of the spider, motor chainring on the outside, RaceFace Bashguard chainring bolts are used (they're long, the sleeve passes from one chainring to the other). The new position of the motor chain is 14mm outboard of the mounting plate (20mm outboard of BB face). 5mm of BB spacer is used between the FW and crank arm to move the FW farther inboard.

Altering the arragement of the spider/chainrings is easy (mount spider on outside of flange, remove BB spacers, etc). Additionally, it's sorta tough to see with the raw aluminum, but the entire drive unit can be shifted left (non-chain side) a few mm's if your frame is wider than 73mm:



If the spacers on the motor side were removed so the plates would be flush with the drive housing, they'd be 73mm apart. There is space between the crank and motor to accomodate a little shift. In the pic below you can also see the gold heat sink sandwiching the ESC against the mounting plate. Many fancy frames have a wide attachment to the BB shell, similar to this 951, so the ESC can't protrude inboard of the BB face very far or at all. A few spacers between the ESC and mounting plate shift the ESC/heat sinks outboard until the frame is cleared. The kit will come with nice spacers, not the cheap-o washers in the pic.




The motor freewheel adapter will be made a bit shorter so it stays within the FW. We could also easily use the M6 screw in the center for a chain guard.


-dave

Thanks Dave, I'm proud to be order #00042!!!!

Is the additional heatsink going to be offered for sale as well? Love all the upgrades, I can't think of anything left out. Wiring/shunt upgrade, lubricant containment, liquid cooling... The last one really sets off the enthusiast PC overclocker in me.

Did 3M Fluorinert come to anyone elses mind as a cooling fluid? Since so little is needed I'm going to see if I can find a sample from some friends at 3M. Necessary? No. Hecka cool - yes please!

The heatsink would be $35, I order them from arrow.com.

I could put M6 threads on either side of the motor and leave a few baffles in the coolant cavity to convolute the flow. A PC radiator and pump would probably be enough to move the heat away....

So, the datasheet for Flourinert shows a thermal conductivity of 0.06W/m-K while google tells me water is 0.6W/m-K...the environment around the motor is all aluminum (aluminum Tangent housing, aluminum 3220 housing). The issue I see with water is the thermal expansion/100deg C temp limit (can be mitigated with some ethylene or propylene glycol). I'm not upside down in comparing the two liquids am I?

Not upside down at all. In this usage the 3M fluid isn't ideal as we don't need electrical isolation. I know an ethanol mix is sometimes used in geothermal installs. A glycol mix that is boil proof and could be filled all the way (minimal expansion) would probably be best for heat transfer. Moving the fluid would be a plus but I don't think it's really needed for these power levels. Anything is better than air in this situation.

Hello Dave,

I need some clarifications before buy your kit:

What is the diferences between the 3kW and the 6kW kits? Torque, speed, both? I remember that the PAS is not possible with the 6kW, is it still true with your new drive?

I don't need to go faster than 25mph but I need torque...

About the battery, can you confirm this is the best:
https://lunacycle.com/52v-pansonic-ga-14-ah-performance-long-range/

Last point: when do you expect to release the 3kW with PAS kit?

Best regards

Why not use CPU heat paste instead of water?

Take a bow you deserve applause, for those of us considering alternative mounting please add separate motor, drive, and controller dimensions to the webstore?

That looks amazing !
Could you share the weight of the new 3220 kit or how much weight you saved with GEN2 ? I am trying to estimate how much weight I would save by switching to the Tangent (I have a cyclone 3000W right now)

Also color wise, will it come as pictured or is it going to be all black (heat sink, mounts,...) ?

Rube, good idea, will do. The website is obviously unfinished.

I forgot to weigh the unit before installing on the bike, doh. It's close to the same weight as before but I'll get an actual measurement shortly, cutting parts for #2 today/tomorrow to double verify the CNC code then start production batches. I'll offer these in black as well, with the gold heat sink unless it proves ugly. This next unit will be black.

Thermal paste is messy, like really messy (the silver paste will ruin a black finish). Also, with this design the heatsink is not clamped to the motor so there no pressure to create good contact.

Now, I only intended this water jacket for customers with an existing 32xx motor, otherwise I plan on bonding the stator directly to the Tangent housing and eliminating the separate motor. The stator would be bonded directly to the heatsink. This will also let me fully seal the motor end from the environment. The phase leads would exit near the end of the drive and I'll seal the opening with potting compound. The separate Astro engine with water jacket would be available as a special order for all you ES tinkerers, but the vast majority of customers wouldn't use the motor in another project so the added cooling and completely sealed unit is the way to go. I'll have the first example of the bonded engine in a week or two after the rotor/stator arrive. The only difference between the 'upgrade' water jacket version and the bonded engine version is the dimensions of the interior motor bore and an end cover piece to support the rotor bearing (which will use an o-ring to seal the motor side).

The difference between the 3kW and 6kW units is really speed. 3kW uses a larger reduction and less amperage (amp=motor torque), while the 6kW uses less reduction and more amperage. Because people use the smaller motor for PAS situations, it makes sense to me to use a 10turn 3210 with the new Tangent gearbox. A 14t/32t chain reduction will give us 45:1 overall, so with the 10turn's 135kV at 52V, we'd get 7000 motor RPM and 156 crankset RPM. The 10turn could handle 40A continuous (~200W of heat, calculated), which is 2000W at our 52V, but could peak 60A/3000W fine (432W heat calculated, but this would make shitton of torque so you'd be accelerating). 200W of heat is what I used as the limit for the previous generation; bonding the rotor to the heat sink should allow us to increase this. The 10turn will produce substantially more torque and spin the gearbox at a lower speed, which is conducive to those who want to pedal.

Totolito, that pack is a 4p made of GA cells with a rated 10A continuous discharge. It would be fine for the 3210 under normal circumstances and tolerate the occasional 60A excursions. Based on feedback, I wouldn't recommend the THUN for PAS functionality, it's not durable enough for off-road and the square taper cranks are garbage. We can add PAS with a cadence sensor which can be added to either 3kW or 6kW (throttle function is retained).

-dave

Dave,

Is the offer for discounted upgrade (as a 1st gen owner) open for a limited time or time unlimited?

As an aside, I've not had issues with heat in the motor/housing, but can I still use a heat sink compound with my clamp style housing? Would it be a concern that the motor might spin within the housing if the heat sink compound starts acting like a lubricant? Would thermal adhesive also be suitable or not recommended over a plain heat sink compound?

No time limit for the discount, it's a thank you.

I've tried thermal compound between the motor and housing, but didn't notice any difference other than the mess. The motor spinning inside the housing is a concern also, but thermal adhesive would eliminate that (and the ability to remove the motor). With the 3 motor clamp bolts tight, there's good contact between the engine and sink.

Hey Dave

So can you confirm that the complete second gen kit will not require the addition of water within the housing (water jacket)?

Thanks.

Post by Remi812 » Thu Jan 11, 2018 2:22 am

That looks amazing !
Could you share the weight of the new 3220 kit or how much weight you saved with GEN2 ? I am trying to estimate how much weight I would save by switching to the Tangent (I have a cyclone 3000W right now)

Click to expand...

I am interested to know what is the total weight of the new V2 kit , with 3220 6kw, and all the chains controllers covers etc ?with and without chainrings and cranks maybe ?

Thanks Dave for your reply. You probably be very busy with all those orders!

I had choose this https://lunacycle.com/52v-pansonic-ga-14-ah-performance-long-range/ but it seems a bit weak, even for the 3kW version. So I need to find another one

I need some feedback about the users of the Dave's drive. Could you please tell me what kind of battery you use, where to buy them, etc?

- Kit 3kW or 6kW
- Chemical of cells
- Arrangment (14s4p, 14s5p)
- Provider? (DIY, web link...)
- weight

PS: I'm working in embedded electronic, so I'm not afraid to use a RC battery...

Alex07 said:

Post by Remi812 » Thu Jan 11, 2018 2:22 am

That looks amazing !
Could you share the weight of the new 3220 kit or how much weight you saved with GEN2 ? I am trying to estimate how much weight I would save by switching to the Tangent (I have a cyclone 3000W right now)

Click to expand...

I am interested to know what is the total weight of the new V2 kit , with 3220 6kw, and all the chains controllers covers etc ?with and without chainrings and cranks maybe ?

Click to expand...

Take a look here if you haven’t already for the previous version :
https://www.google.com/amp/s/electricbike-blog.com/2016/09/19/tangent-ascent-welcome-to-the-world-of-impossibly-light-electric-motocross/amp/

I am also interested in where everybody is getting their battery that can provide 120+ Amps

I need some feedback about the users of the Dave's drive. Could you please tell me what kind of battery you use, where to buy them, etc?

Click to expand...

I'm running a 3210 kit and another bike on both 30q samsung cells (14s6p) and turningy hobby lipos (6s+4s+4s), 16ah (+a simple 100a fuse and an extra per pack enclosure, made of acrylic and shrink tube).

I get a lot more voltage sag with the 18650's than with lipos (mainly affects top speed runs), but 18650's + BMS combo feel a bit safer to handle regularly and in the office. 18650 might be more economical in the long run, not sure yet. Hopefully - since I payed at least twice as much for it!

So use my rc lipos for weekend bashing in the forest and the 18650 for safer commuting.

knurf said:

So use my rc lipos for weekend bashing in the forest and the 18650 for safer commuting.

Click to expand...

Can you tell me more about your RC packs?

totolito said:

Can you tell me more about your RC packs?

Click to expand...

Sure, I used these:
https://hobbyking.com/en_us/multistar-high-capacity-4s-16000mah-multi-rotor-lipo-pack.html
https://hobbyking.com/en_us/multistar-high-capacity-6s-16000mah-multi-rotor-lipo-pack.html

I haven't pulled them very low yet but they really seem to deliver their amp hours. I normally pull up to 70 amps from them, but they can definitely take more. They heat up towards the end of their capacity as expected, but nothing before. Dunno if they are capable of 160 like their specs (definitely not for long), but probably 100?

It's actually kinda hard to stay on a bike in the forest at those power levels for long, and it's not going to use that current on road top speed tests either, on flat ground, I hit max motor rpm well before that with my winding and gearing.

I made separate enclosures to protect them a little more from bumps and accidents, then some Velcro to link them in my backpack and a XT90 series harness with a forklift fuse or something of 80 or 100A (don't remember right now).

I charge them at 8-10 amps with balancing to 4.1v using three good hobby chargers powered from a 750w computer PSU. They don't change their temp while charging at that rate.

Edit: one of these 4s packs was severely puffed at delivery but hobby king just sent out a new one (didn't even return the first one) with little fuzz. They all balance and discharge just fine so far.

Thanks a lot! And since how many time do you use them? I heard about low life time of those packs, but I think that depend a lot about how we use them. And some brands are better than others...

I don't really know, yet..
The Tangent pack is very new so I've only cycled a hand full of time, 5-10 at most.
I also have a 6s+6s+6s pack of same brand that I use for a hub drive bike. It has seen maybe 50 charges with no drama yet.
My 30Q pack has probably 200-250 cycles on it (most of them charged to 3.95-4v, but many full charges too), it's not much different from when it was new.

I use the Multi-stars as well and consider them the best bang for the buck. I use two packs configured the same (4s + 4s + 6s) in a smaller 10amp/hr size as well as the 16amp/hr size. Mostly use the smaller pack because of the lightweight. I've heard these cells are only good for a 4C discharge however. Doesn't bother me because my bike is used for singletrack use only and its impossible to ride at high speeds. Use the PAS 3210 kit with very conservative settings on my CA3. Have about 25 cycles on my smaller pack charged to 4.1v per cell and never discharge below 3.6v per cell.