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

Discussions related to motors other than hub motors.
This includes R/C motors, botttom bracket, roller and geared drives.
RiverRat
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Re: Dave's 80:1 RC mid drive kit build log

Post by RiverRat » Jan 13, 2018 4:01 pm

8888A92E-30E8-4F17-B5E5-ECB3D0C6A26F.jpeg
F1BDD320-C068-48BB-B981-6A511E1E5207.jpeg
(156.15 KiB) Not downloaded yet
https://www.propain-bikes.com/RageCF
11C83A19-3683-482A-B936-9C28A925CAA3.jpeg
https://www.propain-bikes.com/Rage?Language=en

Got my eye on either of these two. Mainly because of the inner triangle space. Prefer the carbon and am thinking some extra carbon wrap could be an option given any potential frame weakness issues. Thoughts?

12-C
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Re: Dave's 80:1 RC mid drive kit build log

Post by 12-C » Jan 13, 2018 5:26 pm

Nice bikes.

I would go with the second one. The rear shock area looks like a box section and would naturally be more robust is the face of lateral flexion and stresses. I wouldn't worry about carbon wrapping. Any dh carbon frame would be robust enough to handle what the most badass dh rider can throw at it. And that would be more than what 99% of us here can do. Look for large diameter pivot areas and bearings for
Robustnes. The presence of grease ports on pivot/linkage areas is a real bonus!

Personally I would avoid carbon. Aluminum can be dented and gouged without much thought but carbon is a bit of a worry. Imo carbon is redundant with a heavy motor batteries electronics etc especially when you have 6hp bolted to a bicycle.... Carbon is a must with competition level riders and bikes.... Expensive paperweights for our uses. My 2¢

But most importantly go with whatever makes you giggle.

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

Post by Alex07 » Jan 14, 2018 8:48 pm

I just ran a bunch of these tests with different lubricants. I have a 3turn 3220, a few hundred miles on it (30+ hrs). The CA is reading ~130W for the motor alone, no gearbox, just sitting in my hand (brand new is about 70W IIRC). With the Nabtesco RE0 grease, a good loading of it (25mL+), at 55V (all measurements are via CA, 225kV x 54V is 12,150 RPM) full speed the brand new unit reads 350W on the CA (via battery shunt measurement). So I was wrong, a gearbox with 4 miles on it needs 200W
is that normal that a gearbox uses 200w full throttle no load ? it seems to be a lot ? If the motor is 130w and 200w extra for the gearbox i.e 350w full throttle no load that's like 150% increase ! this is a concern as one of the main benefits of an astro is high efficiency but this is lost if you double the full throttle no load with a harmonic gearbox ? high rpm and low load occurs more often in normal street/mountain rideing stop starts. whereas on a racetrack you would be full throttle full load most of the time this would not matter as much or say on an RC plane.

I already new efficiency was not one of the benefits of harmonic drives , but is it that much worse than a planetary gearbox ? what readings do others get ? i will ask over on the cyclone 3000 thread to see what they get

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

Post by sephespid » Jan 15, 2018 1:41 am

Cycloidal gearbox is compact, but has less efficiency than planetary.

Image

Clyon2
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Re: Dave's 80:1 RC mid drive kit build log

Post by Clyon2 » Jan 15, 2018 8:23 am

Graphs and data need to be accompanied by source and methodology. Great discussion, but we need to be sure we are not comparing apples and kumquats.

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

Post by totolito » Jan 15, 2018 9:53 am

Hello here!

Waiting for the release of the 3kW dave' kit, I'm still searching for the battery.

I hesitated between RC LiPo and 18650, but even if I can reduce height and the cost with the RC Lipo, I prefered the security (BMS), the praticity (all in the same package) and the durability of the 18650.

I found the site em3ev.com which proposes 14s5p, 14s6p and 14s7p batteries. I want to be able to take full power from the kit, so I'll probaly use 25R cells. With this type of cells, what your thought about the 14s5p? Will it be able to provide a constant current for full power the 3kW kit? (Yes I'm a brute)

With the 50.4V 12.3Ah, does it mean that I can run at 2000W during ~20min ? (2000W@50V -> continuous 40A, 12.3Ah*60min / 40A = 18,5min)

Thanks for all

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

Post by dtx » Jan 15, 2018 10:01 am

25R has a max continous discharge current of 20A so with a 5p config you can get up to 100A continous and even more for a few seconds. Since the 3000w kit uses the 80A controller iirc you are fine cell wise. Problem seems to be the BMS. Afaik Em3Ev has 40A continous, 80A peak for a short while. That's likely going to be the bottleneck.

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

Post by totolito » Jan 15, 2018 10:21 am

Image

So what, no battery exists for this kit?


Another option is to remove the BMS, since Cycle Analyst can cut off ? I've heard that well-balanced cells stay for a long time...

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

Post by totolito » Jan 15, 2018 10:37 am

dtx wrote:
Jan 15, 2018 10:01 am
25R has a max continous discharge current of 20A so with a 5p config you can get up to 100A continous and even more for a few seconds. Since the 3000w kit uses the 80A controller iirc you are fine cell wise. Problem seems to be the BMS. Afaik Em3Ev has 40A continous, 80A peak for a short while. That's likely going to be the bottleneck.
And so, a 14p4s with 25R can be enough for the 3kW kit if no BMS limitation...?

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

Post by dtx » Jan 15, 2018 10:48 am

> And so, a 14p4s can be enough for the 3kW kit if no BMS limitation...?

From a mere manifacture rating perhaps but i suspect voltage drop would be rather high and you wouldn't get much range (~500Wh isn't much for a 3kw kit would be what? 10 Minutes of full throttle at at 6C discharge? It's almost universally not a good idea to push the cells to their absolute limit since they don't deliver the full power and degrade rather fast.

> I've heard that well-balanced cells stay for a long time...

In any case, balancing must happen at some point either via BMS or with an external balance charger or you risk (possibly dangerous) failure in the long run

> So what, no battery exists for this kit?

Sure you could use the Em3Ev kit and it'll probably be fine just dont expect more then the 40A contionus with peaks in the 80s. Or go for LIPO with all the ceveats or maybe talk to paul at em3Ev maybe he can make a battery that has an output without BMS and you only use it for charging convenience.

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

Post by totolito » Jan 15, 2018 11:26 am

dtx wrote:
Jan 15, 2018 10:48 am
> So what, no battery exists for this kit?

Sure you could use the Em3Ev kit and it'll probably be fine just dont expect more then the 40A contionus with peaks in the 80s. Or go for LIPO with all the ceveats or maybe talk to paul at em3Ev maybe he can make a battery that has an output without BMS and you only use it for charging convenience.
Does you mean that every user of Dave Kits use RC Lipo solution?

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

Post by dtx » Jan 15, 2018 12:04 pm

No but if they use a BMS they either use one thats rated for their needs or have a smaller battery/smaller BMS and run with less then maximum power. There are several here who use their batteries as described with the BMS only regulating charging, not output which is fed directly from the batteries without a BMS.

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

Post by tangentdave » Jan 15, 2018 12:51 pm

I am curious about the power draw of the Cyclone and Bafang kits, if anybody has one with a CA, please share the full-speed power draw when the chain isn't connected to the rear. I think 200W loss at 12,000RPM is fine. Virtually all riding is done at a fraction of this speed and gearbox efficiency increases under load (unless your gears are bending...ahem...plastic...). This 200W loss doesn't speak to the actual efficiency measurement of power-in minus power-out, this is speed related so windage/pumping losses and bearing friction. I don't have a way to measure the mechanical power output of the system other than wheelies.

There are packs available that support 3220 powers. 14s8p of 30q or 25r support the current fine (15-20% sag at peak current). I've been steering people towards Hi-C Battery; Patrick builds nice packs down in Colorado (for shipping within the USA). The black pack in the previous picture is his, 14s8p of 30q, double nickel strips, 150A BMS and a measured IR of 56mOhm IIRC. The black box convenience of one pack, one plug is worth the additional cost over LiPo in my opinion. In Australia, I've spoken with E-max ebikes (https://www.emax-ebikes.com.au/) and they are capable and willing to build 6kW packs. EM3EV does make nice packs- I've been trying to talk them into a larger BMS for us, but they're dragging their feet. Eric at Lunacycle can do make 'em but he's busy with his own stuff.

14s4p of 25r is rated for a continuous 100A, it could be used on the 3kW fine. Two of these 4p packs in parallel would support 150A of 3220 and provide 20Ah. 14s4p of 30q is rated for 60A continuous, two 4p 30q packs will support 120A of 3220 and provide 24Ah (my 14s8p 30q measures 23Ah).


-dave
Zerode G2/Tangent 6kW
Intense Tracer 29er/Tangent 3kW PAS

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

Post by BonesNis » Jan 15, 2018 1:12 pm

I have Dave's first gen 6kw tangent and I currently use EM3Ev's triangle battery (High Power-25R 50.4V 22.1Ah 1111Whrs ~40A ~80A 6.4kg) in my backpack and although I don't get the full benefit of the 6kw, it works well enough for me to get 45-50 km/h while in PAS mode (PAS sensor hooked up to my CA). I currently get 60 km range. I would recommend this battery for either the 3kw or 6kw.
Carbon Fat Bike - Tangent 6kw First Generation (Winter)
Carbon XC Full Suspension 29 - Tangent 6kw Second Generation (Summer - Pending 6kw Batch 1)

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

Post by dtx » Jan 15, 2018 3:41 pm

tangentdave wrote:
Jan 15, 2018 12:51 pm
EM3EV does make nice packs- I've been trying to talk them into a larger BMS for us, but they're dragging their feet.
I just wrote paul/cellman a mail that i would love to have him build a pack for us. I think if we can show him there's interest he might change his mind. EM3EV Packs are super high quality and have single cell fusing which is a huge plus for me.

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

Post by Mad Matt » Jan 15, 2018 4:30 pm

Hi Dave. Can your gearbox run counter clockwise for a left drive?

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

Post by tangentdave » Jan 15, 2018 6:58 pm

Sure, the gearbox doesn't care which way it turns. The mounts would even work backwards, but I'd make you mirror copies so the features were on the correct side.

Quick video showing how well the PAS works on the 6kW kit. I installed a 36t front chainring so my feet could pull more chain to keep up with the motor power better. This bike uses a 42-15t rear cassette which is a little slow (could really benefit from the 14-11t cogs for pedaling). BTW, top speed with the 36t front ring is 60+mph, you can see me hit 45mph without trying. I do really like the range of gearing the cassette provides. 14s8p of 25r in the backpack.

Zerode G2/Tangent 6kW
Intense Tracer 29er/Tangent 3kW PAS

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

Post by Leeleeducati » Jan 15, 2018 7:35 pm

That looks like crazy amounts of fun!!!! I just ordered the 6kw from you. Can’t wait to get it to start shredding!!!

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

Post by Alex07 » Jan 15, 2018 10:23 pm

Unread post by totolito » Tue Jan 16, 2018 2:21 am

Image

So what, no battery exists for this kit?
That's probably another downside of such Astro motor kits finding a battery ! if you want to use normal ebike batteries and not lypo you will have a hard time getting 120 amps out of any 18650 batteries especially the BMS most people use. Partly a problem of having such a high KV means u need a low voltage 52v batterie . Compared to say the cyclone 3000w or LR 6kw kits that make that power at 72v volts and more friendly ~75 amps.

Most people in the past used LIPO but they are a right royal pain in the butt and a fire hazard so I can see why you want a commercial ebike pack. If you get a very large 14s 8P or more heavy pack then yes its possible, but fitting one on a lightweight ebike is an issue I see ?

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

Post by totolito » Jan 16, 2018 3:50 am

Hum, seeing the video of Dave, I will go search some extra money for the 6kW version :lol:

A question for Dave: how long is your range at this cadence?

About EM3ev packs, someone already open the box (screws version) for shortcut the BMS?

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

Post by Rube » Jan 16, 2018 4:56 am

Dave, thanks for the video. I'll address a couple ideas about noise. Firstly, your voice provides a great reference for powertrain sound. Powertrain sound seems very low during in the cadence demo. IMO speaking in "motorcycle mode" and a view of camera setup might help customers to better understand the sound profile.

Just an idea but it would also be great if your site had a gearing calculator including single, two stage and cassette. I know you are busier than a weatherman in a tornado but maybe the hive mind could help with the gearing calculator? Could reduce customer questions and get these Astro powered beauties out the door faster :D

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

Post by dtx » Jan 16, 2018 5:12 am

For gearing calcualations i recommend

http://ritzelrechner.de/

though you may have to fudge with the URLs a little to get the higher cadences set up

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

Post by tangentdave » Jan 16, 2018 11:15 am

Fancy graphics, very helpful actually. The 3220 unit will turn the crankset at 350-375RPM under load. Multiply that by your front chainring count, then divide by the tooth count of the rear cog(s), then divide again by 13 to convert a 26" wheel RPM into mph. 30-35mph is a great performance sweet spot for 6kW off-road.

Camera is a GoPro Hero on a chesty mount. For a motorcycle, these units are essentially silent. I can't go back to shredding trails on a combustion rig, these bikes are way fun, way convenient, way cheaper overall.

PAS range is pretty easy to calculate when the cadence sensor is used. When the motor is engaged, you program the watts it draws manually. 500W could support 30mph on flat, so our 1000watt-hour battery (14s8p that supports 6kW) could keep the motor running for 2 hours, or 60 miles. A 14s4p pack is half the capacity, 30 miles (500W @ 30mph for 1 hour). The website is embarrassingly unfinished, am working on it.
Zerode G2/Tangent 6kW
Intense Tracer 29er/Tangent 3kW PAS

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

Post by ScooterMan101 » Jan 16, 2018 12:04 pm

What is the KV of the Astro 3220 that you are using ?

What do you then divide again by to convert a 27.5 inch wheel and a 29 inch wheel RPM into MPH ?

tangentdave wrote:
Jan 16, 2018 11:15 am
Fancy graphics, very helpful actually. The 3220 unit will turn the crankset at 350-375RPM under load. Multiply that by your front chainring count, then divide by the tooth count of the rear cog(s), then divide again by 13 to convert a 26" wheel RPM into mph. 30-35mph is a great performance sweet spot for 6kW off-road.

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

Post by tangentdave » Jan 16, 2018 12:17 pm

I'm using the 3turn 3220, 225kV. I believe Recumpence has settled on this wind also for the DaVinci drives.

26" wheel- 13rpm/mph
27.5"- 12rpm/mph
29"- 11.5rpm/mph

But arithmetic, somebody shout if these numbers are off.
Zerode G2/Tangent 6kW
Intense Tracer 29er/Tangent 3kW PAS

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