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

[macribs]

What he just said. And I would prefer if the competitor would take it up on themselves to finally make ESC's that can do high voltage and absurd amounts of currents.
I really don't get it why their ain't a single true 400-500 A ESC. I don't care how big the heat sink needs to be, ESC could be bolted on the frame to use the frame as a heat sink. Yeah I know there are a few ESC out there that claims 400A but reality is their peak is around 100A for a few seconds.

If people know how to make a high powered ESC that also can run sensored, why not make some bucks and design something that will just work for high powered applications straight out of the box.

 

[tangentdave]

We don't even need absurd current anymore, I just want 80A continuous and 100V. There are a couple automotive oriented controller manufacturers making reference board stuff that make product development very easy. Texas Instruments even has workshops on how to combine their chips to make an ESC, develop the parameters and how to manufacture the product. Check out the TI website on motor controllers- google it, you'd be amazed how much back end is already in place for developing the product we need...

-dave

 

[etard]

There are sensorless ebike controllers on the market, I think Kelly Controllers sells one. They are bulky, but more robust, IMO.

On the Astro motors issues, it would be nice to have another motor option for the bargain builders out.

 

[morati]

Nice additions to the website Dave. Happy to see you went with the 18t freewheel.

 

[Archer]

Hi Guys,

Any ideas when we will start seeing video and reviews on Dave's mid-drive? I really am looking forward to this.Since I'm an extreme newbie on e-bike stuff I will have to follow you experienced guys and also make sure Dave has all the bugs worked out.

However even a newbie can see the high quality parts Dave is using for the Tangent Ascent!

Will keep up with the thread and wait it out.

Tim.

 

[tangentdave]

I can't speak for anybody else with a kit, but this cold ain't gonna keep me off this thing...

Crash cam to follow.

-dave

 

[joostj]

Wow Dave,
That looks like the ideal bike for your kit.

How does the chain and sprockets hold up? Any skipping?

 

[Dogboy1200]

Sooooooo Sweet!!!!!!

 

[tangentdave]

The drivetrain is fine. It's a 10 speed with a Shimano Zee derailleur and works like it should. The cassette is 11-28t with a 36t front chainring- I'm going to switch the cassette out for an 11-34 I think. Also, the 18t freewheel gives a nice ride; the power lasts longer like you would expect and with my limited riding on it haven't noticed a difference in battery consumption.

 

[StinkyGoalieGuy]

Would it be possible to wrap a sound dampening material around the motor housing such as Dynamat or something similar to further reduce noise? I know cooling would be affected, but if I were to run a 3220 or 3215 and geared it for a top speed of 30MPH, it should be so under worked that heat shouldn't even be an issue. Is there enough space around the motor housing to add this material?

 

[cwah]

looks nice. yes sound dampening is important!

 

[macribs]

Not so sure I would choose sound dampening material over effective and well proven cooling. If you ride on flat land, and feel the need to quiet down a bit you could drop your chain to smallest cog on the rear and ease up on the throttle. If you really need dead silent ride, you might wanna stick to sine wave hub. Or you could place the hub in the frame for mid drive. Those tiny lightweight motors are bound to make some sound due to high RPM. What you get here is 80:1 reduction gear in a powerful and lightweight package that will take you further up the mountain then you ever been before with a bike. Now that is worth a little noise. :wink:

If you look at the video I think the decibel meter was almost the same for the car passing and the bike passing - but the bike was ridden harder. When rider eased off throttle sound was less noticeable. Those who already got the Tangentdrive reports that the sound is OK.

 

[tangentdave]

1)Thanks for the patience, it's worth the wait, I'm making sure of it. There's just a ton of work to do getting the processes lined up but now that the hardware is finalized, things should start to sail. The last two days work resulted in 30 gallons of aluminum chips while I use Astro Flight's slow down to get ahead by a batch.

2)No sound deadening. I love the way it sounds, I dream about it now, 12,500RPMs is intoxicating. Instead of rippin on a 2-stroke, I want to rip on this. It can be plenty quiet, the video shows this, but when I want to rip, I want to feel it. Electric vehicles are great but they're gonna have a hard time winning over petrolheads with a silent whine, and until we make the petrolheads jealous, we won't replace the ICE. No sound deadening.

3)I shoulda went riding today 'cause now it's raining, and it's Seattle which means it'll never stop.

I should receive the new anodized pieces and grease seals this week, so pics to follow shortly.

-dave

 

[adriftatsea]

The new frame looks fresh without stickers!

I've done quite a few rides in the rain and no issues to report.

 

[rodgah]

Hey Dave,

have you tried riding the bike with a simple throttle interface instead of the CA? I gather you probably limit the power to keep the derailleur etc happy. If you haven't already seen it, there is a controller being developed in the E Skateboard section of ES called VESC. It is doing good things and might be interesting to you....sensorless torque from stand still, FOC, very accurate current sensing and limiting etc etc. I don't think it would work with such high kv motors on 12s though (12500rpm @ 50v = 250kv?).

 

[StinkyGoalieGuy]

If you ride on flat land, and feel the need to quiet down a bit you could drop your chain to smallest cog on the rear and ease up on the throttle.

Dave, is this thing fairly quiet at moderate RPMs when it's under heavy load? What i'm thinking is if I'm on a steep section, say 25-30% grade and there are hikers around so I keep it at a nice easy 10MPH, can I use half throttle on a middle rear cog? We know that these motors like to spin at high RPMs, but with an 80:1 reduction, would it still be ok spinning at half of it's top RPMs and climbing such a steep grade for say 200 feet?

 

[Ralith]

If you ride on flat land, and feel the need to quiet down a bit you could drop your chain to smallest cog on the rear and ease up on the throttle.

Dave, is this thing fairly quiet at moderate RPMs when it's under heavy load? What i'm thinking is if I'm on a steep section, say 25-30% grade and there are hikers around so I keep it at a nice easy 10MPH, can I use half throttle on a middle rear cog? We know that these motors like to spin at high RPMs, but with an 80:1 reduction, would it still be ok spinning at half of it's top RPMs and climbing such a steep grade for say 200 feet?

I don't know about exact numbers, but it's absolutely true that low RPM + high load is very quiet (can be downright stealthy), as has been discussed previously in the thread. This is of course harder on the motor/controller than high RPM, but it works (so long as you aren't outright overloading the controller) and it should take much more than 200ft to overheat the system. I've never gotten anything dangerously hot despite doing entire hilly rides at as low an RPM as I can manage on some occasions.

 

[macribs]

If you ride on flat land, and feel the need to quiet down a bit you could drop your chain to smallest cog on the rear and ease up on the throttle.

Dave, is this thing fairly quiet at moderate RPMs when it's under heavy load? What i'm thinking is if I'm on a steep section, say 25-30% grade and there are hikers around so I keep it at a nice easy 10MPH, can I use half throttle on a middle rear cog? We know that these motors like to spin at high RPMs, but with an 80:1 reduction, would it still be ok spinning at half of it's top RPMs and climbing such a steep grade for say 200 feet?

Hard to tell, many variables. Your weight, bikes weight, weather/temperatures etc. But to be in the known is always better then the unknown. Get yourself a thermo probe and keep an eye of the motor temperature and you should be golden. Even a cheap ass grill probe will work. Remember the Astro motors are rated to withstand 200 degrees Celsius without failure. More then twice the heat of what a traditional hubmotor can take.

 

[tangentdave]

I am very interested in Vedder's ESC. The builds I've seen are good for 12S/50V, right? The 3210 7turn is 195Kv. I wonder how much hassle it would be to increase that voltage handling up to 96V...?


btw, that's the optical black.


-dave

 

[tangentdave]

On the high load, low RPM topic, if you're in the bottom 5 cogs of the cassette, you can't overload the drive, essentially. You can tool around all day at quarter throttle without the drive getting hot (quarter throttle means 15A), and as long as the motor is spinning, the ESC won't get hot. Plus, quarter throttle in the low gears is all you can use, as Adrifatsea found out.

 

[joostj]

Dave,
Is that part of my kit?
That black looks awesome....
How is it going with Astro?

 

[Ralith]

Can confirm, this drive will happily climb trees all day long in low gear. Or just flip you on your back, if your throttle response isn't tuned down enough.

 

[rodgah]

I am very interested in Vedder's ESC. The builds I've seen are good for 12S/50V, right? The 3210 7turn is 195Kv. I wonder how much hassle it would be to increase that voltage handling up to 96V...?

Yes 12s capable. Though I do believe a low Kv is required and a few have fried DRV chips (from memory) maybe 195 might be low enough. At a guess id say there would be a ERPM limit due to the current sensing and everything else going on. Vedder seems conservative with his recommendations and thats a credit to him.....realistic numbers not faux claims.....I wish I could follow more closely but its all above my head. 24S?? why would you want to spin an astro that fast....I'm imagining the magnets flying out of the epoxy on the rotor at 20,000 rpm :lol: . If you have no or little heat and copious amounts of power you are onto a good thing!! Is there room to move on the reduction ratio.....it seems you have gone too far and have to gear up again. Would this reduce noise with larger teeth (if I understand how the reduction works correctly).

Rodger

 

[tangentdave]

Is that part of my kit?

Yuuup.

How is it going with Astro?

No new word, no call back. I wonder to whom and how many motors they sell when my ordering 10 at a time and asking about quantity orders doesn't pique their interest.

On the higher voltage idea, if we were to move from a 7t to a 12t motor at 96V we could almost double the torque for the same current demands, or double our range with the same performance. Two 48V packs is series aren't as convenient as only one and the extra power would only really be needed if you're intending to move beyond the 30mph realm. Just dreaming, there aren't any advanced 100V controllers available yet...I am curious about how the gearbox would handle very high RPM tho, some destructive testing might be required.


-dave

 

[joostj]

I have a luna cycle 52v pack that fits perfect in my camel back. I have no desire to up the voltage unless the kit is lethargic with a 3215....I suspect that won't be the case.