The e-bike thread.
03-29-2013, 02:47 AM
#503
Boost Pope
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Haha. Yes, my daily commute is actually a bit like that. Around here, we have a pretty fair number of Armstrongs who commute on a daily basis using their >$3,000 carbon-framed ultralite roadbikes, and I generally have the opportunity to breeze past one or two of them every day on my motley looking, grocery-basket-equipped mountainbike over the hillier parts of my ride.
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03-29-2013, 06:37 AM
#504
Very San Francisco, and the motor's on the wrong wheel, and it's a hipster fixie..
..but it is very stealthy.
The Sleeper Bike by George Schnakenberg – Electric-Bike-Kit.com « Clean Republic
This page has a top five stealthiest e-bikes, and a top five most obvious.
Stealthy E-bikes; For the Discreet and the Cheaters | ELECTRICBIKE.COM
..but it is very stealthy.
The Sleeper Bike by George Schnakenberg – Electric-Bike-Kit.com « Clean Republic
This page has a top five stealthiest e-bikes, and a top five most obvious.
Stealthy E-bikes; For the Discreet and the Cheaters | ELECTRICBIKE.COM
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03-29-2013, 07:08 AM
#505
mkturbo.com
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Haha. Yes, my daily commute is actually a bit like that. Around here, we have a pretty fair number of Armstrongs who commute on a daily basis using their >$3,000 carbon-framed ultralite roadbikes, and I generally have the opportunity to breeze past one or two of them every day on my motley looking, grocery-basket-equipped mountainbike over the hillier parts of my ride.
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03-29-2013, 01:01 PM
#507
Boost Pope
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1: These motors do not support cassettes. They have a threaded hub and use conventional freewheels. I admit that the terminology is weird, and this may not be an obvious distinction to one who is not well versed in bicycle mechanics, as I was not when I built my first e-bike. Here is a basic primer: Freewheel or Cassette?
2: While not especially common, there are a few freewheels out there which have an 11T sprocket. In fact, EM3EV sells several of them:Ebike Kit Accessories I would highly encourage you to get one, assuming a significant portion of your ride is either flat or slightly downhill.
You will find that once the motor is installed, you no longer need or want large numbers of gear ratios. I would be perfectly content with a three-speed rear, consisting of 11T, 15T and 21T. In addition, I never use the lowest gear on the crankset (front shifter) at all, even when climbing 20% grades. I alternate between 2 and 3 in front, and usually between 4 and 7 in the rear.
Last edited by Joe Perez; 03-29-2013 at 02:09 PM. Reason: Added threaded hub clarification
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03-30-2013, 02:29 AM
#508
Oh, I figured the terminology on his website was wrong, didn't think these motors used the old style. But I suppose it makes sense for packaging.
I was thinking about swapping on just a loose 11T sprocket onto the stock cassette to keep the low gear, but if you're not even dropping onto the rockclimbing front crankwheel, then I should be fine using Paul's 11T freewheel.
I was thinking about swapping on just a loose 11T sprocket onto the stock cassette to keep the low gear, but if you're not even dropping onto the rockclimbing front crankwheel, then I should be fine using Paul's 11T freewheel.
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04-01-2013, 11:00 AM
#509
I got a reply from Paul the next day. Suck it, lol.
Hi Matt,
As chance would have it, I am now working on a new version of triangle pack using NCM cells, I have not had the A123 triangle pack available for some time now. These NCM packs are more energy dense, so you can very easily fit a 50V 19Ah pack into the attached bag with room to spare. I'll have these new packs finalised this week, we are close to having the first of them ready and once completed I will take some pics with dimensions etc. We'll make a batch of the triangle packs after we have the first of them built.
I would say you need at least the larger 50V 19Ah triangle pack, maybe even a bit more, 36 miles is a long way. If you keep speeds fairly low (around 20mph) and pedal a little, it should be enough.
Maybe you could check back in a few days and I should have more details n the new Triangle Pack or even have it listed on my site. Cost for the pack including bag will be a little over 700USD, I have not finalized the details yet. I've copied some info below.
Thanks
Paul
Battery Info
At the moment I currently offer Packs made from A123 20Ah cells and can offer these in various configurations up to 24 or even 30S, but typically we offer 12S (38V) and 16S (50V) layouts. We have a range of BMS available with different series counts and current ratings as required. I’ve recently started to offer NCM type Li-Ion cells. I am now able to offer regular rectangular NCM Packs in custom configurations and we have many BMS options on this type Pack as well. We will soon be offering NCM packs in a triangle layout and in various Aluminium cases.
The Samsung NCM cell, are an 18650 type cell, 18mm diameter, 65mm long. Capacity is 2.15Ah nominal. 2.05Ah min, 3.62V nominal (1C discharge), weight 44.5g, max continuous discharge is 10A, close to 5C. Cycle life is not as good as the A123, but this can be significantly improved by limiting charge and discharge percentage. Cost on a finished Samsung pack is approximately 20% cheaper than the equivalent capacity A123 pack. I am also offering a cheaper NCM, 2C rated NCM cell, dimensions and weight are almost the same, only discharge rate is lower at 2C. They are from a reputable Chinese Manufacturer. Cost is approximately 30-35% cheaper than the equivalent sized A123 pack.
The NCM packs require only about 50% of the volume for the equivalent capacity of A123 26650, so they will be good for triangle packs and should be able to easily fit 1KWhr plus into a frame bag and mounted within the triangle of a regular bicycle frame.
Battery shipments are now getting checked very thoroughly and sent back very often using regular shipping methods, I recommend DHL for any battery shipments to avoid issues. DHL Battery has a pricing policy that makes it a little more expensive for parcels below 20kg so it can pay to have a total weight of 20kg plus or close to it. We generally add some ballast if weight is a little low to bring it up to 20kg.
Originally Posted by Paul
Hi Matt,
As chance would have it, I am now working on a new version of triangle pack using NCM cells, I have not had the A123 triangle pack available for some time now. These NCM packs are more energy dense, so you can very easily fit a 50V 19Ah pack into the attached bag with room to spare. I'll have these new packs finalised this week, we are close to having the first of them ready and once completed I will take some pics with dimensions etc. We'll make a batch of the triangle packs after we have the first of them built.
I would say you need at least the larger 50V 19Ah triangle pack, maybe even a bit more, 36 miles is a long way. If you keep speeds fairly low (around 20mph) and pedal a little, it should be enough.
Maybe you could check back in a few days and I should have more details n the new Triangle Pack or even have it listed on my site. Cost for the pack including bag will be a little over 700USD, I have not finalized the details yet. I've copied some info below.
Thanks
Paul
Battery Info
At the moment I currently offer Packs made from A123 20Ah cells and can offer these in various configurations up to 24 or even 30S, but typically we offer 12S (38V) and 16S (50V) layouts. We have a range of BMS available with different series counts and current ratings as required. I’ve recently started to offer NCM type Li-Ion cells. I am now able to offer regular rectangular NCM Packs in custom configurations and we have many BMS options on this type Pack as well. We will soon be offering NCM packs in a triangle layout and in various Aluminium cases.
The Samsung NCM cell, are an 18650 type cell, 18mm diameter, 65mm long. Capacity is 2.15Ah nominal. 2.05Ah min, 3.62V nominal (1C discharge), weight 44.5g, max continuous discharge is 10A, close to 5C. Cycle life is not as good as the A123, but this can be significantly improved by limiting charge and discharge percentage. Cost on a finished Samsung pack is approximately 20% cheaper than the equivalent capacity A123 pack. I am also offering a cheaper NCM, 2C rated NCM cell, dimensions and weight are almost the same, only discharge rate is lower at 2C. They are from a reputable Chinese Manufacturer. Cost is approximately 30-35% cheaper than the equivalent sized A123 pack.
The NCM packs require only about 50% of the volume for the equivalent capacity of A123 26650, so they will be good for triangle packs and should be able to easily fit 1KWhr plus into a frame bag and mounted within the triangle of a regular bicycle frame.
Battery shipments are now getting checked very thoroughly and sent back very often using regular shipping methods, I recommend DHL for any battery shipments to avoid issues. DHL Battery has a pricing policy that makes it a little more expensive for parcels below 20kg so it can pay to have a total weight of 20kg plus or close to it. We generally add some ballast if weight is a little low to bring it up to 20kg.
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04-01-2013, 02:07 PM
#511
Boost Pope
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Remember that this stuff is mostly intended for the Chinese Domestic Market. They seem to lag a bit in embracing the newest in bicycle technology- there's a huge installed base of bikes with freewheels, and freewheels tend to be cheap as compared to cassette-based systems. I think this has less to do with packaging than simply with wanting to save a few pennies.
It's no biggie. Either system works just fine. Cassettes are basically the equivalent of quick-change diff gears for oval-track racers. Total overkill on a commuter bike, especially one with a motor.
I was thinking about swapping on just a loose 11T sprocket onto the stock cassette to keep the low gear, but if you're not even dropping onto the rockclimbing front crankwheel, then I should be fine using Paul's 11T freewheel.
Holy crap- 52v 19Ah in the triangle for $700?
****, dude. That's an amazing battery *and* and amazing price, even if these are Chinese amp-hours.
A word about discharge rates: He notes that the Samsung batteries work up to 5C, and the cheap ones to "only" 2C.
Since the overall capacity of the pack is 19Ah, 5C would be 95 amps, and 2C would be 38 amps.
On my bike, I have the maximum current limited to 25A in the CycleAnalyst, since this is enough to give me good hill-climbing power and thus improves the useful range of my throttle. I cannot even *begin* to imagine what 38 amps would feel like, and I'm pretty sure that 95 amps would tear the rear wheel clean off. (Literally- if the gears in the motor survived, the spokes on the rim would not.) 95 amps at 52v is 4.9 kilowatts, which is 6.5 HP. That's getting into the territory of a 125cc 4-stroke.
Remember, cheap MIG welders only put out about 90 amps.
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04-01-2013, 02:46 PM
#514
But the 9 FET controller maxes at 30 amps, right?
So given this info, the 2C is the one to go with, or is there any reason to go with the 5C?
So long as I can climb the hills and not run out of juice, I'm happy. My next priority is the life span of that battery pack.
I'm sure I've misinterpreted something having to do with electricity here. Have I mentioned I'm not that smart with electrons?
So given this info, the 2C is the one to go with, or is there any reason to go with the 5C?
So long as I can climb the hills and not run out of juice, I'm happy. My next priority is the life span of that battery pack.
I'm sure I've misinterpreted something having to do with electricity here. Have I mentioned I'm not that smart with electrons?
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04-01-2013, 03:14 PM
#515
Boost Pope
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Yes, by default, the 9 FET controller will self-limit at 30 amps. If you wanted to dig into the controller firmware, you can even re-program this to other values.
That's kind of what I was getting at. At 19Ah, even a battery which is "only" rated for 2C will have plenty of headroom for a controller that's limited to 25 or 30 amps.
I cannot even imagine what I would do with a 5C battery at that capacity.
Well, that's not true. I can imagine it quite clearly, but it would require a motor which is *way* different than the geared MAC motors he sells. You'd need something like Hubzilla, which is actually rated to deal with that kind of power. (I'd also want to bump the pack voltage to the full 30S configuration, as you'd need the extra voltage to get the motor up to the speeds necessary to achieve ~60 MPH.)
Hubzilla is a BIG motor:
I don't think you will come anywhere close to running out of juice with that setup.
Battery life is kind of a squishy thing. Manufacturers tend to describe it in terms of cycles, but that raises two questions:
1: How do you define a cycle? Is a light discharge to 60-70% followed by a recharge the same as a discharge all the way down to 20% followed by a charge?
2: What, specifically, happens after the rated number of cycles?
The answer to question 1 is "no, but there's not a good method for calculating this." And the answer to question 2 is "nothing at all. At least, nothing noticeable."
Lithium batteries age very gradually. Every time you cycle them, they lose a tiny amount of capacity. Generally speaking, if a manufacturer says "500 cycles" what they mean is that after 500 cycles, the battery will have degraded to 80% of its rated capacity. So after the rated number of cycles (assuming these cycles were all exactly conformant to the test cycle), a 10 Ah battery will have degraded to only 8Ah.
Not very dramatic.
This is why over-spec-ing the battery is a good idea. If you start out with a battery that's 50% larger than it needs to be (in terms of Ah), after a couple of years it will have degraded a bit, to the point where maybe it's only 35% larger than it needs to be. But obviously that's still more than enough capacity to get the job done.
So the point is that if you over-spec the battery by a reasonable amount, it will last well beyond its rated number of cycles for your application.
Of course, battery aging is not linear. It starts out pretty flat, and tends to accelerate after it hits 80%, which is why they choose that particular number. So if it takes 1,000 cycles to hit 80%, it's going to take fewer than 1,000 cycles to hit 60%. Different chemistries age differently- some won't even make it to double the rated number of cycles before they're dropped so much that they're essentially worthless. This is something I can't speak to for this particular battery.
So given this info, the 2C is the one to go with, or is there any reason to go with the 5C?
I cannot even imagine what I would do with a 5C battery at that capacity.
Well, that's not true. I can imagine it quite clearly, but it would require a motor which is *way* different than the geared MAC motors he sells. You'd need something like Hubzilla, which is actually rated to deal with that kind of power. (I'd also want to bump the pack voltage to the full 30S configuration, as you'd need the extra voltage to get the motor up to the speeds necessary to achieve ~60 MPH.)
Hubzilla is a BIG motor:
So long as I can climb the hills and not run out of juice, I'm happy. My next priority is the life span of that battery pack.
Battery life is kind of a squishy thing. Manufacturers tend to describe it in terms of cycles, but that raises two questions:
1: How do you define a cycle? Is a light discharge to 60-70% followed by a recharge the same as a discharge all the way down to 20% followed by a charge?
2: What, specifically, happens after the rated number of cycles?
The answer to question 1 is "no, but there's not a good method for calculating this." And the answer to question 2 is "nothing at all. At least, nothing noticeable."
Lithium batteries age very gradually. Every time you cycle them, they lose a tiny amount of capacity. Generally speaking, if a manufacturer says "500 cycles" what they mean is that after 500 cycles, the battery will have degraded to 80% of its rated capacity. So after the rated number of cycles (assuming these cycles were all exactly conformant to the test cycle), a 10 Ah battery will have degraded to only 8Ah.
Not very dramatic.
This is why over-spec-ing the battery is a good idea. If you start out with a battery that's 50% larger than it needs to be (in terms of Ah), after a couple of years it will have degraded a bit, to the point where maybe it's only 35% larger than it needs to be. But obviously that's still more than enough capacity to get the job done.
So the point is that if you over-spec the battery by a reasonable amount, it will last well beyond its rated number of cycles for your application.
Of course, battery aging is not linear. It starts out pretty flat, and tends to accelerate after it hits 80%, which is why they choose that particular number. So if it takes 1,000 cycles to hit 80%, it's going to take fewer than 1,000 cycles to hit 60%. Different chemistries age differently- some won't even make it to double the rated number of cycles before they're dropped so much that they're essentially worthless. This is something I can't speak to for this particular battery.
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04-03-2013, 01:28 PM
#520
Boost Pope
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BTW - What're you up to with the wheel pulled?
Additionally, while I was replacing the wheel the first time, I noticed that because of the thick torque plate which I have on the wire-side, I'm not getting full engagement of the axle nut on that side. Because that side of the axle is cut out to allow the wiring to pass, when I applied too much torque it actually squeezed the axle down and allowed the nut to skip.
So I'm going to have a few days of downtime while I come up with a solution to that. I have ordered an M14x1.5 ID by M20x1.5 OD threaded insert, which is intended to be used to repair bolt holes. I am going to use it in the opposite way; threading it over the end of the axle and affixing it with DP-420, and using it as an axle extension with a larger nut on the outside.
This is apparently a semi-common issue with the MAC motors in applications with extremely thick dropouts. Simple mechanical issue that should be easy to fix.
Yes, I actually have a stand almost exactly like that one. It is possible to get the rear wheel off with it, but trying to get it re-installed and aligned is difficult. The motor adds a lot of weight to the wheel which makes it want to fall out of the dropouts, and there are a couple of shims which have to be re-installed in just the right spot to get everything to line up properly. (The shims compensate for the extra width of the hub as compared to stock, and move the brake disc back into the proper spot.)
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