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View Poll Results: Which is better? Brushless hub motor or a standard brushless motor?

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  • Hub Motors are Better

    7 63.64%
  • Standard Mounted Motors are Better

    4 36.36%
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  1. #1
    Member simplecj's Avatar
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    Cool Engineering student needs suggestions: Solar-Electric Trike!

    Hi, I'm a senior engineering student and I've chosen to build an electric-solar bike for my senior project.

    So far I have a brand new Schwinn Meridian adult tricylce and about 66 A123 LiFe batteries (loose cells).

    I've been trying to decide on what motor system to go with and what other components I will need.

    With a 36v setup, I'm at 36.3v on a full charge. I have enough batteries to put 11 in series, 6 in parallel, giving me a 19.2 Ahr pack.
    With a 24v setup, I'm actually over voltage to 26.4v on a full charge with 8 in series, 8 in parallel, giving me a 25.6 Ahr pack.

    What's better 24V or 36V?

    At first I was looking at a 600W 24v brushless motor, but then I realized that I would have to design mounting brackets and a pully system to hook into the chain... then I started looking at hub motors and right now I'm looking at a 600W 36V brushless hub motor.

    Basically the hub system would save me a lot of time and money by not having to design and build the mounting system for the motor. Are there any major drawbacks of using a front hub motor instead of a normal motor running the back wheel(s) by chain?

    Also, can anyone recommend a good controller/charging system to use with my LiFe batteries? You can quick charge these cells at up to 10A per cell in parallel, so most chargers won't give me as good of charge times as I could get. Most controller and motor systems I've been looking at give very little specifications as to maximum RPM, voltage range, amps, how to set cutt-off voltage (if you can set or adjust it), if it's compatible with brushless motors etc... These LiFe bats have high power capabilities, what system will let me get the most out of them?

    I was looking at the 1000W systems, but they're a bit more pricey and they don't make them in brushless hubs (as far as I know).

    I am also wanting to make sure 600W is enough power for me on a trike and some extra weight. I'm about 210, not sure how much the trike weights, shipping weight is 70 pounds, so I'm guessing around 60 pounds out of the box. Then there's about 10 pounds for batteries and approximately another 10 pounds for other equipment. That makes a total guess at 290 to 300 pounds. I don't need or want that much speed because this is a trike and I'm not sure how well it will handle over 20mph, so 20 is my max. I guess I could always gear down and get a lower top end and more torque. But I'm also thinking that 1000W is a bit more than I need and would probably drain my batteries a lot faster than a 600W.

    Any suggestions would be much appreciated! I'm new, so be nice!
    Last edited by simplecj; 12-05-08 at 05:36 PM.

  2. #2
    Senior Member wernmax's Avatar
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    Hubs of course. 5303 Racers.

    Higher the power....the higher the fun factor.

  3. #3
    Member simplecj's Avatar
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    Quote Originally Posted by wernmax View Post
    Hubs of course. 5303 Racers.

    Higher the power....the higher the fun factor.
    Ok, I figured hubs would win, but I'm having problems finding any stats on them and it seems a lot of suppliers are sold out right now. And they all want you to buy the full kit. All I really need is a speed controller and charger that's compatible with my system.

    Also, I know I want higher power, but with the hub motor, there's no way to adjust top end/power ratio.

    I want a high powered hub that is geared to top out at around 20 to 25. I'm guessing the sweet spot is right between 600W and 750W and probably a 36V system (I'm not going to 48V, I want power and range, not speed).

  4. #4
    Senior Member wernmax's Avatar
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    I think it's a cool project.

    Here's a hub site, there are many. Some cheaper hubs are at Goldenmotors, but Electric Rider is stateside. http://www.electricrider.com/

    Check http://www.endless-sphere.com/forums/ for mind blowing detail on this subject.

    About 30 threads down is some pictures of a trike I built, in "High power recumbent trike", and more in a thread even further back in time, this forum.

    I went 48 volt, 40amp with DeWalt a123 packs, and get about 35mph for a top end. Of course you don't have to go full throttle all the time, that will increase your range. It's just nice to have the power if you want it.

  5. #5
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    The answer is, it depends. Inline motors are easiest to install on recumbents or other bikes with long chain lines. The advantage is the motor is lighter and can climb hills and go fast. Hub motor is easy to put on most bikes but is very heavy, doesn't climb well unless you get really heavy and less efficient. However, I am waiting for one of the BMC geared hub motors which are supposed to climb hills and go about 25 mph.

  6. #6
    Hooligan Abneycat's Avatar
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    Simpleci: Frame mounted motors that utilize the drivetrain can be very powerful and efficient, as they can be run through variable gear ratios, however your Schwinn meridian is a single speed thus neutralizing that benefit, and you are looking at considerably increasing project complexity to both go with frame mounting and redoing your trike's drivetrain to include multiple speeds.

    I believe that from your descriptions of what would best suit your needs, that you are looking for a geared hub motor.

    For obtaining torque and efficiency in a hub motor, there is simply no comparison between a geared hub motor such as BMC, eZee or Heinzmann, and between a direct drive system like a Crystalyte. The geared hub motors will simply crush the direct drive variants in efficiency and torque output per watt. They have additional benefits, such as lower weight and freewheeling ability which you may find enjoyable, but for meeting your core requirements of being fed by solar, and having high torque output, a geared motor will provide more value by far.

    Out of those 3 mentioned geared hub motors, Heinzmann is difficult to get a hold of and pricier, and BMC is rear drive only I believe. eZee is your best bet, in my opinion.

    eZee is available in a front drive variant which is likely to meet your needs for pairing with a trike. You can obtain them from http://ebikes.ca as a package with the motor, controller and throttle - sans battery, so it has everything you need and will allow you to use the cells you already have for your battery pack.

    On the ebikes.ca website is also a motor simulator which contains many popular hub motors, including the eZee and the Crystalyte so that you can make some rough comparisons and find out if there are other solutions that work for you. And if you have any questions, the staff are very knowledgeable.

    I hope that this has helped, good luck on your project!

  7. #7
    Member simplecj's Avatar
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    First, thank you for your replies they have been very helpful.

    I looked at the eZee motor, while it does give excellent torque (about 60 lbs thrust off the line), with a 36v system my max speed would be like 15mph.

    I think I like the Crystalyte 5304, AKA the Phoenix Cruiser... with a 36V40A controller, I can get a good 45 lbs thrust off the line and a top speed around 25.

    So... I'm looking at about $750 for the 5304-F26, 36V40A Phoenix controller, twist throttle, wiring kit, and torque arm(do I really need a torque arm?).

    Man... this is going to be a pricey project. I'm hoping my parents will help fund me, cause I don't want the school to pay for it then want to keep ownership when I'm done.

    Now.. Chargers! What good chargers are there out there that can do my A123 LiFe batts reliably. These batteries have a different charging algorithm than other batteries, so I need to make sure I get one that works right. Or there's also a kid at school who said he had designed a circuit that would do it, but not at that high of volts. He was using it for model airplane batteries...

  8. #8
    Member simplecj's Avatar
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    I also have another question... With this higher power system (~1400W), will I get a noticeable decrease in range over using a smaller 600W system? Or does the higher power cancel out in range calculations? It seems like it should since you can reduce range to available power (Ahr) and applied power over time (W), so more watts just means you get there faster right? Of course you still have to consider system inefficiencies such as heat loss. Higher power systems will probably generate more heat...?

  9. #9
    Senior Member Tourezrick's Avatar
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    Ah, you might want to che k out my post on my experiences building a solar - electric trike, just scroll down the page until you see "Solar charged e-trike". For me, a hub motor was the only way to go, started with a Wilderness Energy 'Pedal first' 400W BL36, but with 150# of trike, 36v 12ah sla batts, solar, other 'schtuff', I needed more 'umph'! Went to a C'lyte X5303 w/ 36v40a controller - plenty of speed now. My record load (trike, solar, me and 120# of bagged concrete) is 520#! Rode home at 41wh/mile on a cold day. Lesson learned? Need a better trailer, LiFePO4 or NiMH batt set. Problem is, LiFe packs are only rated at 1.5c (Ping), NiMh packs (ebikes.ca) at 3c, and the Cycle Analyst says that my max draw (short term) has been 60a, so, LiFe packs look like a self-fulfilling prophecy for early demise.

    Sorry! Back to what you are doing. Until those 40% efficiency panels are available at a reasonable price, real time solar charging is a beautiful promise, only. My cheap amorp. thin film panels at 36v give me only 45w - with the 400w motor, that's 12% real time charge benefit, with the 1440w X5, less than 3% real time charge benefit. So, maybe, as a student you have access to better panels at school, or maybe not.
    As far as higher power systems reducing range - it's all about speed - how you use watts available (poor pun, sorry). I'm a 4000 mile/year recumbent trike rider and know I can output about 150 watts for an hour, and then drop down to 100 - 125 watts. Being 60 y/o, at that rate, I want to take a nap, a long one, after riding at a pace of (16 - 18 mph) on a route with about 700 ft gain/loss over 25 miles (12.5 each direction). That's on my Scorpion trike, a nice, comfortable, LIGHT touring recumbent trike. With the solar trike being 4X as heavy, I lean on the power more - especially with a heavy tow load, high wind and/or cold, plus the sla pack puts out well below it's 12ah rating in the cold. So, I can go faster/shorter dist., easier w/heavier load but shorter dist. If I drop the solar from the bike and trailer, I can go faster, farther, easier because of less weight.

    Did ANY of this make any sense to you or help in the least? Can't do 'stream of consciousness' writing like I ustacould, sorry!
    Tourezrick
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  10. #10
    adrenaline junkie
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    Quote Originally Posted by simplecj View Post
    so more watts just means you get there faster right?
    Motor efficiency and wind resistance are nonlinear, so no: More watts means you won't go as far on a charge. Hard acceleration is inefficient, but especially so with direct drive hub motors. The power wasted can be very significant, especially when you realize that your contribution from pedaling decreases are motor input in increased.

    Also, I worry about the safety of a trike like that at speeds above what you could comfortably pedal with its fixed gear.

  11. #11
    Member simplecj's Avatar
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    Tourezrick: Well, some LiFe batteries might not be able to supply the current, but the ones I have certainly can produce more than enough amps for even the most powerful motor systems.

    These cells are the A123 M1 cells, they can pump up to 60A (rated 70A max) per cell in parallel, meaning a 6 parallel configuration can supply up to 360A. I use them in my 60A brushless RC car and they supply max power without the batteries getting over 100F even on a hot day.

    I did a battery pack design last semester for a 200hp motorcycle running 423V and something like 600A, that's 128s8p configuration.... These batteries can do it, they are the best LiFe's on the market and that's if you're lucky enough to find them outside of a DeWalt 36V pack.

    Unime: The motor I'm looking at claims 80% efficiency at around 15 to 20mph. It has a max speed of 25 (at 36v), but the efficiency drops off. I think most of the time I will keep it in the most efficient range, maybe even put a limiter on the throttle to keep it from exceeding max effeiciency.

    I understand your concern about safety on a trike, but really 25mph isn't that fast and I'd certainly not take a corner without slowing down signifigantly. Plus if I limit the throttle, then 20 is my max and I don't see any serious problems as long as the person riding it isn't stupid or crazy with it.

    I guess I might still consider a lower watt system. They do offer a 36v 20A or 25A controller for 725W or 900W total power. It is a bit cheaper, but it doesn't have the power I think I'll need with a 300+ pound load.
    Last edited by simplecj; 12-06-08 at 04:47 PM.

  12. #12
    Member simplecj's Avatar
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    Ok... now I'm looking at the eZee again and I'm thinking that really would be a better choice. I just wish it was a bit cheaper... I've sent an email to their sales department to see if I can get them to sponsor me or at least give me a discount since this is for educational purposes. I'm hoping to also get a local solar company to sponsor me with the solar panels I need.. keeping fingers crossed...

    My main issue is the extra moving parts (gears), the increased wear and the noise generated from the gears. Has anyone actually used the eZee and know if it's very loud and how it's performance is as far as hill climbing and acceleration from a stop.

    AND, how about that Cycle Analyst unit?? Looks pretty sweet, nice functions to it. I think I want that, but I don't know if it will work with anything other than the eZee system.
    Last edited by simplecj; 12-06-08 at 05:37 PM.

  13. #13
    Senior Member Tourezrick's Avatar
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    A123's are a different dog than Chinese packs like . . .

    A123's are better packs than Ping and YESA. Lots of folks swear by the Ping packs, but they are not hauling the heavy loads I do. A recent trip to the lumber yard came in at a total (trike w/motor, batts, me, trailer, solar and 120# of Sacrete) weight of 520#. Sure, I coulda geared down and crawled home at 8 mph or so, or I could pedal hard and use 40wh/mile to achieve a safe speed in traffic, on a cold day with the sla sagging from the cold. Throttles are fine things, in my book!

    I wish I had the knowhow to make my own battery packs, but my background is special education, with minors in sportscar racing, martial arts and recumbent trike riding, not EE! Maybe some day soon I'll start to experiment and try to teach this 60 y/o dog a new trick. Until then, it's gotta be storebought for me.
    Tourezrick
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  14. #14
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    The cycle analyst used in conjunction with their digital crystalyte controller (36-72 volt) would be perfect. Also, I would get the 5305 instead for the extra torque/efficiency and raise the voltage to 48 volts intead. You might have to upgrade to a heavy duty steel front fork - one used for major off-roading. Using the cycle analyst, you can limit speed and or power draw so you can prevent major energy usage (or simply pedal during acceleration).

    I'm using that controller right now using 37 volt LiPoly and I'm topping out around 30 mph with the 5303 motor. However, the 5303 is sooo current hungry, I keep on tripping the 50 amp current limit. I've seen it go as high as 80 amps. I've run it at 74 volts also and with that much power, it's VERY easy to hit the 50 amp limit. These Phoenix motors are truly brutal in their power capabilities and would probably benefit from a 200 amp controller! SO, DO NOT use a lower power controller. Get the 48 volt controller and get the 5305. Top speed would be about 25 mph and you'd have gobs of torque for pulling that trike around. Actually, forget the cycle analyst. Keep it simple - get the 4840 controller (analog so it won't cut out like the digital controller), get the 5305 and you're golden. If you really want, get a simply Astro-flight wattmeter and that'll tell you volts, amps, power, energy and you can simply plug that inline with your battery to controller.

  15. #15
    Hooligan Abneycat's Avatar
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    Quote Originally Posted by simplecj View Post
    Ok... now I'm looking at the eZee again and I'm thinking that really would be a better choice. I just wish it was a bit cheaper... I've sent an email to their sales department to see if I can get them to sponsor me or at least give me a discount since this is for educational purposes. I'm hoping to also get a local solar company to sponsor me with the solar panels I need.. keeping fingers crossed...

    My main issue is the extra moving parts (gears), the increased wear and the noise generated from the gears. Has anyone actually used the eZee and know if it's very loud and how it's performance is as far as hill climbing and acceleration from a stop.

    AND, how about that Cycle Analyst unit?? Looks pretty sweet, nice functions to it. I think I want that, but I don't know if it will work with anything other than the eZee system.
    Wear is an unfortunate consequence of having moving parts, however it is very manageable - the nylon gears on the eZee will last several years of regular use and are very easy to replace. The eZee is a fairly quiet system, it does generate some audible noise but is not loud.

    When you compare the hill climbing and acceleration capability between a geared motor such as an eZee and a direct drive unit, at comparable wattages the geared motors are considerably more powerful. You need to run a lot more current through the average direct drive motor to get comparable torque output.

    The Cycle analyst is an exceptionally useful piece of hardware, it provides a lot of useful information and the stand alone version is compatible with just about any electric bike (or other light electric vehicle) you can imagine. Given that the voltage cutoff of the eZee is 20 volts, you will want the cycle analyst to set a cutoff suitable for your custom battery pack, as if you go for your 36v proposal, it would be possible to irreversibly damage your pack by letting it run below safe levels, which the eZee controller on its on would let you do, unless you programmed a cutoff into your BMS.
    Last edited by Abneycat; 12-06-08 at 08:21 PM.

  16. #16
    Member simplecj's Avatar
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    I don't know... I compared the eZee to the 5305 hub with a 36V 20A system and really there isn't much difference. The eZee has a few more pounds thrust off the line (42 vs 35), but the 5305 has a higher efficiency rating in the 15 to 20mph range AND with an Analyst system I could limit the amps for longer distance or turn it up if I need more power.

    With the eZee system I pay a bit more money, but I'm limited to a 20A system. The 5305 with a 36-72v 48A controller and the CycleAnalyst gives me a very flexible system with the ability to increase amps for more power or voltage for more speed.

    Hmm... it's looking like the Brute 5305 might be a winner....
    Last edited by simplecj; 12-06-08 at 11:20 PM.

  17. #17
    Hooligan Abneycat's Avatar
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    Well, there isn't anything wrong with the 5305 if a high powered system is what you're after. While the eZee can accept more than a 20a controller with a switch out, it hasn't got the wiring to take extreme current like the Crystalyte can. Crystalyte motors have the most robust wiring of any hub motor i've seen. They will handle some seriously excessive current.

    The 5305 is going to be more efficient in optimal conditions, but thats what the simulator represents. In true usage, the consistently higher RPMs of the geared motor translates to a higher real world eff. At a lower power output, you're going to get better value from the eZee, but as you have figured out, the 5305 has more high end potential. It all comes down to how much solar energy you're going to have at your disposal, and what your ultimate goal for the vehicle is, I suppose. The Crystalyte 5 series are certainly a choice pick for those looking for very high power potential.

    I suppose one important factor would be finding out how much photovoltaic capacity you're going to have available as well.

  18. #18
    Member simplecj's Avatar
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    As for the motor selection... I'd rather have more flexibility in my system and the ability to handle more power if I want it to, especially if it's not going to cost me any more money, which it appears it is not, it's actually about the same price for the higher powered crystalyte setup.

    My solar capacity is yet to be determined. I'm going to build a small lockable "trunk" to replace the basket on the back of the bike. The lid of the trunk will hold the solar panels and the battery pack and other electronics will go inside the trunk.

    With the 36v setup, I'll have 3 12v panels wired in series, if there's enough room I'll double up with 3 more in parallel. The question that remains is how big of panels I can fit on the trunk. I should be getting the bike itself within a week, then I can actually measure things out and get a better idea of what I'm dealing with.

    I will of course put as much capacity as I can fit, but really, the solar part is just more of a passive charging system. I would like it to be able to charge the packs from dead to full in about a day. I figure if I can do that, I will have a noticeable extended life (range) on the pack. The best thing about the solar is that it's just there charging whenever the sun is out.

    Any suggestions on solar panels to use? I am going to try to get these donated, but there's a chance I will have to buy them myself.

  19. #19
    Senior Member wernmax's Avatar
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    You know....at this point, what occurs to me, is that those type of trikes have hubs that are fixed to the drive axle.

    You can't put a standard electric hub motor on the rear wheels, anyway.

    Forgive the repeat if someone else already mentioned this.

  20. #20
    Member simplecj's Avatar
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    I know that, that's why I'm getting the front wheel hub. It'll actually make it a 3 wheel drive with both electric and pedal power!

    What I'm really hoping is that I can rig up a disc brake on the rear axle.
    Last edited by simplecj; 12-07-08 at 11:31 AM.

  21. #21
    adrenaline junkie
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    Quote Originally Posted by simplecj View Post
    As for the motor selection... I'd rather have more flexibility in my system and the ability to handle more power if I want it to
    Successful solar vehicles are highly optimized for efficiency. Permanent magnet motors lose efficiency at low power (I don't understand the details, but I've read that maximum efficiency is reached when the magnetic fields of the rotor and stator magnets are equal). I suspect you will get noticeably better efficiency with the eZee motor at the lower power level needed to make good use of solar power. The eZee is also significantly lighter in weight than Crystalyte 5 series.

    My solar capacity is yet to be determined. I'm going to build a small lockable "trunk" to replace the basket on the back of the bike. The lid of the trunk will hold the solar panels and the battery pack and other electronics will go inside the trunk.
    Have you done a back of the envelope calculation? Say you get 10 watts per square foot of solar panel and 4-6 effective hourse of use per day. That's about 50 Watt houts per day. I think you'll need a big trunk lid.

    The best thing about the solar is that it's just there charging whenever the sun is out.
    You know about the strict charging requirements of lithium batteries, right? Lithium batteries cannot be fully trickle charged. Best to contact your battery manufacturer to see how to adapt a solar charger, though limiting to 4.05 V/cell might be acceptable (4.20 is the normal max voltage for li-ion cells).
    [/QUOTE]

  22. #22
    Member simplecj's Avatar
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    Well, the eZee is only 20% lighter than the Crystalyte hub, and I can limit the amps to 20A on the Crystalyte with only 16% less torque off the line. According to the simulator, almost everything else is very close.

    The eZee efficiency peaks between 15 and 20mph at about 74%, the Crystalyte peakes between 13 and 21mph and hits 80% efficiency.

    AND>> The efficiency peak for the eZee happens when the motor is at full power, 500W. The Crystalyte hub reaches peak efficiency after peak power, when power use is actually reduced from 500W down to between 400W and 300W. Meaning that while cruising in the similar efficiency speeds, the Crystalyte actually requires less power then the eZee. That is becuase the gearing actually shifts more torque to the low end, sacrificing top end efficiency.

    If I bump the Crystalyte up to 35A, I get slightly more torque than the eZee and even better efficiency, peaking at around 82%.

    I know these are "ideal" figures, but I think it proves my point well enough. The eZee costs more than the crystalyte, but considering it is a much lower powered system, it doesn't appear to deliver that much of a benefit other than slightly higher torque off the line.

    The extra few pounds of the Crysalyte hub are dwarfed by what I'm guessing will be a total vehicle and passenger weight (me) of over 300 pounds. With that much weight and excellent lithium batteries, I think it would be silly to limit myself to 20A motor system. I might very well need more power considering weight and the Crystalyte can provide it if needed.

    Besides all that, "not making use" of solar because it is a high power system is a misnomer. Any power that can be harnessed from the sun for free is certainly not wasted, even on a high power system. Even if it has to sit in the sun longer to recharge, so what? If quick charging is an issue, I can always plug it in.

    Again... with my specific batteries, you guys are not realizing that they are not LiPoly nor are they your average LiFePO4 cells. A123 cells are the most robust and forgivable batteries on the market. They have a maximum continuous discharge rating of 70A (Per parallel cell), and a maximum charging rate of 10A (per parallel cell). They are 3.3v nominal (3.6v peak charge) each and are very forgivable. You can even drain these batteries to 0v (although it's not recommended) and get them to charge back up with almost no noticeable effect in capacity. Cell capacity is 2.3Ah (6 parallel gives 13.8Ahr)

    If there's a lithium battery out there that can take a solar trickle charge, these are the they!!

    Here's the website: http://www.a123systems.com/
    Here's the battery spec sheet: http://a123systems.textdriven.com/pr...UGUST_2008.pdf

    My proposed batty pack will be 6 in parallel, 11 in series. This will give me a total of 36.2v/13.8Ahr and a max rated continuous discharge of 420A, max rated charge rate of 60A. Peak charge voltage will be 39.6v, but I won't be using the solar to do peak charging, only to help refill the batteries when they are below nominal voltage.

    They are rated at a 120A max pulse discharge, meaning 6 in parallel could do a 10s pulse of 720A. Despite this rating, we failed to see how it was possible because the cell voltage would drop to about 1v under a 120A load due to internal resistance. We figured it's better to keep it under the continuous rating, about 60A or less for continuous discharge (6p = 360A).

    These are quite possibly the best batteries for EV and LEV low and high power applications. One of the main reasons besides performance, safety! These cells do not explode like LiPo cells do. If they are extremely overloaded, they simply short out internally instead of combusting. Even puncturing them with a nail will not produce and explosion or any fire for that matter.

    I am going to try to track down our documentation from the 200hp electric motorcycle project I worked on last semester. Me and a teammate actually drove out to Boulder Colorado right before finals and assembled 35 modules (a few more than we needed) of 4s8p 13.3v packs to be arranged in 128s8p for the motorcycle, that's a total of 1024 cells. These packs are in the process of being installed in the motorcycle right now and will be looking to set land speed records next summer.
    Last edited by simplecj; 12-07-08 at 12:51 PM.

  23. #23
    adrenaline junkie
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    Quote Originally Posted by simplecj View Post
    Well, the eZee is only 20% lighter than the Crystalyte hub
    Isn't the eZee motor around 7 pounds, and the Crystalyte 15? These are from memory, but I'm sure the difference is noticeable.

    The eZee efficiency peaks between 15 and 20mph at about 74%, the Crystalyte peakes between 13 and 21mph and hits 80% efficiency.
    Typical efficiency loss for planetary gears is about 3%, which should made up by the faster spinning motor. Something is wrong with that 74% efficiency number - either your simulation is wrong, or the eZee motor sucks.

    Besides all that, "making use" of solar is a misnomer. Any power that can be harnessed from the sun for free is certainly not wasted, even on a high power system. Even if it has to sit in the sun longer to recharge, so what? If quick charging is an issue, I can always plug it in.
    If you have access to the power grid for recharging, then putting the solar panel on your bike is counterproductive. You'll waste energy accelerating the panel's mass and overcoming its aerodynamic drag, while a fixed panel can be better oriented for much greater effectiveness.

    You guys are not realizing that they are [A123 cells]
    My bad. All you need is a voltage limiter.

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    Okay... The weight of the 5305 is 24 pounds including the rim and spokes.

    The eZee motor itself weighs 8 pounds, maybe 10 pounds with the rim and spokes?

    So I guess I was wrong about the 20% figure, thought I had read that in the eZee description. I guess I just don't care that much about 14 pounds when it comes to a much more powerful and robust motor that can be limited if I want long distance travel between charges.

    I just had another idea... if I limited my pack to 10 in series, I could use extra DeWalt Packs to increase my capacity for long distance travel. The DeWalt packs have exactly 10 of my cells in series, which is actually only 33v nominal while they rate the packs as 36v which is the peak charge voltage.

    That would make a good option... I wouldn't be surprised if people are already using just the DeWalt packs with like 4 to 8 of them in parallel. Of course that would be pretty pricey, I got my cells used for much much less... about $5 per cell.
    Last edited by simplecj; 12-07-08 at 01:22 PM.

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    Quote Originally Posted by unime View Post

    If you have access to the power grid for recharging, then putting the solar panel on your bike is counterproductive. You'll waste energy accelerating the panel's mass and overcoming its aerodynamic drag, while a fixed panel can be better oriented for much greater effectiveness.
    Hmm... damn, you may be right.. but really, those tiny 12v panels are not heavy at all and they would be laid flat on the top of the trunk and not adding to drag, and drag really isn't a huge factor under 20mph anyways. Rolling resistance is probably bigger with bad tires on. That's another thing I plan on addressing with some good street slicks.

    I wish I could get my hands on a piece of that Nano-Solar thin film paneling. You can literally cut it to size and lay it flat on any surface, that would be perfect! Too bad they're sold out and probably won't be selling to consumers but through third party suppliers who won't have any until some time next summer.

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