Hi there!
I've been lurking for a couple weeks here, gathering information for an ebike I'll be building. I have very little mechanical experience and even less electrical experience. A week ago the only thing I new about electricity was some trivial stuff I'm memorizing for my x-ray boards next month. Volts x Amps = Watts, etc. I know only slightly more this week, but I think I'm obsessive enough to see this through to completion. Please feel free to critique my project along the way, especially at this early stage. I appreciate any input, and other lurkers will probably learn from my blundering as well.
So far I have 2 of the 36V Dewalt (a123) batteries and the stock charger, and everything else for the bike (that I could think of anyway) will be here within a week or two. A 409 crystalyte motor mounted in a 26" wheel, a 48-72V 20A controller, a twist throttle, and a battery cord are all on order from Earl Witcher over at The Poweride Store. I plan to use my current mountain bike. A kitchen magnet confirmed it's made of steel, and I've measured the front fork. Admittedly, my ruler only shows inches and I'll probably end up crashing into Mars.
I have a lot of questions, and I haven't even started building my bike. To keep everyone's interest I've set up a competition. The winner will get bragging rights here and will receive recognition, in a manner of their choosing, on the viral video to be made after the project is completed. I'll also continue to post questions of incrementally increasing value while I build my ebike.
Each of the following questions is worth 1 point initially. Every time 1 or more questions is answered in a post, to the satisfaction of the majority of the forum, the remaining questions go up 1 point in value.
1. My first question is regarding the controller I purchased on faith. The description states that the cut off voltage is 29V. With the low dropoff rate of the 36V dewalt packs, does this mean that I could use one battery at a time and run the motor at 36V if I chose?
2. Would there be more risk to my equipment running the batteries in series, at 72V, or 1 at a time (36V)?
3. Would running the batteries in series give twice the power to the motor while leaving my potential range unchanged? To ask the same question another way: would having 72V available instead of 36V at a time give me better performance but the same range if I didn't change my driving habits (acceleration) and kept the speed at the same level I was able to reach at 36V?
4. From what I'm told, this controller and motor both use Anderson connectors and will be happy together. My battery cord uses an Anderson connector on the controller side but has none on the battery side. How is this connected to my DeWalt battery pack, and what connectors (if any) are needed?
5. My 2 batteries and the battery charger all fit nicely into my lunch pack. Would it be possible to leave one of them permanently in the charger and have them connected in parallel for easy charging while still on the bike?
6. Where can I find a walk-through (including parts I might need) for connecting these batteries in series?
7. Where can I find a walk-through (including parts I might need) for connecting these batteries in parallel?
7. Where can I find a walk-through (including parts I might need) for setting up a switch if I decide to run them one at a time?
That's it for now! Thanks in advance and don't forget to check back from time to time to see how many problems I've run into.
Tim Leibrand
Everett, WA
`timleibrand,
Sounds great, and welcome to V is for Voltage Community. We suggest you also look in the Building E-Bikes Collaborative Hand Books..
Bernie,
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Quote:
1. My first question is regarding the controller I purchased on faith. The description states that the cut off voltage is 29V. With the low dropoff rate of the 36V dewalt packs, does this mean that I could use one battery at a time and run the motor at 36V if I chose?
Yes.
2. Would there be more risk to my equipment running the batteries in series, at 72V, or 1 at a time (36V)?
The failure rate for controllers is higher at 72v. The design isn't the best. Many people have run them at 72v with no problems.
3. Would running the batteries in series give twice the power to the motor while leaving my potential range unchanged? To ask the same question another way: would having 72V available instead of 36V at a time give me better performance but the same range if I didn't change my driving habits (acceleration) and kept the speed at the same level I was able to reach at 36V?
Yes. Double the energy would give double the range if the power consumption remains the same.
4. From what I'm told, this controller and motor both use Anderson connectors and will be happy together. My battery cord uses an Anderson connector on the controller side but has none on the battery side. How is this connected to my DeWalt battery pack, and what connectors (if any) are needed?
You can take apart the DeWalt pack and solder a pair of short wires to the contact points and bring them out to an Anderson connector. Plan B is to buy a replacement battery block (the part that goes inside the power drill, etc) and use that to connect to the batteries. This way you don't modify the battery and void the warranty.
5. My 2 batteries and the battery charger all fit nicely into my lunch pack. Would it be possible to leave one of them permanently in the charger and have them connected in parallel for easy charging while still on the bike?
I think so. The DeWalt batteries can be charged in parallel, but it will take longer to charge.
6. Where can I find a walk-through (including parts I might need) for connecting these batteries in series?
7. Where can I find a walk-through (including parts I might need) for connecting these batteries in parallel?
7. Where can I find a walk-through (including parts I might need) for setting up a switch if I decide to run them one at a time?
6,7,8: http://endless-sphere.com/forums/viewtopic.php?t=1312
Also worth checking out Mr Aerorider's post on connecting up dewalt packs as their are complications, from what I read he had pretty much sussed everything out but I can't find the thread. I think we really need an advanced search feature on this forum and also a feature where you can click on a person and view all posts by this person.
I think we really need an advanced search feature on this forum
This already exists ... enter a search phrase, and if the results don't help then you can click on Advanced Search and it opens up a whole set of other search parameters.
You can also use Google and enter
site:visforvoltage.org search query
The site:xyzzy limits a search to a given site.
and also a feature where you can click on a person and view all posts by this person.
This is already available. Click on the user name in a post, then on their profile page see the "Track" tab. Click on that and you can access all the posts by that user.
- David Herron, http://davidherron.com/
- David Herron, The Long Tail Pipe, davidherron.com, 7gen.com, What is Reiki
Thanks David. I suppose I should know this by now :) I managed to find the essential connecting dewalt packs together thread
http://visforvoltage.org/forum-topic/batteries-and-chargers/578-a123-developer-packs
might be worth using that thread as an ev handbook?
Got all the parts for my ebike before the weekend and got it working (with one problem) in just a couple of days. I had fun learning how to solder, among other things.
For 2 points..
The one problem is that my hub motor wasn't fully functional out of the box. It receives power from the controller and spins as it should - except that it makes a clunking noise. :? Has anyone heard of a similar problem with hub motors?
The noise is from the motor itself, and it can also be heard when I spin the wheel without applying throttle. There's 8 clunks per rotation of the wheel.
Thanks for any help! I'll keep searching in the mean time.
I tested my motor a bit more and found that the 8 clunks per rotation disappear when I unplug the motor from the controller (but they're still audible when the motor freewheels, without power, so long as it is plugged in). I'm reading about the sensors in brushless hub motors and thinking that 1 of mine might be bad.. does that sound like a good theory?
Thanks again,
Tim L
I'm not sure what you mean by "clunks" but brushless DC motors like your hub motor has what is called a "cogging effect". Due to its basic design there is a small resistance to rotate from stand still, and this resistance can be felt as steps or cogs. It is hard to start the rotation, but then it rotates by itself to the next cog. Number of steps per turn depends on the number of poles in the motor. If this is what you mean by "clunks" then don't worry.
But there should be no mechanical noises, friction or rubbing from the motor. If the clunks are mechanical, you do have a problem.
Thanks for the response rgx.
I'm pretty sure this is more than a cogging effect. When I unplug the power from my controller, I can spin the wheel without any of the dull clunking. I've taken my bike to the grocery store and back a couple times; at speed the clunking turns into a shimmy which fatigues my hands and arms in a rather short amount of time. If this is normal then I'm ditching the ebike idea for a road bike.
I have my two 36-volt dewalts in parallel right now, and the motor is providing enough power to kill hills and boost my top speed on the flats.
I'll probably know more Tuesday or Wednesday, when I get my new controller to swap. After I explained in detail what sounds the motor was making (and under what conditions) the Crystalyte distributor decided that the controller and not the motor is the most likely cause. I'm respectfully dubious and praying that he's right.
Tim L