I'm trying to build an electric motorcycle on a limited budget. I've bought John Bidwell's "EL Ninja" book, I can weld, I'm familiar with the fact that DC can kill, and I've got a fair bit of experience with metal fabrication.
So far, I'm thinking of either 60V or 72V of FLA group-24 type deep cycle batteries, an ADC motor (one of the smaller ones that will handle the voltage), whichever Curtis or Alltrax controller is cheap enough that I can afford it, and as many onboard 12V chargers as it takes to charge the batteries separately. All of these will be stuffed into a Goldwing or some similar large-framed motorcycle, running a 4.7:1 (or so) gear ratio, which should give me about 60MPH top speed with sufficient range to get me to work at that speed, or both ways if I go slowly (40 mile round trip).
There are a few questions I have, mostly revolving around batteries. Using separate chargers for each battery, they should balance themselves, right? I know that if I charge them as a pack with a higher-voltage charger, I'll have the risk of having a weak battery soaking up more than its share of the charge, leaving the others either over- or under-charged as a result. Another question - as the accessories on the bike are going to be 12 volt, is there a simple way to get 12V out of 60V or 72V? I expect that just running the 12V stuff off of one battery would unbalance the charges - but would the individual chargers solve that problem? My budget is quite low - a "solution" that costs several hundred dollars isn't likely to work for me, I'm more likely to opt for a solution that is ugly, or labor-intensive, rather than expensive. Any ideas?
You might look at the Kelly Controls controllers (kellycontroller.com) in that they have interesting specs, interesting capabilities, and are even less expensive than the alltrax.
Doesn't the Goldwing have a shaft drive? I think some have looked at this bike and chosen to not do EV conversions because of being a shaft drive.
My bike is a Lectra.. the setup is similar to what you describe. It has a 60v 50ah pack on a frame that's much smaller than a goldwing and using an ADC a89 motor. I see, group 24 batteries are a bit larger than what I have. I'm getting 10-15 mile range with my bike and then only if I'm careful to not overdo the throttle. That means keeping the speed below 40 mph. I was pondering this morning and realized it would be worthwhile to study up on gearing ratios and see what I can do from that angle, as well as looking for a freewheeling sprocket to reduce motor drag during coasting. The max speed I have right now is 47 miles/hr but if I hit the throttle that hard the range is really short. But I haven't looked at gearing ratios and have no idea whether what I have is a good ratio or not. In any case for the speed you're thinking 72v would be a better choice.
You're heading in the right direction with the charger thinking. The flip side is having 5-6 chargers on-board a motorcycle would likely mean they're small chargers possibly with a low charge rate.
For the 12v system it's a bad idea to draw 12v off just one battery. As you say it would unbalance the pack. The lighting system is gonna draw 10-15A and since you're talking goldwing there's a bunch of doodads which goes with that scene (CB Radio etc) which will draw even more power. The most convenient method is a DC-DC converter that takes pack voltage and synthesizes 12v.
- David Herron, The Long Tail Pipe, davidherron.com, 7gen.com, What is Reiki
Very useful site, that! I think I'll go over my wish list with their products in mind and see if I can trim my list down to something I can afford.
I hadn't checked the shaft-drive problem out - it's definitely something I'll keep in mind, and for simplicity I'll stick to chain drive, as it's something I understand reasonably well. Kelly Controller has some converters (60V to 12V for $99, for example) that can solve much of the problem with unbalancing the battery pack.
A few notes on my project:
If I go with 60V, I'm likely to use the following.
(5) group 24 deep cycle batteries $400
(5) 12V 12A onboard chargers $500
(1) 60VDC to 12VDC converter $100
(1) Etek 3001 $450
(1) KD48200 Controller $200
$1650 total (estimated 51 MPH top speed, 37 mile range)
If I go for higher speed and range at 72V:
(6) group 24 deep cycle batteries $480
(6) 12V 12A onboard chargers $600
(1) 72V to 12V converter $100
(1) ADC A00-4009 $575
(1) KD72200 Controller $280
$2035 total (estimated 60 MPH top speed, 41 mile range)
In both of these cases, I'm leaving out a lot of details, but those are details that will be similar in both cases - battery boxes, motor mounts, meters, welding cable, crimp tools, angle iron, the "donor" bike, etc. However, if I'm leaving out any parts of the electrical system, I'd love to hear about it - I'd rather find this out now, rather then when I've built it and can't figure out why it won't go. :)
Do I need contactors? The bike won't have a reverse, but I'm nto entirely clear on that particular component. I'm planning to have a removeable link to keep the bike from being used when I'm not riding it, but I was just planning to use a 350A PowerPole for that, and take it with me, like a large key.
Ah, contactors.. An absolute must is a quick and reliable way to kill the power. These controllers can fail such that they're stuck full on. Riding @ 60 miles/hr and unable to stop would very likely end in a mess.
The contactor on my Lectra is a big-red-button ™ which is right in the middle and easy to reach. If there's an emergency I figure I can easily take one hand and give the button a good smack. This is a sort of manual disconnect, and the setup you propose with a loop on a 350A powerpole would be a similar manual disconnect. In fact I have a powerpole based disconnect that I built but am not using because I couldn't figure where to mount it. I'm also unsure if in an emergency the powerpole disconnect could be easily disconnected -- it does take a good strong pull to make it actually disconnect.
The solenoid type contactors are nice. It makes for a nice user experience to just switch the key and have everything turn on without having to do anything else. The downsides are: a) they take a continuous draw of power such as 1A, and b) their contacts can weld shut.. Well, the contacts on any switch can weld shut. I think the better way to say the second one is the manual disconnect I have is rated at higher amps than the solenoid contactors I've looked at. So in terms of $$$'s per disconnect device a manual disconnect like my big-red-button gives more for the bucks than do solenoid type contactors. On the other hand turning on my Lectra requires setting three switches (the keyswitch, the handlebar run/stop switch, and the big red button).
- David Herron, The Long Tail Pipe, davidherron.com, 7gen.com, What is Reiki
Ok, that makes sense. I'm willing to cut corners where I can - but not that one. I'll get a contactor, and probably use the PowerPole as a backup, to be sure the batteries are out of the loop before I work on it. I've been on a few vehicles that decided to go full-speed-ahead, and every one of them, without fail, ended badly... I still have scars from some of them. Thanks for clearing that up. Is the big red button a specific brand, or was it a stock accessory for your vehicle?
Hi, I'm just a lurker maxi-scooter rider who's fantasizing about building or buying an electric scooter someday. Pardon me for interjecting a comment here.
On a regular motorcycle or scooter, the engine kill switch is located on the right hand grip, operated via thumb. Among the safety-conscious, it's supposed to be the normal method by which a rider shuts off the bike (before removing the key), to develop the habit of using it as the default method of shutting the engine down. That way, if there's a problem of some sort and you need to kill the engine, your first habitual response to kill the engine will not be to take your hands off the handlebars. I've read accident reports in which the bike engine stuck at WOT in a crowded area, and the rider "couldn't" shut off the engine because, in the heat of the moment, they were afraid to take a hand off the handlebars to go after the key. They ended up crashing the bike hard, when a simple flip of the thumb kill switch would have shut the bike off.
I wonder if there's a way to emulate this functionality on a home-built conversion bike.
BTW I was looking at Cloud Electric's web site just now and they have some solenoid contactors that take much less current to hold closed. The one I saw required only .1 A versus the 1A of the solenoid contactors I'd looked at before. At .1 A I'm rethinking what's the best to do as that's a low enough current draw to not notice. Especially as some of their solenoid contactors also have higher coil voltages meaning they could be operated off the pack rather than off the DC-DC.
As the other reply said.. there is this habit that's built to flip the thumb up to kill the motor. That's a good habit to maintain, yeah. The big-red-button approach nor your 350A powerpole approach is such an easy flip-the-switch-on-the-handlebars action. The handlebar switch would have to be electrical and part of a circuit which controls the solenoid contactor and also the power input to the controller.
My big red button is an albright switch, very heavy duty, but I don't see it on either cloudelectric.com nor evparts.com ..
- David Herron, The Long Tail Pipe, davidherron.com, 7gen.com, What is Reiki
No need for pardon - you're contributing. If cloudEV has contactors that can work with a thumb switch, I'll put one in the traditional place, for ease of use - I've had bikes get unstable, and the last thing I'd want to do was release the handlebars to deal with it! I'll peek at Cloud's site after work, I have them bookmarked at home. The big red button, while practical, is less attractive than a thumb switch.
yes, when utilizing the auxilary power that operates the lights is used to also operate the thumb kill switch in series to the ignition which both control a contactor. A big red button can also be used like a foot stop or centered in an easy location. Mike Reish has employed both in his build. http://www.evalbum.com/628 http://www.flickr.com/photos/11287591@N04/2125134378/
Another person on the endless-sphere.com also employed the same thing
Bidwell's book uses the big-red-button, and the thumb switch is to the power supply for the controller. Correct me if I'm wrong, but if the controller has no power, it's not like a servo drive - it will stop giving the motor power, right?
Another thing from the Bidwell book, he left the motorcycle battery in place and used it to power the 12V accessories. One reason he did it this way was so that the main batteries don't ground to the frame. If I bought a separate 12V charger for this battery (so I could, as I hope, just plug the bike in to a single 110VAC plug, if it had high enough amps to handle seven onboard chargers) this would be about the same cost as buying the DC-DC converter to get 12V from a 72V battery pack. Is one solution better than another for this?
I hate to rain on your 60mph parade but the 4:1-ish ratio will burn your Etek up. My suggestion is 6:1 or better. You will get 50-ish mph. Also, I doubt you will get 41mi range unless at slow speeds. I have read Bidwell's book but real-world hills, wind and weight are things you forget. I also highly suggest a fan on the Etek, Go to All Electronics site and look for the big 48v one. It will go up to 72v. Finally, this site is great but have a look at all the big motorcycle conversions at EV Album. You will be glad you did.
Not necessarily, it depends on the wiring of the controller and the rest of the system. Afterall, there are more than one set way to wire any of these electric vehicles. I wish I had a copy of mike's wiring to show you, so instead I will describe different options (BTW to keep it simple, I am not including regen at this time).
Here are some possible options:
1. the big red button (a manual switch) which goes to the contactor inline with the batts. Hit the big red button and it disconnects ALL power in the circuit. This is great for accidents especially when bystanders dont know how to shut off the bike (This is required in FIA electric motorcycle racing)
2. An electrical contactor that operates off of a secondary power source (the auxilary power that as soon as you turn your key runs your lights). This contactor engages when another switch enables a voltage to it and once the contactor senses the voltage, it closes the circuit main power for the controller and the motor. You have to imagine it as two separate circuits - one the low voltage initial control and the other the higher power/drive circuit. This way allows all the functions of a regular motorcycle even when the contactor is off, but NO POWER is on the Drive circuit. The problem with this method is that for 72V contactors (not the lower 48V) typically need a larger voltage than 12V to operate.
3. A controller switch that utilizes the ignition wire on some controllers. This disables the controller (sometimes at the power supply internal to the controller and sometimes as a sensing on/off method for the controller), but power is still available going into the drive circuit. The problem with this method is IF THE CONTROLLER SHORTS (FULL ON), it will still be running the motor. And that will lead to the affore mentioned by you accidents of a stuck throttle.
4. A throttle disable either inline to the throttle or as a function of the brake switch wire on some controllers. This has the benefit of still allowing the controller to be ready to provide forward momentum without shutting completely down but has the controller thinking that the throttle is not applied (like you are waiting at a stoplight). This method can be used to prevent over revving the motor if you have a clutch installed or when shifting gears. But again, if the controller shorts (FULL ON), there is still power on the drive circuit and the resulting possibility of an accident.
These methods will depend upon what you wish to accomplish on your bike.
"...a simple flip of the thumb kill switch would have shut the bike off..."
I always wondered why the thumb kill switch could flip both up or down to stop. I figured "Why can't they make up their mind?". It now makes sense.
The first year Honda produced their 4-cyl 750 in 1969, the 4 carbs had a spring return instead of the now-common double cable. Not hard to imagine carbs suddenly stuck open at a time when you'd rather not take your hands off the handlebars. Just pulling in the clutch could explode the engine from unloaded high RPM's.
I thought for years that scooters had an open floorboard because in Europe it would allow traditional women to ride with a dress on. I found a reference a while back that indicated much of it had to do with side impacts with cars.
With an open floorboard the scooters leg injuries were much less severe.
Assuming I'm willing to sacrifice some acceleration, would 5:1 ratio(approximately) give me the 60MPH I crave? I'll take your advice about the fan. The 41 mile range may be overestimated, but my 38 mile round-trip commute also involves 8 hours of down time, which will usually be spent on a charger - I'm hoping that, if there's some reason I can't charge during the day while I'm at work, the bike will still get me all the way home, instead of just most of the way. The battery pack will be flooded lead acid, six batteries @ 85Ah each, totalling about 6.1kw.