OK, I'm already on to the next question. I want to power my ebuild with a 24 volt 350 watt motor. I am willing to pedal start and then have the motor kick in to help on the hills. Deacon has written eloquently about the pulse jet method of operating and I think that would work for me. So should I get a controller, a 24 volt relay or just a big heavy duty 30 amp switch? I'm leaning towards the controller as I think it might help keep me from burning up the motor. Razor has one matched to the motor I am interested in for $19 + $6 s/h, but I'm no electrical engineer and there's a lot of wires coming out of those things! There are generic controllers as well for a little more on eBay. Are they simpler to hook up? Would anybody here be willing to walk me through the process with either the Razor one or a generic? thanks - jd
controller, relay or...
- Thread starter jdcburg
- Start date
I use the controllers these days thought I honestly don't see any big advantage. I wouldn't recommend one over the other to be honest. With a controller you need a throttle so the pulse method really isn't much of an option.
The truth is you are going to run it wide open throttle most of the time with a controller. But if you do get one you can leave most of the wires unhooked. You need to hook up the battery wires, the motor wires, the throttle wires, and if the controller has a switch set you need to jumper them together or use them for a kill switch. My kill switch is a household switch inline on the battery side.
If you do not use a controller you need a heavy duty fuse and switch for sure. Your biggest stress on the engine is starting from a dead stop and hills so high they slow you to a crawl. The controller keeps your wiring from burning up in those situations I think.
The truth is you are going to run it wide open throttle most of the time with a controller. But if you do get one you can leave most of the wires unhooked. You need to hook up the battery wires, the motor wires, the throttle wires, and if the controller has a switch set you need to jumper them together or use them for a kill switch. My kill switch is a household switch inline on the battery side.
If you do not use a controller you need a heavy duty fuse and switch for sure. Your biggest stress on the engine is starting from a dead stop and hills so high they slow you to a crawl. The controller keeps your wiring from burning up in those situations I think.
Controllers are mainly used for speed control. Depending on the size of your motor and your application they may not be what you are looking for. If you are just going to full load amps with the throttle instantly then a switch may be what you are looking for. It's slightly more dangerous to do that though as you may get all that torque at an unexpected time if you aren't careful.
When you are sizing fuses for your application a quick way to do it is to multiply the full load current rating of the motor by 1.25 this will allow for the inrush current to establish the field and still protect your equipment during normal operation. You don't want to put a massive fuse on a motor that is only drawing a few amps, might as well just hard wire it because that is defeating the whole purpose of the fuse.
When you are sizing fuses for your application a quick way to do it is to multiply the full load current rating of the motor by 1.25 this will allow for the inrush current to establish the field and still protect your equipment during normal operation. You don't want to put a massive fuse on a motor that is only drawing a few amps, might as well just hard wire it because that is defeating the whole purpose of the fuse.
Gents - thank you for your responses. I just ordered a 40 amp relay. I will probably use a deadman switch to power up the motor. That way if things get too exciting I can just release the switch and that should shut everything down. So if my math is correct, a 24 volt 350 watt motor will draw 14.6 amps. 14.6 times 1.25 = 18.25, so a 20 amp fuse or circuit breaker is about right? As I said, I plan to pedal start and use the motor to help on hills. I have ordered a geared down motor designed for a Razor Dirt Quad ($36 + s/h) and hope to get it put together fairly quickly, so I'll let you know how things progress - jd
Thanks Deacon. I'm not sure what you are asking me about attaching, so I'll give you the whole enchilada: I acquired a matched pair of old Huffy 3-speed bikes. The kind with the internal gears in the rear axle. What we called an English bike when I was growing up. I put the rear wheel from one on the front of the other with the sprocket on the right, so it will engage to drive forward and freewheel when the motor is shut off. I've already done that and it fits fine. I'll mount the motor on a rack above the front wheel with the sprocket on the right. I'm shooting for a final drive ratio of 12-14:1 and speeds in the mid-teens. I think I read in the archives that you did something like that. Did it work for you?
Because I'll be using a relay, I can use a lighter duty switch. Probably Radio Shack has a deadman rocker or toggle switch. Interestingly, I emailed Razor about the motor, asking questions about final rpms, sprocket size, etc, explaining that I wanted to use the motor to power an ebike. They wrote back saying: "We are not able to assist with making modifications to or building a product. Our goal is to make sure that your product is as safe as possible." Big help, hey? I'd like to mount the batteries (2-12v 12ah sla's) between my legs above the crank or along the front tube but I'm waiting to see them before I make the final decision on that.
So that's the plan. See any major flaws or have any suggestions? jd
Because I'll be using a relay, I can use a lighter duty switch. Probably Radio Shack has a deadman rocker or toggle switch. Interestingly, I emailed Razor about the motor, asking questions about final rpms, sprocket size, etc, explaining that I wanted to use the motor to power an ebike. They wrote back saying: "We are not able to assist with making modifications to or building a product. Our goal is to make sure that your product is as safe as possible." Big help, hey? I'd like to mount the batteries (2-12v 12ah sla's) between my legs above the crank or along the front tube but I'm waiting to see them before I make the final decision on that.
So that's the plan. See any major flaws or have any suggestions? jd
I wanted to let you know i went back to a simple on off switch on a 350 watt motor with a friction drive and it works perfectly. I did that after the controller died for some reason.
Thanks Deacon. The relay came and I think I've figured out how to hook it up. I'll be working off the place the next few days so I won't have a chance to work on it but maybe over the weekend...
let me know how it goes I'm always curious about other builds. My progect not is to build a friction drive mechanism from scratch. Right now I'm using scooter wheels assemblies.
It works! I finished it and took out a couple of times for test runs this evening. I ended up using a 40 amp Bosch type relay from ElectricScooterParts.com (~$8 w/s&h) and a momentary toggle switch from Radio Shack ($3). The Razor motor had a #25 sprocket on it. The shaft is 11mm (7/16") with a 2x4mm key so I bought a 9 tooth bike sprocket that fits the shaft from EScooterParts ($23). It was a little narrower so I had to file notches in a couple of 7/16 washers to shim it out. I built a rack out over the front wheel out of a 2x4, 2 pieces of 1x1 angle aluminum and some shelf brackets. The 2 12v 12ah SLAs are secured to a shelf between my legs just above the crank.
I'm happy with the way it performs. I had the 3-speed front axle set to low gear and it climbed "heart attack hill" near my house pretty well with me pedaling like I was on level ground. When I stopped pedaling, it slowed down to where I thought it might cause problems, but picked up nicely when I started pedaling again. Later I set the front axle to high gear and it went along on level ground about as fast as I could pedal comfortably in high gear - I'm guessing about 18-20 mph. I doubt if it will have enough "hill power" in high gear but I may get a shifter for the front axle sometime. For now I just tie it tight for low gear and let it loose for high gear.
I took some pictures during construction and I'll take some more tomorrow if the weather cooperates. I'll take it for another (longer) test run too. Probably another post or 2 and I'll be able to post the pictures here.
Thanks again to all of you for the helpful suggestions and encouragement - jd
I'm happy with the way it performs. I had the 3-speed front axle set to low gear and it climbed "heart attack hill" near my house pretty well with me pedaling like I was on level ground. When I stopped pedaling, it slowed down to where I thought it might cause problems, but picked up nicely when I started pedaling again. Later I set the front axle to high gear and it went along on level ground about as fast as I could pedal comfortably in high gear - I'm guessing about 18-20 mph. I doubt if it will have enough "hill power" in high gear but I may get a shifter for the front axle sometime. For now I just tie it tight for low gear and let it loose for high gear.
I took some pictures during construction and I'll take some more tomorrow if the weather cooperates. I'll take it for another (longer) test run too. Probably another post or 2 and I'll be able to post the pictures here.
Thanks again to all of you for the helpful suggestions and encouragement - jd
Glad to hear that it works. I have pretty much retired all my controllers now. With the friction drive I love so much they really aren't worth the effort let alone the money.
Happy motoring. I would love to see the battery rack as I might have to do something else with mine.
Happy motoring. I would love to see the battery rack as I might have to do something else with mine.
I am warming up to the relay idea. I had a 15amp on off switch melt down today. I believe that my controller circuit is less powerful than my on off circuit, but I had to go back to the controller since I didn't have a spare switch laying about.
I took it out for another test this evening. I went down into town - about 1 1/2 miles but also about 400 vertical feet. I didn't write it down but from glancing at my watch I think it was about 7 minutes down and 12-13 back up. I pedaled the whole way back and engaged the motor as a power assist on all but the most gradual inclines. I was able to maintain a speed that was about a fast jog with the effort it would take to pedal on level ground. That's faster than most bicyclists can pedal up that hill.
I'm going to try to post some pictures. The first one shows the bike with the only mod being the front wheel replacement. 2nd - the racks. 2x4 in front and 2x8 for the batteries. I drilled the 1 1/4" holes at the tube angles, cut off board at the edges of the holes and used a jig saw to cut the sides of the holes to a "U" shape. Then I dropped the board onto the tubes and secured it with mending plates screwed on (image 3). 4 & 5 are self-explanatory. I'm guessing the gearing on the motor is about 1:7. The motor sprocket is 9 teeth and the wheel sprocket is 19 teeth. The low gear in the hub has the wheel turn 3 times for every 4 sprocket revs. 2nd gear is 1:1 and 3rd is 5:4. I will continue testing and tweeking and will keep you posted. jd
I'm going to try to post some pictures. The first one shows the bike with the only mod being the front wheel replacement. 2nd - the racks. 2x4 in front and 2x8 for the batteries. I drilled the 1 1/4" holes at the tube angles, cut off board at the edges of the holes and used a jig saw to cut the sides of the holes to a "U" shape. Then I dropped the board onto the tubes and secured it with mending plates screwed on (image 3). 4 & 5 are self-explanatory. I'm guessing the gearing on the motor is about 1:7. The motor sprocket is 9 teeth and the wheel sprocket is 19 teeth. The low gear in the hub has the wheel turn 3 times for every 4 sprocket revs. 2nd gear is 1:1 and 3rd is 5:4. I will continue testing and tweeking and will keep you posted. jd
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Is the balance on the bike pretty good. It looks like a lot of weight for that frame. I pull my batteries on a trailer to keep the weight on the frame down. The bike seems to handle better that way.
I tried that configuration with a scooter motor, a bike sprocket welded onto it, and a china gas bike kit sprocket. I never good keep the chain on, so I gave up. I have been working with friction drive again and now I know why it wouldn't stay on the platform I made was bolted together and not ridged enough.
Looks like a fun project. I bet you got a lot of looks in town. The speeds you are talking about is pretty much what my last friction drive with the scooter rear wheel manages. I'm going to try to goose it up a little, but actually it has the torque to help me up the hills.
I have a couple of hills that are a strain, but otherwise it is a day in the park kind of pedaling. I can do that.
I tried that configuration with a scooter motor, a bike sprocket welded onto it, and a china gas bike kit sprocket. I never good keep the chain on, so I gave up. I have been working with friction drive again and now I know why it wouldn't stay on the platform I made was bolted together and not ridged enough.
Looks like a fun project. I bet you got a lot of looks in town. The speeds you are talking about is pretty much what my last friction drive with the scooter rear wheel manages. I'm going to try to goose it up a little, but actually it has the torque to help me up the hills.
I have a couple of hills that are a strain, but otherwise it is a day in the park kind of pedaling. I can do that.
Deacon - Thanks for the comments. I weigh 180 and the bike is 70 lbs now, for a total of 250. I didn't weigh the bike before I started but the cannabalized bike parts (frame and 2 front wheels, no chain) weigh 36 lbs, so it was probably close to 40 before I started. It has 26" wheels and I suspect it was designed for riders up to at least 200 lbs, so with the 40 lbs of bike weight, I think I'm near but not much above the max design weight for the frame. The steering is a little different, especially under power, but it doesn't seem dangerous. (famous last words?) The brakes, however, are not great. They are the old style side pull calipers and the wheels are obviously not the highest quality - they each have a slight irregularity where the seam is welded, so they chatter and grab a bit. Also, I think I'll lose a lot of stop when they're wet. I don't think a trailer would help that, but I may do that in the future for add'l carrying capacity (groceries, etc).
But the main thing is, the concept works. The bikes were free and have interchangeable parts, so that was convenient. I will probably redo it on a mountain bike or cruiser with either disc or center-pull calipers. The front rack is pretty solid, with the 2 angle aluminum pieces bolted to the front fork carrier as well as u-bolted to the handlebars. I'm attaching 2 more images showing that. Also, the 2x is more solid that a 1x or plywood. I think more modern bikes have predrilled holes for attaching a front rack, so the next one might be easier - jd
But the main thing is, the concept works. The bikes were free and have interchangeable parts, so that was convenient. I will probably redo it on a mountain bike or cruiser with either disc or center-pull calipers. The front rack is pretty solid, with the 2 angle aluminum pieces bolted to the front fork carrier as well as u-bolted to the handlebars. I'm attaching 2 more images showing that. Also, the 2x is more solid that a 1x or plywood. I think more modern bikes have predrilled holes for attaching a front rack, so the next one might be easier - jd
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I try to always use a coaster brake on the rear of my bikes. It frees up the accessory hole for mounting the friction drive motor. Plus I am one of the few people who like coaster brakes. The old style side pull caliper brakes seems to work much better on the front so I stick one on as an emergency brake system.
With the pusher bike the brakes could be anything since I didn't need the hole for a motor mount.
I might try to build a battery rack on the friction drive frame, but frankly that adds a lot of weight onto the bike.
My plan is to keep working on the new friction drive till I get a good solid performance then decide what kind of bike I want to transfer it to. By the bye I ordered two 40amp relays from ebay. I got the 12v version but since the motors will seldom pull more than 20amps it should be okay. Even though they are now rated at only 20amps on 24volts. If they don't burn up the switch I will feel some better. If they get up there they will blow a fuse before they do any real damage.
I just found out that a 40amp automotive fuse is really only 20amps on the 24volt system. So that's a good thing to.
With the pusher bike the brakes could be anything since I didn't need the hole for a motor mount.
I might try to build a battery rack on the friction drive frame, but frankly that adds a lot of weight onto the bike.
My plan is to keep working on the new friction drive till I get a good solid performance then decide what kind of bike I want to transfer it to. By the bye I ordered two 40amp relays from ebay. I got the 12v version but since the motors will seldom pull more than 20amps it should be okay. Even though they are now rated at only 20amps on 24volts. If they don't burn up the switch I will feel some better. If they get up there they will blow a fuse before they do any real damage.
I just found out that a 40amp automotive fuse is really only 20amps on the 24volt system. So that's a good thing to.
(Long post warning) - I finally got out for a few test rides this week. I am pleased with everything so far. Here is a rundown of the rides: the first was to a place where I do a per diem shift once a week or so. It is 2.6 miles, down into town (1.8 miles and about 400 vertical feet) and then back up a moderate hill of about 125 vertical feet. It took 12.5 minutes to get there and 16 to get back home. I don’t think I’ll bother bringing a charger but I might bring the batteries inside for safe keeping.
The e-drive sprocket is attached to an internal gear 3-speed hub. I can shift this hub but did this ride all in 1st gear on the e-drive. The pedal crank is attached to the rear 3-speed hub that I can shift as necessary. The pedaling cadence when the motor is barely engaged (I can tell by the sound) is about 66 rpm in 1st gear and slower in the other gears. I’ll get back to this in a minute.
The 2nd ride was a 9.5 mile pleasure loop that took me about 45 minutes. It is level then slightly downhill for the first mile, then gradual uphill (about 150 vertical) for 4.8 miles, then, on the return, has 2 steeper up and down hills. On this ride I found on level ground and the gradual uphills, I could shift the e-drive hub into 2nd gear and maintain better speed as long as I pedaled. With the rear hub also in 2nd gear, the pedaling cadence at “barely engaged” was (surprise!) 66 rpm. With front hub 2nd, rear hub 3rd , the pedaling cadence was about 45.
The 3rd ride was a 7.5 mile ride to my other regular job. Gradual down for a mile, moderate up for ½ mile then down about 400 vertical in 2 miles, with one steep section. The rest (~4 miles) is generally level. During the last mile, however, the nice 4 lane with wide shoulders narrows to 2 lane with parked cars on the side, and the speed limit drops from 45 to 30 mph. Not much fun rubbing shoulders with trailer trucks through that section, so in the future I will take an alternate route that will add a few minutes. I made it down in 32 minutes, but was a little sweatier than I like to be arriving for work, so I’ll probably pedal less and use more battery at the end. With the alternate end of the route, I figure 38 to 40 minutes and will plan on charging the battery at work. I did a good bit of this ride with the e-drive hub in 3rd gear. I don’t have a throttle/controller, just a momentary toggle switch and relay, so I pedaled and pulsed the e-drive in 2nd, then shifted up to 3rd. I pulsed it in 3rd probably 50% of the time through the level sections and nearly 100% on the gradual up inclines. Again, the cadence with both the e-hub and rear hub in 3rd gear is 66 rpm at full motor rpm.
I’m still testing the battery depth, so although there seemed to be plenty of charge, I didn’t want to go back the same way because of the steep section in the middle. I took a route that is about 8 miles back, mostly level for 6 miles then moderately uphill for 2. It took 41 minutes. I pedaled the whole way, mostly in 3rd, and pulsed the e-drive in 3rd until the final hill. I used full e-assist in 1st and 2nd for that hill and arrived home with what seemed like plenty of battery. I’m using a 12 volt 5 amp auto charger with a built-in ammeter. I reconnect the 2 12v SLAs from series to parallel to charge them. After this ride they charged at 5 amps to start, had dropped back to 4 amps when I checked them at 90 minutes and were at 1½ amps at 2 hours.
I guesstimate the e-assist speed at full motor rpm to be 11-12 mph in 1st , 15-16 in 2nd and 19-20 in 3rd. I will try to confirm these with a GPS or maybe with my wife following in the car, although I realize the 2nd choice is risky, given the time I have spent on this project. I’ll try to keep you posted on further developments - jd
The e-drive sprocket is attached to an internal gear 3-speed hub. I can shift this hub but did this ride all in 1st gear on the e-drive. The pedal crank is attached to the rear 3-speed hub that I can shift as necessary. The pedaling cadence when the motor is barely engaged (I can tell by the sound) is about 66 rpm in 1st gear and slower in the other gears. I’ll get back to this in a minute.
The 2nd ride was a 9.5 mile pleasure loop that took me about 45 minutes. It is level then slightly downhill for the first mile, then gradual uphill (about 150 vertical) for 4.8 miles, then, on the return, has 2 steeper up and down hills. On this ride I found on level ground and the gradual uphills, I could shift the e-drive hub into 2nd gear and maintain better speed as long as I pedaled. With the rear hub also in 2nd gear, the pedaling cadence at “barely engaged” was (surprise!) 66 rpm. With front hub 2nd, rear hub 3rd , the pedaling cadence was about 45.
The 3rd ride was a 7.5 mile ride to my other regular job. Gradual down for a mile, moderate up for ½ mile then down about 400 vertical in 2 miles, with one steep section. The rest (~4 miles) is generally level. During the last mile, however, the nice 4 lane with wide shoulders narrows to 2 lane with parked cars on the side, and the speed limit drops from 45 to 30 mph. Not much fun rubbing shoulders with trailer trucks through that section, so in the future I will take an alternate route that will add a few minutes. I made it down in 32 minutes, but was a little sweatier than I like to be arriving for work, so I’ll probably pedal less and use more battery at the end. With the alternate end of the route, I figure 38 to 40 minutes and will plan on charging the battery at work. I did a good bit of this ride with the e-drive hub in 3rd gear. I don’t have a throttle/controller, just a momentary toggle switch and relay, so I pedaled and pulsed the e-drive in 2nd, then shifted up to 3rd. I pulsed it in 3rd probably 50% of the time through the level sections and nearly 100% on the gradual up inclines. Again, the cadence with both the e-hub and rear hub in 3rd gear is 66 rpm at full motor rpm.
I’m still testing the battery depth, so although there seemed to be plenty of charge, I didn’t want to go back the same way because of the steep section in the middle. I took a route that is about 8 miles back, mostly level for 6 miles then moderately uphill for 2. It took 41 minutes. I pedaled the whole way, mostly in 3rd, and pulsed the e-drive in 3rd until the final hill. I used full e-assist in 1st and 2nd for that hill and arrived home with what seemed like plenty of battery. I’m using a 12 volt 5 amp auto charger with a built-in ammeter. I reconnect the 2 12v SLAs from series to parallel to charge them. After this ride they charged at 5 amps to start, had dropped back to 4 amps when I checked them at 90 minutes and were at 1½ amps at 2 hours.
I guesstimate the e-assist speed at full motor rpm to be 11-12 mph in 1st , 15-16 in 2nd and 19-20 in 3rd. I will try to confirm these with a GPS or maybe with my wife following in the car, although I realize the 2nd choice is risky, given the time I have spent on this project. I’ll try to keep you posted on further developments - jd
Hey JD, have you considered a battery bag? That 2x8 you're using to hold your batteries weighs a mile or two worth of extra or lost distance.
edit: You just hang the bag from your top post.
edit: You just hang the bag from your top post.
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Thanks Robert, but that bag is too small for my batteries. This one ComCycle USA - Product Info would work. I'll think about it. jd