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I intended to start this earlier, but decided to wait for the BO so more people could see the electric stuff. I am not an electrician, but hopefully, it will be a help. Anyway, this has been leaning here for months waiting (those trees out the window have leaves now!). It's a 1995 Giant Innova being converted to a Bafang 1500W midmount with a 52V 35aH battery split into two Dewalt tool cases as panniers. I plan on using the rear fairing I started for Interrobang, a left over tank from Cyclops, another tank between the seat tube and rear fender, and a motorcycle front fairing housing an old foglight from the long-departed Duchess. I did do the wiring diagram ahead of time.

IMG_7937.jpg
Duchess VI Wiring.jpg
 
Electric info: this will be 52V motor with a step-down voltage converter for the 12V for the lighting as shown in the diagram.

I come from an extensive knowledge of internal combustion engines, so learning electric was a little confusing at first as I tried to think of the components as being analogous to ICE when they're really even more of a complete system than that. Most of the stuff I read on electric seem to assume an electric familiarity or were written by other ICE people who don't really get it, either. So, I am not an expert, but I've pieced stuff together over time that I think can help other people new to this understand.

At its basic, you have battery > controller > motor. The motor has a rating, usually for continuous power, meaning they can likely take more for a short amount of time. How much you find out when it melts, I guess, but I'm not messing with it. Anyway, the motor just converts electrical power to work according to load demand (in this case, either pedal assist or throttle up to its cutoff limit). What regulates how much current the motor gets is the controller. They can be external or integrated. The Bafang motor is integrated and the one I'm using is sold either as a "750W" or "offroad use only" 1500W because 750W is the legal max in much of the US. They are the same unit except that the controller limits power on the 750W to 15A and the 1500W limits it to 30. Watts is a measure of power, kind of like HP (~750 W=1 HP). W=A x V, so either more voltage or more amps will allow the motor to perform more work. Motors and controllers are rated for a particular voltage range, so that's kind of a fixed part of the equation. The Bafang I got is a 48/52V unit. Using a 52V battery like I am, that part of the equation stays the same for either the 750 or 1500W motors, so the controller's allowed upper limit on amps is the difference between the power ratings.

I am building a battery out of these:
IMG_8211.jpg

I got them for about $1.33 each from batterysurplus.com. These are 3.7V cells with individual BMSs. That voltage rating is a nominal rating, which is an average since a fully charged pack will rate up to 4.2V. As it discharges, the voltage drops until the BMS cuts off the battery so it doesn't get damaged and/or catch fire (demanding the same power—watts—from the lower voltage of a discharged battery means a higher amp draw to meet that, which means more heat and these types of batteries are particularly sensitive to heat due to bottleneck limitations of the anode and cathode that cause more resistance, which generates more heat, which leads to thermal runaway). Battery packs are built in a sequence of series and parallel wiring. In series wiring (S), you're adding up the voltage of each cell you add, but the capacity of the finished pack doesn't increase over the single cell's. In parallel wiring (P), the voltage doesn't change, but the capacity does. With my motor rated for either "48V" or "52V", I could build the battery pack in either a 13S or 14S configuration to get the voltage at about that respective nominal rating. I'm going with 14S for 52V (though with each cell fully charged to 4.2V, that actually gives me a 58.8V pack). For capacity, each cell is rated at 4.4aH, meaning it can theoretically discharge at 4.4A for an hour. Because the pack of 14 cells is series wired, the whole pack is still only 4.4aH. To get up the capacity, I need to make multiple 14S packs and wire each of those in parallel. I'm doing 8 to get to a max of 35.2aH. This would make it a 14S8P battery and, if you've seen batteries advertised as xxSxxP and didn't know what that was, now you do (hopefully—nobody's ever accused me of being a good teacher). The BMS is like a mini controller for the cell(s). These cells are surplus from some kind of medical device, so they have integrated BMSs (battery management), but if you buy just cells to build a battery or buy a pack made up of cells alone, you'd need to include a BMS. Discharging a battery too fast or too far can generate too much heat, likewise with charging and the BMS largely regulates this (though you also want a smart charger to slow charging rates as capacity nears maximum or to even cut it off at a percentage of full capacity for the sake of longevity in terms of charging/discharging cycles). The less cells a BMS controls, the finer the battery pack can be maintained in terms of charging or discharging, which is better for performance and longevity, so these little easy-to-package flat cells are a real steal.

Now we can talk about how the battery factors into getting the power. The controller has a maximum power limit, but what about the battery? Well, the safe maximum discharge rate of a battery cell/pack wired-in-series varies and it is measured in "C". C is a multiplication of the rated capacity so 1.5C = 1.5 x the rated capacity. In this example, my 4.4aH battery would allow 6.6A discharge per cell/pack wired-in-series. Lets say I wanted to run my motor on one 14S pack, well all I'd be able to get for power out of it would be 343.2W (52V x 6.6A) and only for about 40 minutes at max power (of course, all this is ignoring losses to inefficiency, temperatures, etc), so the controller is only regulating how much power the motor puts out that the battery can provide based on the rider's demands between 0-100% throttle, but the max power is ultimately restricted by the battery being too small of a capacity to hit the controller's limit. Though my cells can handle it, I don't want to exceed 1C on my battery pack because I highly value longevity, so if I used half of the battery I'm building for 14S4P, I would be just over the controller cut off on the 750W Bafang and I would have probably just gotten that model.

This also answers a question I've heard multiple times from people thinking in internal combustion terms lamenting the price of electric cars—why don't they give me only 250hp instead of 500 and just give me more range instead? It's because, with electrics, you have either both or neither—the battery pack capacity can be used for maximum acceleration and holding top speed by using it in the shortest time allowable or to maximize range by using as little power as possible over the longest period of time. Of course, the reality is a mix of the two, but the point is that a smaller battery has less power available whether it's used for maximum distance or maximum load. A large battery pack is expensive and costs increases match capacity, so OEMs will throw in a bigger motor to make it more commercially appealing as it's a small additional cost for them in comparison to the bigger battery and they can probably tack on a bit more profit to match. The question for them becomes: how many customers would pay double the smaller battery price (a very large portion of the car's overall price) for a larger battery to get the longer range, but have the same available power as the cheaper model when they could pay only a small percentage more on top of that for a lot more available power with effectively no other penalty, especially for an expensive vehicle that sells to a decently well-off demographic? That's an answer car companies have had that predates modern electrics since cars with more expensive drivetrains, be they higher power or something like a hybrid, almost always come with more standard equipment (usually low cost/high profit to begin with) to make their higher prices more appealing to the greater number of consumers (I prefer less stuff with more power, but I'm definitely in the minority).
 
Last edited:
I say, I say, you gonna need Egghead Junior to help figger this 'un out!!!

egghead.jpg
egghead2.jpg
 
Will the bike and wheels take the torque? I bend my axle constantly, gone thru 3 already(but thats because the hub is wide... Luv the bafang mid drives, smooth riding,easy to mount. I feel some speed wobbles coming on...
 
Will the bike and wheels take the torque? I bend my axle constantly, gone thru 3 already(but thats because the hub is wide... Luv the bafang mid drives, smooth riding,easy to mount. I feel some speed wobbles coming on...

I have no idea, but I converted it to a solid axle and I hope that and maybe a little mechanical sympathy is enough. I bought a 90mm drum brake for the front as I also plan on reinforcing the fork using the old cantilever mounts as truss rod supports because I figure it can't hurt. Playing with this motorcycle fairing, I think it might help hold it up, too. I have mounts to hold the fairing on the handlebar—I just need to make the simple brackets—but with the weight of the Hella 500, I think I need some solid lower support to keep it from flopping around and my eyeballs tell me the truss rods will be in a good spot or at least allow me to add another bracket. Hopefully, by the end of the day, I'll have the truss rods finished, fairing mounted, and a stronger torque arm for the motor made. By end of the weekend, I want to have the front wheel at least assembled and have the rear fairing extended to make for the backrest. Motor's mounted axle's swapped, which was super easy.

I also have to fit in removing the rear shocks on my car to retighten the top nuts as the clunking and rattling tells me (confirmed from another source) that the torque spec they gave me for them was way too low. I don't think I've ever gotten a torque spec that was too high, but have had some nearly serious problems from them listed as too low (almost lost an engine in my old Subaru when the crank pulley came off, partially breaking the keyway due to way too low a torque spec—80 vs 120 lbs/ft. Luckily, the pulley did most of the breaking and there was enough keyway left to throw a new pulley on.). Anyway, break over.
 
I have no idea, but I converted it to a solid axle and I hope that and maybe a little mechanical sympathy is enough. I bought a 90mm drum brake for the front as I also plan on reinforcing the fork using the old cantilever mounts as truss rod supports because I figure it can't hurt. Playing with this motorcycle fairing, I think it might help hold it up, too. I have mounts to hold the fairing on the handlebar—I just need to make the simple brackets—but with the weight of the Hella 500, I think I need some solid lower support to keep it from flopping around and my eyeballs tell me the truss rods will be in a good spot or at least allow me to add another bracket. Hopefully, by the end of the day, I'll have the truss rods finished, fairing mounted, and a stronger torque arm for the motor made. By end of the weekend, I want to have the front wheel at least assembled and have the rear fairing extended to make for the backrest. Motor's mounted axle's swapped, which was super easy.

I also have to fit in removing the rear shocks on my car to retighten the top nuts as the clunking and rattling tells me (confirmed from another source) that the torque spec they gave me for them was way too low. I don't think I've ever gotten a torque spec that was too high, but have had some nearly serious problems from them listed as too low (almost lost an engine in my old Subaru when the crank pulley came off, partially breaking the keyway due to way too low a torque spec—80 vs 120 lbs/ft. Luckily, the pulley did most of the breaking and there was enough keyway left to throw a new pulley on.). Anyway, break over.
My first ride I ripped of the number 11 tooth right off the freewheel. I have gear sensor now, that cuts the motor. I also need a better engine mount(extra arm) as it rips the motor lose at the bottom bracket. Oh and brakes, really good brakes. Like I said, I have had mine up to 60km. Live fast, die young, leave a good lookin corpse.:21:
 
Electric info: this will be 52V motor with a step-down voltage converter for the 12V for the lighting as shown in the diagram.

I come from an extensive knowledge of internal combustion engines, so learning electric was a little confusing at first as I tried to think of the components as being analogous to ICE when they're really even more of a complete system than that. Most of the stuff I read on electric seem to assume an electric familiarity or were written by other ICE people who don't really get it, either. So, I am not an expert, but I've pieced stuff together over time that I think can help other people new to this understand.

At its basic, you have battery > controller > motor. The motor has a rating, usually for continuous power, meaning they can likely take more for a short amount of time. How much you find out when it melts, I guess, but I'm not messing with it. Anyway, the motor just converts electrical power to work according to load demand (in this case, either pedal assist or throttle up to its cutoff limit). What regulates how much current the motor gets is the controller. They can be external or integrated. The Bafang motor is integrated and the one I'm using is sold either as a "750W" or "offroad use only" 1500W because 750W is the legal max in much of the US. They are the same unit except that the controller limits power on the 750W to 15A and the 1500W limits it to 30. Watts is a measure of power, kind of like HP (~750 W=1 HP). W=A x V, so either more voltage or more amps will allow the motor to perform more work. Motors and controllers are rated for a particular voltage range, so that's kind of a fixed part of the equation. The Bafang I got is a 48/52V unit. Using a 52V battery like I am, that part of the equation stays the same for either the 750 or 1500W motors, so the controller's allowed upper limit on amps is the difference between the power ratings.

I am building a battery out of these:
View attachment 155719
I got them for about $1.33 each from batterysurplus.com. These are 3.7V cells with individual BMSs. That voltage rating is a nominal rating, which is an average since a fully charged pack will rate up to 4.2V. As it discharges, the voltage drops until the BMS cuts off the battery so it doesn't get damaged and/or catch fire (demanding the same power—watts—from the lower voltage of a discharged battery means a higher amp draw to meet that, which means more heat and these types of batteries are particularly sensitive to heat due to bottleneck limitations of the anode and cathode that cause more resistance, which generates more heat, which leads to thermal runaway). Battery packs are built in a sequence of series and parallel wiring. In series wiring (S), you're adding up the voltage of each cell you add, but the capacity of the finished pack doesn't increase over the single cell's. In parallel wiring (P), the voltage doesn't change, but the capacity does. With my motor rated for either "48V" or "52V", I could build the battery pack in either a 13S or 14S configuration to get the voltage at about that respective nominal rating. I'm going with 14S for 52V (though with each cell fully charged to 4.2V, that actually gives me a 58.8V pack). For capacity, each cell is rated at 4.4aH, meaning it can theoretically discharge at 4.4A for an hour. Because the pack of 14 cells is series wired, the whole pack is still only 4.4aH. To get up the capacity, I need to make multiple 14S packs and wire each of those in parallel. I'm doing 8 to get to a max of 35.2aH. This would make it a 14S8P battery and, if you've seen batteries advertised as xxSxxP and didn't know what that was, now you do (hopefully—nobody's ever accused me of being a good teacher). The BMS is like a mini controller for the cell(s). These cells are surplus from some kind of medical device, so they have integrated BMSs (battery management), but if you buy just cells to build a battery or buy a pack made up of cells alone, you'd need to include a BMS. Discharging a battery too fast or too far can generate too much heat, likewise with charging and the BMS largely regulates this (though you also want a smart charger to slow charging rates as capacity nears maximum or to even cut it off at a percentage of full capacity for the sake of longevity in terms of charging/discharging cycles). The less cells a BMS controls, the finer the battery pack can be maintained in terms of charging or discharging, which is better for performance and longevity, so these little easy-to-package flat cells are a real steal.

Now we can talk about how the battery factors into getting the power. The controller has a maximum power limit, but what about the battery? Well, the safe maximum discharge rate of a battery cell/pack wired-in-series varies and it is measured in "C". C is a multiplication of the rated capacity so 1.5C = 1.5 x the rated capacity. In this example, my 4.4aH battery would allow 6.6A discharge per cell/pack wired-in-series. Lets say I wanted to run my motor on one 14S pack, well all I'd be able to get for power out of it would be 343.2W (52V x 6.6A) and only for about 40 minutes at max power (of course, all this is ignoring losses to inefficiency, temperatures, etc), so the controller is only regulating how much power the motor puts out that the battery can provide based on the rider's demands between 0-100% throttle, but the max power is ultimately restricted by the battery being too small of a capacity to hit the controller's limit. Though my cells can handle it, I don't want to exceed 1C on my battery pack because I highly value longevity, so if I used half of the battery I'm building for 14S4P, I would be just over the controller cut off on the 750W Bafang and I would have probably just gotten that model.

This also answers a question I've heard multiple times from people thinking in internal combustion terms lamenting the price of electric cars—why don't they give me only 250hp instead of 500 and just give me more range instead? It's because, with electrics, you have either both or neither—the battery pack capacity can be used for maximum acceleration and holding top speed by using it in the shortest time allowable or to maximize range by using as little power as possible over the longest period of time. Of course, the reality is a mix of the two, but the point is that a smaller battery has less power available whether it's used for maximum distance or maximum load. A large battery pack is expensive and costs increases match capacity, so OEMs will throw in a bigger motor to make it more commercially appealing as it's a small additional cost for them in comparison to the bigger battery and they can probably tack on a bit more profit to match. The question for them becomes: how many customers would pay double the smaller battery price (a very large portion of the car's overall price) for a larger battery to get the longer range, but have the same available power as the cheaper model when they could pay only a small percentage more on top of that for a lot more available power with effectively no other penalty, especially for an expensive vehicle that sells to a decently well-off demographic? That's an answer car companies have had that predates modern electrics since cars with more expensive drivetrains, be they higher power or something like a hybrid, almost always come with more standard equipment (usually low cost/high profit to begin with) to make their higher prices more appealing to the greater number of consumers (I prefer less stuff with more power, but I'm definitely in the minority).
I get it now. Just like my math or algebra class. When they offered me a piece of chalk to add to the equation, I complimented them on a perfect formula that needed no additional help.

1620000101454.png


The same goes for electric power for bikes. Once you have it down, I'll do the same thing with no modifications.
 
More or less got what I wanted done. I think the truss rods came out pretty slick, in particular.

You can see the fairing I'll be using and I modified the green Columbia Fire Bolt tank from the Cyclops to fit the angle of the head tube. I was expecting that to be kind of a pain, but it was super easy with some tin snips. Of course, it's just wedged in and held with tape, so it's not exactly done.
IMG_8765.jpg

Mounted the motor (more or less) and got the rough idea for the extended torque arm because the one it comes with is way too inadequate, using just the torque of the BB nut and 3 small nubs on the torque arm to bite into the BB shell. I didn't get the chance to finish cutting out the sea serpent shape (inspired by 19th Century sea serpent sightings in Cape Ann, which is my area) because I had to redo the lower truss rod brackets when I screwed up the angle and my patience was done with the scroll saw for now. Anyway, the pen is pretty much what it will look like.
IMG_8764.jpg


The back piece on the rack is what I built for Interrobang. It has to be remounted to the rack because the different angle of the seat tube necessitates it. It's just sitting on there for now. The cushion is the old one I made, but I'll have to make a new one that's larger. below that, I plan on having the panniers holding the halves of the battery on sliding mounts so that the seat can still be adjusted up and down.
IMG_8766.jpg


Top mount for the truss rods is just some 1/8" aluminum. Rods are 3/8" aluminum rod with the end threaded for the screws.
fullsizeoutput_3b5.jpeg

Used the old cantilever posts and cut the heads off some long M6 bolts I had to use as threaded rod to fit the female eyelet end fittings and a couple of pieces of aluminum tubing to both match the post diameter to the eyelet for aesthetic purposes and so I could set the distance for the eyelets to where they tightened at the appropriate orientation. Without the tubing, they wanted to tighten about 90 degrees from where I needed them and I didn't want to leave them loose. I had to hit 2 hardware stores to find the right diameter, but it was worth it.
IMG_8769.jpg

More 1/8" aluminum sheet and some electrical grounding blocks I drilled out for the rod to pass through. I still have to fine tune the length of the bolts with a file. Right now, one of them is a little loose. The grounding blocks are threaded and the bolts use those threads, but they also have to work to bite into the aluminum rod and hold it, which is some hand work. I got it close enough for pictures for now. The holes in the bottom of the aluminum will bolt into the fender mounting screws on the drop out. Also, as can be seen, I got the front wheel assembled, though it's not trued up at all.
IMG_8770.jpg


Fairing brackets are for a motorcycle. I'm using 1" PVC scraps as shims and, as you can probably see, I need to pick up more of the correct length bolts, but this was otherwise easy. However, once getting a better idea of everything put together, the fog light mounting will be a little more challenging than I was initially thinking.
fullsizeoutput_3b7.jpeg


Anyway, angry eastern water snake says: That'ssss allsss for now and go away, I'm trying to get warm, over here! (Had to push it off the driveway with a stick while it kept trying to strike out at me. It didn't understand that it's liable to get run over.)

IMG_8763.jpg
 
Dig that mod using the front caliper braze ons to tie in the mounts for your fork braces! Lots of innovative stuff here.

RaT oN~!
 
Started on the rear fairing. I need to extend the front of it so that it reaches the seat. It's ABS, so it's a weldable thermoplastic and that's what I'll be doing with some ABS sheet I have. The pictured parts are just some reinforcements as I don't trust just a stitch weld. The holes are countersunk on both sides, so it will sort of work like a rivet mechanically if it doesn't melt into the surrounding plastic quite right (it's hard to keep it pre-heated without overheating it then removing the heat to weld before it cools a little). Also assembled the battery packs with hot glue and electrical tape (they still need to be shrink wrapped and series-wired) and fit them into one of the Dewalt cases I'm using as pannier/battery compartments. Also weighed the half-battery setup. This is going to be pretty heavy. I kind of knew with the 10 lbs. it weighs for the 40 battery cells that make up the E-kayak's battery, but I guess I was thinking in boat terms and 10 lbs is nothing there. Maybe I'll rig these up so I can remove half of the battery packs if I don't need the whole thing.

IMG_8718.jpg
IMG_8220.jpg


IMG_8213.jpg
 
Nice work!
That fairing is KILLER!!!!!
 
Finally found the (good) Hella 500. It's just kind of jammed in there, but you get the idea.

IMG_8778.jpg
 
Any more progress on the plum??
 
A little plastic welding to extend the rear fairing, but a lot of things have pushed it aside for the moment. I've got the first of my animal books about to go to an editor, so that's good.
 
Good luck with your book. I didn't realize there was so much involved with getting anything published until I wrote a novel over the last few years. I'm not going through all the hassle and cost of copyrighting or publishing. If I was starting out to be a writer, I would, because it would be an investment.
 
Ah, with that fairing I feel like I have fallen thru a hole back into my youthful days.
 
Good luck with your book. I didn't realize there was so much involved with getting anything published until I wrote a novel over the last few years. I'm not going through all the hassle and cost of copyrighting or publishing. If I was starting out to be a writer, I would, because it would be an investment.

I have one published, but this is the first going it alone. I've done the cover art and the chapter illustrations, as well. It's the first of a YA/adult series of three books so far. This is the panorama version of the wraparound cover art (most of the boat will get cut off on the back of the cover and, of course, the title is arranged differently to be on the front cover alone).

SandGB Panorama Title.jpg
 
Got a little done on the cowl. Now I need to form the cowl extension onto it without melting the reinforcements, drill and weld through. For the spot welds, I used countersunk bores on both sides and used a piece of wood underneath so that when I pushed the ABS weld rod through, it filled the countersink on the backside with the idea being that it would work like a rivet. Unfortunately, the heat gun is overkill and a blowdryer too weak to hit a good temp for the plastic, so ]pre-heating it without overdoing it (which I did a little, hence some waviness), then maneuvering the welder and getting the weld rod into place before it cooled too much was tough, so that's why I decided to go with countersinks. I also went over the weld ends with the welder to blend it further. To clean up all the ugliness, I'm going to take the scrap ABS bits and melt them in acetone to make a filler. I read that works, but I haven't tried that particular thing before. If it does work, I imagine it would be a lot better than epoxy or body filler since things don't like to stick to ABS. Plus, it's free. I have plastic welded a little with polycarbonate (really tough), polypropylene (fairly easy), and high density polyethylene (similar to PP), but I have never tried ABS before nor this filler technique. Car bumpers and kayaks are a lot easier than this was, but I'd still take it over PC.

IMG_8866.jpg
 

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