Zcommuter Electric Recumbent Hybrid Bicycle
Easy Commuter electric recumbent.
A project by Warren Beauchamp
This project will be to build a high powered electric assist recumbent bike for use in commuting, using off the shelf parts. While some assembly will be required, no machining or welding will be needed. My target range is around 25 miles.

As in my past electric assist recumbent projects, the platform will be a fully suspended recumbent bicycle. This bicycle should be high enough to be seen over car hoods, with a long wheelbase and capable of using tires that are at least 1.25" wide. It should have disk brakes to ensure safely stopping this heavy bike from high speeds.

Because I prefer short wheelbase bikes, over seat steering bikes, that's what I will be looking for. With an electric bike, durability is more important than weight, so I am considering one of these Chinese made 26" suspended highracer bikes. Price? ~$1700
While my current 450 watt motor does fine when the road is flat, there is no head wind, and it's warm out, changes in these factors quickly reduce the speeds of the bike. Add in heavy winter clothing and cold stiff tires and speeds drop even further. What's the answer? Lots of "overhead". This will allow an electric bike operating at reduced efficiency to still provide good performance. I am aiming for 1000 watts this time.

You can buy all sorts of motors. My previous motor used gears and a chain to transmit power to the rear wheel. It worked fine but was a bit noisy, and required special mounting. This time I will be looking for a rear wheel hub motor, mounted on a 26" wheel. This will allow the motorized wheel to just bolt on to the rear dropouts. These hubs are available with up to 9 speed hubs and disk brakes.

High speed rear hub motors

Hub Watts Volts Speed Weight Disk 
Price with controller Source
Phoenix Racer 4840* 1000+ 48 36+ 23 lbs N $700 http://www.electricrider.com
5303* 1000+ 48 35 23 lbs N $750 http://ebikes.ca/
5302* 1000+ 48 55 (?!) 23 lbs N $750 http://ebikes.ca/
BMC 600W 1100 48 32 10.3 ? $944 http://www.hi-powercycles.com
BMC Black Lightning 1000+ 48 40+ 10.3 Y ~$1000 http://www.hi-powercycles.com
Phantom Green Hornet ? 48 33 15 ? $1000 http://www.forsenusa.com

* Crystalyte

I chose the BMC 600W, which is rated at 600 watts, but can easily demand over 1000 watts when used with a 40A controller and a 48V battery. If I want to be able to get to work and back, which is 1/2 hour each way, I need a battery that can deliver 1000 watts at 48V. This converts to needing about 20 amps (1000W / 48V = ~20A) for an hour, which means I need a 48V 20AH battery.

Lithium Battery overview
There so many types and configurations of batteries right now that it can all be quite confusing.

Batteries are rated by voltage (volts or V), amperage (current) that the battery can deliver for an hour (Amp-Hours or AH), and the maximum current the battery can safely produce. The maximum current is typically listed as a multiplier of the AH rating, or "C". For example, a 5AH battery with 3C rating can safely produce 15AH.

Lithium formulation batteries are now proliferating in a variety of chemistries. The two main types now being sold are LiFePO4 and LiPoly. The basic difference is that the LiFePO4 batteries are safer, but do not have as much ability to quickly dump their energy. LiFePO4 batteries are typically rated below 5C. The LiPoly batteries are the ones that have been getting the bad reputation for shooting jets of flame, but this only happens when LiPoly batteries are severely abused. The LiPoly batteies can deliver up to 30C!

Because Lithium batteries are all 3.7V, and bicycle motors require higher voltages, the batteries need to be strung together in series to generate those voltages. To get the 48V needed by my motor, I would need fourteen 20AH batteries in series.  If I saw a good deal on 5AH batteries and decided I wanted to use those, I would need fifty six batteries strung together in series and parallel. 

All lithium batteries require a battery management system (BMS) to ensure that the individual cells all charge to the same voltage. This is called "balancing" the batteries. Also the BMS normally ensures that they do not discharge below a certain voltage. Basically this means that the battery pack must have a separate circuit for each battery. You can this that this can get quite complicated! This is the dilemma of the electric cars manufacturers who need over 100V and a couple thousand AH. Fortunately, 20AH batteries are available, and so I will focus on those. Large cells are easier to manage with the BMS.

At 1000 watts and 48 volts, the motor uses 20 amps (watts / volts = amps). To get the range I need, the battery will need to run at 20 amps for about an hour, so I need a 20Ah battery.

Volts Amp
Price Ship C Lbs Size inches Formulation BMS? Charger? Lg
48 20 $725 ? 5 28 9.5x9.5x7.5 LiFePO4 Y N - $125 Y Forsen
51 20 $1399 $30 3 19 10x7x5 LiFePO4 Y Y Y Hi-Power Cycles
48 20 $600 $125 2 22 6.3x6.1x11 LiFePO4 Y Y Y Ping
48 20 $912 ? 15 32 7x8x12 LiFePO4 Y N Y Foxx
48 20 <$1000 ? 3 ? ? LiFePO4 N N Y Headway
51 20 $623 ? 3 26.4 7x6.5x12 LiFePo4 N Y Y Elite Power
                      High Tech
48 20 $328 ? 1 60 7x6x24 Lead-Acid N N Y Panasonic

If you like to live dangerously, and must have absolutely the highest power batteries possible, You can go with RC spec Lithium Polymer (LiPo) batteries. The best deal on these can be found on the Zippy Lipoly batteries, but it would still be almost $1000 for the fifty six 5Ah 3.7V 15C batteries which would be required to build the 51V 20AH battery pack. That's without any BMS or charger. On the other hand, because these batteries have such a high C rating, you could make a very lightweight 5AH battery pack with only 14 cells, that could generate the maximum current when needed, but would not go as far. If I kept the amount of electric assist low and only used 500W for the 1/2 hour ride to work, then recharged the pack at work, this would be a viable solution. Wow, it would weigh only 4 pounds!

Also important is a way to see how much power you are using. There are a few choices here as well:
RC Data Logger to use as a Wattage measurement device
Watts Up power measurement device
Cycle Analyst power measurement device

I have decided on the BMC 600 Watt motor, which will run at over 1000 watts with a 48 volt battery through a modified Crystalyte 40A controller. This BMC is a geared hub motor. I did not initially want a geared hub motor, but geared motors have their advantages. This motor has metal impregnated composite gears for greater strength, and the gearing allows it to freewheel when the motor is not running, unlike the direct drive hub motors which have some drag when the motor is not running. The motor's freewheel also means that this it cannot be used for regenerative braking, but that does not work so well on bicycles anyway. Motors on geared hubs operate at higher RPMs, so they can be smaller, lighter and higher efficiency. Advantages of this particular motor are that it can be fitted with a 9 speed cluster and a disk brake, and that it can be flogged to more than 30 MPH with the 48V battery (if needed).

The BMC motor has arrived, and it looks nice. It has the 9 speed cluster, and still fits in a standard 135mm MTB dropout. Now I need a bike and a battery. Also it has the mounting holes for the disk brake, but I need to add the spacer and brake
Times are tough and I don't know if I can afford to buy a recumbent bike to put this hub on. That means I may have to make a dual 26" bike to put this on. I think I have most of the parts already...

Here's my scale drawing of a dual 26" fully suspended highracer recumbent, that uses roughly the same geometry as the bike I was considering above. The box on the back would house the battery and controller.

Tony noted that if I'm building a bike, it should probably have the same riding position as my streamliner. After some measuring I found that my streamliner has a 45 degree seat back and the BB is 10" higher than the seat, Wow, no wonder that my streamliner performance has been lacking. The NoCom that I train on has an extremely open position, and the streamliner that I only ride at the races has a very closed position.
I drew another version of the commuter bike with a higher BB and more upright seat. This design needed two idlers for the power side, yuck. On the plus side, I found an old Turner fiberglass seat which should work well for that upright position.

After giving it a few days thought, and thinking how much of a PITA it was going to be to fabricate that rear swing arm, I decided to go an easier route similar to the way that I did that I built my last electric bike. I did that by buying a cheap full suspension bike and using it's parts.
This time I need 26" wheels and want it to be lighter. Due to economies of scale, you can get a nice full suspension mountain bike with disk brakes, quick release skewers, and aluminum frame for cheap. I found this one online for $420 shipped. I will be able to use almost all of the Mtn bike except the frame and seat!
I drew a third version of the commuter bike, using the Mountain bike suspension rear triangle and front suspension. It uses just one power idler, much better! It's very tall though, with a 26 inch seat height and 36" BB height, good thing I have long legs! This height will be fine since this will be a commuter bike.

I'll be able to mount the electric stuff to the Mtn bike and test it out while building the recumbent frame.

Here's the Windsor Ghost Mountain Bike I received from bikesdirect.com. I added the kickstand and rack. This is the "before" picture.

I'm still deciding on the battery pack.

The motor is now mounted on the bike. This was very easy. I had to drill out the air valve hole as it was drilled for presta and I'll be using schrader tubes. I added a new rim strip, and mounted the bike tire and tube from the original rim. I removed the disk brake rotor from the original wheel, and mounted it onto the motor. Then it just a matter of bolting the wheel onto the bike.
The motor is noticeable if you look closely, but it's still pretty stealthy. The motor wire, which I attached to the brake cable with velcro straps, is also not too noticeable.

I decided to order a ping battery, and have them break it into two packs 6.3"x3"x11". This will make it easy to put the two packs into panniers, leaving the main part of the bag free for clothes and lunch and stuff.

Also I ordered the Cycle Analyst. There are couple different styles, but the one I ordered (C-DPS) plugs right into a modified Crystalyte controller and will allow me to set the maximum current and speed, as well as see all the geeky specs about how much power I'm using. This will be important as the Ping batteries  should not be run at over 40 amps. The motor and controller I'm using are capable of higher current, and I don't want to shorten the life of the battery, or have it cut out while I'm cruising like my current system does. This system should be practically plug-n-play.

The Cycle Analyst arrived, but I discover that my controller had not been "modified" with a connector to plug it directly in. Fortunately, High Power Cycles said they would supply the correct controller, so I sent the original one back.

Eventually I will need to use connectors to allow the with the batteries & controller to be easily removed. Anderson PowerPoles are the connector of choice for this task.

According to the Gear inch Calculator, I need a 52T front chain ring to allow me to pedal at 30 MPH. Ok, time to raid the parts bucket.

The Ping 48V 20A battery arrived today from China. It was packed in about 5 layers of packaging, and was in good condition. 2 weeks is great turnaround time to have a battery made in China and have it delivered to your doorstep.

I had them build the battery in two 24V packs. This will give me more options to hang the batteries. These packs weigh 10 lbs each. That seems pretty heavy, but is actually pretty light considering the power that these will deliver.

Because the lightweight aluminum post rack was not designed to support 25 lbs of stuff, I added a support to triangulate it.

I had originally planned to use the plastic Otivia box for the batteries, but it seems too flimsy for the weight of the batteries. One crash and it would fly to pieces. Next I made a cardboard box the same size as my batteries, went to Performance bicycle, and tried some pannier bags. I bought some on sale, but they are much deeper than I need. 

I found some small pannier bagss at the LBS which seem to be a better size and the modified controller finally arrived from Hi-Power cycles, so I was able to put it all together.
I strapped everything together, plugged it all in and went for a test ride up and down the street. It works! I did not have the speedo hooked up yet so I could not tell what the top speed was, but the acceleration was brisk. The CycleAnalyst said that the peak power was around 1600 watts, and at top speed the battery seemed like it was cutting out. I think this was because I had not charged the battery. High voltage was 54V and the low voltage was 36V. I think the battery pack turns itself off at the low voltage. I need to charge it up and try again.
This picture shows the 9 speed cluster and the torque arm. The torque arm is required on hub motors over about 300 watts to prevent the axel from spinning in the dropouts. This is especially important on aluminum frames like this one.
I mounted  the controller to the rack, and made some panels out of black coroplast to hide all the wires.

The issue with the CycleAnalyst seemed to be that it had the limiting setting set too low. I charged the battery, set the CA to 50amps max and it seemed to cure the problem. Also Hi-Power Cycles said to set the shunt resistance to 1.2mOhm. The CA is a nice device, but needs to be calibrated to the specific controller/motor combination, not many of these calibration values are documented, and you need fancy current measurement equipment to calibrate it for yourself.

Here is the completed mountain bike version of the Zcommutor. I'll ride it like this until I can build or obtain a dual 26" suspended recumbent frame.

Testing the bike around and around the block showed that it gets up to about 30MPH within a block. That seems to be the top speed in this very un-aerodynamic format, and with slow knobby mountain bike tires.

Looks pretty stealth!

Finally we got a nice day for me to ride the e-mountain bike to work. This was the first time I have ridden an upright bike for any distance for over 10 years and it felt very strange. It's a tall bike, and I'm a tall guy and I was way the heck up in the air. The bike did perform well though, cruising at 30 MPH and going up hills at 25 MPH. Acceleration was brisk and with all the weight in the back I had to be careful not to pop a wheelie when taking off from a stop. While this is all well and good, this is an upright bike, and I am performing an unnatural act by riding it. As such I will be working toward building or obtaining a recumbent to use this e-assist system with. In the meantime, I'll be trading off between commuting on the faired e-cuda and the e-MTB.
Along those lines, I was able to work a deal with the Performer Bicycle company. This company has been quietly churning out a variety of recumbent bikes for 9 years and selling them through US importers like Actionbent. They are now selling them direct. They were kind enough to donate a Performer "Goal" rear suspended dual 26" recumbent frameset. It arrived last week and I am acquiring parts to build it up. After I build it up I will write up a review on the bike. Later, I'll move the e-parts from the MTB above to this bike.
I tried to charge the Ping battery for the first time and the little charger seemed to think that the battery was already charged. After much troubleshooting and emails back and forth to Ping, we decided that the BMS was bad and he sent out a new one from China. After soldering the new BMS in, and putting everything back together, the battery charged fine and all was good in the world. Not exactly plug-n-play, so unless you can put up with that type of excitement, a vendor from the good 'ole US of A may be a better choice. Fortunately there are now a couple new vendors in the USA who supply LiFePo4 batteries at a good price point.

I have ridden the e-MTB a couple more times to work and it's actually faster then the low powered recumbent because it accelerates quickly, even though I feel like a giant 6 foot 6" parachute being shoved through the air. When I let off the brakes at 30 MPH it feels like I put the brakes on as opposed to the recumbent that just coasts. Part of that is the knobby tires but most of it is my huge frontal area.

Here are some round trip statistics from the CycleAnalyst
Amp hours used: 15.65
Watt-hours: 724.43
Watt per mile: 44
Max current: 79.66 A
Minimum voltage: 26.5V
Max speed: 34.4 MPH Average speed: 24.1 MPH
Trip time: 40m 59s


The CycleAnalyst measures the battery current (watts and amps) by sensing the voltage across a shunt resistor. If you have the CycleAnalyst model that comes with a shunt resistor that is designed to fit between your battery and the controller, the shunt resistance is preset.  If you have the CycleAnalyst model that plugs directly into the controller, it measures the voltage across the shunt resistance inside the controller., which varies for every controller model. The CycleAnalyst is set by default to 1 mOhm, but that may not be the correct setting for your controller.  To test the CycleAnalyst shunt resistance setting, you can use a volt-ohm meter (VOM) with current measuring ability, like the Fluke meter which can measure up to 10 amps. Hook up you meter in series between the battery and controller, and with the wheel off the ground, crank up the motor so it uses around 5 amps on the meter. Compare that to the CycleAnalyst. You can vary the shunt resistance on the CycleAnalyst until it matches the VOM.

I purchased some Kenda Kross tires to replace the mountain bike tires. These 1.95" wide tires are smooth in the middle of the tire and have a row of knobs on the sides where they normally stay out of the way. Wow, what a difference. The bike is about 2 MPH faster now, and it doesn't feel like the brakes are on as hard when I let off of  the throttle. Also the bike seems to handle better, which is a good thing as I still don't feel at home on an upright bike.

Here's my Performer Goal, it is almost completely built now.  Despite several digressions, making this bike electric assist is the "goal" of this exercise. 
I have discovered that riding at the high speeds that are inherent with motorized travel (30MPH) means that you need more eye and ear protection than are provided by a traditional bike and glasses. On colder days my eyes were tear up to the point where it was hard to see, and on days with a headwind, the wind noise was so loud that my ears would hurt after a commute. I investigated many options, and finally ended up with a Casco warp II helmet (Thanks Garrie!). This helmet is lightweight, provides excellent eye protection, and good ear protection. I still may add some foam or carbon to further protect the ears. It feels like a very lightweight motorcycle helmet...
I'm considering changing the battery location to be mounted up by the head tube. The tube mount rack is laterally unstable, so it rubs the tires occasionally. Also, all the weight behind the seat makes the bike handle a bit squirrelly. The batteries will be a bit wide, but I think there will still be enough room for me to pedal normally. I'll be able to stash the controller between the batteries.  The bike won't look as stealth, but it should handle better, and I won't be scared about taking it over big bumps or over curbs.
I'm still riding the upright bike to work, but the Goal recumbent is getting closer to being e-bike ready. I still need to obtain a kickstand and a rear rack.
I obtained a kickstand and rack for the Goal recumbent from Actionbent. Both need some modifications to make them work properly, but it looks like they should be able to hold the batteries securely.

I am getting increasingly intolerant of the Ping Battery's BMS cutting off the power during my commutes. After it gets warm, it appears to cut off any time the current gets above 40A (2000 watts). This means any time I try to accelerate up hills or take off fast from a stop I need to turn off the battery power and turn it back on. The CycleAnalyst has an option to limit the battery current, but it does not seem to be able to react fast enough to prevent the BMS cutouts. One thing that has been discussed is adding A123 batteries in parallel with each Ping cell. These batteries have high current capabilities that should help the Ping cells during high current situations. Or I could just buy another battery. Adding the A123 cells would be expensive anyway.
I decided to move the Ping batteries on the mountain bike to the head tube area. The batteries will be attached to the bike with a frame built from 1/8"x 3/4" aluminum strap. I made a cardboard box the same size as my batteries to size it. The aluminum strap was formed using the tools shown here, and is fastened together with steel pop rivets.
Here are the two frames on the bike. The battery actually extends forward of the head tube to provide knee clearance. There is plenty of clearance for the fork and handlebars. I will mount the BMS between the batteries, and the controller will be mounted to the frame behind the batteries. I'll cover it all with black coroplast.
Here's the first connection strap. This fastens the frames together and provides more support for the battery.
I mounted the Ping batteries to the frame. The Ping batteries are in Coroplast boxes, which were slid into the framework. I also shortened up some wires and added a heavier duty switch and fuse holder. The top normally is covered with a black coroplast panel.

I did my usual 14 mile round trip commute today, and the bike now feels different, but handles much better.

I still need to move the controller from the rear rack to inside the frame triangle, between the batteries.

I moved the controller to under the top tube, behind the batteries and covered it with some sheets of black Coroplast.
Yes, I'm still riding the upwrong to work. To increase the "stealth" factor and make it faster I made the following changes:
  • Moved the controller from under the top tube to on top of the batteries
  • Added thicker phase (power) wires from the controller to the hub.
  • Shortened the wires from the batteries to the controller
  • Changed connects to 50A Anderson connectors
  • Hid the wires under white tape.
  • Covered the batteries in black nylon.
  • Replaced the rear boingy shock with a Fox air shock to prevent wheel hop over bumps.
The FETs on the V1 Signalab BMS got so hot that they unsoldered themselves from the BMS backplane and the bike didn't work so well like that.

I soldered them back on and added a heat sink. After putting it all back together and taking it for a ride around the block I found that the heat sink was already hot. Wow it's amazing it worked for 2 years like that.

The BMS used to shut down the battery any time I accelerated a little too fast, even though the Cycle Analyst limits the controller to 20A (2C). This issue was always worse after I had been riding for a while so apparently this was due to the FETs heating up. Since I added the heat sink I have not had this issue.

After a commute last week I noticed a strong burning electronics smell. That smell did not improve when I charged the battery, so I took it apart again. Those cracks in the FET do not look so good. The FETs must have been damaged when they got hot enough to unsolder themselves last month. Note that the FETs have all identifying markings sanded off of them. This makes them more difficult to replace. I have sent an e-mail to the battery manufacturer Ping to get the replacement part number. PIng said to replace them with  IRFB 4110 or 4310. I cross-referenced it to a STP165N10F4 at mouser.com
I replaced the FETs and had a great commute - about half way to work, but then the BMS started to cut out repeatedly, so I had to limp home and then drive my car to work. I'm not sure what the deal was and was tired of messing with it, so I just ordered a new V2.5 BMS from Ping and installed it. This one has spiffy LEDs to indicate the charging status of each cell. I took it for a test ride and it seems to work fine. Hopefully there will be a nice day to test it out on a commute to work soon.

2/3/2013 - CODA

Replacing the FETs did not completely fix the BMS, so I ordered a new one from Ping. The new BMS worked great. Because I have been riding my CF weight weenie high racer I was not riding the Performer Goal, so I sold it. Because I have been commuting on my Cuda - E fully suspended RC motor powered recumbent, I stopped riding the upright E-bike, so it was time to try something new with that e-bike drive system. The
"Barracuda Bobber" Electric Chopper was born in 2012. After building the chopper, I sold the MTB bike frameset. So, I sold both bikes on this page, and am riding 3 bikes I built in their place.

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