Water cooling is happening

One of our test motors being fitted for water cooling.

Time to get back into some technical work
I have been working on a way to detect if a cell goes low in a LIFEPO4 pack without monitoring every cell. The method works only if the cells are top balanced. The pack I did the development work with is a 42 cell 40AH GBS pack from Elite power solutions using there basic balancer board that sits on top of the cell. This is a stand alone board with no commutation to any readout board or computer. So I have no wires coming off the cells for monitoring.

The method I proposed is based on the principle that if you top balance then when the pack starts to be drained one cell, the cell with the lowest capacity will drop in voltage first. This being said if one broke the pack into two half for measurement purposes  

Positive














Center tap














Negative


Now if we  measure the balance between the two half's when the pack is near drained one cell is going to drop in voltage first causing a measured imbalance between the two half's secondly the voltage difference between the two half's will become noisy meaning the voltage will bounce around as the cell hit there knee and drop in voltage. This setup can also detect which cell is fully charged first as it's voltage rises above the other cells again causing a pack imbalance.

This is how I set up to measure the balance between the two half's

All the resistors are .1% 100ppm drift very high precision wire wound resistors
Observations:

1. The balance between the two half of the pack has never deviated more than 20mv
2. A one volt drop in a single cell is 200 mv
3. When the pack is full charged and in balance mode I see no more than 70mv
4. I I intentionally unbalance the two half's .1watt drain on one half of the pack for 48 hours, when the pack started top balancing I observed 1 volt of unbalance, The balances did there job and the pack settled out at 70mv

For a first test to manually see if this is a viable method to detect a first cell or a series of cells at there knee voltage I concluded it is a good method to detect the point in which one should stop using a battery pack and call it drained. This method is very poor at determining state of charge and can only detect when to stop using a pack or risk cell damage. In combination with counting Watt-hr per mile to determine range I feel a almost fool proof method for a battery gauge and  protection can be developed without running wires to monitor every cell or communication links daisy chaining from cell to cell. 

You know you want a Fighter

New video of our latest build - You know you want a Fighter

Our newest Demo bike The EnerTrac Electric

She's almost finished
Specifications

• Donor bike Electromotorsport GPR-S with extended swingarm
• EnerTrac Dual motor system DU-603 (30KW continuous power) with a 18 X 6.25 forged aluminum wheel
• Batteries elitepowersolutions.com/  40 cell 136 volt 40AH with cell balancers
• Controller Kelly Controller KHB 144 volt 500 amp
• Instrumentation ebike.ca  Cycle Analyst

That covers the basics  
She'll be on the road in a few days

Latest addition

As the number of projects increase we were in dire need of a additional Lathe We got one this week

Time for new batteries

I have been struggling with thundersky batteries for way to long and have decided to try a Lipo pack in the bike

Here is a picture compilation of the process from cells to pack in the bike. As of this writing she still isn't back together but will be in a few days.
The cells come from Hobby King Turngy four cell 5AH hard case packs. I'm building this up as a 8P 28S pack or 115 volts @ 40AH. We'll see how these fair over time and hopefully without any incidents

A second side benefit is the bike is losing over 50 pound of weight!

eFXC final race

Another great video from Andy

Street fighter build

We have had these rollers in the shop for a while just waiting for a time when we could build them up. With the Dual motor setup being a best seller we needed a demo bike to show off what the DU-600 series motors could do and how they look. So we took a GPRS extended the swingarm (150mm) and turned it into a street fighter style bike.

She is far from being finished but here is the bike outside after the first Frankinride using a 500 amp 144 volt Kelly controller. with a 96 volt Lipo pack capable of over 300 amps

Lots of work still needs to be done to make her a proper show bike but the foundation is there.
Customer reaction:

Two motors in a light weight frame = fast of the line

Race #2 Winton race track

EnerTrac continues it's sponsorship of the Catavolt team and Thanks to Andy of evmotorcycle.org we have a great video of the race event

EnerTrac sponsors the CataVolt race team

Dual motor Big bikes get a hub motor

 

Dual Motor/wheel setup in a swingarm

Multi speed motors and gear boxes

Now the question
What if you want to accelerate well and go fast?

lets all agree it takes the same HP to go say 100MPH regardless if there is a gearbox, multispeed motor or not

So there is no free ride here if the motor can't put out the power no gearbox or multispeed motor is going to get the bike to speed.
The power plant needs to be in a proper operating RPM to be efficient and output the power needed for the speed required.

If you have a wide torque curve as most electric motors do then maybe you don't need a gearbox or multispeed motor but even an electric motor has a most efficient RPM and that is up around 60 to 80% of the max RPM (BEMF) So even thought a gearbox may not be necessary, it will result in more HP because the motor is operating in its most efficient region. For a multispeed motor implemented correctly this is also true. Since a high wind count motor has more amp-turns it has higher torque for the same current (which will result in overheating if sustained) or half the current for the same torque (the correct way to look at it) but it trades speed for torque and will be voltage starved at half the RPM, So the 60% of max RPM is reached early and so does Max efficiency. Then if one switches to half the turns and doubles the KV of the motor it is now possible to get higher RPM and again achieve max efficiency.

In Conclusion more power is achieved with both the gearbox and the multispeed motor because the motor is spending more time at higher efficiency really no other reason, but the gearbox has losses that make the gain in motor efficiency sustainably less power to the tire. The gearbox losses are not present in the multispeed motor design.

MHM-602 race motor

EnerTrac is sponsoring team Catavolt
here are some pictures of the bike.

More to report as the bike goes on the Dyno, then raced in the TTXGP
Here is my thinking The bike that has the best batteries and holds more of them wins

Team Catavolt is using excellent batteries and with no motor in the engine bay the bike can hold more of them

She is still pretty

I'm back on the bike Oh glory its good to be riding again. The Lipo boost pack is proving out well, I'll have more data shortly. What has been speculation as to road performance and only measured on the Dyno is now fact. The Lipo pack starts sharing current at 60 amps at 100 amps the balance is about 60/40 and I've seen peaks as high as 80 amps from the Lipo booster. On the highway at 60 MPH and 80 amps the Lipo pack will contribute 20 amps. Temperture just isn't a big factor in how the LIFEPO4 and Lipo packs share current.

Just to Review
This Motorcycle started life as a New Lifan 200
Battery:
34 cell 40AH Thundersky LIFEPO4 pack 115 volts fully charged
Boost pact Diode summed 25 cell 10AH Lipo pack with contactor disconnect
 Boost pack schematic
Motor:
BLDC (5RPM/volt -10RPM/volt) 10KW, 30KW peak Hub motor with two speed winding and on the fly switching
Controller:
Kelly Controller KBL12401I adjusted for 250 amps peak
Weight:
350 pounds
Speed:
65 to 70 MPH (Depends on tire size and voltage)
Acceleration:
0 to 50 in about 6 to 8 sec. (Depends on tire size and current)

Miles to date on the motor over 4000
Miles to date with two speed winding 1000
Miles to date on rotor spokes rim and magnets over 5500

Can she be duplicated YES is she cheap NO

Lipo and LIFEPO4

I'm doing a interesting mixed chemistry setup that uses the best of LIFEPO4 and Lipo in a diode summed system.
My motivation in doing this stems from the fact that the 40AH Thundersky cells just don't put out enough voltage under load (Sag). For EnerTrac this makes it difficult for my customers to get a true understanding of the power and speed of the 600 series motor, when test riding my bikes. So I need a way to boost voltage under load, without replacing the complete battery pack.

 In the above picture you'll see the CA meter (lower) and a second smaller meter up top. The top meter monitors the Lipo pack current while the CA meter monitors the total system. Up to 1.5C or 60 amps, the LIFEPO4 batteries run the bike, then as current exceeds 60 amps or beyond 2C the LIPO kick in. At 100 amps the LIFEPO4 pack maintain 1.5C and the Lipo pack does the remaining 40 amps. My 40AH LIFEPO4 cells now never see much over 60 amps while my 20C rated Lipo see as much as 200 amps peak.
The Lipo are bulk charged with a separate Meanwell type power supply. Separate balance units are used as needed, they are connected in parallel with the display units.

I accomplished this by exploiting the fact that Thundersky cell have much higher IR than the Lipo cells and setting the Thundersky pack to be at a higher no load voltage. The diodes are 150 volt schocky diodes.
Testing was done on my Dyno. The box under the bike is the Lipo pack 25S 2P

 

I have only done 4 miles of road testing before the snow hit. I had the Lipo up to 100 amps while the LIFEPO4 stayed under 80 amps during this on road test.
My Dyno Currently can only do 100 amps continuous, measured at controller input. My plan is to do a video record of the display system so I can record in real time the speed, current of both batteries and then put the data in a spreadsheet.
My data so far shows temperature not to be a big problem I've had the batteries on test from 45F to 70F
My big concern is
The 4 to 1 AH ratio - is it correct, only on road testing can determine that.
Battery pack

I think the battery box weights more than the batteries.
The big challenge was getting all the hardware into the bike and still be able to get the skins on.

The bike with the skins back on

I have under belly skins that will mostly hide the Lipo battery box

Conclusion:
More data is needed but my testing to date, shows it's possible to mix two chemistry types and use the best characteristics of each respective battery type.

Mark

Custom Wheels

We have been busy working on using our existing 602 and 603 motor and integrating them into aluminum rims. This is a customer job in progress. We machined all the parts in house. We started with a RC components rim and worked from there. One thing you'll notice is the dual rotors for dual disc brakes.

 This is a 16 inch X 3.5 inch rim.
 With the customers permission I'll show the wheel fitted to his fork.
EnerTrac can now offer rims from All American Wheel
2011 will be the start of custom wheels from EnerTrac.

Enertrac is also doing custom spoked wheel at different sizes and widths.
We just finished this wheel for a customer in CA.

3.5 X 17 inch
Warp 9 rim 602 motor

The next update we'll show is forced air cooling. We have been testing it on our dirt bike build. The blower motor is temperature and throttle position controlled. Our experiments are leading us to believe that twice the output power maybe possible with our forced air cooling method.

Chopper wheel

As powerful as the 602 motor from EnerTrac is it really wasn't powerful enough for the 600 to 800 pound 
chopper Hence the DU-602 product. Its two motors locked together using one controller.

Two stators one on common shaft

The axle is 250mm long. I can get cast aluminum rim 16 to 21 inches in size any width

If it needs an electric motor, EnerTrac will move it

One place a very efficient traction motor is needed is in Solar cars. The only motor to address this market at the 10KW power level is way expensive, like 6 times the cost of a EnerTrac product. EnerTrac is capable of doing the same job being a 10KW product.

EnerTrac is offering a two speed motor 602/604 that can vary the torque speed ratio depending on the winging chosen. For the solar car application we are hand fitting the bearings and doing other trick to squeeze as much efficiency as possible out of the motor.

Can EnerTrac claim to be as good a a NuGen motor, I'll let the teams decide. What I do know is at our price many more teams can enter the engineering challenge of solar car racing. I'm sure properly used the EnerTrac 602/604 will prove to be a strong contender in the solar drive system world.
SO WHO IS FIRST:
Newburgh Free Academy Solar Racing Team
EnerTrac is proud to be supplying the motor for this team and bring a race ready car down in price so many more can experience the challenge. We are preparing the motors now, They are built, being tested and characterized, every motor for this application will be custom built and individually tested.

EnerTrac rides the dirt

E-transmission refinements

I now have over 100 miles on the 4 turn /2 turn system.
The most important operating parameter is not to switch when there is drive current in the phase wires. I designed a simple system to detect throttle position using a micro switch on the throttle body

When in the zero throttle position the switch is closed
 allowing winding switching












I also added momentary push button switching with the use of a latching control relay