# My eZuma project (Elektra)

Discussion in 'Electric Motorcycles' started by MJSfoto1956, Sep 16, 2018.

1. ### MJSfoto1956Been here awhile

Joined:
May 12, 2017
Oddometer:
505
Location:
Boston, MA
It took a while for the parts to arrive from China, but I finally have the rear-end parts/mods sorted out. The list of mods includes the following:
1. Installed rear fairing
2. Removed rear fender with Dremel but kept original license plate mounts and reflectors
3. Installed one-arm tire hugger/fender
4. Adjustable aluminum swing-arm (this will be key to allow me to install a much taller tire on a 13" rim)
6. Upgraded leaking turn signals with a proper pair from Baja Designs

This is what she looks like now:

Next up is to install an upgraded programmable controller...

M
voltsxamps and RCmoto like this.
2. ### MJSfoto1956Been here awhile

Joined:
May 12, 2017
Oddometer:
505
Location:
Boston, MA
Lesson 1: the relationship of battery pack size to electric motor size

For those of you new to how to calculate lithium battery pack sizing vs. electric motor sizing here is what I am using for my build.

Basically, I have decided on an 8000W hub motor with the goal of achieving 100kph top speed on level ground. Additionally since this is a scooter, I am somewhat restricted to a 20s16p 18650 battery pack which just happens to fit into my existing battery tray (i.e. a lithium battery pack consisting of 20 serialized sets of 16 cells in parallel, total 320 cells). But how did I come to this setup? For the best results, one must match one's battery pack to the motor. So for starters, we need to convert the 8000W to Amps. Since I will be using 72V (i.e. 20 series @ 3.6V = 72V) the math is easy:
• 8000W / 72V = 111A
From the equation above, I conclude that in order to make best use of a 8kW motor, my 72V battery pack must be able to supply 111 Amps to it on demand. Since I am using a pack made up go 17p modules, one of the most-powerful, most-reliable battery cells I can pack into that space is a Panasonic 18650B Li-ion battery which delivers 3400mAh each. That leads to the next calculation:
• 17p @ 3400mAh = 57.8Ah
Ok, my pack can deliver 57.8 Amp hours -- so far so good. But how do I "convert" Amp hours into "Amps"? Well, we need to know the max discharge rate of the cells. In general pretty much any lithium cell these days can discharge @ 1C. So at a constant rate an "ordinary" 3400mAh 18650 24s16p battery pack could theoretically deliver:
• 57.8Ah @ 1C = 57.8A
Which is just over half of what the motor is capable of. Put another way, if I only use "ordinary" 18650 cells, I might as well limit myself to just a 5000W motor. So I either need to nearly double my battery pack or use cells that can discharge @ 2c. It turns out that Panasonic 18650B Li-ion batteries can indeed discharge @ 2c. Thus we have::
• 57.8Ah @ 2C = 115.6A
Which is slightly more than what the motor is asking for, so I'm good to go with the Panasonic's. As a side note: lithium battery life would be much better @ 1c than 2c due to heat and stress, but this being Phase 1 of my build the numbers add up nicely and I am going with it.

Michael
flinders_72 likes this.
3. ### MJSfoto1956Been here awhile

Joined:
May 12, 2017
Oddometer:
505
Location:
Boston, MA
So if I ditch the BabyBloc balancers (one per parallel module) and replace them with a traditional BMS, what might that look like using a pack made of NESE modules? In particular, what might it look like if I max out the capability of a PowerVelocity controller which is limited to 100V?

Well, this is what it would look like. Basically swapping one form of complexity for another. No free lunch folks.

I might add that 84V 150A relays are not cheap...

4. ### MJSfoto1956Been here awhile

Joined:
May 12, 2017
Oddometer:
505
Location:
Boston, MA
Here's an alternate battery setup using a different BMS. Much simpler layout, similar specs.

5. ### MJSfoto1956Been here awhile

Joined:
May 12, 2017
Oddometer:
505
Location:
Boston, MA
Pretty close to final layout, now including the controller and accessories:

PowerVelocity 20kW Controller + QS273 + 20s BMS + eighty 5p N.E.S.E. Modules: 20s20p pack (72V 72Ah)

BOM (Bill of Materials) for the above 20s20p system:
• (80) N.E.S.E. 5p Modules
• (80) N.E.S.E. Serial bus bars
• (80) N.E.S.E. double caps
• (400) 18650 3400mAh Li-ion batteries
• (1) VLDL DANL 72V max 20A charger
• (1) Daly 20s 150A BMS
• (1) 72Vdc/12Vdc Waterproof 25A converter
• (1) PowerVelocity 20kW controller + Bluetooth app
• (4) 6AWG 2-hole lugs
• (3) 6AWG 1-hole lugs
• (3) 6AWG non-insulated flag terminals
• (3) 8AWG 1-hole lugs
• (4) 10AWG 1-hole lugs
• (4) 6AWG Silicone Wire
• (1) XT90 spark resistant adapter
• (1) C-13 panel mount 110V adapter
• (1) US 110V --> C-13 extension cord
• (1) J1772 --> C-13 adapter cable
• (1) 75A circuit breaker
• (1) 25A circuit breaker
• (1) 20A circuit breaker
• (2) recharge resistors
• (1) zener diode
6. ### MJSfoto1956Been here awhile

Joined:
May 12, 2017
Oddometer:
505
Location:
Boston, MA
The basic idea: My eScooter as the center of a modular charge/discharge system

7. ### MJSfoto1956Been here awhile

Joined:
May 12, 2017
Oddometer:
505
Location:
Boston, MA
here is an updated design detail for the 20s20p battery pack:

8. ### MJSfoto1956Been here awhile

Joined:
May 12, 2017
Oddometer:
505
Location:
Boston, MA
So after consulting with a few experts in the field of electric golf carts and fork lifts, they are all aghast at the idea of running a system without a contactor. Given that, I went back to the literal drawing board and now have come up with the following layout.

New this version 6a:

1.) Re-introduced a contactor to the main power to the controller, controlled by a ZEVA smart recharger (see http://www.evwest.com/catalog/product_info.php?products_id=299)
2.) As per above, added 12Vdc ZEVA smart precharger circuit to control the contactor, powered by the (optional) 12Vdc output from the PowerVelocity controller
3.) gave up on the Curtis DC-DC converter as it cannot be sourced in the USA as a switched version ("we never heard of that..."). Replaced with a converter from electriccarpartscompany.com instead

Michael

PowerVelocity 20kW Controller + QS273 + 20s BMS + (80) 5p NESE Modules: 20s20p pack (72V 68Ah)

BOM (Bill of Materials) for the above 20s20p system:

(400) 18650 3400mAh Li-ion batteries
(80) N.E.S.E. 5p Modules
(40) aluminum U channel sections -- silver plated
(1) 20s BMS
(1) VLDL DANL 72V 20A charger
(1) 72Vdc --> 12Vdc Waterproof 50A DC-DC converter
(1) PowerVelocity 20kW controller + Bluetooth app
(2) 4AWG 2-hole lugs
(4) 4AWG non-insulated flag terminals
(2) 4AWG 1-hole lugs
(4) 6AWG 1-hole lugs
(4) 10AWG 1-hole lugs
(1) roll of 4AWG Silicone Wire
(1) roll of 6AWG Silicone Wire
(1) C-13 panel mount 110V adapter
(1) US 110V --> C-13 extension cord
(1) J1772 --> C-13 adapter cable
(1) 80A circuit breaker
(1) 20A circuit breaker
(1) 10A circuit breaker
(1) 2A circuit breaker
(1) ZEVA Smart Precharger
(1) Gigavac P195 Minitactor
(1) 125A Time Delay Blade Fiberglass Limiter Fuse 80VAC/DC
9. ### MJSfoto1956Been here awhile

Joined:
May 12, 2017
Oddometer:
505
Location:
Boston, MA
Some details I've been sketching regarding my preference for waterproof electrical boxes to protect the majority of the various controller/motor connections.

Michael

PowerVelocity controller + ZEVA smart recharge circuit + Gigavac P195 Minitactor +
10. ### MJSfoto1956Been here awhile

Joined:
May 12, 2017
Oddometer:
505
Location:
Boston, MA
Ok. Reality set it. Budgets need to be viable. After much consideration, I calculated that it is cheaper/faster/easier for me to order a custom-made battery pack directly from AliExpress. As such, I had to revise my design a bit. Further, I had to scale back what constituted "Phase 1" -- i.e. the bare minimum to bootstrap the project. So by trimming things to the bare bone, I now present to you
Phase 1: PowerVelocity 20kW Controller + QS260 + AliExpress Battery Pack 20s17p @ 72V 57Ah

Whose bill of materials now looks like the following (most items have been ordered as of today):
• 20s17p Li-ion Battery + 120A BMS + 5A Charger. 330x220x140mm (+/-5mm)
• Wuxing half-twist throttle
• 125A circuit breaker
• 10A circuit breaker
• 2A circuit breaker
• 100mm DIN 35mm rail
• PowerVelocity 20kW controller + Bluetooth app
• PVC junction boxes
• Tyco EV200 Contactor
• ZEVA Smart Precharger
• Bussmann 2P Miniature Distribution Block
• 4AWG Tinned Marine Battery cable
• 2AWG Tinned Marine Battery cable
• 4AWG lugs
• Terminal boots
• Anderson SB120 connector kit
• ProTool Heavy-Duty Battery Cable Terminal Crimping Tool - 8 to 4/0 AWG - Taiwan
TOTAL: \$2590

Given the 57Ah lithium battery pack @ 80% discharge vs. 20Ah lead battery pack @ 50% discharge, I estimate I will have approximately (57*.8/20*.5) 4.5x more distance with the new lithium system -- or darn close to 100mi range per charge. I also expect some improvement in top speed and acceleration due to the improved PV controller (even though the 2000W motor remains unchanged for Phase 1). Next up is to set up a test bench in my basement to wire everything up during the cold winter months ahead.

M
voltsxamps likes this.
11. ### MJSfoto1956Been here awhile

Joined:
May 12, 2017
Oddometer:
505
Location:
Boston, MA
FWIW, this is what Phase 2 might look like:

Michael

PowerVelocity 20kW Controller + QS273 + AliExpress Battery Pack 20s17p @ 72V 57Ah
12. ### MJSfoto1956Been here awhile

Joined:
May 12, 2017
Oddometer:
505
Location:
Boston, MA
And finally, here is what the 340 cell, 57Ah battery pack will look like when installed next spring:

13. ### MJSfoto1956Been here awhile

Joined:
May 12, 2017
Oddometer:
505
Location:
Boston, MA
While I await the parts from various suppliers, my next focus is where to position all the bunches of items most efficiently. To that end I'm thinking that the primary junction box might best be situated into the base floor of the scooter itself. While I "could" steal room from the underseat storage, I'd like to keep that space if possible (after all, this is a scooter!). To wit:

14. ### webmonstroA Aventura Continua....

Joined:
Jul 21, 2008
Oddometer:
1,163
Location:
Portugal
Awesome information you are providing . This is really going to be great when finished . !
MJSfoto1956 likes this.
15. ### MJSfoto1956Been here awhile

Joined:
May 12, 2017
Oddometer:
505
Location:
Boston, MA
The parts are starting to arrive from all over (China, Australia, USA). I expect I get get it all together on my bench within the next three weeks. In the meantime, here is what my bench test will look like:

Michael

Bench test: PowerVelocity Controller + AliExpress custom battery pack + QS 260 2000W motor
16. ### MJSfoto1956Been here awhile

Joined:
May 12, 2017
Oddometer:
505
Location:
Boston, MA
So I'm just now starting to bench-test my eZuma upgrade build and the first thing to tackle was making my wiring more manageable. To that end, I decided to start with the controller and its spider-web of wires and (un-waterproof) connectors. The concept was simple: keep it neat and keep it cheap. So off to Lowes to pick up a basic 1" electrical conduit box and two junction box adapters. From Amazon I ordered two large Daystar universal firewall boots, which just so happen to fit perfectly to the 1" junction box adapters. And of course you'll need some heat-shrink tubing as well as self-fusing tape. The picture below should say it all. On to the next item...

M

voltsxamps likes this.
17. ### MJSfoto1956Been here awhile

Joined:
May 12, 2017
Oddometer:
505
Location:
Boston, MA
So I took a chance and purchased a 20s17p 57Ah battery pack from an AliExpress vendor touting 8 years experience. The nice thing was how easy it was to work with them -- I asked for a custom layout (i.e. 20s17p/120A BMS) and within a day they gave me a link to make the purchase. Took more than 4 weeks to get here, but I expected that. Here is the actual pack after it arrived via Fedex Ground (N.B. I Photoshopped the background out):

voltsxamps likes this.
18. ### MJSfoto1956Been here awhile

Joined:
May 12, 2017
Oddometer:
505
Location:
Boston, MA
Being the curious type, I wanted to see how this battery was constructed. So off came the PVC shrink wrap et voilĂˇ. Interesting how little Kapton tape they used. Instead opting for double-stick + six plastic panels. They used hot glue to glue the cells together into a grid pattern. The Anderson plugs are soldered not crimped. Not shown, but there are 140mm long serial bus bars on the bottom that carry the load from one side of the battery to the other (essentially two 10s17p batteries in series). One weakness I can see is that all the power flows through just the very end of a single nickel strip. The dumb BMS they installed on this pack is this one: http://www.best-way.cn/html/product/580.html.

There are obvious issues that become readily apparent once the innards are revealed. The serial bus bars are the most egregious flaw -- there are only seven but ideally there would be 17 per row. Ditto for the base of the battery where the two 10s17p banks are joined together using 140mm long bus bars. And lastly, the power terminals are woefully inadequate being soldered only at the end of a single 12mm wide bus bar. Oh well. Time to upgrade this puppy!

voltsxamps and flinders_72 like this.
19. ### MJSfoto1956Been here awhile

Joined:
May 12, 2017
Oddometer:
505
Location:
Boston, MA
Given that I will be using a PowerVelocity 20kWh controller with this pack and that PV's new iPhone App now supports "smart" BMS's, I'm definitely leaning towards replacing the supplied "dumb" 120A controller to a "smart" 150A controller and then perhaps even mounting it external to the battery optionally with a heatsink. Something like this:

20. ### MJSfoto1956Been here awhile

Joined:
May 12, 2017
Oddometer:
505
Location:
Boston, MA
So I'm leaning towards buying a bunch of 1" braided tinned copper cable and then solder it to the existing pack as shown below. Shouldn't be that hard to make happen. Probably can finish it over a weekend.