MJSfoto1956

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About MJSfoto1956

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MJSfoto1956's Activity

  1. MJSfoto1956 added a post in a topic eZuma   

    Ok. Reality set it. Budgets need to be considered. 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 throttle125A circuit breaker10A circuit breaker2A circuit breaker100mm DIN 35mm railPowerVelocity 20kW controller + Bluetooth appPVC junction boxesGigavac P195 MinitactorZEVA Smart PrechargerBussmann 2P Miniature Distribution Block4AWG Tinned Marine Battery cable2AWG Tinned Marine Battery cable4AWG lugsTerminal bootsAnderson SB175 connector kitProTool Heavy-Duty Battery Cable Terminal Crimping Tool - 8 to 4/0 AWG - TaiwanTOTAL: $2510
    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 vs. the AGM 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
     

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  2. MJSfoto1956 added a post in a topic eZuma   

    A solar charge controller is definitely required if one wants to charge lithium battery packs via solar photo voltaic panels. 
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  3. MJSfoto1956 added a post in a topic eZuma   

    this is my vision for Phase 1:
     
     

     
     
     
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  4. MJSfoto1956 added a post in a topic eZuma   

    No firm total yet. But as you say there's no fun in that. I'm designing the system to be modular so that I could actually power some of the lights in my house during an emergency. Also to be able to hook it up to solar panels. So I really am designing something unique, one that closely meets my requirements.
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  5. MJSfoto1956 added a post in a topic eZuma   

    BOM (Bill of Materials) for my proposed 24s16p system:
    (48) N.E.S.E. 8p Modules (48) N.E.S.E. Serial bus bars (48) N.E.S.E. double caps (384) 18650 3400mAh Li-ion batteries (1) VLDL DANL 84V/98.4V max 20A charger (1) Daly 24s BMS (1) 100Vdc/12Vdc Waterproof 50A 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) 100A circuit breaker(1) 50A circuit breaker(1) 20A circuit breaker(2) recharge resistors(1) zener diode
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  6. MJSfoto1956 added a post in a topic eZuma   

    Now we are getting closer. This is a nearly finished system design for my future eScooter upgrade. This layout includes details on the controller + Motor + BMS + lithium battery pack. Lots of little details that in total make a difference. A final BOM (Bill Of Materials) to come later. It won't be cheap...
     

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  7. MJSfoto1956 added a post in a topic eZuma   

    Here's an alternate battery setup using a different BMS. Much simpler layout, similar specs.
     

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  8. MJSfoto1956 added a post in a topic David Pearson   

    Unbelievable!
     
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  9. MJSfoto1956 added a post in a topic eZuma   

    So if I ditch the BabyBloc balancers (one per parallel module) and replace them with a traditional BMS, what might that look like?
    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...

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  10. MJSfoto1956 added a post in a topic eZuma   

    And lest you think this is the end of the evaluation, here is a "spreadsheet" comparing how upping the battery bank Voltage reduces overall "stress", thereby lengthening the life of the battery pack. Of course, higher voltages come with their own issues. 
    The plot thickens...

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  11. MJSfoto1956 added a post in a topic eZuma   

    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 20s20p 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 20 cells in parallel, total 400 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 = 111AFrom the equation above, I conclude that in order to make best use of this 8kW motor, my battery pack must be able to supply 111 Amps to it on demand. Since I am using a 20s16p pack 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:
    20p @ 3400mAh = 68AhOk, my pack can deliver 68 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 20s16p battery pack could theoretically deliver:
    68Ah @ 1C = 68AWhich is only slightly more than half of what the motor is capable of. Put another way, if I only use "ordinary" 3400mAh cells, I might as well limit myself to just a 5000W motor. So I either need to 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:
    68Ah @ 2C = 136A68Ah @ 1.6C = 111AWhich is more than enough cover to what the motor is asking for. As a side note: the battery life would be much better @ 1c than 2c due to heat and stress, but this being phase 1 the numbers add up nicely and I am going with it.
    Lesson over. Any questions?
    Michael
     
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  12. MJSfoto1956 added a post in a topic eZuma   

    That would be a wine-bottle bush! :P
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  13. MJSfoto1956 added a post in a topic eZuma   

    This is what she looks like now:
     

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  14. MJSfoto1956 added a post in a topic eZuma   

    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:
    Installed rear fairingRemoved rear fender with Dremel but kept original license plate mounts and reflectorsInstalled one-arm tire hugger/fenderAdjustable aluminum swing-arm (this will be key to allow me to install a much taller tire on a 13" rim)Adjustable progressive clevis-end shocksUpgraded leaking turn signals with a proper pair from Baja Designs 

    Next up is to install an upgraded programmable controller...
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  15. MJSfoto1956 added a post in a topic Had a bad crash yesterday   

    yikes. hope all is well.
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