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Yours Truly | Switchblade 40" + eboosted Enc | N.E.S.E. 12s4p | eLofty 58kv | Neptune15 | Go-FOC SV6 | 200A Antispark | Janux hubs

Yours Truly

A streamlined and versatile board built for fun, easy maintenance, durability, and more fun.

Foreward

This is my first build. I have been lurking here and on the other forum for about (4) years waiting for parts and the market to match what I had envisioned. With the advent of lower kv DD motors, I decided it was finally time to make the leap. I am a maker, so I have some experience with complex projects and am looking forward to all the learning and surprises coming with this build. I’m hoping this thread will help share my progress as well as garner feedback from a thriving and verdant community. Thanks ahead.

Philosophy

It should coast It should be easy to fix It should last It should tell you how its doing It should roll over that divot you never saw You should long for another ride

BOM

My current BOM can be found here

The major components:

Drivetrain

eLofty DD 58kv system

This is why I held out for so long. In the early days I was super excited about the hub motors Jason was building for the Raptor2, and was over the moon when he posted the video of his one off AT build using hub motors back in early 2016. I patiently waited for some movement in this space, but as the market matured, some of the shortcomings of hub motors reared their head. In mid 2018 info on the new TB Direct Drive motors started to flow in (CarvOn seemed to make a splash and disappear in the mean time) and then came Corey’s early review of these motors. After results came in with PU wheels on these motors, things started to look really good. There wasn’t a lot of information on matching these motors with AT wheels, and as time went on it seemed an AT build required either a) some ratio reduction for additional torque using higher kv motors or b) new DD motors with a lower kv. Enter eLofty with two DD options, one of which is 58kv.

There were some production issues with early eLofty axles but that seemed to later be addressed. Additionally, more recent versions had an issue where the entire can would come unscrewed, As of late December, this should now be addressed with a set screw in the can. Various other quality assurance problems plagued this drive throughout 2019, but after several iterations, things seemed to have finally settled a bit.

++Other thoughts++

  • Based on several discussions, it sounds like a good idea to harden the bushings on DKP trucks to gain stability at higher speeds. I have yet to define the parts for this.
  • Based on tests, it may be a good idea to remove the drives from the hanger, apply some thermal paste to the square mount point then reinstall the drive. This appears to help move heat away from the stator and on to the hanger where it can be more easily dissipated.
  • In a more recent tests, users have been applying statorade to their DD motors to help move more of the thermal load out onto the can, again, which helps dissipate heat. Experiments seem to be ongoing here.
  • It would be nice if they could get a thermistor mounted internally for these drives. Having accurate temperature readings could help the VESC reduce load on the drives before cogging and performance dip are experienced.
  • TorqueBoards was looking at building Direct Drive motors with a 50-65kv rating but they currently offer 75 and 90kv options. While limiting top speed in software is an option, the lower kv rating on the eLofty parts seem to be a better fit for 6" AT wheels. That said, if TB dropped a 60kv DD I would totally jump on that.

Battery

N.E.S.E. 18650 12s4p battery using Sony-Murata VTC5D 2800mAh 25A 18650 cells

The philosophy is what drove me toward a modular battery approach instead of the spot welded monolithic approach. Since a multi-cell battery is effectively a weakest link problem (cell MTBF / cell number), I wanted the ability to pull any one cell out of a P group and replace it without needing to pull the pack apart. I know this requires more physical space, but I like the idea of this modularity and it matches my “it should be easy to fix” philosophy.

Originally I looked into using the VRUZEND approach, but it appeared this was not as tolerant to vibration nor peak current. After looking around I landed on the N.E.S.E system and ordered (8) 2s4p enclosures. By necessity, this helped guide my deck selection as the standard depth N.E.S.E. 2s4p modules with bus bars, BMS wire loops, and 3D printed terminal covers came out to at least 181mm wide.

Also, going with 12s seemed like the best choice to:

  • minimize heating on the drives by keeping a higher voltage
  • provide higher torque for better acceleration and (more importantly) better breaking
  • maximize fun

For 18650, it seems that builders typically land on using Samsung 30Q cells. In looking at the need to push higher peak current (at least for short periods), it seems that the Sony/Murata VTC5D cells would be a better fit. These cells have 6.6% less capacity while providing headroom for 66% more current compared with the 30Q cells. When looking at the total output capability of a 12s4p battery, a 100A ceiling seems like a better match than 60A for a DD AT build.

++Other thoughts++

  • Seems like best practices around building a new battery are to bin all your cells such that each P group is extremely close in voltage when assembling. Once assembled, you can then use active balancing in the BMS to level out all the P groups then charge the pack as a whole. Likely with new cells purchased in bulk, only minimal voltage differences should be present but it’s still worth verifying.

Deck

Landyachtz Switchblade 40" deck + enclosure from eBoosted

Based on the dimensional requirements of the battery above, I needed a deck with lots of space in the enclosure. I looked into double stacked enclosures, but I liked the idea of maintaining the clearance provided by a single stack. This meant that the enclosure also had to be sufficiently long in order to accommodate the 12s battery. I was looking for a stiff deck with good concave shaping without an extreme drop. After searching around, I landed on eBoosted’s Switchblade 40" deck + enclosure.

Notably, I wanted to ensure that this deck would be compatible with an AT setup and optionally have the truck mounted dropthru. After some searching, I found JoeFourMan’s Reddit Post where he deck swapped the Switchblade 40" in for his broken Ranger X1 deck. This looked like he had great clearance and had mounted the trucks dropthru. Since the current eLofty offering has a similar looking DKP truck setup, this looked promising.

While there are no dimensional specs on eBoosted’s site, I estimated the enclosure capacity from the photos provided. After receiving the N.E.S.E. modules and deck + enclosure I was able to get a real measurement of the enclosure, which helped me define the remainder of the build and formalize some dimensional drawings.

++Other thoughts++

  • It looks like AT wheel bite will not be an issue with this deck but I think the jury is still out on motor clearance if the trucks are mounted dropthru.

BMS

Neptune15

As part of “It should tell you how it’s doing” philosophy, per cell (or P group) reporting is an important feature. Reading through the Monitoring Individual Cell Voltages thread, and taking into account my space constraints, the Neptune15 BMS seems like the best fit. In this way I can monitor each P group on my smartphone, apply active balancing, and set upper limits for charge current (along with standard P group charge balancing and cut offs).

This BMS has a peak discharge current of 60A, so I will need to make this a charge only BMS.

++Other thoughts++

  • The Neptune15 has leads for charging, battery, and load (which differs from their user manual). It is not clear how to wire this BMS for charge only. I have an unanswered question sitting on the forums regarding this subject and I’m hoping someone will step up and validate/correct the wiring diagram I submitted.
  • At one point I was considering using a cheap charge only BMS and dropping a Neptune 20 lite in parallel for monitoring, however, having everything in a single solution more closely aligns with my “it should last” philosophy.

Electronic Speed Controller

Maker-X GO-FOC SV6 VESC

My original build plan was to make use of a FOCBOX-Unity but with the recent reports of insolvency around Enertion, I needed to rebase my approach. Based on my choice of battery, my space constraints, and general warnings around anything Flipsky, I eventually arrived on the Maker-X GO-FOC SV6 VESC.

This part fits my requirements:

  • It is based off of VESC6, which allows me to run the motors fully sensored
  • It can handle 100A (which means it should be reliable at the max 40-50A I’m going to need)
  • It has an integrated heat spreader, which should help extend the longevity of the part
  • It appears to have all the interconnects for various remote options
  • It’s compact and built in a “landscape” form factor (instead of the “portrait” form factor used by other VESCs)

++Other thoughts++

  • It’s not clear if the 100A rating is continuous or peak
  • I can’t seem to find any data on the size of the bullet connectors used on these VESCs. Since the eLofty drives use 4mm connectors I may need to get adapters here.
  • I can’t find a CANBUS cable on their site. Since I will need two of these controllers, my current plan is to source this cable from diyelectricskateboard.com
  • I can’t find an XT60 splitter on their site either, so current plan is to source this part from mboards.co
  • USB-micro… really? Come on! It’s 2020, this should have been USB-C.
  • I looked at the VESC6 MKIII but this was a BIG jump in price and was a bit larger. I do like the hibernation feature however.

Antispark & Power Button

Flipsky 200A Anti spark

Just above I avoided selecting a Flipsky part for my ESC based on forum advice, but it seems like the 200A Anti spark is one of the best options out there. After reading the very interesting Tackling the anti spark problem thread, this iteration of the anti spark appears to address the inrush current issue, allowing for a much more reliable part without the need to resort to loopkeys.

Wheels

Janux eLofty hubs

Although pricey, these forged wheels seem like the best (only?) option for getting AT pneumatics paired with eLofty DD hardware.

++Other thoughts++

  • I wish they came in purple. If I can’t get a custom color from the vendor I will look into getting them raw and having them anodized locally.
  • These hubs will definitely fit Bergmeister tires, but I’m leaning toward the Evolve 150x50 tires instead. Based on the measurements available these should work but I can’t find anyone who has tried this pairing explicitly.
  • At one point, user Movation was looking into if the airless tires could be converted into pneumatics using the same hubs. I have a pending question on the forum for this.
  • I really like the TorqueBoards Direct Drive All Terrain
    adapters, but these are not yet available and would be better paired with a lower kv drive. Still, this would make a really excellent AT solution.

Misc Parts

Remote: OSRR or Trampa Wand

One thing I really like about the OSRR and Trampa wand are the resilience of their connection between the remote and the communication dongle. It seems the NRF SoC used in both utilize the underlying 802.15.4 standard which has a more robust connection. Both will provide lots of information about the ESC (and the remote), which matches my “It should tell you how its doing” philosophy.

When I originally spec’d the use of the FOCBOX Unity, this appeared to eliminate the Trampa Wand as an option, which is why OSRR became the front-runner for me. With my rebasing over to VESC6 compatible hardware, this opens my build back up for use with the Wand (I believe). Two things are keeping me on the fence right now:

  • Form factor: I like the look of the OSRR nano a bit better than the Wand. It seems like it would be more comfortable to hold for multiple hours and would seat in the hand better
  • Rechargeable battery: I like not having to replace batteries.

Power Supply: MeanWell HLG-185H-48A

Originally taken from the 12s charger for 12s4p pack thread, the MeanWell adjustable voltage LED driver power supplies seem like a great value.

  • Fully waterproof
  • CC -> CV charging which matches the Li charging profile well
  • Adjustable voltage so you can charge to just under peak (which should increase cell lifetime, matching my “it should last” philosophy)

Charging Connector: Panel Mount Barrel with IP67 Cap

There are a number of requirements for this connector:

  • It needs good waterproofing
  • It needs to be small since the sidewalls of the eBoosted enclosure are not that big
  • It needs to handle at least 3.67A

I spend a lot of time trying to find the best connector for this. I looked at LP20, a bunch of stuff from cnlinko, some boat connectors, SAE connectors, and regular 5.5 x 2.1 barrel connectors. All of them were either too big or had some other downside. Eventually I found a special threaded barrel connector with an IP67 cap. The connector is rated to 5A and while the pin is 2.0mm, it should work with a standard 5.5mmx2.1mm DC plug.

Lights: Smartlights Sensored Rechargeable Lights

Although I considered stepping down to 12V and running lights off the main battery, I decided to minimize the holes in the enclosure and go with independently powered lights. Additionally, I wanted to prioritize safety while minimizing maintenance, and so landed on the Smartlights Sensored Brake and Sensored Front lights.

I like the idea of communicating what the board is doing to those behind, so the break lights were a must. With sensored lights there is no need to tie into the VESC to determine breaking, since this is done through the onboard accelerometer. Additionally, having light sensors in the front lights allows for easy auto on/off if need be.

Schematics

With the parts selected, it’s important to ensure a) all the parts fit within the enclosure and b) all the parts logically connect with one another. I have built out a schematic for each task. As above, I would love feedback on these two assets.

Dimensional Schematic

In this schematic, all components are scaled to their physical dimensions and arranged to approximate the optimal position for wiring. Although slightly tight, I believe that all the interconnects should fit in the slack room around the BMS (some of it above the BMS since it’s so low profile).

Key:

  • Dark Grey: Flat bottomed section of the enclosure
  • Medium Grey: Sides of the enclosure
  • Light Grey: N.E.S.E. modules
  • Pink: 18650 Cells
  • Light Blue: N.E.S.E. tabs and bus bars
  • Dark Blue: BMS
  • Light Green: Antispark
  • Dark Green: On/Off button
  • Purple: Charging Port
  • Orange: ESCs

Wiring Schematics

This schematic is optimized for displaying the wiring in a simplified and logical manner, and so physical representation is not captured. As mentioned in the BMS section above, I’m still hoping someone will chime in on how to wire the Neptune15 for charge only.

Key:

  • Light Grey: N.E.S.E. modules
  • Dark Grey: BMS balance wires
  • Light Blue: N.E.S.E. tabs and bus bars
  • Dark Blue: BMS
  • Light Green: Antispark
  • Dark Green: On/Off button
  • Purple: Charging Port
  • Orange: ESCs
  • Yellow: XT60 connectors
  • Red & Black: Wire (AWG Specified)
  • White with blue outline: motors
  • Tan: Bullet connectors

What’s Left

I’m sure lots. In addition to the questions above, I still have at least:

  • lots of soldering and tube shrinking
  • initial VESC programming
  • remote adjustment
  • adjustment of acceleration and breaking curves (seems like smart reverse might be a good choice)
  • Figure out vibration dampening material for inside enclosure
  • Downloading of apps for BMS + VESC
  • All the other things I don’t know about yet

Thank you to all who contribute to these forums. Your willingness to share your knowledge and offer guidance keeps this an exciting place to visit with new ideas, new hardware, and new solutions surfacing all the time.

Cheers!

27 Likes

Nice writeup and very detailed so far :slight_smile: Im sure you can find most answers to your questions on here and people will definitely be willing to help out. Im quite curious to know your experience with the janux hubs on the DD after you’ve ridden for a while! Looking forward to seeing more!

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This is an impressive introduction. Have bumped your account and will follow with interest. Welcome!

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Duuuuuuude. Way to research! Fucking excellent writeup bro, look forward to seeing this one come together.

I have recently ordered the SV6s for a build I am doing for a mate, I hope they can stand up to some punishment!

8 Likes

I’m planning a pneumatic tire build with the eLofty DD 58kv edition. :wink:
Bookmarked!

3 Likes

Huh, had never heard of the VTC5D cells. I wonder how they compare with 30Qs after a few dozen recharge cycles though…

Your build looks super promising! Switchblade + elofty + Janux bergmeister hubs seem like an amazing combo :smiley: :crossed_fingers: the acceleration doesn’t suffer too much.

Also, I had never heard about that site you bought your lights from. Let us know if they function properly; I have my doubts about smart lights like that working on bumpy roads.

Can’t wait to see this come together :slight_smile:

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N.E.S.E. modules fit can fit a 12s4p 18650 on my enclosure, I’m glad it did, I’ve been asked several times about this.

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If it was ~2mm wider then a NESE 12s4p of 21700 would also fit I think. Was quite sad when I did the math and realized it was just off.

2 Likes

Some discussions on 58kv DD’s and pneumatics here:

If you’re not heavy, they should be fine. But keep your expectations about the performance. And I’m also not sure if the elofty DD’s can sustain 100a motor amps?

So even though the pack can push that much I was going to err on the side of caution and limit at the VESC to 40A or 45A per motor. The specs on the motors say they will handle 50A, but I’m going to wager this will come down to how well heat can be moved away from them.

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Yeah- I thought about that but would have probably needed to to move from 12s to 10s since I think that would have eaten up too much of the spare room at the back of the pack leaving things pretty sparse for the BMS + VESCs.

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It looks to me like that site is just using the standard bike smartlights available on Amazon. It looks like someone has had good luck with them over on the let-there-be-esk8-lights thread

If the only thing special is the adapter I think I’m going to just get the ones from Amazon and make my own mount.

1 Like

Impressing writeup!
Very interesting as I am planning a similar build on Switchblade 40 with elofty 58Kv, 12S4p 21700s. Havent decided on wheels yet though, pneumies or TB 110s. This will be my first build, so I will try to learn from yours… Have built ebike before so not totally unfamiliar, but board is still very different in many ways.

Havent started to buy stuff yet, in the planning and reading phase…

Damn that’s one clean detailed post :heart_eyes: excited for the result :ok_hand:t2: I have the same switchblade and the deck feels awesome without anything on it now just imagine with AT :drooling_face:

Thanks @Nikos and @amms50 - it is progressing slowly but surely. I have purchased a number of items off the BOM and have only some bigger items left. As parts begin to arrive, I will try and drop in some pictures and reviews where appropriate.

1 Like

Update 2020-02-20

New

Lugs

I realized I had not defined lugs for connecting my 12AWG battery leads to my XT60 connector. Since I need to connect to the bolts on the N.E.S.E. pack, these need to handle an M5 stud size while handling higher current. After some research I settled on Wurth Elektronik lugs from Mouser.

These have now arrived and look great, I’ll get some pictures posted once I crimp.

Changed

Charge Connector

I was being very conservative on my initial criteria for selecting a charge connector. I wanted:

  • A waterproof cover that could be firmly affixed to the body
  • A port which required only a small hole in the enclosure
  • A port which could handle 5 amps. (Even though I will be charging at slightly less than 4A)

This is how I arrived at the screw top DC barrel connector in my original BOM. However, after seeing this picture I was inspired to look back into offerings from CNLINKO again.

I don’t like the screw hole mounting option in the above picture. I’m doubtful the enclosure material will hold up when having holes in such close proximity. Luckily, CNLINKO offers a clamping style connector for mounting. Additionally they offer some smaller size ports (M16 and M12) with this style. The M12 port (while being smaller and capable of handling 5A) is made of plastic, but there is an M16 option which is made from metal, is still small, and can handle up to 10A. The one criteria it doesn’t fulfill is the strongly affixed waterproofing (since it’s a push cover), but I have relaxed on this requirement a bit. In addition, this port has a very short incursion into the enclosure (most of the structure will be outside) which should allow mounting of this port to a location similar to that in the picture (which is advantageous to my design).

Tail Lights

As I mention above, it appears that the Smartlights company is simply making their own mount for (2) standard Xlite100 bike lights. Instead of taking a risk here I just bought (2) of these lights from Amazon. I looked around for a mount that may already exist, but only found these two Thingiverse options for hummie decks:

In this case I’ll need to design and print my own mount for these two lights. I’m taking this as an opportunity to learn Fusion360 (although I still enjoy FreeCAD)

I have only tested these lights under limited circumstances, but I’m relatively impressed by their performance thus far.

BMS (maybe)

This is a tough one. Here’s been my food for thought:

As I mention in the initial post, the Neptune 15 will work as a charge only BMS with per P-Group monitoring. After reading the above two threads (and more) it seems like the other option would be the TinyBMS which would allow for both charge and discharge and (according to my dimensional drawing) barely fit into my enclosure. I’m not, however, totally convinced this is the right path. The statements of “I’d rather a P-Group go low than get thrown from the board” seem compelling. As an alternative, perhaps I can set an alarm with the Neptune app which would alert me when a group goes low. The TinyBMS also has an onboard audio alarm option, which could also be useful if I were to wire it as a charge only BMS. It also seems that the chance of a P-Group coming out of balance is low, especially if you are conservative about the low voltage cut-off setting. Even if a P-group were pulled down and damaged, it seems that the N.E.S.E. enclosures would allow P-Group replacement to be relatively simple. Lots to consider here.

Help Needed Re: Battery Cell Selection

Here’s where I could use some input from the community.

My background reading is from the following articles:

What I’m trying to figure out is how to spec the battery pack cells (based on total current capacity) when using (2) eLofty motors. As per my original BOM, I was planning on using Sony/Murata VTC5D cells (2800mAh with 25A discharge) but it seems that the Samsung 30Q cells (3000mAh with 15A discharge) are the standard for most builds. I also wanted to take a look at Sony/Murata VTC6 cells, as I think these may be the sweet spot. Based on the content in the linked articles I’ve tried to gauge how much max current I can pour into these motors and therefore what the optimal cell should be for this build. I believe my math is sound, but I’m still not clear on what the reliable upper limit of these motors should be.

My one concern here is too much heat since these motors do not have a temperature sensor. I’m not sure how far these can be pushed before the magnets are affected or the wire insulation starts melting.

On the other hand, I want to maximize torque since I’m not using a transmission here and running everything 1:1. So while I’m not really concerned about top speed, I do want the acceleration and (more importantly) braking curves to be predictable and consistent with 6" pneumatics.

I could really use some input here on helping to clarify this subject.

Looking at the characteristics of the eLofty motors and pulling the equations out of the above threads:

Known Quantities

  • eLofty motor Resistance: 0.19 Ohms
  • eLofty motor rated power: 750W
  • eLofty motor max power: 3000W
  • eLofty Maximum Current: 50A
  • Peak battery pack voltage for 12s4p: 50v
  • Peak battery discharge current for 12s4p using Samsung 30Q Cells: 60A
  • Peak battery discharge current for 12s4p using Sony/Murata VTC5D Cells: 100A
  • Peak battery discharge current for 12s4p using Sony/Murata VTC6 Cells: 60A
  • Peak battery charge current for 12s4p using Samsung 30Q Cells: 16A
  • Peak battery charge current for 12s4p using Sony/Murata VTC5D Cells: 24A
  • Peak battery charge current for 12s4p using Sony/Murata VTC6 Cells: 20A

Equations

  • volts = amps * resistance
  • volts * amps = watts
  • % duty cycle = (battery amps / motor amps) x 100 (@ full throttle & below 200RPM)

For 60A max battery output:

  • Substitute into second equation:
    • volts * amps = watts
    • 50v * 60A = 3000w
    • per motor max battery draw = 1500W

For 100A max battery output:

  • Substitute into second equation:
    • volts * amps = watts
    • 50v * 100A = 5000w
    • per motor max battery draw = 2500W

So:

  • Insert Resistance into the first equation:
    • volts = amps * 0.19
  • Substitute volts into second equation:
    • 0.19 * amps * amps = watts
    • 0.19 * amps^2 = watts
    • amps^2 = watts / 0.19
    • amps = sqrt(watts / 0.19)

For the motor’s 750W rated power:

  • Isolating for motor amps:
    • motor amps = sqrt(750 / 0.19)
    • motor amps = sqrt(3947.4)
    • motor amps = 62.82
  • Plugging back in for voltage:
    • volts = amps * resistance
    • volts = 62.82 * 0.19
    • volts = 11.9358
  • VESC batt/motor/absolute: 15/63/63
  • Duty cycle: 23.87%

For 1500W (per motor) max of 30Q / VTC6 cells:

  • Isolating for motor amps:
    • motor amps = sqrt(1500 / 0.19)
    • motor amps = sqrt(7894.737)
    • motor amps = 88.852
  • Plugging back in for voltage:
    • volts = amps * resistance
    • volts = 88.852 * 0.19
    • volts = 16.88v
  • VESC batt/motor/absolute: 30/89/89
  • Duty cycle: 33.76%

For 2500W (per motor) max of VTC5D cells:

  • Isolating for motor amps:
    • motor amps = sqrt(2500 / 0.19)
    • motor amps = sqrt(13157.895)
    • motor amps = 114.708
  • Plugging back in for voltage:
    • volts = amps * resistance
    • volts = 114.708 * 0.19
    • volts = 21.79v
  • VESC batt/motor/absolute: 50/115/115
  • Duty cycle: 43.58%

Equally (if not more) important is total breaking power. Looking at our (3) options:

  • Peak battery charge current for 12s4p using Samsung 30Q Cells: 16A
  • Peak battery charge current for 12s4p using Sony/Murata VTC5D Cells: 24A (taken from VTC5A datasheet)
  • Peak battery charge current for 12s4p using Sony/Murata VTC6 Cells: 20A

Looking a bit deeper into the spec sheets gives some kudos to the VTC6 cells:

  • A nominal cell capacity of 3120mAh
  • Cells can handle discharge currents above 15A for short bursts
  • Cells can handle charging currents up to 6 amps in pulses

So, based on the above, it seems like the VTC6 cells might be the best bet. Setting these to a somewhat more conservative setting of 50A battery discharge would result in:

  • Substitute into second equation:
    • volts * amps = watts
    • 50v * 50A = 2500w
    • per motor max battery draw = 1250W
  • Isolating for motor amps:
    • motor amps = sqrt(1250 / 0.19)
    • motor amps = sqrt(6578.947)
    • motor amps = 81.11
  • Plugging back in for voltage:
    • volts = amps * resistance
    • volts = 88.852 * 0.19
    • volts = 15.41v
  • VESC batt/motor/absolute: 25/81/81
  • Duty cycle: 30.864%

For braking I could then set:

  • -81 breaking (seems like this should be as high as possible with the pneumatics)
  • -8 max regen (since the spec sheet lists the high temperature recommended charging current as 2A per cell and the high temperature recommended max current as 5A per cell)
  • I’ll need to figure out how to enable smart reverse below a certain RPM to help the 1:1 on 6" pneumatics stop.

With these somewhat conservative settings, it seems like the VTC6 cells should have enough cushion in them that battery degradation should be minimized. Even in the case where one P-group loses a cell, this cushion should be enough to avoid damage to the remainder of the cells in the group until the offending cell is replaced.

I would love some feedback on the above. I’m slowly purchasing items off my BOM but the next decision really comes down to the battery cells. Thanks in advance. :smile:

2 Likes

Let me know if you run into a problem with the antispark.

1 Like

80A. Everyone runs them at 20A per P group. Mooch (famous, trusted, cell reviewer) classified them as 20A. A lot of web-sites even list them as 20A. They have better capacity than VTC6 after a dozen runs, and are super cheap because of their popularity. I highly recommend them! It’s what most of us use. Better safe than sorry for a first build.

3 Likes

that’s nothing. Most 18650 cells (30Q for sure) are rated for 4A fast charge, and most of us consider them to be safe to up to double that. So 16A per ESC, or 32A total. That still might feel weak, and if you’d rather stop in an emergency with the small risk of burning your board down than hit a car and die, then you could even do 40A in total.

As long as you’re using a BMS in charge only mode (discharge bypassed), then you don’t have to worry about any BMS limits.

4 Likes

Yeah came to say 30Q are tested to be 20A capable. I would go with the 30Q for capacity and current (charge and discharge) sweet spot.

Also for breaking, DDs are particularly at a disadvantage at slow speeds. I would recommend programming in some reverse to help with braking. Here’s a link, first post: eLofty Direct Drive Discussions-read before buying

3 Likes