Can you tell me what lipos you are using for this? I am also looking for a new battery in combination to a vesc for a diy summerboard
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I guess it is not super obvious those are 2X 6S 22.22Vnominal lipo packs.
Summerboard uses somewhere around 190KV motors so 12S is ideal. Leiftech motors are 400KV meaning ~24V or 7S is well suited. 8S if you like a high speed VESC build.
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Any 12S batteries would suit, these boards use hardly any power most of the time. These are pretty chunky, no idea how much range they will give but should be a fair bit more than the standard battery. I chose these ones as I wanted to buy 3 and swap them around between running 3 on one of my mountainboards in an 18S config and 2 on the summerboard.
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Carrying on with this this evening, got that weird looking part printed, fits well though.
After messing around with a couple of test prints, like this…
We are printing the box insert on the Voron.
This basically goes into the box and then you bolt through the box and the weird base plate into the deck. Batteries in the top and ESC underneath.
@Fosterqc can you remember the capacity of the OG battery? I can’t remember what it was now
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Leiftech battery
7S2P x2 xt60 out
4.4Ah each side so 8.8Ah total at 7S.
I am kinda confused about the L2X and L3X, that might have been 7S6P
…
oh wait lol you meant SBX battery prob. I think still to this day uses Samsung 25R cells, 12S2P split into 6S2P internally.
Does this have something to do with protection or performance regarding the slip ring and possible contamination on this board? wondering your guess.
would it be easy to look in the firmware provided for the SBX to find out what this “traction control” does? @jchum
With 2x4S lipo 6200mah I can ride 10-12km with 3.6V/cells remaining.
At 15km/h average and 28 max speed (can’t do more because of the 4S).
Just buy 6S 7000mah, I hope a 20km range.
I’m curious to see how all these prints will be installed!
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I was wondering about this too, as Aron seem to be playing up to in on facebook the other day, making it seem like a lot of R&D was put into the ‘traction control’. Wonder what some DIYers say about their traction using VESC compared to stock sbx firmware
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lots of center wheel burnouts on the leif but those wheels have crap grip on wet pavement.
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That’s it, 5Ah battery. I should expect around 12 miles of range from these lipos then (fingers crossed)
Thanks, that’s good to know. I guess it depends on your weight etc as well. If I can get 12 miles out of this it will be enough for me for sure. 12 miles of summer board is a hell of a workout, but should allow me to actually ride this to places rather than just in a carpark.
I’ll get some more pictures tomorrow. Hoping to finish this off! The last part that I printed turned out great so I think i’m ready to go.
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@Fosterqc I do have a binary dump of the latest official SB FW, but I don’t know enough about disassembly to know how to start decoding the FW to see what is being done for traction control.
I’ve made a bit more progress in getting the mainline VESC FW ported. There were a bunch of pins that SB re-map’d relative to a VESC6.6, so I’ve slowly been ohm’ing through the board to figure out what goes where.
I think I know what was causing my front wheel not to spin, the motor temp was reading back as 300C for the front motor and like -200C for the rear motor. There’s actually no motor thermistor wire going through the castors so I hard coded the temp function to a fixed 30C.
My bench power supply tops out at 25V @ 1A and that doesn’t seem to be enough to run dual motor detection wizard. I’ll have to switch to LiPos once I do a bit more pin scrubbing.
On the topic of traction control there is an ICM-20948 IMU connected to ARM B that drives the back wheel, which I did get working. The remote nRF receiver is tied to ARM A that drives the front wheel. There are no Hall effect sensors and I’m not sure if VESC FW can determine the wheel RPM with only back EMF, at least it’s not obvious to me from the real-time panel that the FW knows how fast each wheel is spinning.
Maybe someone that understands esk8 physics better can comment, but I could see that the IMU could determine which motor is leading and which is lagging and under the assumption that the rider has their weight distributed more towards the back it slightly boosts that motor to compensate for the additional weight?
Do traditional esk8s typically have an IMU? If so what does it do?
I think board speed is normally calculated with the wheel RPM (Hall effect) and a known wheel diameter right?
Oh interesting, so those other “mosfets” are actually diodes on the phases (ST PS30H). Never seen that before
I don’t have the ESC in front of me at the moment, but I’m pretty sure those are MOSFETs and the DRV8301 is used in the normal way. If I’m wrong I’ll report back.
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I got this finished up today
Its a bit janky but its what I needed to get this back on the road, I kept the phase wires deliberately long just in case I need to mess around again.
Then this piece goes in the box and we bolt all the way through to the deck. However seems like when I originally did this I didn’t put the inserts in straight looool. 3 bolts it is. It will be fiiiiine.
evidence of my crimes, this was done in a rush last time tbf
Then the batteries go in the top, I just need to make a series harness for this
Ta da
Just need to buy a decent charger to get both of these charged at the same time
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It can. It only uses halls for very low rpms when there isn’t enough back emf to measure. Silent HFI works pretty well on some ESCs and can be a replacement for halls at low RPMs
You can see the erpms in the realtime tab of the vesc tool
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As far as I know the traction control (at least on the Leif that came before) detected when there was caster rotation and limited the power available when a rotation was initiated. At least that’s how I remember the board behaving with traction control on. I remember it feeling weird and turning it off even when I was a very beginner as it was so odd feeling.
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@jaykup Thanks I missed that there is an ERPM tab in RealTime section, I confirmed this also reads back values on the sensor-less SBX ESC. I also realized that mainline VESC has traction control which appears to read in ERPM values for all the motors and limits any motors spinning faster to the slowest motor. I’m not sure if that’s something that would help or hurt a e-freeboard.
I also finally got mainline VESC FW working, although not extensively tested.
I even got the SB remote working. It turns out SB uses the vanilla nRF24 driver with the one exception that they’re running at a quarter of the baud rate and decreased the retry rate, presumably to improve the radio link? So actually you should be able to use any nRF24 based remote with the SBX ESC.
driver/nrf/nrf_driver.c
- conf.retry_delay = NRF_RETR_DELAY_1000US;
+ conf.retry_delay = NRF_RETR_DELAY_250US;
- conf.speed = NRF_SPEED_1M;
+ conf.speed = NRF_SPEED_250K;
For some reason enabling the IMU prevents the back motor from spinning, but as far as I know the IMU isn’t used for anything, except for OneWheels applications, so I’ve just commented it out.
hw_sbx_b.c (7.4 KB)
hw_sbx_b.h (7.1 KB)
hw_sbx.h (6.6 KB)
hw_sbx.c (7.6 KB)
Next up, I’ll see if I can get the BMS working with the goal to be on entirely stock HW but running latest VESC FW.
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Wow, you’ve made a ton of progress. Nice work!
There was well known interference and other issues with the early sb remote connection. if you search their FB group you might find some dead links to said update files.
I mention this in case if seems something is tweaked in an odd way regarding that.
Interestingly I couldn’t find any discussions on VESC-Project or on this forum about recommending to change the nRF24 data rate to mitigate interference.
The nRF24L01 data sheet Table 7 shows a typical 9dB sensitivity and 5dB blocking improvement performance when using 250kbps vs 1Mbps; trading off latency/responsiveness.
So it would make sense that Summerboard would go down this route and do a software update to the ESC & Remote if people were reporting interference issues in the field. Putting a battery over the receiver probably doesn’t do the radio any favors.
Looking at the VESC code, it looks like the nRF24 is fixed at 2476MHz as opposed to Trampa Wand/Hoyt Puck which are frequency hopping and inherently more robust.
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The nRF24 wasn’t used very long with vesc. They went to nRF51/52 almost right away.
One of the more reliable remotes out there, the z.mote, uses nRF24. Maybe the creator @zyb can provide some insight as to how his remote firmware is configured to get the signal quality so good
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