So it begins...... Battery spot welder

[sternwake]

The cells in 38$k8 are BFN 18650 3.7V 2000mAh 5C

5C at 2.0ah means 10 amps continuous diacharge rating.

350watts ÷ 29.4v 11.9 amps
350 ÷ 25.9 = 13.51amps.

so if motor was 350 watts at 29.4 v, these cells are underrated for the task.

But i suspect it is far less wattage at 29.4v and 350 watts is only at 42v input.

Lets call it 250 watts at 29.4v
250watts ÷29.4v is 8.5 amps
250 ÷ 25.9 nominal is 9.65 amps.
3.3vpc x 7 = 23.1v
250÷ 23.1 =10.82 amps.

Anyway a 10 amp rated cell is right on the edge of acceptable, and they are likely cooking hot if ran hard from 4.2 down to 3.3 volts per cell
perhaps hot enough to pop the mechanical overtemperature protection of a single cell,, rendering the pack useless.

There are 18650s available with 1/3 more capacity, and 3x the CDR rating.
Such cells would stay waY cooler, holding higher voltage , for longer, and likely degrade much slower due to the lesser heat they generate within the en losure

If 2!700s could fit , then capacity can easily be doubled, and CDR quadrupled .

so it goes.

[sternwake]

The battery spot welder has been ordered.


As has a 7s BMS, and kapton tape, and fishtape insulation.

Gonna hold off.on new.cells.for now, still shopping.

Gonna hold off on a 10s ESC and a 10s battery. i think tbat voltage might allow too fast of speeds.

I could swap first 350 battery into other skate, see if i like how it rides.
the first 350 is so maneuverable.
the 38$esk8 has an all plastic deck.

The 7s bms says recommended charge voltage is 30v?

I guess top charge balance function needs a little bit more voltage.

[Scott7022]

Are we allowed to use too and fast in the same sentience?

Interesting stuff.


Sent from my iPhone using Tapatalk

[sternwake]

Above a certain age, too fast can be a thing.

On a skateboard, amongst those who believe their phone deserves more attention than does driving safely, and in a considerate manner, too fast is definitely a thing.

I just assume every driver or pedestrian, is completely unware of anything other than their phones, and assume some basic belligerent maliciousness on their part.

These little short wheelbase narrow track boards are not really stable at higher speeds, and all it takes is one pothole.

[sternwake]

I should be mixing epoxy, not typing.

Definitely going overboard on the Sapele cormorant hunting perch, but such a beautiful wood deserves respect, and im trying a few different new methods

The 38$esk8 has a slightly longer wheelbase than original 350, but is still disassembled, as is the 700.

The original 350 loves to call my name when I stall in the slightest at workbench.
So i bust it out and proceed to make urethane wheels hiss in the driveway. loops, figure 8s, knees brushing body panels at full speed, and half the width of outer back wheel over the edge as i orepare to run out of it
79's style soul arches, unintentionally necessary, and other times u necessary but just feel so damn right.

Like surfing, which has a thousand additional facets to becoming competent, the better one becomes at skating, the more fun one can have.

I have seen other people riding some eskates, but most look so uncomfortable, and unstable, and timid, and scared and if they saw video of themselves would and should be embarassed.



I have progressively pushed this little 350 into such hard, tight long turns, both frontside turning right, and backside, turning left, the confidence in obstacle avoidance is now scary high, and I am still riding barefoot, unless it is a beer store run the i wear double stacked flioflops, which are so.soft and squishy they reduce board feedback and reduce confidence greatly.

Using the kicktail, lifting nosewheels.off ground, to turn even tighter at low speeds, is a skill also returning.

It is so damn fun, just carving, never having to push, or time and position those pushes, the fun level.is so far beyond what i ever expected.

The "700" is still disassembled. It needs finned heatsinks attached to undersized flat aluminum heatsink.
Glad i have the 350 to ride. which will also benefit from better heatsinking.
The 350 is so much smaller and.lighter, its actually a better board for beer/store runs.

The 38$kate, im kind.of eager to see how it rides, but jt's ESC basically has no heatsink, which i need to rectify rather than smoke it premaTurely. It has a lesser weight rating, with the molded plastic deck.

Im still torn as how to best utilize it.

Gotta keep hunting for 'parts only' e cheap skates which can be easily fixed and used, or their parts rspurposed, for the Kayak thruster(s) motors.

Im kinda eager to build some batteries too.

So many other projects ars backburnered.

[sternwake]

I probably had 10 mental health hissing turn breaks today, and the 350 was down to 2 bars when i decided a few Fosters oilcans were in order.

Ssw some asphalt resurfacing equipment 0.2 miles away, having rattled slowly at max throttle, over insanely rough old asphalt to that point.


Once it is smooth.......

Oilcans insulated in backpack, Took the long way back, through busy strip mall, traffic. pedestriams everywhere

I could have , bjt didnt. Almost, but.....
Yep, I was stuck behind traffic, one a transuitan smoking a joint.

Some people have obviously never seen an electric skateboard, some others appear jaded but are likely just oblivious, and too numb to be jaded about anything ever.

The skateboard hand remote started beeping and flashing when I was a half mile away. wS voing uo a very slight but long incline. Other side of apex and was ba k to 2 of 4 bars and made it back no worries, but obviousky down on top speed.

This is a case where a higher capacity higher CDR battery, would become more obviously beneficial,. and i might have been able to open an oil can 20 seconds faster.

But the 700 skate is upto o 50% faster. with 80% more baTtery capacity.

The voltage was 23.24v when i got back

The battery ESC enclosure was radiating some heat, but not as much as hub motor.
the 3 passive wheels were pretty warm too.
Its noticeable how much smoother warm wheels are on rough pavement surface compared to cool ones.

Good excuse to tear up driveway with full throttle soul arches before heading out.
when capacity and range is not an expected issue.

I decided to use original 29.8x V 1.5A AcDc power supply with CcCvXl4015 bucker inline set at 28.7v and dialed down 0.25 amps max current.

The green light on power supply/charger comes on as soon as the current drops below 0.32amps regardless of voltage.
0.33 amps and above, red light, 0.32 amps and below, green light.

Is the BMS smart enough?
I think the designers decided to hope so.

I am hoping a slow 330mA recharge to 28.7v allows all 7 cells to reach 4.1v -/+ as little as possible.

Without the cc cv bucker, inline, and using my Dc to dc booster on from deka GC 2s, setting voltage to 28.7v, the battery would gobble up 12+amps andi have to lower voltage way down an manualky raise jt in stages towards 28.7v.


but its nice to be abke to charge at 200 watts when the provided supply maxes out around 43., and then happily overvolts the baTteries, unless the BMS is just bleeding off heat and topping off tthe low cells.
but this seems unlikely with such a cheap battery bms.

[sternwake]

I found some specs on the discontinued parts only 38$ Esk8.
160lbs max rider weight
I'm in the 185lb range.

No doubt this limit is the plastic deck flexing, flexing the incorporated enclosure, whose battery is not designed to flex.

I can feel the other 350skate deck flex and twist underfoot too though. The trucks are the same. it is rated at 200lbs but has shorter wheelbase.

Anyway this excessive flex and itty bitty ESC in the 38$kate are going to prevent me from returning it to intended function.
hopefully. can never tell when curiosity will exceed wisdom.

But it was still great 38$ Spent. back up motor and wheels, black wheels instead of orange. and an itty bitty esc and hand remote for potential kayak thruster motor duty
and 6 18650s likely with only one cycle on them.

Im gonna be scanning the parts only eskTes listings, for similar deals.


The extra motor has me thinking about putting it on the front truck of my 350, for double the torque. this would require a dual motor esc, which can be had for as low as 43$, and the original 7s 1p battery would be woefully inadequate, and pretty much teeters on that fulcrum with just one motor

But I could then take the dual motor esc from the 700 and get a higher quality ESC for the dual hubmotor 700 with the desirable larger wheels.

The ESCs are basicLly for 6s, 7s, or 10s battery packs. 24 to 36 nominal volts.
If I am building batteries, might as well go for 10s for added torque and top speed.

But 10s will not fit inside enclosures, meaning fairly maJor redesign.
and when going above 8s, a huge spark can occur when hooking battery to ESC, possibly frying it, meaning antispark connectors become closer to necessary.

Rabbithole.

But a hideously fun one.

the road resurfacing has begun nearby. I located and explored some new pavement, about 3 miles there and back total, and some super rough roads en route which takes too speed from nearly 11mph, to maybe 5 and rattles eyeballs in skull.

The hub motor was really hot and battery was at 24.34v, or about 3.33 v per cell on my return.
under 3.3v it seems there is only 25% capacity left and torque and top speed are way down.

Some finned heatsinking of the hub motor seems possibly effective at increaSing range and longevity, but would depend on an epoxy bond, but perhaps a fastener is.possible too.



The Sapele platform is ready for final layers of Epoxy, but some much needed light rain has humidity levels high, which can cause fisheying and excessive amine blush, which then prevents proper secondary bonding without a whole bunch of extra work.

So its a heatsink kind of day.
so many heatsinks, in a box on a shelf, in California.

[rvpopeye]

So. Will we see a custom deck or mod on one of those in the near future ?  

Murphy's Law for pack rats. Err , I mean part recyclers.
As soon as you get rid of something , you'll soon have a need for it .
That one burns me more than I want to remember...  
It wouldn't happen so much if I didn't stay in one place too long  (at all).

[sternwake]

Probably not, not unless one breaks.
The mini 350 penny board is pretty thin and light, and flexible. the plywood0 layers are laid up in form, and press which induces the concave and a kicktail.
The 700 is a thicker deck also with concave and kicktail.

My long push skate is a long flat piece of finnish baltic birch pkylwood, nearly aircraft grade.
Im debating putting a motor on the long skate , but it is so flexible any enclosure near the middle could slam pavement on a hard turn.

Id noticed that the 700 riderless, woukd remain slightly leaned over from the last turn, and thus not track straight.

I got softer bushings, shortys doh dohs. the name rung a memory bell,

New bushings not as tall as originals, so I cut 1/8" from each original bushing, stacked them with the dohdobs, reassembked, stood onnthe skate deck and had the complete range of truck motion avaikable, and when i steo off boarx it straightens itself out to neutral.

In fact, the trucks move so much the wheels could hit the deck, and as suspected, they do not align with the cutouts.

So i moved the trucks apart 1/2 inch each, widening the wheelbase by an inch.
only had to drill 2 new holes on each truck, not 4.

There is epoxy curing inside all the holes, sealing the plywood edges, but the unused ones were taped off from below and a column of epoxy allowed to soak in deep to the end grains, hopefully returning some strength to the deck.

Before drilling the new holes, a straight edge revealed the factory holes were not square and parallel, which causes it to turn better in one direction and worse in the other. ever see a rear axle be off a bit and cause a vehicles rear tires to be off to left or right of front tires. severe misalignment, well this skate had the same.
Emphasize past tense.

It should really ride tons better when i reassemble it. Perfectly aligned, with new bushings which allow full range of movement, and return to zero on their own.
Also, being softer sbould absorb more road vibration.

The cupped washers which cradle these bushings, had super sharp squared off edges.
They are now rounded into a smooth radius and should not shred the new bushings. They shoukd also.provide more progressive resistance, when nearing full tilt.

I did have some heatsinks, the type which attach to vertical tranzistors on circuit boards wjth a small machine screw.

i made their backaides perfectly flat and smooth, and JB welded 6 of them to the aluminum plaTe heatsink that attaches to the ESC.
The bottom of this ESC was also not flat.
Now aluminum plate, and bottom of the ESC, are totally flat and will mate far far better than how it left the factory.

The finned heatsinks i added likely quadruple the surface area for airflow to dissioate the heat generated by the mosfets.inside the ESC, which should greatly extend their lifespan, and reliability and maybee oerformance and efficiency.

Hopefully this cleans up the jerky hot brakes and inconsistent acceleration when i hot


Rerouting the wiring inside enclosure might also help reduce the jerkyness when accelerating and braking, but if not, im getting a new ESC.

the one HUB motor which feels a bjt less crisp when spun by hand, well each motor's squared axle fits in a square receptacle, and is then covered by a thick steel plate, which is held in place with 4 aluminum screws, that thread into the cast aluminum truck.

One of the screws on iffy motor, is off at an angle. does not appear to be stripped, or loose, but i am not taking it off, to satisfy curiosity, as it likely will strip if i do.

These screws loosening and stripping, were mentioned in almost every 1 start review on Amazon.

I never got a response from the outfit regarding the suspect motor, so i might have to write a detailed negative Amazon review , with pictures, and see if i get a response then.

Squeaky wheel wants a new dual hub motor truck.

This one screw off at an angle, has a gap under the head on one side, I might stuff some JB weld in that gap, to spread the load of the screw bead across the steel plate.

Pics in next post

[sternwake]

The newly rounded cupped washer edges
   

Bad  drill and tap job
   

Look at that gap under screw/bolt head