GCinDC's Giant DH Comp

[GCinDC]

my pseudo scientific test... took too long to get to middle of the mass ave hill - i drove WOT to get there, when i could, trying to heat it up. we know she's a cooker. motor temp in colors.

hs3540inMC_preOil_cmprsd.jpg (81.84 KiB) Viewed 466 times

i should be able to repeat tho w/ oil in there and get good comparison numbers. map was reversed to follow timeline better.

the raw data, a video of the CA/HK VT monitor:


for some reason i'd been thinking there was a wirehole inside the motor that i could caulk/fill up, but it's a slot... and what with the wire vulnerabilities in that slot, i'm thinking i'll have to use less oil to keep it from leaking out..

[hjns]

Very nice. I planned to do something similar, but can't find the time. Will take me another month, so I am anxiously following your thread.

[rui_fujino]

cool vd greg, whats your controller settings? (phase current ..etc)

[GCinDC]

never programmed this controller. requested these settings back in 11/10 (excluding sp sw settings):

[GCinDC]

before smear campaign:

after:


removed wire side after all, jb welded wire/hose ends to withstand hot oil turbulence. some marine sealant up around the axle slot, though that probably won't last, but hopefully will fill any gaps to discourage spooging my disc rotor.

of course the bearing stuck to the axle. and notice how the end rusted? must have retained some moisture from last night, despite my 1/8" vent hole.

more after it dries.

[GCinDC]

leaving it all to dry overnight:

[shorza]

Great job!
I'll be copying this. Please keep us updated on how it all works out.

[GCinDC]

cross posting, so kill me:

w/o oil it took me 1 minute to get up to 70C.

w/ oil, it took 15 minutes of pulling mostly 4kw, heavy starts, stops, bad throttle.

got some weird cut outs tho. almost like hall dying, but power resumed right away. happened a bunch of times. not good.

also, i was VERY glad i removed rear caliper, as the seal on the disk side blew and a bulb of oil appeared. not sure why vent didn't work!

perhaps should have waited longer for sealant to dry. i'm used to painting caulking while wet...

i did some tests with round tupperware, and figured out that 1/4 full put oil at a good level:


i hated the thought of not knowing how much was in there, so decided to fill it halfway, then siphon out half of that. i ended up putting in 400 cc total, but 50cc probably leaked out axle. i made the mess so you won't have to...

and 350cc is still too much, if oil covered my vent hole, there would be too much pressure in there.

some of the work:

[GCinDC]

[Stone Meadow]

Okay...I don't get it. Why seeing red?

What was I looking at

[pwbset]

Okay...I don't get it. Why seeing red?

Oil leaking.

Very cool video though.

[Hyena]

So where'd she sprint a leak from ?
What size is your wheel and tire again ? 18" ? 2.75 ?

[GCinDC]

reposting from the snake oil thread:
just had a romp in the woods...completely different riding. whereas it took forever to get up to 80C at street speeds, it was not hard to get to upper 90's on steep uphill sections. still much better than 144C tho...

after yesterday's run, i thought all the juice had squirted out, but some nasty jolts in on roots, etc made a nasty mess of my wheel, and the rear brakes, which i'd decided to put back into place... they're a bit more like bad mechanical brakes now...

perhaps too much oil still. i released some more, just leaning the bike over, drained easily through clear tube.

no leaks from drive side. all from disc/WIRE side. that slot is the issue. will an oil seal matter at all if there's a friggin slot underneath it? or did i read that i should load the slot up with sealant....
pics from before. rubber wire cap off

[electr0n]

Is your motor still cutting out? Any idea what is causing it? Are you running a 24" front tire with a 17" rear, maybe closer to 21" with the tire? Do you have issues with the pedals striking the ground at all? Hows the acceleration and riding with the smaller rear wheel compared with what you had before? Would you say the HS3540 could be good for around 4kw continuous with the oil? I like everything you've done with your bike and enjoy your videos.

I haven't had any heating issues with my stock HS3540 yet but I don't push it very hard since I've only got a half kilowatt hour battery capacity it runs out quick if I ride full throttle.

[GCinDC]

Is your motor still cutting out?

not once during dirt bike ride! for that ride, btw, you may have noticed in the vid the 5 x 4s2200mah lipos that i was testing:

no regen for me at 24s, but who cares. yummy, yummy.
ok to park outside CVS, but not near a police station:

but there was a minor drop in acceleration once this morning. perhaps the bungee was too tight over the controller connector mess (gathered in a stretchy velcro sleeve) and caused a poor connection? not sure. i hope it doesn't happen. pedaling that wheel would really suck.

Are you running a 24" front tire with a 17" rear, maybe closer to 21" with the tire?

amazing how much confusion this wheel causes, huh?
26" bicycle front (27" actual Outside Diameter), 2.75 x 19" Motorcycle Tire (25" OD), read back some... to compare to 20" bike wheel:


now reposting, from snake oil thread:
unoiled motor got to 70C quickly on first uphill, then was more or less flat/downhill until 7 min uphill section, after which i had to pedal unoiled motor to keep it from overheating...

oil_v_no_oil.jpg (10.44 KiB) Viewed 188 times

video of CA/temp sensor mostly synched:

ride map again w/ unoiled temps listed:

[electr0n]

Good news your motor wasn't cutting out. The oil makes a dramatic difference. Temperature is pretty much cut in half or better. Very helpful. The oil should help with internal rusting too. Seems like a better solution than drilling holes in the side covers to me.

[GCinDC]

Seems like a better solution than drilling holes in the side covers to me.

i'm not ready to make that judgement yet. yes, heat problem solved, but disc brake is critical, and losing it at cause of a couple bumps is not worth it. might be better mod for 9C with sealable wire hole. we shall see...

[GCinDC]

ps. it should be noted that this hulk of a wheel takes tremendous energy to rotate.

my lightly vented hs3540 in a 26" bike wheel w/ the hookworm takes much less, and runs much cooler, and faster for that matter. i should run it on the same track and get it's numbers. it will get hot, but takes 3 times as long?

pic of the day:

fender taped on 2 min before morning departure cause it was raining...
eventually i'll get that slop around the pack cleaned up... but don't be surprised if it takes a while...

[shorza]

Looking good, where did you get your fenders from?

[electr0n]

That's interesting about that wheel taking more energy to rotate and causing the motor to overheat sooner than the standard bike wheel. I would have thought the slightly smaller diameter would improve efficiency somewhat, at least during accelerating from a stand still. Would the oil leaking affect a v-brake setup as well, does it get all over the rim?

[Hyena]

amazing how much confusion this wheel causes, huh?
26" bicycle front (27" actual Outside Diameter), 2.75 x 19" Motorcycle Tire (25" OD)

Aaah, it IS ia 19" - I thought it was 18" for some reason. I've found some 19" rims locally - 19x 1.85 and 19x2.5"
I was thinking the running less than 3" tyres on it wouldn't be worth the effort of the motorcycle wheel build when I have 24x3" knobbys on there now, but looking at yours the 2.75 looks pretty chunky.

it should be noted that this hulk of a wheel takes tremendous energy to rotate.

So for commuting it makes it a thirstier beast ?
The trade off of more heat dissipation not worth the extra weight and power consumption ?
Maybe I should rethink my plan to buy the 19x2.5" rim and 4.1" dual sport tyre I've been eyeing off...


Any updates on the oil leakage ? Any recurrance since the initial venting ? With any luck it might have been just a bit too much in there and when it heated up the pressure and expansion just squirted a bit out. Not sure why a jolt should have caused it though...
Any reason the vent hose is so long ?
If you had a more controlled way to load the motor up (eg on a dyno) it'd be good to start off with a sealed up motor (with the vent) and then progressively add more oil to find the sweet spot between cooling efficiency and volume of oil.

[GCinDC]

hey hy,

this wheel is a monster and sucks current to move. i've been meaning to take a picture of it's paw print somehow, maybe after going thru the water? gotta be like 4 times the traction/friction w/ pavement. makes for a very solid feel, but god help you if you gotta pedal it.

re heat, all i can say is that on my 5 mile commute, where mile 3 to 4 is a long steady uphill, the:
- hs3540 in bike wheel reaches 125C at mile 4.5, after the hill
- unoiled hs3540 in MC wheel reaches 125C at mile 3.3 (one third up the hill, so i have to back way off the throttle make it to the top w/o cooking)
- oiled hs3540 in MC wheel reaches 80C at mile 3.3 and as long as i'm moving doesn't rise above 90C.

bottom line, w/o cooling this wheel is unsustainable for heat reasons alone for more than a couple minutes at 4kw.

sure is a beast to look at tho, isn't it?

but let's remember, i got it cause i wanted a bombproof rear wheel for stupid stuff. guess how i feel now that every bump squirts oil onto the rotor?

not good. it's not every bump, but i lost all rear braking power sometime during the morning's commute.

is there a way to seal the wire side? i don't know. as far as i can tell now, i need:
- sealed bearings, not shielded ones, but first need to find out if there're compatible w/ the sidecover/motor. look at the sealed rubber capped bearing on the cromotor:

then look at the shielded ones i've got in the hs3540:

also to do:
- somehow seal/caulk the wire slot -- this i can't figure out how to do. either i'll have to leave the bearing on the axle and caulk around the inside of the wire. or i'll have to push the sidecover down over wet caulk, and perhaps squeeze more down from the outside? messy, messy.

you (and everybody now) is running higher current than i am, so maybe she'd perform for you. i'd love to get my hands on an 18fet, if i weren't totally hemoraging cash...

Any reason the vent hose is so long ?

yeah, so i can bend the end out and attach the seasoning injector. and be able to access it behind the large freewheel gear. i hardly put any jb weld under it so it's come a bit loose. i didn't know if it would work at all, and was ready to epoxy over hole if i had to! sure is handy to be able to lean it over and see the oil, and i can point it to drain in a cup if i wanted to. but that tube can't survive long with that heat before it hardens and cracks i imagine...

it is also worth noting that seems to be no leaking at high speed. i imagine the oil is way against magnets and windings with tremendous centrifugal forces. it's just the hard stops when it comes flying down and splashes into the slot.... but i confess, i'm not watching the motor all the time..

[Hyena]

this wheel is a monster and sucks current to move.

Have you measured an increase in the no load current or do you think it's all friction/rolling resistance related ? Sounds like it's not settling down once up to speed and rolling along which is a bummer.

- hs3540 in bike wheel reaches 125C at mile 4.5, after the hill
- unoiled hs3540 in MC wheel reaches 125C at mile 3.3 (one third up the hill, so i have to back way off the throttle make it to the top w/o cooking)
- oiled hs3540 in MC wheel reaches 80C at mile 3.3 and as long as i'm moving doesn't rise above 90C.

Did you ever do the run with just air cooling ?
I've never had issues but then I've never sustained high kw loads for more than a minute or so. If there is a big long hill I drop my speed to bring the power down to around 3kw. 5kw peak on my commute with regular jaunts around 3500-4000w but no really long hills - just a series of little ones where it pulls that sort of power for a minute then quickly cools when dropping back to 1500-2000w on the relative flat.

guess how i feel now that every bump squirts oil onto the rotor?

I bet it gets rid of the rotor squeel though

i lost all rear braking power sometime during the morning's commute.

Bah, don't be a nancy - I don't think I've ever had rear brakes on my commuter - 8" front hydros and regen on the rear 4tw

is there a way to seal the wire side? i don't know. as far as i can tell now, i need:
- sealed bearings, not shielded ones, but first need to find out if there're compatible w/ the sidecover/motor. look at the sealed rubber capped bearing on the cromotor:

Should be, most of the motors I've played with have those rubbed capped bearings. I'm not sure they'd still be totally sealed though.
What about making up a cone like shield fixed to the side cover around the edge of the bearing ? It wouldn't totally keep the bearing free and dry but it'd keep alot of the splash and drips away when you stop and it all sloshes down from the top and runs straight down the side covers. It'd also help with keeping the oil away from the wiring exit/slot and if you fitted the breather to the inside it'd largely vent pressure as intended rather than oil.

hub bearing oil guard.jpg (23.58 KiB) Viewed 363 times

- somehow seal/caulk the wire slot -- this i can't figure out how to do. either i'll have to leave the bearing on the axle and caulk around the inside of the wire. or i'll have to push the sidecover down over wet caulk, and perhaps squeeze more down from the outside? messy, messy.

After looking at how water gets into hub motors in Justin's water ingress videos I reckon you're flighting a losing battle. But I reckon my idea above has merit.
I'll let you beta test it as I haven't got time but I'll take all the glory if/when it works

[lazarus2405]

Do you have any numbers for side cover temperatures with and without oil cooling? Perhaps with an infrared thermometer, or holding a probe to it at the top of your big hill. If we know exactly how much hotter the side covers are, we could calculate how much extra oil cooling gives you. Without having any to make any assumptions about the heat path inside the hub, knowing the dimensions of the hub, your speed, the ambient air temperature should let us fairly easily calculate how much heat the hub can dissipate via forced convection. Remember if you double the delta-T (say the side cover temperature goes from 40°C to 55°C, 25° ambient), you double your rate of heat dissipation and thus double your max continuous power. I'd be really interested in some hard numbers.

[sn0wchyld]

Do you have any numbers for side cover temperatures with and without oil cooling? Perhaps with an infrared thermometer, or holding a probe to it at the top of your big hill. If we know exactly how much hotter the side covers are, we could calculate how much extra oil cooling gives you. Without having any to make any assumptions about the heat path inside the hub, knowing the dimensions of the hub, your speed, the ambient air temperature should let us fairly easily calculate how much heat the hub can dissipate via forced convection. Remember if you double the delta-T (say the side cover temperature goes from 40°C to 55°C, 25° ambient), you double your rate of heat dissipation and thus double your max continuous power. I'd be really interested in some hard numbers.

do you know what difference a given increase in surface area has on heat dissipation? is it the same linear ratio as delta T? (ie double surface area = double heat dissipation)? modifying the side covers to look like heatsinks might have a significant effect...