Search found 216 matches

by Buk___
Dec 16, 2017 3:58 am
Forum: E-Bike General Discussion
Topic: Aluminum vs Steel vs Carbon E-bike Frames
Replies: 34
Views: 838

Re: Aluminum vs Steel vs Carbon E-bike Frames

Because a tube's stiffness varies as the cube of its diameter (actually, the fourth power of its outer diameter divided by its inner diameter), the stiffness break-even point given the same wall thickness as steel is at 1.4 times the tube diameter. At that size, the aluminum tube weighs less than h...
by Buk___
Dec 16, 2017 1:31 am
Forum: E-Bike General Discussion
Topic: Aluminum vs Steel vs Carbon E-bike Frames
Replies: 34
Views: 838

Re: Aluminum vs Steel vs Carbon E-bike Frames (The video)

Take a look ; then choose wisely :) That's pretty cool. The aluminum tube they used had the same dimensions as the first two steel ones, which means it weighed 1/3 as much. I think if the aluminum one had been matched by mass rather than dimensions, it might have fared better than the steel samples...
by Buk___
Dec 16, 2017 12:56 am
Forum: E-Bike General Discussion
Topic: Araldite as filler between frame and bracket?
Replies: 11
Views: 144

Re: Araldite as filler between frame and bracket?

Another thought. Mouldable silicon; otherwise known as Sugru. Amazing stuff. I used it to make heat resistant handles for a couple of my wife's large ceramic coated cooking pots that had metal handles. It sticks very well, but peels off if need be; moulds like playdoh, but sets up overnight and turn...
by Buk___
Dec 15, 2017 7:33 pm
Forum: E-Bike General Discussion
Topic: Snapped fork dropouts
Replies: 17
Views: 132

Re: Snapped fork dropouts

I'm trying to figure what could of caused my fork dropouts to just suddenly snap on me.. I've had the bike frame for about 3 month's, and before that I had a front suspension Sport Check bike, that lasted several winters with frame issuses, that could cause safety issues. I do have a few idea's as ...
by Buk___
Dec 15, 2017 2:12 pm
Forum: E-Bike General Discussion
Topic: OpenEbike - open source frame design
Replies: 26
Views: 446

Re: OpenEbike - open source frame design

Here is the simulation of both structures. Triangles are in fact stronger. Conditions of experiment Dimensions of beams - 548x60x10 mm Distance of support points - 524 mm Strength applied - 1000 N Weight of a each single beam - 1.005 kg (mass exactly the same) Material for calculations - steel If y...
by Buk___
Dec 14, 2017 10:45 pm
Forum: Battery Technology
Topic: Known good BMS (for 10s)?
Replies: 0
Views: 24

Known good BMS (for 10s)?

The Amazon 10s4p battery pack that I recovered thanks to the kind help if the guys here seems to be standing up well. However, one thing I've measured is the difference in voltage/capacity drop if I leave the BMS connected and without. If I just let the pack stand without the BMS connected, there is...
by Buk___
Dec 14, 2017 1:59 pm
Forum: E-Bike General Discussion
Topic: OpenEbike - open source frame design
Replies: 26
Views: 446

Re: OpenEbike - open source frame design

wturber wrote:
Dec 14, 2017 12:59 pm
None of the pictures show on the latest post.
Weird. They show for me directly in the post?
by Buk___
Dec 14, 2017 1:57 pm
Forum: E-Bike General Discussion
Topic: Araldite as filler between frame and bracket?
Replies: 11
Views: 144

Re: Araldite as filler between frame and bracket?

Hi Guys, I hoping to get comments on the above, I have made some brackets to hold a battery enclosure to the downtube of my specialized enduro 2014. Unfortunately for me the down tube is an irregular oval shape. By hook and by crook I've managed to make my bracket quite close and was planning to us...
by Buk___
Dec 14, 2017 8:38 am
Forum: E-Bike Technical
Topic: Specific heat absorption capacity of disc brakes
Replies: 40
Views: 760

Re: Specific heat absorption capacity of disc brakes

I agree with Chalo about rim brakes... I mean disc brakes are getting larger and larger diameter, only a few more years till the disks are as large as the rims.... at which point everyone will realise rim brakes are basically disc brakes with the biggest disk possible. I'd still rather spend £6 on ...
by Buk___
Dec 14, 2017 4:09 am
Forum: Battery Technology
Topic: Surface resistivity & volume resistivity?
Replies: 10
Views: 106

Re: Surface resistivity & volume resistivity?

It might be worth testing. I've seen that stuff used in medical equipment (for RFI shielding). Being a foam, the more you compress it, the lower the resistance will be. it can be used as a force sensing resistor. I've requested a sample. If the send one, I'll try it out. My idea is to attach circle...
by Buk___
Dec 14, 2017 3:54 am
Forum: General Discussion
Topic: Mounting odd hub into truing stand
Replies: 8
Views: 79

Re: Mounting odd hub into truing stand

If it weren't for the scabby welds holding the broached disc into the end of the hub tube, it would be plausible to find a fender washer that could center a small diameter thread or rod in the hub. But no. Schwines are for selling, not riding or servicing. He might be able to grind/file 3 notches i...
by Buk___
Dec 13, 2017 7:39 pm
Forum: Battery Technology
Topic: Surface resistivity & volume resistivity?
Replies: 10
Views: 106

Re: Surface resistivity & volume resistivity?

Punx0r wrote:
Dec 13, 2017 5:00 pm
Reduce thickness to 1.5mm (0.0015m): 59 x 0.0015 = 0.089Ω
Yeah. That's about what I got.
Punx0r wrote:
Dec 13, 2017 5:00 pm
*I think*
That too :)

At 2C discharge from 2600mAh cells, that's a bit under 0.5W. Times 2 for each end and 60 for a 12s5p pack and it's not negligible.
by Buk___
Dec 13, 2017 7:13 pm
Forum: Battery Technology
Topic: 4-prong battery connector; identification?
Replies: 2
Views: 69

Re: 4-prong battery connector; identification?

eZip blade terminal https://www.electricscooterparts.com/images/currie/CTE-24076.png That's certainly the beasty. Thanks. But $20 for the cable that I only need the socket; double it to get it here; and double it again to get it here before March. I guess I'll be looking for an alternative solution...
by Buk___
Dec 13, 2017 3:45 pm
Forum: Battery Technology
Topic: Surface resistivity & volume resistivity?
Replies: 10
Views: 106

Re: Surface resistivity & volume resistivity?

Ah--when I clicked the link, a blank page opened, no article, so I didn't see that. Either way, you still have to know which unit they're actually using, but you could "assume" it's mm since the other unit on the same line is mm. :/ According to the "Sheet resistance" section of this (I cannot link...
by Buk___
Dec 13, 2017 3:19 pm
Forum: Battery Technology
Topic: Surface resistivity & volume resistivity?
Replies: 10
Views: 106

Re: Surface resistivity & volume resistivity?

fechter wrote:
Dec 13, 2017 2:51 pm
In your example, if the foam is sandwiched between the cell and a bus bar, you will have something close to the volume number.
So basically, less heat generated by the foam connector, than the internal resistance of the cell?
by Buk___
Dec 13, 2017 2:33 pm
Forum: Battery Technology
Topic: Surface resistivity & volume resistivity?
Replies: 10
Views: 106

Re: Surface resistivity & volume resistivity?

You'd need to find out from the manufacturer what unit of measurement they intended to (but did not) put there. Given their other measurement on the same line is in mm, then it's likely the unit is metric, and probably mm, but you'd have to ask. If none of their data sheets use a unit there, then t...
by Buk___
Dec 13, 2017 11:04 am
Forum: Battery Technology
Topic: Surface resistivity & volume resistivity?
Replies: 10
Views: 106

Surface resistivity & volume resistivity?

I have the data sheet(pdf) for some Kemtron conductive foam. The specs give two figures for the foams resistivity: Surface resistivity: 0.05Ω/sq Volume resistivity: 0.015Ω/sq I was trying to work out what energy would be consumed if this was used to connect to a 18650 battery, but the units; Ω/sq, i...
by Buk___
Dec 13, 2017 10:07 am
Forum: E-Bike Technical
Topic: v-brake front fork mounting points?
Replies: 15
Views: 229

Re: v-brake front fork mounting points?

IMO, hand fitting shit is what custom is all about. If you plan to use stock stuff, same typical rim width as mtb's and cruisers, then of course no need to hand fit anything, just make it same as you measure down at Walmart. I don't plan to "use stock stuff", so much as design something that has th...
by Buk___
Dec 13, 2017 9:49 am
Forum: Battery Technology
Topic: bluetooth BMS?
Replies: 61
Views: 3589

Re: bluetooth BMS?

Still I don't understand the purpose of those "release" input boxes. I would assume it means that for over-voltage (CellOVF), the protection cuts in if the voltage goes above 4250, and releases again when it drops back below 4100. For under-voltage (CellUVF) the protection cuts in when the voltage ...
by Buk___
Dec 12, 2017 6:38 pm
Forum: E-Scooter and Motorcycle General Discussion
Topic: Random tools and EV related projects
Replies: 17
Views: 344

Re: Replacing wheel bearings

Ball bearings don't tolerate lateral forces very well. They are intended to take radial forces almost exclusively. Bearing balls -- the balls themselves -- don't care in what frame of reference force is applied to them. They are balls! Any force applied to them acts through the diametric centre, an...
by Buk___
Dec 12, 2017 5:28 pm
Forum: E-Bike Technical
Topic: v-brake front fork mounting points?
Replies: 15
Views: 229

Re: v-brake front fork mounting points?

If you're going to use the brake bosses as pivot points (or have other pivots along the same axis), you have to use smaller diameter motors and in place of the brake arms, or else it won't be on the rim, it'll be on the tire at an angle to the wheel some distance from the fork. Hard to show without...
by Buk___
Dec 12, 2017 1:09 pm
Forum: Battery Technology
Topic: 4-prong battery connector; identification?
Replies: 2
Views: 69

4-prong battery connector; identification?

Hi,

My searches to find out what type or brand this connector is have failed:
4prongConnector.jpg
4prongConnector.jpg (48.51 KiB) Viewed 69 times
Does anyone know what they are called; or suggest a search term; or the best place to look?

Thanks, Buk.
by Buk___
Dec 12, 2017 8:09 am
Forum: E-Bike Technical
Topic: v-brake front fork mounting points?
Replies: 15
Views: 229

Re: v-brake front fork mounting points?

I suppose you could go with a median-fit and use a bracket like the stiffening-U braces (brake booster, booster arch, etc) for brakes; they typically have slots (rather than round holes) for the screws to go thru them and into the bosses. \ This image shows the arch I have installed on the front-fr...
by Buk___
Dec 11, 2017 2:10 pm
Forum: Motor Technology
Topic: Flexible OpenSource firmware for BMSBattery S/Kunteng KT motor controllers (0.25kW up to 5kW)
Replies: 1092
Views: 26742

Re: OpenSource firmware BMSBattery S/Kunteng KT controllers STM8

3. In terms of hardware, you will need what is listed here: https://opensourceebikefirmware.bitbucket.io/Development_tools--Linux--Step-by-step_tutorial_development_tools--Hardware_tools_to_flash_and_debug_the_firmware.html#h1-2 Are you guys using the £100+ STMICROELECTRONICS - ST-LINK/V2-ISOL - DE...