Search found 469 matches

by Buk___
Feb 16, 2018 12:34 pm
Forum: Battery Technology
Topic: Common pack design mistakes, how to avoid?
Replies: 230
Views: 18265

Re: Common pack design mistakes, how to avoid?

The fuse&bms can handle max 80A. I wil use this pack on a motor-compressor that take maximum 45Amps. I like the way building a pack + coper serie bars and no soldering on top of the cells....this is the way i can make a save strong pack ,cells in holders.The coper wire are on top of the serie nicke...
by Buk___
Feb 16, 2018 12:30 pm
Forum: Battery Technology
Topic: Would you charge a 4s LiFePo with a "15V" wall wart (intended for charging a 12V SLA)?
Replies: 5
Views: 80

Would you charge a 4s LiFePo with a "15V" wall wart (intended for charging a 12V SLA)?

The title says it all. I'm looking to replace a 12V SLA (portable vacuum) with Li***, and would like to reuse the existing charger, because it is a wall mount&charger with bespoke connectors, and to save money. 4 x 3.65 = 14.6; but the 15V is the OCV; once loaded it will inevitably drop. Would you d...
by Buk___
Feb 16, 2018 10:13 am
Forum: Motor Technology
Topic: PM Motor theory - formulae etc.
Replies: 69
Views: 24648

Re: PM Motor theory - formulae etc.

Punx0r wrote:
Feb 16, 2018 7:57 am
They do :)
So, my "must probably" wasn't definitive enough for you :)
by Buk___
Feb 16, 2018 9:44 am
Forum: Battery Technology
Topic: Common pack design mistakes, how to avoid?
Replies: 230
Views: 18265

Re: Common pack design mistakes, how to avoid?

The most important thing is that you haven't put any resistors for the nickel connecting the 7 cell row. I don't know the thickness of that, so, I wouldn't suggest a number for the resistance to put between them. Look again. Each of the 6 gaps between the 7 cells has a nickel strip connection, but ...
by Buk___
Feb 16, 2018 4:53 am
Forum: Battery Technology
Topic: Homemade Battery Packs
Replies: 1518
Views: 324949

Re: Homemade Battery Packs

... Need reliable connections for charge\discharge\charge test. Problem - method of connecting to test leads. As temporary solid contact, I do not wish to permanently attach. Using Neodymium magnets attaching leads is somewhat sketchy. ... There's a photo in one of the (IIRC) 3-way cell tests of th...
by Buk___
Feb 16, 2018 4:49 am
Forum: Motor Technology
Topic: PM Motor theory - formulae etc.
Replies: 69
Views: 24648

Re: PM Motor theory - formulae etc.

My limited experience of sensorless operation on ebike controllers is they are not good. From a start under load they can initially hunt backwards and forwards a fraction of a turn until finding forwards. Generally it's good to get the bike rolling with an initial push before applying throttle. Thi...
by Buk___
Feb 16, 2018 1:41 am
Forum: Battery Technology
Topic: Common pack design mistakes, how to avoid?
Replies: 230
Views: 18265

Re: Common pack design mistakes, how to avoid?

tsourorf wrote:
Feb 15, 2018 7:59 pm
This is nice Buk! Basically, you are using copper to minimize resistance and trying to keep equal distances from root to each parallel cell. I say it's perfect enough for pragmatic applications.
All the props go to Joachim, he built it. All I did was try to model it :)
by Buk___
Feb 15, 2018 8:01 pm
Forum: Motor Technology
Topic: PM Motor theory - formulae etc.
Replies: 69
Views: 24648

Re: PM Motor theory - formulae etc.

Part 1: Output power is torque * rpm. At pull away, rpm is 0, so power is 0, until ...? ... As you say, BEMF of a stalled motor is zero and the resistance seen by the controller is indeed only the (very low) winding resistance. If you connect a controller without current-limiting and apply full thr...
by Buk___
Feb 15, 2018 7:37 pm
Forum: Battery Technology
Topic: Common pack design mistakes, how to avoid?
Replies: 230
Views: 18265

Re: Common pack design mistakes, how to avoid?

This pack good for 80A max discharge :?: 1mm pure copper wire for the series 6x The pack:3s 28P 10.8V 81Ah 8AWG wiring no direct heat to the cells on soldering the copper serie/parallels :D As best as I can model, that is a near perfect pack; with all the individual cells delivering 2.86A or 2.85A ...
by Buk___
Feb 14, 2018 8:43 am
Forum: Alternative Energy
Topic: EV Investing?
Replies: 5
Views: 93

Re: EV Investing?

wecharg wrote:
Feb 13, 2018 2:14 pm
If you had $100,000 in cash today... How would you invest the $$

Just curious what people would do with the 100k
- New EV Dealerships
- EV Charge Stations
- Cryptocurrency
- Combo of each??

Appreciate any thoughts you may have.
SpaceX stock.
by Buk___
Feb 14, 2018 3:58 am
Forum: E-Bike General Discussion
Topic: 2 Controllers one motor
Replies: 17
Views: 369

Re: 2 Controlles one motor

Impedance is the combination of resistance with inductance or capacitance. Only the resistive part dissipates power and generates heat. The loss in the controller comes from a combination of the FET resistance, the body diode voltage drop (not exactly resistance in that case), and the traces carryi...
by Buk___
Feb 14, 2018 3:35 am
Forum: E-Bike Photos & Video
Topic: '98 Quintana Roo panamint mxus xf07 350w fr hub
Replies: 42
Views: 1067

Re: '98 Quintana Roo panamint mxus xf07 350w fr hub

eCue wrote:
Feb 14, 2018 3:30 am
I want to find a flatter and smoother road to run on to be sure Im not peaking the speedo on a 1 degree slope
Do timing runs in both directions and average; slopes (and head/tail winds) will cancel.
by Buk___
Feb 12, 2018 4:21 pm
Forum: Motor Technology
Topic: 2 controllers in paralell for one hub motor, is it possible?
Replies: 31
Views: 520

Re: 2 controllers in paralell for one hub motor, is it possible?

In a buck converter topology, when the switch is off and the magnetic field is collapsing, the current is circulated by a diode. Buck Converter Basics.JPG In a motor controller, this diode is really the body diode in the low side FET. When this diode is conducting, there will be a voltage drop acro...
by Buk___
Feb 12, 2018 9:45 am
Forum: Motor Technology
Topic: 2 controllers in paralell for one hub motor, is it possible?
Replies: 31
Views: 520

Re: 2 controllers in paralell for one hub motor, is it possible?

...If the controller are using synchronous rectification, then you could get shoot-through and destruction.... Agree on synchronous rectification. This is one case where you want to use simple controllers that depend on diodes for carrying the circulating motor currents - not high performance or si...
by Buk___
Feb 12, 2018 4:10 am
Forum: Motor Technology
Topic: 2 controllers in paralell for one hub motor, is it possible?
Replies: 31
Views: 520

Re: 2 controllers in paralell for one hub motor, is it possible?

It doesnt cause shoot thru within a *single* controller--it would be from one controller into the other. If the top leg of any phase of controller A was turned on, and the bottom leg of the same phase of controller B was turned on, (however unlikely it might be to happen) and they are in parallel a...
by Buk___
Feb 12, 2018 4:05 am
Forum: Motor Technology
Topic: 2 controllers in paralell for one hub motor, is it possible?
Replies: 31
Views: 520

Re: 2 controllers in paralell for one hub motor, is it possible?

Remember that in the 4QD stuff, the brushed motors do not have any commutation perfrmed by teh controller--it's all mechanical inside the motor. But in brushless ocntrollers such as those generally discussed here on ES (especially in threads like this one), the controller not only performs PWM to c...
by Buk___
Feb 12, 2018 3:51 am
Forum: Motor Technology
Topic: 2 controllers in paralell for one hub motor, is it possible?
Replies: 31
Views: 520

Re: 2 controllers in paralell for one hub motor, is it possible?

Samd was posting that he'd had some successes using two controllers a couple of years ago, but no follow up on actual road use and longevity. Personally I'd just get a bigger controller. :D https://endless-sphere.com/forums/viewtopic.php?f=2&t=75186 Thanks for the link. Damn! I wish I had read that...
by Buk___
Feb 12, 2018 3:26 am
Forum: Motor Technology
Topic: 2 controllers in paralell for one hub motor, is it possible?
Replies: 31
Views: 520

Re: 2 controllers in paralell for one hub motor, is it possible?

Something else not covered is electric braking: ... The way it switches the FETs is different than when it's causing current to flow to the motor from teh battery, so I don't know if there's even any possiblity of shoot-thru in this case, but I suspect there is. Even if there's no battery-shoot-thr...
by Buk___
Feb 12, 2018 2:57 am
Forum: Motor Technology
Topic: 2 controllers in paralell for one hub motor, is it possible?
Replies: 31
Views: 520

Re: 2 controllers in paralell for one hub motor, is it possible?

Hm. Gonna overstay my welcome with this post, but this (my misunderstanding or failure to convey my point) is niggling me. then once fed out to the RC of the motor windings and smoothing caps, There aren't any smoothing caps on the motor side of the FETs--those are only on the battery/gate side, on ...
by Buk___
Feb 11, 2018 10:44 pm
Forum: E-Bike Photos & Video
Topic: Making a carbon fiber swingarm
Replies: 4
Views: 542

Re: Making a carbon fiber swingarm

I assume it to be annodised Al. Possible, but I've never heard it termed that. And whilst anodizing might prevent galvanic corrosion and has a pretty good bond with the Al, it is a notoriously difficult surface to get a good bond to. When Lotus were researching the gluing&pining together of the Alu...
by Buk___
Feb 11, 2018 10:29 pm
Forum: Motor Technology
Topic: 2 controllers in paralell for one hub motor, is it possible?
Replies: 31
Views: 520

Re: 2 controllers in paralell for one hub motor, is it possible?

The controller is using the motor windings as the inductor in a buck converter topology. If the PWM isn't synchronized, sometimes they would be in phase and sometimes they would be out of phase. There are two possibilities for the PWM being in or out of sync. The start/end of each sine wave (or tap...
by Buk___
Feb 11, 2018 9:08 pm
Forum: E-Bike Photos & Video
Topic: Making a carbon fiber swingarm
Replies: 4
Views: 542

Re: Making a carbon fiber swingarm

flat tire wrote:
Dec 18, 2017 10:38 pm
... floxed Al. Any questions?
What is "floxed Al"; searches for that term all bring up stuff about some neuro-degenerative disorder.
by Buk___
Feb 11, 2018 9:36 am
Forum: Motor Technology
Topic: Halbach array Inrunner or Outrunner
Replies: 13
Views: 212

Re: Halbach array Inrunner or Outrunner

monie jacobsen wrote:
Feb 11, 2018 8:47 am
Do you have a suggestion for the codes?
Sorry, no. I'm a raw beginner myself in this field.

I'm hoping to learn from the responses to your questions from the experts .
by Buk___
Feb 11, 2018 9:24 am
Forum: E-Bike Photos & Video
Topic: Your Creation's Before & After Pics
Replies: 1704
Views: 484889

Re: Your Creation's Before & After Pics

tmp-cam--432769977.jpg My Thai Panther Hercules One Fat Bike, as I originally received it from 888bikes in Thailand, and now after I have completed its transformation into a Mxus 3000w powered proper Electric Bike! I love it, and it suits my daily recreational riding needs around my home in rural T...
by Buk___
Feb 11, 2018 9:23 am
Forum: E-Bike Technical
Topic: Hot-setting 6061 Frame
Replies: 17
Views: 241

Re: Hot-setting 6061 Frame

Looking into the newer QS Motors line with 200mm dropout widths for a custom Ebike project based on the A2B Octave/Metro Frames. Have developed newer 1/4" 4130 dropouts for both sides of the swingarm but am now looking to stretch the dropouts width from 155mm to 200mm to accept their higher torque ...