Search found 73 matches

by halcyon_m
May 30 2017 10:53am
Forum: Motor Technology
Topic: Field Weakening VS Gear Box VS Higher voltage battery
Replies: 145
Views: 12201

Re: Field Weakening VS Gear Box VS Higher voltage battery

Designing a motor with a characteristic current (current when shorted) to the nominal rating allows the controller to just short the motor terminals in a fault scenario. The issue bobc mentioned just goes to show that "converter fault --> all switches open" is not always the best assumption. Bottom ...
by halcyon_m
May 20 2017 6:41pm
Forum: Battery Technology
Topic: turnigy multistar lipo batteries, are they good?
Replies: 16
Views: 1618

Re: turnigy multistar lipo batteries, are they good?

I purchased 3 of these. 1 was puffed, and then 1 cell died after I left it connected to a small load for a week. All other cells were fine. I'm split on buying a replacement, since it was ~$160 for 3 4s, 16Ah shipped. Now it will be ~$100 for a single replacement 4s, 16Ah. So, good? if you're lucky,...
by halcyon_m
Jul 23 2016 1:42am
Forum: Items Wanted
Topic: Where to buy BMS units in North America
Replies: 2
Views: 255

Re: Where to buy BMS units in North America

Ive been working on a 12s bms that ive been using for a few months now. If youre interested in being a beta tester, let me know
by halcyon_m
May 19 2016 12:43am
Forum: Battery Technology
Topic: features for 4,8, or 12S li-ion manager
Replies: 0
Views: 107

features for 4,8, or 12S li-ion manager

Hi everybody. I've been using my 12S balancing manager for a few weeks now on my 1kW e-bike, and I'm about to do another board spin. Does anyone have any request for features? Here's the quick pitch: It makes sure you don't over-charge or over-discharge any cell in the batch, and has some small bala...
by halcyon_m
Jul 03 2015 9:57am
Forum: EV Business World
Topic: Taking Charge: Let's Develop the Products That We Want!
Replies: 34
Views: 20031

Re: Taking Charge: Let's Develop the Products That We Want!

I should specify that when i offered to develop products for the ES community, that it would be as a separate venture. My current employer is not currently in a position to serve the enthusiast community. Im guaging market needs. There are currently many electric cars and bikes on the market. Where ...
by halcyon_m
Jun 28 2015 10:23am
Forum: EV Business World
Topic: Taking Charge: Let's Develop the Products That We Want!
Replies: 34
Views: 20031

Re: Taking Charge: Let's Develop the Products That We Want!

Hi all, I wanted to bump this thread, since it's been a few years. I used to have some EV projects that centered around making items that weren't easily or cheaply sourced. I imagine many of the people here have similar issues. I currently work for a electric vehicle manufacturer, but I, and some of...
by halcyon_m
Feb 21 2015 1:16am
Forum: Large EV General Discussion
Topic: Electric Miata/MX5.
Replies: 61
Views: 13284

Re: Electric Miata/MX5.

Yeah, I'd like to know as well. Did the lipo's last at all?
by halcyon_m
Jan 11 2015 1:40pm
Forum: Large EV General Discussion
Topic: ARPA-E LiteCar Challenge
Replies: 3
Views: 827

Re: ARPA-E LiteCar Challenge

The deliverable is a 7 page explanation with designs and material lists.

With the right people together, this could take a weekend.
by halcyon_m
Oct 29 2014 8:56pm
Forum: Motor Technology
Topic: Motorbike Motor
Replies: 60
Views: 8426

Re: Motorbike Motor

I am going to do a 3 piece like the YASA article I am going off of. I would suggest doing a 2-piece (T-style including one face and half the core) that can be more easily machined if you go away from the solid construction. This would allow you to wind the copper separately and then insert the half...
by halcyon_m
Oct 15 2014 7:01pm
Forum: Motor Technology
Topic: Advice requested YZ 250 motorcycle to electric
Replies: 4
Views: 525

Re: Advice requested YZ 250 motorcycle to electric

It would help to know more about what you're expecting from the project in terms of performance, available budget, time to completion, among other things, but I see you need a proposal quick. For simplicity purposes, I'd suggest a DC motor (PERM, AGNI, E-TEK) and a Kelly controller. I'm sure others ...
by halcyon_m
Oct 15 2014 6:47pm
Forum: Motor Technology
Topic: Advice requested YZ 250 motorcycle to electric
Replies: 4
Views: 525

Re: Need help finding a motor for YZ 250 motorcycle to elect

Misgif wrote:i need help finding the right motor and controller for my class project any ideas or links
What are the goals of your project? How much time do you have? What is the experience level of you (and your team)?
by halcyon_m
Oct 13 2014 6:19pm
Forum: Battery Technology
Topic: 1000kW DC powersupply - Help
Replies: 66
Views: 3932

Re: 1000kW DC powersupply - Help

This is very interesting to see that even at 340A, it falls off quickly, but then rebounds to 4V, presumably where ~80% capacity can be extracted. When they say 'burst 90C', they really mean it. At 300A, I calculate with rough numbers for weight from a 3.5Ah pack on HK, that this cell only gives 5.2...
by halcyon_m
Oct 13 2014 5:30pm
Forum: Battery Technology
Topic: 1000kW DC powersupply - Help
Replies: 66
Views: 3932

Re: 1000kW DC powersupply - Help

It'd be a bit odd if hobbyking RC lico, being some of the cheapest available also turned out to be some of the best performing. Aren't there any superior RC lico pouches from more specialist manufacturers? I always figured Hobbyking stuff was near the bottom end of the RC market. A battery fab faci...
by halcyon_m
Oct 13 2014 4:37pm
Forum: Battery Technology
Topic: 1000kW DC powersupply - Help
Replies: 66
Views: 3932

Re: 1000kW DC powersupply - Help

[A]s far as anything I've tested, the >100C discharge hobby cells are the highest power density cells I've seen by a pretty healthy margin. Do you have any data points you could throw out at us? I see the test from the SAFT cells got 14kW/kg at 20C initial temperature, but considering a 3S, 2600mAh...
by halcyon_m
Oct 13 2014 3:32pm
Forum: Battery Technology
Topic: 1000kW DC powersupply - Help
Replies: 66
Views: 3932

Re: 1000kW DC powersupply - Help

What happened to the SAFT 200-400C cells we were discussing or other similar pulse-power cells? LiveForPhysics brings up a good point about the 50% rule (peak power from a cell comes at or above 50% of the open-circuit terminal voltage). Also, thanks for the 70% (30% sag) rule-of-thumb. Maybe we can...
by halcyon_m
Oct 12 2014 12:50pm
Forum: E-Bike Non-hub Motor Drives
Topic: RC motors, efficiencies, gearboxes and more?
Replies: 88
Views: 7821

Re: RC motors, efficiencies, gearboxes and more?

That is a cool idea. It has me really wondering about the forces at work on the wheel. In a normal motor there is a lot of rigidity so the fields driving the motor cause it to spin rather than just deforming. If you had a high powered wheel motor like that I wonder if the field would push/pull the ...
by halcyon_m
Oct 09 2014 7:03pm
Forum: Battery Technology
Topic: 1000kW DC powersupply - Help
Replies: 66
Views: 3932

Re: 1000kW DC powersupply - Help

As halcon_m said,.. a well designed controller(s) would eliminate the need for a clutch pack...but also as you say, it seems unlikely that you could design a realistic high power EV drive that doesnt require rpm reduction to the wheels I didn't say there wouldn't be a gear reduction. What I did say...
by halcyon_m
Oct 09 2014 5:37pm
Forum: Battery Technology
Topic: 1000kW DC powersupply - Help
Replies: 66
Views: 3932

Re: 1000kW DC powersupply - Help

Thanks for the info. Why a clutch or a diff though? To say this would be purpose-built would be an understatement, so mounting the motor(s) transversely would be entirely possible. Totally possible - however then you have issues with reduction. There's no way you can run without some form of reduct...
by halcyon_m
Oct 09 2014 5:01pm
Forum: Battery Technology
Topic: 1000kW DC powersupply - Help
Replies: 66
Views: 3932

Re: 1000kW DC powersupply - Help

They don't have a transmission. Direct driven 12" rear end with hydraulic multi plate clutch that's computer controlled. Over the course of the run RPM actually drops as the clutch is released before climbing again at the end. Clutch plates last one run. Fuel flow is primary means of metering out p...
by halcyon_m
Oct 09 2014 1:14pm
Forum: Battery Technology
Topic: 1000kW DC powersupply - Help
Replies: 66
Views: 3932

Re: 1000kW DC powersupply - Help

Hillhater wrote:
Punx0r wrote:.
Does anyone know the weight of a typical top fuel engine?
230 kg complete with ancillaries.
including transmission and fuel tank or no?
Transmission (including clutch and gear reduction/differential) would probably be around 100kg
Fuel tank would be around 15kg at least.
by halcyon_m
Oct 09 2014 11:46am
Forum: Motor Technology
Topic: Field Weakening VS Gear Box VS Higher voltage battery
Replies: 145
Views: 12201

Re: Field Weakening VS Gear Box VS Higher voltage battery

I bet there's maybe 3kg of copper and magnets in a decent sized hub motor, not much really even at the wheel rim. If we ever get room-temperature super conductors (or even graphene wire at 10x the conductivity of copper) we could replace the magents with field windings, use an air-core and have an ...
by halcyon_m
Oct 08 2014 6:49pm
Forum: Battery Technology
Topic: 1000kW DC powersupply - Help
Replies: 66
Views: 3932

Re: 1000kW DC powersupply - Help

,.... if you look at the SAFT battery discharge curve, staying as high up (most charged, less discharged) on the curve as possible gives the highest voltage and also the highest power density. Simple matters like this might require only 250kg of batteries versus 300kg.. How do you propose you can k...
by halcyon_m
Oct 08 2014 6:31pm
Forum: Battery Technology
Topic: 1000kW DC powersupply - Help
Replies: 66
Views: 3932

Re: 1000kW DC powersupply - Help

Or do away with the controller and use an SCRs to connect the motor directly to the pack and then use the same mechanical clutch as the ICE top-fuel cars to feed in torque to the wheels. At the end of the run the clutch disengages, unloads the motor and allows a contactor to safely disconnect the b...
by halcyon_m
Oct 08 2014 12:38am
Forum: E-Bike Non-hub Motor Drives
Topic: RC motors, efficiencies, gearboxes and more?
Replies: 88
Views: 7821

Re: RC motors, efficiencies, gearboxes and more?

By gearing down to 40, meaning a higher ratio, should allow the use of less current to get the required torque for this example we are talking about here. The majority of the time the bike would be used below 20mph so im not sure core loss would be that large of a percentage drain on the battery ave...
by halcyon_m
Oct 07 2014 8:10pm
Forum: Battery Technology
Topic: 1000kW DC powersupply - Help
Replies: 66
Views: 3932

Re: 1000kW DC powersupply - Help

Beating a top fuel dragster over 1000' in reality is going to be very, very challenging. I don't think anyone said this would be easy, or even plausible at the end of the day. Entertaining to think about. a substantial challenge - safety... how does one adequately fuse something that's essentially ...