Search found 683 matches

by Tritium_James
Sun, 20 Nov 2011, 01:18
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 52809

Low cost BMS

Yeah it's hard to beat a bolted joint for contact pressure!

Yes, that was a single contact, measured at the back of the straps behind the contact surface.

Fastening hardware was bolt, washer, strap1, strap2, washer, spring washer, nut, all stainless steel.
by Tritium_James
Sat, 19 Nov 2011, 21:47
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 52809

Low cost BMS

It would be good if someone could provide some measured figures for this, but I would not be surprised to find 250 uR per contact, which means your Rc is more like 1 mR, i.e. 25% of your internal resistance. I've only got results for copper/copper resistances. Test setup: 300A lab supply, fluke77 m...
by Tritium_James
Fri, 18 Nov 2011, 17:32
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 52809

Low cost BMS

Weber, maybe I'm missing something but I don't see why the middle cell in your group of three in your gif is going to end up with less current in it. The left cell sees the resistance of two negative busbar connections, the middle cell sees a positive busbar and a negative busbar, the right cell see...
by Tritium_James
Thu, 17 Nov 2011, 17:07
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 52809

Low cost BMS

Because he's bottom balancing, you'd need to clip a larger load on everything *except* the lowest cell.
by Tritium_James
Mon, 31 Oct 2011, 17:10
Forum: Electric motors and controllers
Topic: Copper rotors for sale
Replies: 10
Views: 3180

Copper rotors for sale

Jon, an induction motor running from a VFD does not have a 'starting torque' or a 'start-up current'. Both of these artifacts are only seen when hard-starting with a direct (DOL) connection to the grid. When running from an inverter/VFD, the various rotor & stator fields and currents are controlled ...
by Tritium_James
Mon, 31 Oct 2011, 15:07
Forum: Electric motors and controllers
Topic: Copper rotors for sale
Replies: 10
Views: 3180

Copper rotors for sale

Jon,

Pull out torque, start up torque and inrush currents are completely irrelevant in applications where you're running from an inverter/VFD.

For EV use, there are no downsides to a copper rotor apart from higher cost.
by Tritium_James
Sun, 30 Oct 2011, 00:26
Forum: Batteries, charging, management and monitoring
Topic: Estimating Range
Replies: 6
Views: 1399

Estimating Range

Paul, I think your logic is correct, but the answer you've arrived at is probably still too optimistic :(   The problem with EV use is that you have LARGE current draws when accelerating, and then low draw while cruising. So for example your 24 minute trip might have actually been 2 minutes at 10C, ...
by Tritium_James
Fri, 28 Oct 2011, 13:50
Forum: EV Racing
Topic: WA EV Challenge
Replies: 29
Views: 7072

WA EV Challenge

How do they manage to build a carbon machine for under the $1200 limit?
by Tritium_James
Fri, 21 Oct 2011, 14:20
Forum: Members Machines
Topic: Weber and Coulomb's MX-5
Replies: 1698
Views: 337918

Weber and Coulomb's MX-5

I like the idea that GM used on the EV1, which had a sounder kind of like a cross between one of those tin 'clicker' things that are quite often in showbags, kids toys, etc, and a small bell. Electrically actuated, and it made a 'ting ting' sort of noise when you flashed the high beam lights. Perfec...
by Tritium_James
Wed, 05 Oct 2011, 16:50
Forum: Members Machines
Topic: Weber and Coulomb's MX-5
Replies: 1698
Views: 337918

Weber and Coulomb's MX-5

Weber, the fittings in all our watercooling stuff are 1/4" BSP (also called G1/4), so that might give you something you can try threading into your pump to see if the thread fits.
by Tritium_James
Tue, 04 Oct 2011, 21:58
Forum: Members Machines
Topic: Weber and Coulomb's MX-5
Replies: 1698
Views: 337918

Weber and Coulomb's MX-5

No Johny, that's not different enough from the others - still a parallel thread! :) It's got to be BSPT!
by Tritium_James
Mon, 03 Oct 2011, 15:35
Forum: Members Machines
Topic: Weber and Coulomb's MX-5
Replies: 1698
Views: 337918

Weber and Coulomb's MX-5

Heh, that photo two posts above is great - Monet or Van Gogh or something - "Still life with pear and pump". Regarding the encoder mount, any difference in the speed of the motor and the speed of the encoder is really bad news. The complex D/Q current type control we run ends up in a single output: ...
by Tritium_James
Tue, 06 Sep 2011, 21:05
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 52809

Low cost BMS

The pads look too close together to me. They're about the right distance outside edge to outside edge (ie, the space for the solder fillet) but they go under the component too far. I'd also say they look too narrow, they should be wider than the component. The surface tension of whichever pad melts ...
by Tritium_James
Tue, 02 Aug 2011, 14:07
Forum: Electric motors and controllers
Topic: 2 BLDC motors 1 controller..?
Replies: 12
Views: 4348

2 BLDC motors 1 controller..?

We routinely use either a series or parallel connection on the Ultramotive Carbon motor, which has two sets of windings internally. But I guess in that case they're closely thermally coupled, so the mismatch doesn't show up. I didn't even consider the 'burning out a motor' case, as our controller mo...
by Tritium_James
Tue, 02 Aug 2011, 14:02
Forum: AEVA NSW Branch
Topic: Precharge & PostDischarge
Replies: 16
Views: 6080

Precharge & PostDischarge

Ian,

Shouldn't you also be precharging the input caps on the DC/DC converter? That relay you have switching the HV DC to it won't last as long as you'd like, I suspect. Note that it's also not rated to switch DC above 30V.
by Tritium_James
Mon, 01 Aug 2011, 23:41
Forum: Electric motors and controllers
Topic: 2 BLDC motors 1 controller..?
Replies: 12
Views: 4348

2 BLDC motors 1 controller..?

You'd be able to wire them in parallel or in series, either would work, it would depend on which was the best match for the current & voltage ratings of the controller. If they're fairly close to each other in their various parameters I wouldn't expect any problems running like this.
by Tritium_James
Mon, 01 Aug 2011, 19:40
Forum: Electric motors and controllers
Topic: 2 BLDC motors 1 controller..?
Replies: 12
Views: 4348

2 BLDC motors 1 controller..?

If they're rigidly connected then they're effectively one motor as far as the controller is concerned. Halls or sensorless operation should be possible.
by Tritium_James
Fri, 29 Jul 2011, 15:53
Forum: Technical and conversion discussion
Topic: Mini or Moke conversion
Replies: 25
Views: 7039

Mini or Moke conversion

If the system is actually capable of 150kW in a Moke then I'd say it's over-driven!
by Tritium_James
Mon, 11 Jul 2011, 22:55
Forum: General EV Discussion
Topic: New Blade Electron with New TM4 Powertrain
Replies: 12
Views: 2549

New Blade Electron with New TM4 Powertrain

So much for the 100% Australian drivetrain...
by Tritium_James
Mon, 11 Jul 2011, 22:18
Forum: Technical and conversion discussion
Topic: Minimise finished EV weight
Replies: 15
Views: 3288

Minimise finished EV weight

Yes I must have been thinking solarcars, sorry!

The data I have for a Diahatsu Mira shows the drag from rolling resistance is the same as aero drag at 60km/h. Aero is 2x rolling by 85km/h, and 4x by 120km/h.
by Tritium_James
Fri, 08 Jul 2011, 18:27
Forum: Technical and conversion discussion
Topic: Minimise finished EV weight
Replies: 15
Views: 3288

Minimise finished EV weight

Paul, your tricycle is not the same as a road-going EV. Since it travels slowly, there is hardly any aero drag, so nearly all your losses are from rolling resistance. So reducing the mass of the vehicle will reduce the power consumption by a proportional amount. In this kind of vehicle, less weight ...
by Tritium_James
Mon, 04 Jul 2011, 20:16
Forum: Technical and conversion discussion
Topic: Convert 1975 Afron Cherrypicker?
Replies: 143
Views: 20316

Convert 1975 Afron Cherrypicker?

Sounds like you really want a logarithmic response on the throttle levers.

If they're potentiometers, your high/low can probably just be an extra resistor you switch in series with one end of the pot.
by Tritium_James
Mon, 04 Jul 2011, 20:06
Forum: Technical and conversion discussion
Topic: Minimise finished EV weight
Replies: 15
Views: 3288

Minimise finished EV weight

Paul, It's a bit hard to tell just from the engine capacity. The weight difference between an old cast-iron block (with heavy radiator, water pumps, etc) and a modern alloy block (with lightweight bits) is huge. As a rough rule of thumb, by the time you've taken out all the ICE bits, and then added ...
by Tritium_James
Thu, 30 Jun 2011, 17:30
Forum: Batteries, charging, management and monitoring
Topic: After-build add-on Power Factor Correction
Replies: 12
Views: 2473

After-build add-on Power Factor Correction

Coulomb, a buck-boost converter has poor switch utilisation, making the silicon more expensive (around double) compared to a buck or a boost. This may be negated by the single stage instead of two. An isolated buck-boost is a flyback converter. These have poor transformer utilisation (unidirection c...
by Tritium_James
Tue, 28 Jun 2011, 00:50
Forum: Electric motors and controllers
Topic: My homebuilt VFD progress
Replies: 141
Views: 14548

My homebuilt VFD progress

It's not going to survive too long if you turn it on into a short every PWM cycle - desat should definitely be latched.