Search found 683 matches

by Tritium_James
Mon, 11 Jun 2012, 01:05
Forum: Electric motors and controllers
Topic: RX400H transaxle
Replies: 169
Views: 22262

RX400H transaxle

Didn't see the PM, sorry! Read it now... send me an email so I can send you the data I have. Max speed is rated to 6000rpm, though you could probably balance it to go faster, but torque is dropping off rapidly at that point and it's probably not worth much more to spin it faster. Base speed (peak po...
by Tritium_James
Sun, 10 Jun 2012, 16:11
Forum: Electric motors and controllers
Topic: RX400H transaxle
Replies: 169
Views: 22262

RX400H transaxle

It just so happens that if you choose the right V/Hz for an induction motor you can practically achieve the same thing without one. I'm not so sure you can. You're going to be running at a relatively high frequency (10000rpm / 4 pole = 330Hz) from a low voltage, the power factor is going to be lous...
by Tritium_James
Fri, 08 Jun 2012, 16:28
Forum: Electric motors and controllers
Topic: RX400H transaxle
Replies: 169
Views: 22262

RX400H transaxle

Yes, we get it from the factory wound for 100V - it's a standard configuration for the Japanese market I think. There's certainly nothing off the shelf wound at lower voltages than this, the 100V/50Hz was the lowest option SEW offered. Well, base speed might be low, but you'd be getting lots of torq...
by Tritium_James
Thu, 07 Jun 2012, 19:27
Forum: Electric motors and controllers
Topic: RX400H transaxle
Replies: 169
Views: 22262

RX400H transaxle

I've said this before, but here it is again: breakdown torque is *irrelevant* when you're running from a VFD. For example, the SEW motor we have extensive test data on (DRE132MC4) is listed with a nominal torque of 48.7Nm, and a breakdown torque ratio of 3.2. But we know from dyno testing that we ca...
by Tritium_James
Mon, 28 May 2012, 13:25
Forum: Technical and conversion discussion
Topic: Most aerodynamic chassis?
Replies: 14
Views: 2842

Most aerodynamic chassis?

Really love the shape and the look of the CRX! But... I have a mate with one, and his - like nearly all of them around here - is almost more rust than steel. But if you can find one in good shape I reckon it would be a nice EV.
by Tritium_James
Wed, 16 May 2012, 02:05
Forum: General EV Discussion
Topic: List of conversion workshops in Australia
Replies: 52
Views: 26471

List of conversion workshops in Australia

Borg-Warner probably won't sell you the gearbox, but if you can get one I can't see why you couldn't put an induction motor on it and run it with our controller. Would be a nice system.
by Tritium_James
Mon, 07 May 2012, 21:13
Forum: General EV Discussion
Topic: Charge port standard.
Replies: 4
Views: 809

Charge port standard.

So down to two standards now - about time! Previously it was looking like it was going to be three: Chademo (Japan), SAE (US), Menekes (Europe). So US and Europe have got their act together finally, good to see.
by Tritium_James
Fri, 04 May 2012, 00:35
Forum: AEVA NSW Branch
Topic: Precharge & PostDischarge
Replies: 16
Views: 6149

Precharge & PostDischarge

It's to protect your contactors. Not precharging = welding. It's also to protect anything connected to the switched side of the contactors. Capacitance (in various things, motor controller, DC/DC, etc) with Inductance (batteries & cabling) gives an LC resonant circuit, and a maximum voltage on the d...
by Tritium_James
Wed, 02 May 2012, 00:56
Forum: AEVA NSW Branch
Topic: Precharge & PostDischarge
Replies: 16
Views: 6149

Precharge & PostDischarge

Richo, the reason it's not in the controllers (speaking as a controller designer!) is that you also need to be precharging your DC/DC, charger, A/C compressor inverter, etc, etc.

The real question is: why is that functionality not built into everyone's BMS! :)
by Tritium_James
Wed, 02 May 2012, 00:45
Forum: Technical and conversion discussion
Topic: Cable gauge
Replies: 5
Views: 1405

Cable gauge

Completely off-topic, but I think there's a plugin for Firefox that can save the contents of edit boxes on forums to avoid that exact situation. But I can't remember what it's called anymore!
by Tritium_James
Tue, 31 Jan 2012, 21:58
Forum: Members Machines
Topic: Richo's AC Handi Sports
Replies: 84
Views: 10829

Richo's AC Handi Sports

My data (for the Mira) is from the workshop manual for the car, so it should be accurate... that's for the late 1990's model.
by Tritium_James
Sun, 15 Jan 2012, 01:03
Forum: Batteries, charging, management and monitoring
Topic: A123 ready to go 23kW packs
Replies: 5
Views: 1785

A123 ready to go 23kW packs

That first pack would be a great fit for most cars, because the 10C rating is for 10 seconds, which is all pretty much anyone needs for normal driving. Note that this is not comparable to the '10C' rating on the chinese cells, which is for 1ms or something stupid...
by Tritium_James
Sat, 14 Jan 2012, 22:12
Forum: Members Machines
Topic: Weber and Coulomb's MX-5
Replies: 1698
Views: 342421

Weber and Coulomb's MX-5

Weber/Coulomb: if you want a proper precharge circuit (ie, Automotive OEM quality) then you need contactors with the auxillary contacts, monitor the contacts with your BMS, and don't let the driver controls issue any commands until it sees (from the BMS via CAN) that the precharge sequence is finish...
by Tritium_James
Wed, 11 Jan 2012, 19:03
Forum: Batteries, charging, management and monitoring
Topic: Solar Panels?
Replies: 20
Views: 1994

Solar Panels?

With the losses caused by the extra weight and lousy aerodynamics, you'd be much better off putting the solar panel on the roof of your house. You'd also be getting money for feeding it back into the grid during the day, then charging your car from cheap off-peak at night...
by Tritium_James
Sat, 24 Dec 2011, 18:42
Forum: Members Machines
Topic: Weber and Coulomb's MX-5
Replies: 1698
Views: 342421

Weber and Coulomb's MX-5

Standard relays aren't rated for 450V DC. In a fault situation (eg a fault in the motor controller, DC/DC, wiring, etc that presents a shorted bus), it will weld on, which then means you can't turn off the precharge, which means your precharge resistor catches fire (450V,100R =2kW in a 100W rated pa...
by Tritium_James
Sat, 17 Dec 2011, 03:03
Forum: Batteries, charging, management and monitoring
Topic: Charge Shuffling for Li cells
Replies: 43
Views: 4385

Charge Shuffling for Li cells

Yeah it's a real bummer because the pouch cells are generally fantastic. I think they're best left to the likes of GM/Ford/etc unfortunately...
by Tritium_James
Fri, 16 Dec 2011, 21:48
Forum: Batteries, charging, management and monitoring
Topic: Charge Shuffling for Li cells
Replies: 43
Views: 4385

Charge Shuffling for Li cells

The pouch cells are a mechanical nightmare without spending a LARGE amount of time and money testing. A one-off project is unlikely to get it right, to the point where your pack is reliable for a decent lifetime. Nearly all the solarcars use them, and they nearly all have problems, with the tabs fat...
by Tritium_James
Wed, 07 Dec 2011, 21:40
Forum: Batteries, charging, management and monitoring
Topic: Charge Shuffling for Li cells
Replies: 43
Views: 4385

Charge Shuffling for Li cells

If you can guarantee that there's never any current flowing when you do the switch then they can be lower voltage. But this means you've pretty much got to open the main contactors any time you want to chop out a cell.
by Tritium_James
Wed, 07 Dec 2011, 19:01
Forum: Batteries, charging, management and monitoring
Topic: Charge Shuffling for Li cells
Replies: 43
Views: 4385

Charge Shuffling for Li cells

Woody/Weber - the system with two FETs on each cell (one to disconnect the cell, the other to shunt the connection past where the cell used to be in the string) is certainly possible, but like Weber pointed out, it's not cheap. But even if you don't care about the cost, you've now gone and stuck #CE...
by Tritium_James
Wed, 07 Dec 2011, 16:41
Forum: Batteries, charging, management and monitoring
Topic: Charge Shuffling for Li cells
Replies: 43
Views: 4385

Charge Shuffling for Li cells

Those relays need to be rated to your pack voltage, with a DC rating. They will not be small or low cost. Since I doubt any of this would fit inside the pack, and you're bringing reasonably chunky 15A cables all back to one central point (where they can easily get shorted together/to the chassis/etc...
by Tritium_James
Fri, 02 Dec 2011, 19:13
Forum: General EV Discussion
Topic: Battery pack voltage advice for EV datsun 1200
Replies: 44
Views: 6377

Battery pack voltage advice for EV datsun 1200

I'd be sticking with the 144V. This is 'rated', the same way the optimas are '12V'. They go higher when charging, and the '144V' rating usually allows for this. If you want 3 years out of a set of Optimas (which can't be balanced with a gassing charge, since they're AGM) then you also need a BMS. Th...
by Tritium_James
Fri, 02 Dec 2011, 17:02
Forum: General EV Discussion
Topic: Battery pack voltage advice for EV datsun 1200
Replies: 44
Views: 6377

Battery pack voltage advice for EV datsun 1200

You've got a nice motor and controller, why limit yourself with relatively horrible batteries? Especially with the price of Optimas, I'd seriously consider a lithium pack, which will end up costing about the same amount, and last considerably longer.
by Tritium_James
Sun, 27 Nov 2011, 16:49
Forum: Batteries, charging, management and monitoring
Topic: LiFePo for noobs
Replies: 6
Views: 1148

LiFePo for noobs

The only way to guarantee you don't destroy cells is to have a per-cell BMS running. Anything else that's only measuring the total pack voltage WILL eventually end up with cells out of balance and start killing cells. eg: balanced pack of 4 cells: 4.0V, 4.0V, 4.0V, 4.0V = 16V about to be destroyed p...
by Tritium_James
Sun, 27 Nov 2011, 16:38
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 54121

Low cost BMS

It seems to me that the only advantage of differential drive here is that when the LED is off it is reverse biased, so more noise voltage required to turn it on. But it gives no improvement in the noise margin when the LED is on. Yep, that's it! It can help a lot when you have rapid dV/dt transitio...
by Tritium_James
Sun, 20 Nov 2011, 15:19
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 386
Views: 54121

Low cost BMS

Neville, it's too early in the morning for me to check your maths :P   but a quick spice sim with your resistance values shows a 5.88% difference in cell current, so I think you've got it right.