AEVA Forums

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...

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...

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...

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...

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.

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.

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.

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...

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!

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!

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.

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...

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...

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...

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...

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...

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...

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.

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...

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...

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...

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.

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...

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...

Neville, it's too early in the morning for me to check your maths    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.