[LithiumaniacsEVRacing]

[somanywelps]

There's no kill like overkill?

[Batterypoweredtoad]

Originally Posted by somanywelps

There's no kill like overkill?

That is a good point. Ron-are you really going to have the power to make use of a single Soliton Shiva much less two? If so I am damn impressed!

[LithiumaniacsEVRacing]

Originally Posted by Batterypoweredtoad

That is a good point. Ron-are you really going to have the power to make use of a single Soliton Shiva much less two? If so I am damn impressed!

Yes, my pack will produce 4000+BA for atleast 10 seconds. Each controller will receive 2000+BA each. The weak spot is not my pack, but my motors, I think the motors can take 2500MA each @ 190volts each. I have learned tons of knowledge on motor EMF, so we will be testing shift point and checking brush and comm temps. I am installing blowers and ram air induction to each motor to help cool parts down.

[Salty9]

With that much power you can chase weak points all the way down the drive train until you start destroying the pavement.

[aeroscott]

. It will be amazing to see over 1 meg of power on the track with this setup .

[LithiumaniacsEVRacing]

Originally Posted by somanywelps

There's no kill like overkill?

There is no such word in drag racing "overkill", you can NEVER have enough power!

[epyon]

Ok , I see why you don't want to turn it in to a Pro-Street car . What contactors are you using ?

[Tesseract]

Originally Posted by epyon

...What contactors are you using ?

We put the main contactors inside the controller, greatly simplifying that side of the EV wiring. All Ron needs to provide is the mandatory emergency disconnect (often called the "oh schiesse!" bar).

If you were asking about the contactors needed to do series/parallel shifting of the motors, there aren't any. Or, at least, there better not be. I don't really think S/P shifting is all that great at 1000A, but at 3000A it turns into an exercise in futility. This is because it takes (3) normally open switches (ie - contactors) to shift the motors from being wired in series to parallel. The series connection switch needs to be rated for the maximum motor current - or 3000A in this case - while the two parallel connection switches need to be rated for at least half the maximum motor current, say 1600A, as there will inevitably be a slight imbalance in total resistance for the wiring of each motor.

If the popular Albright SW200 contactor is to be used for all of the S/P switches then it would take *15* of them for the series switch and *8* of them for each parallel switch. A total of *31* contactors. That's just nuts.

To make matters even worse, a quality under/overdrive can shift gears faster than you can electrically rewire the motors. The reason is because before you shift from series to parallel you have to cut throttle to zero and then wait for motor current to do the same. The inductance of motors is high and their resistance is very low so their electrical time constant (L/R) can exceed 0.1 second, and the rule of thumb is that current through an inductor will decay to zero after 5 time constants (e.g. - 0.5 second). If you try to S/P shift before current has dropped to zero then a huge arc will jump across the contactors in defiance. You'll definitely damage the contactors and you might just hurt the controller, too, since this voltage might exceed what the semiconductors inside can handle.

So we don't much like S/P shifting at Evnetics, and judging by the amount of time that I see racers waste on getting it to work properly, I'd say we're on the right side of that argument.

[Arlo]

Originally Posted by Tesseract

We put the main contactors inside the controller, greatly simplifying that side of the EV wiring. All Ron needs to provide is the mandatory emergency disconnect (often called the "oh schiesse!" bar).

If you were asking about the contactors needed to do series/parallel shifting of the motors, there aren't any. Or, at least, there better not be. I don't really think S/P shifting is all that great at 1000A, but at 3000A it turns into an exercise in futility. This is because it takes (3) normally open switches (ie - contactors) to shift the motors from being wired in series to parallel. The series connection switch needs to be rated for the maximum motor current - or 3000A in this case - while the two parallel connection switches need to be rated for at least half the maximum motor current, say 1600A, as there will inevitably be a slight imbalance in total resistance for the wiring of each motor.

If the popular Albright SW200 contactor is to be used for all of the S/P switches then it would take *15* of them for the series switch and *8* of them for each parallel switch. A total of *31* contactors. That's just nuts.

To make matters even worse, a quality under/overdrive can shift gears faster than you can electrically rewire the motors. The reason is because before you shift from series to parallel you have to cut throttle to zero and then wait for motor current to do the same. The inductance of motors is high and their resistance is very low so their electrical time constant (L/R) can exceed 0.1 second, and the rule of thumb is that current through an inductor will decay to zero after 5 time constants (e.g. - 0.5 second). If you try to S/P shift before current has dropped to zero then a huge arc will jump across the contactors in defiance. You'll definitely damage the contactors and you might just hurt the controller, too, since this voltage might exceed what the semiconductors inside can handle.

So we don't much like S/P shifting at Evnetics, and judging by the amount of time that I see racers waste on getting it to work properly, I'd say we're on the right side of that argument.

You can not get anymore power to the wheels when series parallel shifting anyways. The only time you see more power in series is at a low rpm if the controller is limiting the power. But in this case with these two huge controllers I don't think they would notice any difference in power. There has been quite a few of use experiment with this on 3 phase permanent magnet motors to find no gains. It only puts less stress on the controller during phase amp limiting.