RE: Rudman Was Right! (was Dualin'7s Smoked Controllers)

[RichSJ@aol.com]

Roger Stockton wrote:

>"Nearly full power" in this case was still below the Albright's claimed
>ratings though, wasn't it?  (That is <1500A each, and they certainly
>carried less than 1000A for 30s; you say you get 1400A off the line,
>and if you were still coasting down the return lane when you cycled
>the Albrights then they should have seen well under this peak.)

I am sure they can carry 1000A for 30sec, as long as you don't try to open 
them while they're still carrying a 1000A (or even 500A).  :-)

>Why would you prefer to open a second EV500 bypass and wear it rather
>than opening your breakers? 

Only convenience and one more layer of safety would make me want to have the 
two EV500s in series. If the first one welded I could open the second one and 
continue to drive back to the pits under my own power. If I pull the circuit 
breakers, it's tow back time.

>I don't follow your comment about the DCP MOSFETs switching full tilt
>and not carrying much current.

The MOSFETs are switched on through the entire PWM cycle with no current 
limit because there is little or no current flowing through them and my foot 
is to the floor and the battery pack is still connected. The controller is in 
parallel with the bypass and being commanded to provide maximum voltage and 
current, but is actually doing little. The low resistance path is through the 
bypass.

>  Anyway, just before you engage your contactor they
>WILL either be completely off (i.e. engage bypass from dead stop) or
>switching furiously in current limit (i.e. launch with controller and
>then engage bypass), won't they?

By the time the bypass switches in the controller may not be in current limit 
yet. It takes some time for the controller to ramp up to full throttle. It 
may actually be at the point where each controller is trying to provide 
1200A. 

>When running the DCP's what is the peak current you see (battery
>current), and is it total or per controller?  How does this compare to
>what you see when running the bypass?


On controllers alone, I see 1350 amps peak for the two controllers together. 
On bypass I see a peak of 1460 amps at launch. Not a huge difference. The 
huge difference is immediately after launch when the controllers current 
limit and the bypass contactor doesn't.  As I said previously, I will 
probably run a delay before switching in the bypass. I think having some back 
emf built up before switching will be easier on the contactor and my tires.

BFN,

Rich Brown
San Jose, CA
Dualin'7      144V, 3200lbs and 14.990 in the 1/4 mile