# [EVDL] Logisystems Controller KSI Question



## EVDL List (Jul 27, 2007)

Sorry about the previous message. I originally assumed the controller was a
Curtis and put that in the message subject. I then confirmed that the
controller is a Logisystems and forgot to change the subject. This message
now has the correct subject.

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I was helping a friend rewire a Logisystems controller this evening and ran
into a very strange problem. Before we started, the KSI input to the
controller and the DC-DC input were wired to the contactor and pre-charge
resistor (without any other relays). Because of this, the controller KSI
input was always hot and the DC-DC and controller KSI input were draining
the traction cells through the pre-charge resistor.

We tried to wire in a relay that would control both the KSI input and the
DC-DC controller so they only went hot when the key switch 12V went active.
The way we wired it, the output of the relay went to both the KSI input and
the DC-DC controller input (high-voltage side).

We first started out by checking all circuitry with the relay removed. This
meant that the KSI and DC-DC input were shorted together but floating other
than that (no chance they would see pack voltage).

When we turned on the ignition switch, a 12V fuse in the area popped. This
continued until we removed the KSI input from the circuit and let it float.
At that point, everything worked normally. We finally left the vehicle with
KSI wired back to the pre-charge resistor and contactor.

Any idea what could be causing this? It seems really strange that an input
(on the controller) that expects so see traction voltage would short 12V
when it is connected to another input (on the DC-DC converter) that expects
to see traction voltage also.

The DC-DC converter is an Iota DLS-55.

It seems like we would still have the same problem, even if I got the KSI
input its own relay. When switched on, the KSI input would still be
connected to the same node as the DC-DC input (the traction pack positive
terminal). I could wire it like I've seen in some Curtis documentation and
wire the KSI relay HV input to the contactor and pre-charge resistor, but I
don't see why that should matter.

Thoughts?

Mike

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## EVDL List (Jul 27, 2007)

The easy way is to use the switch for the KSI on most pot boxes. It's the 
little switch that clicks when you move the throttle. When the throttle is 
closed KSI is open. When the throttle is moved but before 50 ohms(70ohms is 
usually the high pot for most controllers) is reached the KSI is connected. 
Just a simple switch does it. Don't forget to fuse it with a 1 amp fuse. 
Lawrence Rhodes.......

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| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
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## EVDL List (Jul 27, 2007)

> Mike Nickerson wrote:
> 
> > I was helping a friend rewire a Logisystems controller this evening and
> > ran into a very strange problem. Before we started, the KSI input to the
> ...


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