# Kelly Controller Enclosure at Pack Voltage



## Guest (Feb 28, 2010)

Yes for the old versions of the Kelly. I think the new ones are isolated. 

Pete


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## peggus (Feb 18, 2008)

alxpril said:


> I have a Kelly KD72503 controller and the enclosure of the contoller is at negative pack voltage. I have the enclosure bolted to the vehicle frame, thus bringing the frame to negative pack voltage. I assumed the case would normally be isolated from B-...
> 
> Is this normal?



It may be normal for that controller but still a very very bad idea. 

Mount it in a isolated enclosure, cool it with a fan. Or get a better controller.


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## EVMAN (Jul 26, 2007)

Indeed, very bad idea to have pack and 12V system at same gnd/neg. Pack should be isolated from chassis which is 12Vneg.


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## samoc (Apr 9, 2008)

I emailed Kelly about this, below is what transpired...
The outcome is that even recent "isolated" Kelly KDHB controllers are in fact not isolated. This controller was a replacement for one that blew up. Kelly was not able to find fault with the way I installed or used the original and was not able to provide an explanation of why it failed. I have my fingers crossed that the new one will blow up soon so I can justify upgrading to a Zilla...

On 30/11/2009, at 10:02 PM, Sam O'Connor wrote:

- It seems that the KDH14650B case is not internally isolated from
"B-" as you claim. I measure 220kOhm from "B-" to KDH14650B case.
(On test bench, not connected to anything else)
- This means a person touching chassis and "B+" at the same time
could get a shock of up to ~0.5 mA (144V nominal pack). 
- Is 220kOhm from "B-" to "case" normal?

On 01/12/2009, at 6:13 PM, Kelly Controller wrote:

That is OK. 220KOhm is OK.Only one point,don't wire B- to chassis.
220KOhm is can be used as isolation.


On 01/12/2009, at 7:54 PM, Sam O'Connor wrote:

This is worrying. If the pack is at 168V, a 220kOhm short from B- to chassis
could result in a 0.5mA shock to a person touching chassis and B+.
The IEC safety standards with which I am familiar suggest designing for
current flow though a person below 0.1mA.
It would be more common for a device that claims to be "isolated" to have
several MOhm of isolation resistance.
The Australian regulations say: "The electrical propulsion circuit must be isolated from other circuits in the vehicle."


On 02/12/2009, at 1:18 PM, Kelly Controller wrote:

Yes,220Kohm is a little bit small.We will include 1M resistor between the case and B-.Now you can mount the controller off the chassis.
Or you don't touch the controller.


On 02/12/2009, at 1:10 AM, Sam O'Connor wrote:

I am interested. Why connect B- to the chassis at all??
You suggest that I "mount the controller off the chassis",
but if there is some good reason for the internal high-impedance connection between B- and the case,
then I will defeat it.


.... I never heard back from Kelly after that...


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