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Do I need a new controller?

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Paul9 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Paul9 Quote  Post ReplyReply Direct Link To This Post Posted: 15 December 2016 at 3:55pm
Thanks Richo,

I will have my gloves on! When you say to each traction battery terminal do you mean to each positive and negative traction battery terminal? If to both the positive and negative terminals do I, when testing a negative traction terminal, put the other end on the positive of the aux battery?

Pardon my dumbness!

Thanks
Paul
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Paul9 Quote  Post ReplyReply Direct Link To This Post Posted: 16 December 2016 at 9:52am
I went through every cell terminal and connected each to the neg side of the aux battery. When I eventually got to the last pos terminal of the entire bank I got a zero reading. The last neg terminal, when connected to the chassis, gave me a reading of -120v.

I assume from Richo's comment my short must be from one of the cables attached to the pack's positive terminal? Or maybe the terminal itself?

Apologies for my slowness but not only am I not an EE I'm not even an E! I am in fact a retired A for accountant so the very little I know about E is what I have learned while building this thing!

Thanks again,
Paul
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Richo Quote  Post ReplyReply Direct Link To This Post Posted: 16 December 2016 at 12:38pm
Originally posted by Paul9 Paul9 wrote:

I assume from Richo's comment my short must be from one of the cables attached to the pack's positive terminal?


Bingo

So now you know it's the POS terminal of the pack connected to the chassis.

Start by disconnecting the wiring from the terminal at the traction pack POS.
Measure from the traction pack POS to chassis and traction pack NEG to chassis to make sure the problem is NOT the pack but something that was connected to it.
Be aware that your BMS may also still be connected and causing the problem.

Leave the pack disconnected - for safety reasons...
Measure the voltage at the disconnected wiring trac POS to chassis.
SHould read 0V.
You should now be able to measure resistance at different points along the traction pos in the wiring to chassis to see where this issue is.
You can disconnect devices such as controller, DC/DC, contactor, fuses etc one by one until the short goes away.

Hope this makes sense
If the sun's not up turn your lights ON - duh! Help prevent road rage - get outta my way!!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Paul9 Quote  Post ReplyReply Direct Link To This Post Posted: 16 December 2016 at 1:17pm
Thanks Richo,

Will try that tomorrow. Both your advice and your patience is appreciated!

Paul
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Paul9 Quote  Post ReplyReply Direct Link To This Post Posted: 19 December 2016 at 12:47pm
My investigations have got somewhere (I think?)

Richo's instructions were:

"Start by disconnecting the wiring from the terminal at the traction pack POS."

DONE.

"Measure from the traction pack POS to chassis and traction pack NEG to chassis to make sure the problem is NOT the pack but something that was connected to it."

Traction pack POS to chassis read zero volts. Traction pack NEG to chassis read 2.03 volts. I left the DMM attached to NEG and chassis and the voltage, over a 10 minute period, sank down to zero volts.

"Be aware that your BMS may also still be connected and causing the problem."

I did all of the above with the big red button down which also turns off the BMS.

"Leave the pack disconnected - for safety reasons..."

Left the pack disconnected. I am normally fairly safety conscious. I can only remember a couple of times when I have licked the positive terminal while holding the neg terminal with wet hands! Actually reminding me about safety is good advice - a number of times I have come within a second or two of doing something fatally stupid!"

"Measure the voltage at the disconnected wiring trac POS to chassis.
SHould read 0V."

The voltage of every disconnected red wire attached to the POS terminal and the chassis read zero volts except the DC-DC pos wire. It read 2.50v. Would this be where the short/leak is happening? Or do I need to keep searching?

Thanks tons
Paul

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Johny Quote  Post ReplyReply Direct Link To This Post Posted: 20 December 2016 at 10:48am
Hi Paul
Lacking any response from Richo, I'll chip in.

So now you know that one of the wires that you disconnected from the + side of the pack somehow is connected, or leaks, to chassis/ground.

Two ways to go here.
1/ Change to the Ohms settings on your DVM and measure each of the disconnected + wires to ground.
OR
2/ Connected each of the disconnected wires up one at a time - each time measuring pack- to ground (DVM back on Volts here).

Or do both - 1 first.

John


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Richo Quote  Post ReplyReply Direct Link To This Post Posted: 20 December 2016 at 12:35pm
Thanks Johny I've been busy as a mad hatter
Christmas and all that...

With the pack pos disconnected you still read 0V from trac pos to chassis.
Now that just means there was no voltage differential doesn't imply the short is still there.
What you need to remember is that you CANT measure RESISTANCE while there is VOLTAGE on the line.
So measure the VOLTAGE FIRST to see if it ZERO then measure RESISTANCE.

Measure trac pos to chassis again make sure it is still 0V.
Now change to Resistance and measure track pos to chassis.
If the short has gone you'll see the reading increase to a high value kR/MR or "OL".
This will mean the short is in the wiring NOT the pack.

At this stage it is probably easier to unplug things.
As you say the DC/DC is looking suspicious.

If the sun's not up turn your lights ON - duh! Help prevent road rage - get outta my way!!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Richo Quote  Post ReplyReply Direct Link To This Post Posted: 20 December 2016 at 12:37pm
Originally posted by Paul9 Paul9 wrote:

Traction pack POS to chassis read zero volts. Traction pack NEG to chassis read 2.03 volts. I left the DMM attached to NEG and chassis and the voltage, over a 10 minute period, sank down to zero volts.


Things like DC/DC converters usually have internal caps that "bleed" from the HV lines to the low voltage outputs and visa versa.
This is probably what you are seeing.
I don't think this is an issue or causing the problem.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Richo Quote  Post ReplyReply Direct Link To This Post Posted: 20 December 2016 at 12:44pm
This is pretty much what Johny said but with more detail for the low E ppl.

Measure trac pos WIRE to chassis again make sure it is 0V.
Now change to Resistance and measure track pos WIRE to chassis.
We are expecting a short so a value in the Ohms region is expected.

So trace where the disconnected trac pos WIRE goes.
Obviously the dc/dc will be there which is a good place to start.
Unplug the trac pos WIRE from the DC/DC.
Measure volts trac pos WIRE to chassis.
Should read 0V
Now change to resistance.
Has the low ohms gone?

Repeat for other items on the Trac pos wire one by one until the resistance goes high.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Richo Quote  Post ReplyReply Direct Link To This Post Posted: 20 December 2016 at 12:50pm
Originally posted by Paul9 Paul9 wrote:

I did all of the above with the big red button down which also turns off the BMS.


Ah Yes it may turn it "off" but I bet there are still wires running across your pack connected to the terminals.

So they are OFF but still CONNECTED.
One of those BMS wires can still be connected to the chassis in some manner without causing a fault.

Leave the BMS until the trac pos wire trace returns no cause.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Paul9 Quote  Post ReplyReply Direct Link To This Post Posted: 20 December 2016 at 1:44pm
Thanks muchly Johny and Richo,

I am going to print those instructions out and go through them one by one!

I am going to try to go through the process before Christmas but may end up busier than a Beirut bricklayer in which case I will do straight after Christmas.

Thanks for the step-by-step instructions!

Cheers
Paul
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Richo Quote  Post ReplyReply Direct Link To This Post Posted: 22 December 2016 at 12:39pm
I'll be busy doing stuff for the next few weeks so if you do respond it may take some time before I get back to you.
Have you tried uploading a picture recently?
It'd be nice to see what we are helping you with!

What heater do you have?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Paul9 Quote  Post ReplyReply Direct Link To This Post Posted: 23 December 2016 at 5:04am
Thanks Richo,

No problems as I will be busy for a few weeks also. I have printed out your step-by-steps and will take them over to my electrician brother's place on Christmas day for him to read. Hopefully I can then tee up a day for us to work through your instructions.

I still have the heater we originally put in the car back in 2009. I have never turned it on. It is only 200watts and was only installed to comply with rego requirements in NSW.

I will try uploading a picture or two but have always had trouble with that function on these forums.

I will keep this thread updated with any progress we make but I won't expect much in the way of replies - everyone is on holidays over Christmas and January.

Thanks and have a good holiday break,
Cheers
Paul
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Post Options Post Options   Thanks (0) Thanks(0)   Quote evric Quote  Post ReplyReply Direct Link To This Post Posted: 23 December 2016 at 6:31am
Hi Paul,
For adding images, I have found that it works better to put your post up, then go "Post Options" and "Edit Post" and upload your image from that set of menus.

Merry Christmas.
Eric
Prius Plug-in Conversion: http://www.evplus.com.au ...Holden Barina EV: http://www.evric.kestar.com.au
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