andrewtbennett
Posts: 6
Joined: Sat Feb 03, 2018 9:15 am
Delivery Date: 15 Feb 2014

Help Needed urgently please (range extender problem - have i blown my pre-charge circuit?)

Sat Feb 03, 2018 9:32 am

Hello all,
bit of a desperate plea for help I'm afraid.

I've been working on a range extender for my leaf - The packs are fully built and balance charging as we speak.
This morning I have spliced two high voltage cables to the HV cable between the battery and inverter (No extra battery anywhere near the car yet) this seemed to work fine and when the car was turned on I got a reading of 360volts between the ends of these two cables as expected.

I was then trying to work out how to get the RLY P (yellow cable on the data connector) to control a gigavac relay that will eventually be used to turn the extra pack on and off in sync with the main pack relays.

It was at this point that I've done something obviously rather stupid as the car now will not start.

I connected the yellow cable (again a spliced connection) to the gigavac relay in the boot, and from the relay on to what I assumed would be ground (i.e. the chassis). clearly this is the wrong thing to do and I can now see that there appears to be a RLY P ground wire.

On turning the car on it seems to have less charge than it did earlier in the day by about 10% and will only respond as though started up without the brake pedal depressed. It does not accept charge.

I've read a few forum pages and the common theme seems to be a blown pre-charge resistor - I think???

Will what I have done above have caused the same? can you think of anything else that I can check to see what damage I've done?

Best Wishes and with much gratitude,
Andrew

mux
Posts: 89
Joined: Sat Jan 13, 2018 3:52 am
Delivery Date: 13 Oct 2011
Leaf Number: 6177

Re: Help Needed urgently please (range extender problem - have i blown my pre-charge circuit?)

Mon Feb 05, 2018 2:35 am

First of all, I don't have an answer for you but I'm doing the same thing you're doing, so this is very informative. Your mistake is a learning opportunity for the rest.

What you almost certainly did is temporarily overloading the relay driver. Considering relays are fairly badly behaved in general, they will have engineered this with a PTC fuse or some kind of self-resetting mechanism for overload. The relays are normally open, so when you overloaded the driver, the relay coil voltage sagged and possibly the main pack relay has opened. The RLY P and RLY N signals opening unexpectedly is a critical fault, so the car will NOT restart after that happening. The car thinks the relays have failed short.

This explanation does not account for the charge level of the traction battery seeming to have dropped dramatically. 10% of your SoC is a LOT of energy, about 2kWh. You'll have noticed something vaporizing from that amount of energy being expended. I think either this is a red herring or my explanation is fundamentally flawed.

I think you should be able to see a RLY P failure in your DTCs when connecting to your car with LeafSpy. I don't know if this can be cleared, but other people have messed up much worse than this and got their packs working, so I wouldn't worry too much. Try clearing it and seeing if it works. If you cannot clear it, I believe the maker of LeafSpy has helped people like Leaf XPack clear them anyway with a modified clearing routine. That programmer is awesome.

If the problem persists or reappears immediately after clearing, you have most likely damaged the RLY P driver circuit, and you will have to remove the... I think VCM from your car, open it up (do NOT damage the weathersealing!) and replace most likely just a fuse, maybe some MOSFETs. I am not familiar with these parts, maybe there is an easier to service fuse box, so thoroughly study the service manual before doing anything. Don't take my word. I am currently just as experienced as you are.

andrewtbennett
Posts: 6
Joined: Sat Feb 03, 2018 9:15 am
Delivery Date: 15 Feb 2014

Re: Help Needed urgently please (range extender problem - have i blown my pre-charge circuit?)

Mon Feb 05, 2018 3:20 pm

Thanks for the reply. I'm hoping that you are right. I have come to the conclusion through plenty of research over the last few days that I've done one of three things - damaged the pre charge circuit (worst case scenario as I will then have to break open the main pack to replace the resistor), shorted something within the vcm as you suggest (more expensive but less labour intensive) or simply created an error code that has confused the car completely. There was certainly no electrical burning that would account for such a capacity loss so I really don't understand that, hopefully a red herring as you say.
OBD2 reader arrives tomorrow so I will finally be able to check what's happening on leaf spy and then work through the problem.
The annoying thing is that I was simply testing out whether the power from the rly p wire would activate my pack relay. I now realise that the data connector must ground through the vcm and not onto the chassis at all. So hopefully if I can repair whatever I've done I can, then try again using the yellow and black wires.
I'll keep you posted and let you know if it works.

andrewtbennett
Posts: 6
Joined: Sat Feb 03, 2018 9:15 am
Delivery Date: 15 Feb 2014

Re: Help Needed urgently please (range extender problem - have i blown my pre-charge circuit?) -- SOLVED

Tue Feb 06, 2018 1:27 pm

Wow, what a relief!
OBD2 reader finally arrived at 7:30pm and I've just plugged it in to the leaf.
only had 2 error codes:

P31E7 000B EV/HEV Restart Inhibition EVC-310
P0AA6 0008 EV/HEV Hybrid Batt Volt Sys Isolation EVC-157

cleared DTCs and the leaf is back to the way it was. Suddenly has 28% charge again instead of 21% (really can't explain this but who cares?)

Tomorrow is going to be the big day where I finish wiring everything up and (hopefully) take it for a test drive with the new pack installed.

I'll start a new thread if it works to show what I've been up to.

Best wishes,

Andrew

webeleafowners
Posts: 479
Joined: Mon Oct 05, 2015 5:37 pm
Delivery Date: 06 Oct 2015
Location: Okanagan Valley British Columbia

Re: Help Needed urgently please (range extender problem - have i blown my pre-charge circuit?)

Tue Feb 06, 2018 4:56 pm

Thanks for the Report Andrew. Following with interest.
2015 Smart Electric Drive convertible.
2016 Nissan Leaf SV 30KWh
EV only Family...well except for the big diesel motorhome. :shock:

ElectricEddy
Posts: 428
Joined: Tue Feb 25, 2014 1:42 pm
Delivery Date: 31 Oct 2016
Leaf Number: 313506
Location: Nanaimo, B.C.

Re: Help Needed urgently please (range extender problem - have i blown my pre-charge circuit?)

Tue Feb 06, 2018 10:37 pm

webeleafowners wrote:Thanks for the Report Andrew. Following with interest.


^^^
Pearl White Sl
mfd date 09/16

mux
Posts: 89
Joined: Sat Jan 13, 2018 3:52 am
Delivery Date: 13 Oct 2011
Leaf Number: 6177

Re: Help Needed urgently please (range extender problem - have i blown my pre-charge circuit?)

Wed Feb 07, 2018 12:20 am

Good to know that the VCM output drivers are correctly designed to account for this kind of stuff. You never know with automotive stuff.

andrewtbennett
Posts: 6
Joined: Sat Feb 03, 2018 9:15 am
Delivery Date: 15 Feb 2014

Re: Help Needed urgently please (range extender problem - have i blown my pre-charge circuit?)

Thu Feb 08, 2018 1:08 pm

So things haven't gone quite to plan. For one glorious moment I seemed to have control of the extra pack relay controlled via the leaf itself with a separate breaker switch on the dash.

Unfortunately on restart I now have errors:

P0AA4 0009 EV/HEV QNRH Hybrid Batt Negative Contactor EVC - 151
C118C 0109 ABS EV/HEV System BRC-126
C1A6E 0109 Brake EV/HEV System BR-146
C1A70 0109 Brake Control System BR-160

All of the C codes appear to be related to the regenerative braking system however the P0AA4 seems a little more concerning and may represent a main contactor that is persistently shut (perhaps opening and closing briefly while the new relay was turning on and off - enough to weld itself shut). With a little coaxing and use of leaf spy I can clear all error codes and get the car moving and charging but on turning the car on again the errors re-appear.

I need to find a day to troubleshoot this as it may simply be that I have created a short at the data connector by accident or even overloaded the VCM. Hopefully have some answers by Sunday. If not then I'll need to drop the main pack and check the main contactor.

Talking of which - does anyone know anyone who might have a spare contactor that I could buy from them in the UK? I can source one from America but it won't arrive until 1st March and I'm achingly close to getting this all working.

I'm now beginning to wonder whether I need to use a small relay that sits in the positive wire of the main relay controller so that there Is no fluctuation in power signal to the main pack relays, (and no chance of shorting) I can then use this relay to deliver power to the new pack relay i.e. from the leaf's 12v battery. Lots to think about.

Just hope it's something that is easily rectified otherwise it's going to be a fairly embarrassing visit to the dealership to get the VCM replaced.

I'll keep you updated if I have any breakthroughs. All I can say at the moment is... don't do what I've done so far - because it clearly doesn't work :-)

mux
Posts: 89
Joined: Sat Jan 13, 2018 3:52 am
Delivery Date: 13 Oct 2011
Leaf Number: 6177

Re: Help Needed urgently please (range extender problem - have i blown my pre-charge circuit?)

Fri Feb 09, 2018 1:05 am

A weird constellation of errors like this usually points to some issue with the 12V system, i.e. too much power being drawn and some subsystems not properly initializing. BCM is situated in the rear of the car, so it could well be a vestige of your initial fault.

Having a wire short somewhere also could be the source, but that is possibly even more concerning: those splices need to be super-secure to survive the torture of enduring years under a car. If something went wrong there, you may need to redo them.

andrewtbennett
Posts: 6
Joined: Sat Feb 03, 2018 9:15 am
Delivery Date: 15 Feb 2014

Re: Help Needed urgently please (range extender problem - have i blown my pre-charge circuit?)

Sun Feb 11, 2018 2:14 pm

Checked insulation across high voltage splices and all seems to be ok. Removed all new connections at the data connector and checked for any short circuits there - all seems ok. Still getting the same error set. When the errors are cleared the car drives absolutely normally.

I am noticing that when I measure the voltage at the new splice ends I find that there is an initial drop to 20volts then a very brief spike to 100volts before going back down to 20volts and then diminishing slowly to 0v over a few more seconds.

I've ordered a new battery junction box from America and I'm coming to the realisation that the safest way that I can ensure that all things are working properly is to open up the battery, see(hear) that the contactors are doing what they are meant to do while I finish integrating the new pack and then once I'm happy with everything i can then replace the main pack. If I still get the same error codes then it makes them far more likely to be sensor problems which can be sorted at a later date when everything is bedded in.

It'll be a couple of weeks before the JB arrives so I'll update then.

Best wishes,
Andrew

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