Burned Relay Wires!

[BillE]

Hello,

I built the quick build 30A version with the color display around two months ago. It worked great on L1 at 12A.

I installed a 240V outlet and happily charged for about two weeks on L2 at just 12 amps - then it quit suddenly. The display still operated but it wouldnt charge my Volt. When I opened the case I found two burned wires from the load side of the fuse blocks to the input side of the relays. I thought it was just bad crimps, so I replaced the wires this morning (upsizing them to 10 gauge) - being careful during recrimping. 

I just attempted to charge my wife's Leaf. Everything acts fine; the EVSE boots up, the relays click, blue charge lights on the dash, "EV Connected", but the amperage never goes over 3A and the unit stops charging after 7 seconds.

What do I look for next?

[Craig Kirkpatrick]

From the symptoms it seems that the car is not seeing power delivered when it asks for it, so the car quits.  Check fuses and wiring for good continuity in the main AC path.  Do that with an Ohmmeter with everything unplugged.  It is possible that with the wires from the fuse bock to the relay overheating that the heat stressed the relay also and you now have a relay that "clicks" but maybe the relay is bad and never makes a closed circuit.  It may not be too easy but you can attempt to measure the AC voltage across the output of the pair of relays when the car is connected.  Safer would be to power the OpenEVSE controller with an ISP programmer cable and use an EV simulator kit connected to the pilot signal.  These things are on the OpenEVSE store.

I'm reminded that you should be sure the car you want to charge is off.  If the car thinks it is on and ready to drive then maybe that could cause the same symptom you see.

At your breaker panel the circuit for L2 charging should be a dual breaker and not individual breakers.  Possibly with individual breakers just one side turned off and the other side is on and that could explain the symptoms of not being able to charge at L2 but the controller still getting 120V of power.  I'm stretching with this one.

If you want to post a picture with detail looking into your kit I'll gladly scrutinize it for anything out of place.

High current wires to the fuse block should be copper stranded wires and screwed down rather than with crimp connectors.

Replacement fuses, fuse block, and even relays with new crimp connectors are also available on the OpenEVSE store and they are pretty affordable bits and pieces.

Sorry to hear of your trouble.  Let me know if I can help with more advice.

Craig

[BillE]

Craig, 

I just checked the voltage and am seeing 110 volts on one leg while in L1 and 110 volts for each leg on L2. 

Plugged the Leaf in and it was working for about 30 seconds, then it quit. What was different this time on L2 was that as soon as the relays pulled in, the screen displayed gibberish. On L1, the display reads fine but doesn't charge. 

I think you might be on to something about the relay(s) being damaged.

[Craig Kirkpatrick]

Bill,

Thanks for the photos.  I don't know what wire I see there in the upper left of the photo, the grey wire with some purplish tint and one end looks funny maybe burned or maybe it is just the angle of the photo.  I can't see the pilot and ground wire to the OpenEVSE controller but that is just hidden by the ribbon cable to the display.

Try measuring from hot line to hot line.  You should measure about 240V AC or similar.  Measure at the input side of the fuses, the output side of the fuses, and at the AC Test terminals of the OpenEVSE controller when the car first attempts to take a charge.  It may be hard to measure the 240V at when the car attempts to charge but that will tell whether one of the relays got toasted somehow.

My best guess is that one of the fuses blew.  The wires from the load side of the fuses got super hot which means the fuses may have been the source of the heat or in any case the fuses did feel the heat.

I think the Volt likes to draw up to about 14A at 240V and the Leaf would like to draw up to 28A at 240V.  With 10 guage wiring in the EVSE I'd set the L2 limit to 24A.  It appears you have 12 guage wiring from the AC mains and to the J1772 cable so setting the EVSE to 20A or even lower would be smart.  Maybe you let the Leaf draw 28A with 12 guage wiring and that would explain everything that happened.

If you have a good Ohmmeter you can check everything with the EVSE unplugged from the wall and from the car.

Let me know if I can offer more advice.

-Craig

[BillE]

Craig,

The grey w/purple wire you see is unused (LED light?). The cord to the car was reused from my OEM Volt EVSE, so I have limited the max current to 12A on both 120V and 240V. 

On L2, voltage checks out OK at both sides of the fuse block and at the AC test terminals - 220V everywhere. However, when I plugged the car in I had just enough time to measure, maybe 130 something volts as it ramped up. It never really stayed there before the relay(s) cut out. 

Is this enough information to suspect one of the relays? Do you know how I can isolate which relay is perhaps failing? I can't get the tip of the volt meter probe onto any wire on the load side of the relay due to the plastic around the quick connect.

When operating on L1, do BOTH relays have to operate or does one put out the 120V to the cord? I really appreciate all of the help you are offering.

[Craig Kirkpatrick]

I know it is hard to measure at the AC Test screw-terminal block on the OpenEVSE controller since the car disconnects quickly.  It should not "ramp up" in voltage.  But still It can be nearly impossible to measure if the car disconnects quickly and maybe it was just your meter auto-ranging to get to the 220V looking like it was ramping up.  All of the symptoms sound like the EVSE and the car are communicating OK but  the car expects to see power delivered and sees no power so it gives up wisely.  That means that one of the lines is high resistance or open circuit.  So far with the voltages you measured it seems to rule out a total open circuit but still something could have been turned to carbon within a fuse or a relay so it is now high resistance.

The 220V should only show up between the poles of the AC Test screw terminals when both relays are closed during charging.  I just want to point that out but I'm not sure exactly what you observed there.

Even on L1 you will need both relays since in L1 you are connecting a hot line and a neutral.  For L2 you are connecting two different hot lines without neutral. 

How is this wired at your breaker box?  It would be worth you explaining what you have there and even photos could help.  When you say you measure 220V at the fuses it seems it must be OK at your breaker panel.

If I were in your shoes, I'd relax, sip some wine with the wife, and order these two items for a grand total of $38 plus whatever shipping.  Then rebuild it next weekend with the new relays and fuses.

http://store.openevse.com/collections/accessories/products/30a-spst-relay

http://store.openevse.com/collections/accessories/products/30a-cooper-bussman-fnm-fuse

It still bugs me that it overheated since we have not gotten to the root cause of that.  If you set it to 12A then the only good explanation is a poor crimp connection.  My best advice is to go to Lowes or Home Depot or whatever your favorite store is and find the person who works the electrical aisle and ask them for a high quality crimp tool.  I've used this one building three OpenEVSEs so far and never had a problem:

http://www.homedepot.com/p/Klein-Tools-9-3-4-in-Crimping-Cutting-Tool-1005/100630657

I'm still interested to see you solve this.  So let me know if I can offer more advice.

[BillE]

Craig,

I actually did have some wine with my wife - and the car still will not charge!! I will take your advice on the relays and get some more on the way. You mentioned fuses, but if I have good power on the line and load side of the fuse blocks, aren't they OK?

I think the issue probably goes back to a bad crimp. Anyone else out there have the same issue?

[Craig Kirkpatrick]

Your logic is fine regarding the fuses.  But if changing relays doesn't solve it then the next thing is the fuses.  My thought is spend the extra bit of cash now so you can be sure to be up and running next weekend.  But you decide how you want to proceed.  If you have a way with your meter to measure Ohms it would be useful to measure the fuses to be sure they are near zero ohms.  A high resistance can provide voltage across the resistance but not support the flow of current.  That is why I suspect a fuse may be bad at this point and measuring the resistance could help to isolate the trouble.

Yes I've seen a few cases reported here that I would point to bad crimps as the cause.  And I've been working on firmware to keep an eye on temperatures in the enclosure both the ambient temperature and additionally using an infrared non-contact sensor that would keep an eye on the fuse block and wiring.  Everyone is interested in safety and the EVSE's job is all about safety.  Keeping an eye on temperatures and having some safety shutdown is the idea that I'm working on wrapping up soon.  This will be something easily added to an existing OpenEVSE and not cost a lot.  Stay tuned.

Best Wishes,

Craig

On Saturday, February 21, 2015 at 4:52:45 PM UTC-8, BillE wrote:

Craig,

[BillE]

I did a post-mortem on the relays thinking one had been damaged. The contacts were not welded in either case and a check with the ohmmeter showed that the coils were good; 0.118 ohms. I measured zero resistance with the contacts closed. I guess I should have checekd them before cutting them open (duh) but I am a novice with electronics.

So, what can I check for now??

On Saturday, February 21, 2015 at 9:15:41 PM UTC-5, Craig Kirkpatrick wrote:

Your logic is fine regarding the fuses.  But if changing relays doesn't solve it then the next thing is the fuses.  My thought is spend the extra bit of cash now so you can be sure to be up and running next weekend.  But you decide how you want to proceed.  If you have a way with your meter to measure Ohms it would be useful to measure the fuses to be sure they are near zero ohms.  I high resistance can provide voltage across the resistance but not support the flow of current.  That is why I suspect a fuse may be bad at this point and measuring the resistance could help to isolate the trouble.

Yes I've seen a few cases reported here that I would point to bad crimps as the cause.  And I've been working on firmware to keep an eye on temperatures in the enclosure both the ambient temperature and additionally using an infrared non-contact sensor that would keep an eye on the fuse block and wiring.  Everyone is interested in safety and the EVSE's job is all about safety.  Keeping an eye on temperatures and having some safety shutdown is the idea that I'm working on wrapping up soon.  This will be something easily added to an existing OpenEVSE and not cost a lot.  Stay tuned.

Best Wishes,

Craig

On Saturday, February 21, 2015 at 4:52:45 PM UTC-8, BillE wrote:

Craig,

[Craig Kirkpatrick]

Let's review what we know and have observed.  You say that after replacing the burned wires the symptom is you connect the plug to the Leaf, hear the EVSE relays click meaning it goes to State C which means everything is ready to charge, and then a few seconds later you hear the relays click again which means the car released the EVSE to state B which is connected but not charging.  That behavior is consistent with the Leaf unable to actually get any power from the EVSE but it does tell us that stuff that was working before is still working, namely the Pilot signal and ground connection.

So now we focus on the high current AC path. And that is where trouble began with the wires overheating.  Besides wires and crimps there are two other things in that path within the EVSE, the fuses and the relays.  And now the relays seem to have been ruled out.  If the problem is within the EVSE then I say it is the fuses.  It is however possible that the problem is outside of the EVSE like at your breaker panel or possibly in the J1772 cable or handle but that does not seem so likely.

What do things look like at your breaker panel?  Have you tried cycling the dual breaker that should be there.  Already it seemed to me that the problem wasn't likely at the breaker because you measured 220V in the EVSE but it is time to check all assumptions.  For Level 2 charging the AC mains connection should be three wires; two hot lines and earth ground.  There is also Neutral at your panel but that is not connected at all to the EVSE in North America for L2 charging at 240V.

You could also order the EV simulator kit from the OpenEVSE store and that would permit you to fake out the EVSE and pretend the EV is connected or charging so it would be simpler to debug things all of the way to the J1772 plug.  http://store.openevse.com/collections/accessories/products/ev-simulator-kit   It is cheap and simple.  I keep wires with female sockets on my OpenEVSE controller Pilot and Ground, permitting me to plug-in some male plugs I have wired to my EV simulator.  Mostly I just use the simulator on the bench while testing firmware that I'm enhancing.  Here is a link to the wires, multiple colors, both plug and socket connector ends, can be used to add the EV simulator and also things to the I2C bus of the LCD in the OpenEVSE.

If you have a multimeter that can measure Ohms, touch the leads together and note what resistance you measure when it should be zero Ohms.  Then measure across each fuse and it should measure the same near zero ohms.  If you see anything higher than that then the fuse is bad.

Good luck,

Craig

[BillE]

-The breaker has been ruled out as the Leaf has a Level 2 EVSE (OEM unit upgraded by EVSEUpgrades). It works fine.

-The fuses should be fine, as they each measure 0.00 ohms.

This leaves the cord. Are there any quick ohm measurements I can perform to troubleshoot the pins at the end?

[Craig Kirkpatrick]

With everything disconnected from AC, you can measure the Ohms from the wires inside the EVSE to the plug.  The three big conductors in the plug are the two hot lines and the ground.   The ground is the large conductor between the two smaller conductors.

http://www.rtcmagazine.com/files/images/2719/TechSystems_A_fig2_large.jpg

Basically one hot wire in the EVSE should have nearly zero ohms to one of the  big plug connections and so forth.

I suppose it is possible but not likely that you somehow swapped a hot line and the ground on the J1772 cable.  I've been thinking of a debugging decision-tree already and thought maybe that would be a good thing to confirm before anything else.  Make sure the ground on the J1772A is zero ohms to the ground block in the EVSE.  It seem unlikely that it is wrong, but anything is possible I suppose.

And on that same thought, if you assembled your own AC mains plug from the wall socket to the EVSE it will be wise to confirm that ground is connected to ground there also.  The two hot lines are interchangeable with each other but ground must connect to ground.

Good luck,

Craig

[BillE]

Craig, 

Thanks for sticking with me while I troubleshoot all this! Maybe someone will benefit in the future from this thread.

I ohmed the pins on the plug and the ground on the AC power plug and everything checked out OK. If I purchase the simulator, then I guess I can check the board itself and all the outputs, etc. 

[Craig Kirkpatrick]

Bill, I don't mind helping anyone to debug these. And you are right that it helps others who may read this thread and there are always a few "ah hah" moments where we all learn new things to check upon debugging the EVSE builds. I'm confident we'll get to the bottom of this. And I persist in my belief you have a bad fuse though I know you don't believe me yet. 😜

[chris1howell .]

I would also recommend checking the proximity connection with the button on the J1772 handle pressed and released. Without power attached measure from the proximity pin on the J1772 connector to  ground. You should read 480 and 150.

Also check the pilot line is correctly and securely attached and grounds are all tied together.

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[William Ehrenbeck]

Chris,

 I tested the proximity connection and measured 486 ohms when pressed and 153 ohms when not. Grounds are good. 

I placed an order earlier today for new relays and the testing rig. Craig had suggested new fuses but they tested at 0.000 ohms each when not powered. Is it possible for them to be too resistive when under a load, causing a higher amp draw, hence overheating?

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[chris1howell .]

Sounds like proximity is good. Fuses are likely okay if they read 0 and power the controller fine.

I hate to ask a silly question, but to cover all bases. Have you disabled or overridden any charge timers on the Leaf? The behavior you describe sounds like the normal check the Leaf performs before waiting on a timer.

[BillE]

There are no silly questions! But no, because when I plugged in my other EVSE, it immediately started charging. 

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[chris1howell .]

Okay. The last think to check is that both relays are actually triggering and conducting power. I have seen a few times where the QC terminal was wedged in between the terminal an side instead of on the terminal itself. Verify on boot you hear 2 distinct relays each clicking on then off (4 clicks total). And that each power connector is correctly seated on the terminal.

[BillE]

I don't remember hearing 4 clicks - only 2, but I assumed that they were both pulling and releasing at the same time. So they both cycle independently? Of course it's too late to check this because I cut the relays open this morning for an autopsy! They were both fine visually and measured 0.118 ohms across the coil.

[chris1howell .]

They are tested sequentially so you hear click - click pause click - click.

I think this was your issue, only 1 hot was switched to the vehicle. I'll get the relays you ordered out first thing in the morning.

--

[BillE]

Thanks Chris! I am still confused as to why both wires were burned. Maybe they weren't big enough? I replaced them with 10 guage so that will eliminate that variable.

[chris1howell .]

If both were burnt then that is a sign the gauge was to thin for the current. 10 Gauge is the proper gauge for charging up to 24A continuously on a 30A circuit.

[BillE]

The wire I used did not indicate the gauge on the insulation. It was cut from a roll of pump wire (maybe six wires under the outer sheath) intended for an industrial pump but appeared to be the same guage as the wire in the OEM Chevy Volt charging cord. I set the max current for both L1 and L2 to 12 amps. I am curious now what the guage is, I will mic it when I get to work tomorrow to get the outside diameter.

[Nick Sayer]

To my eye in the picture, the burned wires look like 16 gauge (but I could easily be wrong). But if your EVSE is set to deliver only 12A, then even that would be no problem for 16 gauge wires. Crimp connections can be suspected as well, but again - with a limit of 12A, I can't explain the wires being burned up like that *and* the circuit breakers and fuses *not* blowing (miswired as short circuits, it would burn the wires up, but not before popping the fuses or breakers).

[BillE]

Just a quick update and "Thank You" to everyone who helped me troubleshoot and repair my EVSE. After receiving the new relays and reinstalling (and using heavier guage wire this time), all is well!!

[Craig Kirkpatrick]

Bill, Thanks for the follow-up message. I'm glad you have it rebuilt and working safely.
-Craig