This is a companion to the previous post. All measurements are done by SpeakEV user ElectricBeagle. They are all done using either a granny cable set to 10 amps or a decent chargepoint set to 30 amps.
Here is the current when plugging in, measured using a current coil on the L wire. It doesn’t show the phase angle but all current is reactive as it’s created by the filter capacitors.The stable, reactive current is about 6A RMS, close to 10A peak. Note that the spike occurs when the reactive current would be about zero, so the actual plug voltage would be at it’s maximum, creating the maximum spike current. It’s roughly 40 amps and lasts about 1 ms. Note charging has not started yet.
Ignore the lower curve. The upper trace is measured using a resistor in the PE wire. You can clearly see the two measurement pulses. They are roughly 20 mA and last 1ms. These are to measure earth resistance; the car injects the measurement current between N and PE. This happens after plugging in but before charging starts.
This is a slow trace of the L current, measured again using the current coil. It shows the spike and reactive current. After about 3 seconds the charger kicks in and does gradual current ramp up to about 13A lead current. That is about 12A real current.
We’ve had somewhat of a blank spot when it comes to the start of a charging session. Understanding it well can help diagnosing why the car might refuse. SpeakEV user ElectricBeagle bit the bullet and started measuring currents in all the leads to find out what is going on. For brevity, I assume that the cable is in and locked, connecting protective earth [PE] to the car’s chassis, and everything to activate the chargepoint is done. The main contactor in the chargepoint is about to close.
The main contactor is closed in the chargepoint. This usually creates a significant current spike in the lead(s) as all L lines have a 100 uF capacitor to N, see the blue box in the third picture of this post. Correction: pretty sure now the capacitors are in a delta configuration, not a star.
Car allows for dampening out ringing for a second or two. Note that because of the capacitors, a significant though reactive current (6A per lead) is drawn. This is, ignoring some losses, not a power uptake.
The car injects two 20 mA pulses between PE and N in both polarities to measure earth resistance. If the resulting voltage exceeds 4 V, meaning an earth resistance of more than 200 ohms, the charge point is rejected. *)
The car ramps up power uptake from 0 to the requested power in about one second. It’s very gradual, which is also notable in the ramp up of the “whine”.
Maybe you remember fairy tales about > 500 A startup currents by the ZOE, usually told by chargepoint mechanics. Well, this is what it is, a 100 uF capacitive load. Because of lead resistance and filter coils, inrush is actually limited and the spikes are 30 – 50 amps and last about one ms. This is no big deal whatsoever and any notion that this is problematic can be dismissed.
Now there are other tests done such as lead voltage and earth leak current, but these test can not be detected, though they should be pretty straight forward. I read of one driver seeing it’s car still charge on 180 V from an off grid PV system. I don’t know if the car would actually start a session this low.
I am now tempted to build myself an Arduino based earth tester using the same principle as have an extra diagnostic tool. For the Netherlands though, this is hardly worth the effort as most, if not all chargepoints are connected using decent earthing.
I’ll write in another post about the currents while charging.
*) Entire books have been written about safe earthing of power distribution networks. For the technically inclined Dutchies (or the ones who can bear Google Translate), this is such a book, link to the relevant part. I will only say here that ZOE of course is unable to have a true earth reference. So she assumes a network where N and PE are actually connected. In modern TN-C-S networks this should always be the case. In TT networks, where earth is provided with a local earth rod, things might not work out that way, let alone floating or midpoint-earthed networks. These are dying breeds but still all over Europe, especially in the more rural areas.
The key card of my ZOE was slowly giving me trouble (not the keyless entry one BTW, it’s a simple ZOE Life).
It was slightly iffy for a few weeks, but nothing that a bang couldn’t fix. However yesterday I could almost not start her while away from home. As significant other has another good working card, I decided it was worth to give it a tinker treatment. Unfortunately it is friction welded together and carefully cutting it open along the sides was not enough. Unreasonable force (for the un-initiated, bigclive.com) using spudger and chisel was to be applied.
Remote control antenna and chip is top left, transponder for the slot top right. It’s a flat, probably ferrite brittle core, with hair-thin exposed copper wire wound around it. That thing had come off. The problem probably was a somewhat dry solder joint that had gone bad under regular stress and making an iffy contact. I assume it broke off completely under said unreasonable force. Long story short, I soldered it back on the PCB using leaded solder and put it back together. For now with Scotch tape to make sure it works again, which it seems to do indeed. I will carefully glue it shut again if it keeps up a few more days.
Bottom line: if you decide to open this thing up, be very careful when cutting around that coil area, and be prepared to use quite a bit of close-to-destructive force just below the open/close button pair and around the coin cell area, all to be applied carefully with a blunt chisel tool not to kill the thing. At least you now have a layout.
Fred Leudon disassembled his Q model BCB himself and here a few of his pictures, now including the filter module!
Note that what I earlier identified as the flyback diode is actually a 63 uH coil. Also visible is the modest PCB of the rectifier module.
Here is the filter module, still closed. For orientation, note it is held upside down and the orange connector (normally connected to the loom going to the car’s “nose”), points to the front of the car when mounted. The four cables exit in the direction of the rectifier box; left side of the car. Also note that the N wire is substantially thinner than the three L wires (see below).
And here the filter is opened up, rotated 180 degrees when compared to the previous picture. The crimp on the center orange cable has it’s shrink wrap insulator removed. It was not properly crimped on the coil wires which made this module fail. The coils seem to be used both as filters as well as current sensors. Also note the black plastic box and a substantial PCB pair.
Now there is confusion is about the N <> L3 relay. My stance, based on what I saw on Renault provided schematics and me hearing clicking sounds, the black box should house said relay. The original author swears there was no power capable relay in the entire module, and that ZOE uses two diodes to N. At the moment, both stances are incompatible and we have no way to verify one or the other.
The much thinner N cable suggests there is substance to my stance, or the two diodes should be in this module. But that doesn’t jive with me, since all the rectification is done in the other box, but I am biased and could be totally wrong of course.
More investigation is needed. Maybe I will get brave and open mine……..
Thank you Fred and forumpro.fr user “Pixel”. Here a link to the original source and discussion.
In The Netherlands there is a car sharing initiative called We Drive Solar, basically using car batteries as PV grid storage on the neighborhood-level, as opposed to home-level. In that neighborhood (Lombok in the city of Utrecht), they have long said they have installed public charge-points capable of Vehicle-to-Grid (V2G). It’s a General Electric model if I am not mistaken.
I confess I have always been a bit confused and sceptical. Renault is heavily involved in the project and have stated they will build “custom modified” ZOEs for the initiative. I assumed this would simply be a “pre-2019 CCS enabled ZOE” sort of prototype as it would make the most sense: they had to develop that anyway, so why not pull it a bit forward? But what was nagging me is the charge-points. Looked pretty standard to me with normal Mennekes type AC plugs. Would it even have enough space for a multi kW rated grid inverter?
An unidentified source, so unfortunately unverifiable, has told me that I was wrong, and it is really interesting news: The V2G will be AC based. And it makes a lot of sense really. If the inverter is on board, simple Vehicle-to-Home (V2H, or “V2G light” if you will) will be very easy to implement. No home based special chargers needed at all and normally the charge-point is connected to a separate fuse group anyway.
As for the technicalities (i.e. communications on how much to feed-in), I have no details. However, there is a US filed patent, resembling the other one I mentioned here, describing an extension to the existing charger with just a few components to make it V2G/H-enabled, which I regard as mildly corroborating evidence. From a hardware point of view, it only needs a second black module; the bigger one shown in the third picture of this post. Looks like the Chamelion charger, dismissed nowadays by many “as charging will go DC”, has some extra life in it! Interesting times ahead!
As there is no indication about a degrading 12 volt battery like a struggling starter motor in an ICE, it’s condition that can bite you, and I am sure that is the reason for Renault advising replacement after 3 years. A bad 12 volt battery leads to the “Check Electrical System” dash message, talked about earlier here. It’s both a somewhat confusing message, and it seems to be not exclusively for a bad 12 volt system.
Today I noticed there is a field the EVC called “Battery 14v to be changed display”, with possible values “-“, “Soon”, or “Now”. That seemed to be a fine candidate to add to the 12 volt screen. It’s already on the development branch on github and will make it in the next release. It’s the 4th line called “Replacement advice”.
Feedback is appreciated! We’re interested to know if there is a CanZE “soon” message before the dreaded dash message, if the dash message corresponds to this CanZE message, and if so, whether the “12 volt battery symbol” (rectangle with two knobs on top) was also lit on the dash.
This is a companion post to the BCB pictures post. It makes sense to check all pictures and text there first.
A student in high power electronics contacted me to discuss some design issues and pointed me to this US patent. Doing some comparing it is obvious that the BCB is designed exactly according to the patent. So here is some extra information linking the picture and figure 2 from the patent, reproduced here.
The EMC filter (5a) is not in the image. It also contains the 1/3 phase switching (see this post). Maybe I will get my hands on some later.
The capacitor bank (5b) is the blue box;
The regulated rectifier (11, 12) and it’s control circuit (6) is the black plastic box. It’s incoming connectors are bolted on the capacitor bank with it’s three phases connectors, and it’s bottom is thermally bolted against the aluminium housing for cooling. This can be seen in the other BCB pictures. We suspect so is the free wheeling diode (13);
The potted aluminum device is a 93 uH inductor (the label in the picture is in error, thank you user pixel from renault-zoe.forumpro.fr). It is inserted in the line going to A (10);
The input current measuring device (10) might be tucked away in the far top left corner close to the Neutral point connector, which is actually the center wire of the motor (14). The current sensor is probably a Hall sensor. It’s control wire (blue-white in the picture, (8) in the schematic, running to the control circuit (6);
Everything else in the picture is control wires, CANbus and 400 volt distribution;
The entire inverter section (15, 16, 7) is located in the PEB.
Note that this setup allows for both buck and boost operation, which is needed because rectified voltage is too low when in single phase operation (325 V peak) and too high in three phase operation (562 V peak) for the battery (roughly 350 – 420 V).
Notice the micro-switch at the left side detecting opening the cover. Hmmmmm.
Just like in brain research, often a lot can be learned when things go wrong. A friend driving a ZOE was struggling for months with the weirdest problem. The car charged fine on public chargers, but not at home. However, that home charger did it’s job fine on several other ZOEs. Dealer was helpful but couldn’t find a thing; charger supplier found nothing wrong.
Sequence of events was:
cable plugged in and chargepoint light goes blue;
the usual relays clicking noises from the car (the battery, and the 12 volt bus);
the usual “CLOINK” of the contactor closing in the chargepoint;
after 15 seconds and a bit of clicking in the car, contactors open, light goes green and everything stalls.
All this time, the dash shows “Ongoing checks”. No error, no red nose, but no charging.
After a few weeks of faffing around, trying here and there, including his fivari charger, he is suspecting it is one phase charging that fails, but three phase is OK (hint one). Everyone (yours truly included) says that is very unlikely. In private, he tells me he hears “electric sparking noises” from under the bonnet. Oh dear!
Finally, Renault NL is involved and I am gracefully invited / allowed to join in. So I head over on a misty Friday morning to his house. Three ZOEs present! CLIP tool hooked up and indeed an error is presented (DTC064063), suggesting either chargepoint, cable or filter in the BCB (hint two). All are a bit miffed the dealer missed this.
Then we open the bonnets of two ZOE’s and hook up the charger to each. Lo and behold, his ZOE made some soft, but scary noises the moment charging is supposed to start, just after the “CLOINK” (hint three). It’s not sparks, but it sure isn’t good, more like a rattle. The Renault tech pulls up the functional schematics and explains what might be wrong. To make a long story short: ZOE rectifies current from the 3 phases using a “three-phase full-wave rectifier”.
Note that the N (neutral) is nowhere to be seen. What ZOE does is when you connect single phase (between L1 and Neutral), a relay connects the N wire in the feed line to L3, so now the juice is between L1 and L3, and since L2 is not connected to anything, all is fine. Obviously said relay is not energized when on three phases. It is located in the filter module (see this post). It was this specific relay, or it’s control circuit, that had failed. Friend did a “yessss!!!” as he finally had a diagnosis and as he had confirmation he was right about the single phase after all.
The car has been repaired and is right as rain again. I am hoping for some more info on the filter module; how it works and what went wrong.
Harm Otten had a team from the local electricity distribution company over for an unrelated metering problem, and obtained from them a screen shot of the voltage / current curve of ZOE charging. This is a Q model.
The dark red voltage measurement is between one phase and N. The current, light red line, is measured in that particular phase wire. The current flat line around 0 is consistent with rectifying, and the “bump” after the current has swung up is consistent with 3 phase rectifying using a three-phase full-wave rectifier (see also this post).
Note: it all makes far more sense now, see this post, ignore what I wrote below.
What is harder to understand is why the charger is not able to let the current curve follow the voltage curve better, given the actual design seems to have full input control (see Charger design post).
Edit: I happen to believe, though I was not there, that they used a Fluke 435 using Fluke i430 current probes (Rogowski coils) for current measurement. That is pretty top of the line equipment, so unless they didn’t match up the voltage and current phases, I cannot explain the rather massive phase shift.