Month: March 2018

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.

It’s all rather cleverly done.

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:

  1. cable plugged in and chargepoint light goes blue;
  2. the usual relays clicking noises from the car (the battery, and the 12 volt bus);
  3. the usual “CLOINK” of the contactor closing in the chargepoint;
  4. 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.

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