Fascinating Spreadsheet

Renault EV Interest Group
Post Reply
doggy
Groupie
Posts: 233
Joined: Tue, 24 Jul 2018, 09:59
Real Name: David Kerr
Location: Sydney
Contact:

Fascinating Spreadsheet

Post by doggy » Tue, 13 Aug 2019, 15:33

Zoe folks (and possibly Chris Jones) might be interested in this spreadsheet which shows the relationship between battery temperature and maximum charging rate and SOC.

You need to select the 40kWhr rather than 22kWhr sheet.

Also, the spreadsheet covers Q90 with 43kW charging. Though this might affect regen on an R90 because that can go to 43kW; but the chart might not apply to regen.

But for our R90 Zoes, with 22kW charging, if you run your eye down the interface between green and yellow, it is interesting to see how you cannot charge at full rate if the battery temperature is too low. Also, as known by everyone, the last few percent go slowly presumably in part due to balancing and squeezing in as much juice as possible.

Of course, the Zoe DOES have battery temperature conditioning so it will heat the battery if too cold, but this takes a finite time. Also, I note that the new Teslas pre-condition the battery temperature if they know they are going to be supercharged but I doubt Zoe does this (not that I have tried building a charging stop into a route or itinerary...which is do-able).

I wonder if this influenced Chris's test drive experience? Probably not because I would have expected reduced or slow charging whereas I think he experienced terminated charging and his charger behaved in ways that the rest of us have not experienced.

Cheers,
Dave

https://docs.google.com/spreadsheets/d/ ... 1629118923

User avatar
jonescg
Senior Member
Posts: 2998
Joined: Thu, 21 Jan 2010, 23:05
Real Name: Chris Jones
Location: Perth, WA.

Re: Fascinating Spreadsheet

Post by jonescg » Tue, 13 Aug 2019, 16:19

I couldn't tell if the battery was being actively cooled or now while it was charging at 22 kW. However we did select pre-conditioning while we waited i the darkness for 2 hours, and this might have helped. There was no warning that the battery was too hot or too cold, just said "Battery Charge Impossible". It certainly just stopped, and eventually reset its error after some time later (while we were elsewhere).
AEVA National Secretary, WA branch chair.

doggy
Groupie
Posts: 233
Joined: Tue, 24 Jul 2018, 09:59
Real Name: David Kerr
Location: Sydney
Contact:

Re: Fascinating Spreadsheet

Post by doggy » Tue, 13 Aug 2019, 17:10

Hi Chris,

Your problem was different from what this spreadsheet indicates.

If Zoe cannot charge at the full amperage defined by the pilot signal (eg because of battery temperature), it just scales back but continues to charge, albeit more slowly. Also, when staring charging, it always starts slowly. I find it starts at about 3amps then gradually works up to the Pilot current over several seconds. Some people have reported the dreaded message several seconds after charging actually starts but before it reaches the maximum. This is probably because some of the leakages increase with current (see further on).

You can sure tell if the battery is being cooled or heated because the fans are super loud (if you are out of the car). For cooling, Zoe starts with fans then adds climate control if not enough cooling/heating. You would have noticed the racket.

Now, that error you got is normally associated with an earth problem. Zoe measures the resistance to earth, neutral current (on a 3 phase EVSE), low frequency leakage to ground and high frequency leakage to ground. With CanZE, some of us owners can monitor these in realtime, on a graph, while charging and would be able to see such a fault. But for the average user, there is just this message. I get it on one particular Tesla DC but only on the left, not right cable and about 80% of the time. Another owner has experienced the same on the same DC. But it does not always happen for him either. Teslas do not seem to have this problem on that DC. So in this particular case, two of us get the same error, but it is not a fault as such but definitely indicates that one of the two EVSEs on the DC has worse leakage or grounding performance.

During the charging, Zoe monitors HF, LF leakage and neutral current but earth resistance happens at the start.

So, I do not know if this was the issue for you, but that's normally what your error message means. I have heard speculation about poor grounds due to drought (dry earth) and also some rumours that Zoes are quite pedantic about ground safety. So, maybe this had something to do with your problem or maybe there was indeed a fault in the Chameleon Charger which manifested as a grounding or leakage problem. I guess we'll never know. However, if it only happened to you on one EVSE and others were fine, it would likely be that EVSE but given you had multiple instances things do seem to point to the Chameleon Charger being faulty (or starting to have a fault).

Cheers,
Dave

Post Reply