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Discussion Starter · #1 · (Edited)
After a long trip last night I returned home on about 2kWh remaining (R240)
Range was showing at "--" and the red light was flashing - according to the trip I had used 20kWh.

Plugged in at 0040 and saw an interesting consumption pattern:
upload_2017-9-3_22-39-31.png


You see straightaway the step up to 1.2kWh when I plugged in (the fans were running).

I have Economy 7, so charging is timed to start at 0130.

What I didn't realise was that if i add up the area under the graph and deduct the approx 5-600w base load, it seems to take about 27-28kWh to charge 20kWh in the battery.

Seems a bit inefficient, is this standard with all EVs? I didn't expect the balancing phase to use so much power. We don't have any other heavy loads running overnight so I'm sure this is all the ZOE - apart from the kettle and toaster spike! :)
 

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What charger are you using? The 3 pin charger is notoriously inefficient.

Also I am assuming you do not have any preconditioning activated?

This page gives an interesting breakdown of efficiencies but the numbers are very dependent on what's on the Renault website (i.e. I think they could probably do with some more scrutiny but they're probably a good ball park figure) : Renault Zoe charging time and efficiency - Push EVs
 

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Also, should point out that you don't have a 20kWh battery.. but actually something a bit larger (speculated at 26kWh). The battery comes over spec'd for what they advertise so that when parts of the battery fail it will replace it with this spare capacity.

This video at 9 minutes 43 seconds discusses this :

This post discusses what you have discovered :) : Is the Zoe's battery 24kW? Because if it is..

Also finally, if the battery packs get too warm or too cold and the car is charged when it's too warm or too cold.. the HVAC system can kick in and this will of course eat into your efficiency. Some regions only can cool the pack not warm it (i.e. UK ones can't switch on the heating to warm up the pack). This is discussed here : Battery Upgrade ZE20 -> ZE40
 

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Co-author of CanZE. Q210 nov 2013
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That is not entirely correct. The 22 kWh models indeed have batteries that are "raw" just under 26 kWh, but the BMS does not allow you to use that. It leaves headroom and "legroom" to decrease battery stress. The neat thing is (as indicated in the presentation) that there is no visible degradation while the battery is new and can be processed in those "rooms", and that when finally there is real degradation noticeable to the user it is much slower.

The charging efficiency is not fantastic, especially on low amp settings. On 22 kW it's charging really good, but at 3 kW there are substantial losses. The heat losses in the charger and the A/C when it kicks in take a relatively larger portion of the energy uptake at lower rates. That's the price for having a unique "all you can eat" charger :)
 

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I'm not crazy, the attack has begun.
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Looks to me like you have put in 25~26kWh, minus an overhead load, and probably have 22~23kWh useable. 10% loss. Quite normal.
 

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Discussion Starter · #7 ·
Makes sense I guess.
Curious to see it started to take power from the house supply immediately, despite charging being timed to start at 0130.

It was running the cooling fans when I stopped, surprised they'd draw that much power for approx. 50 mins
 

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Co-author of CanZE. Q210 nov 2013
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The fans don't draw a crazy lot of power, but if the A/C kicks in, if adds substantially. Actually, last time I checked (but it was quite hot that night), I thought it had only started the fans, but then I checked the Climate screen in CanZE to see it had also activated the A/C for active battery cooling. On a low setting and the noise level was remarkably low, but still, the compressor was running.
 
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