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Discussion Starter #1
For those interested in the preheat setup.
Attached is a graph of a R90 preheat at about -3C. Departure time set to 0630.
Total energy consumption 2kWh. Battery soaking kicks in 2 hours before departure at 3kW, after about 30 minutes switches over to 1.5kW. The heat pump starts 30 minutes before departure.

2391547014933.png
 

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What do you mean by 'battery soaking' ? What's the battery temp before departure after this in relation to ambient do you know?
 

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This is presumably a Nordic Zoe so able to heat the battery, unlike Zoes elsewhere? I wonder what the graph would look like everywhere else; would it just be the final 30 minutes of cabin warming?
 

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Discussion Starter #4
Yes the "batter soaking" is the heating of the battery. (called "Pre-Soak" in the instrument cluster). I did not measure the start temperature before the heating this morning but the batteries were at about 10C (8-12C) after Pre-soak, ambient temperature -6C. The battery is somewhat insulated but I would guess the start temperature to be just below 0C. Last year at a stopover at a hotel without charger the temperature of the battery fell from about 10C to -15C in 11 hours at -30C in the morning (fell to -32C on the way). Still got a bit more than 100km with a SOC at 55%. After this drive the battery was up to about 10C again and accepted to be charged at a decent speed.
 

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Yikes, can certainly see why Renault put the battery heater in there! Have you ever seen any kind of warning that the battery was too cold to provide power to the vehicle? I'd have thought at -15C battery temp you'd be well on your way to the point were the battery would say no?
 

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I'm not crazy, the attack has begun.
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So, around 2.0mi/kWh, consumed electricity, for a 60 mile commute? Remind me not to drive EVs in the cold ..... heh ....
 

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Discussion Starter #7 (Edited)
No I have not seen a battery temperature warning ever. Neither when cold or charging multiple times in a row at above 30C ambient (cooling fan at maximum). I rarely get a power consumption above 2kWh/10km, yearly average about 1.5kWh/km as reported by the car, not including charging losses.
 

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Co-author of CanZE. Q210 nov 2013
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AFAIK the real trouble start at around -30C battery teperature. I hear at that temperature the battery won't accept charge, so soaking would be mandatory

As @Gasg indicates and has been discussed here quite a few times, battery and ambient can be substantially different. It's quite a mass to cool down with minimal convection. GOM and Maximum power intake discussions are quite useless to have based on ambient.

Nice measurements. I am actually surprised. A while ago I found documentation stating the resistive battery heater was only a tiny 200 watt. Maybe it is and they push in a bit more heat by charging, or maybe the 200 watt heater is only for the non Nordic versions I don't know.
 

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Discussion Starter #9
In the Swedish manual it states that if the car is at below -25C för a week it might not be possible to charge. When the battery was at -15 maximum charge at SOC 55 was about 1kW. The heating works anyway. I have checked multiple times in the morning and it is about 10C. The pre heat always kicks in exactly two hours before scheduled departure. Attached is the graph from last night including charging. As you can see i tapers down quite fast probably depending on the cold battery. The jagged curve before 2130 is because of current limiting for the main fuse (3x16A). (heat pump, stowe etc). (might be something for the DIY charger? :) ) The total house consumption is times 10 in kW (max 11kW but a bit different phase currents). The Zoe is really responsive on the CP signal and acts within second so this works really good. Fast charging without large main fuses.
chargeing.png
Total.png
 

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Co-author of CanZE. Q210 nov 2013
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Very nice indeed, thanks for that data.

Yes, I plan to replace my OpenEVSE controller with one that has the WiFi control module. It's all build but the first test failed and I haven had the time / inclination to debug it. It will happen. The dongle can pick up a lot of data from the car, Node-RED can process that and data from the charger, and send throttle commands to the charger. Prevent overload when SHMBO switches on the oven, the cooker and the microwave at the same time the car is plugged in, PV curve following, the lot.
 

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In the Swedish manual it states that if the car is at below -25C för a week it might not be possible to charge. When the battery was at -15 maximum charge at SOC 55 was about 1kW. The heating works anyway. I have checked multiple times in the morning and it is about 10C. The pre heat always kicks in exactly two hours before scheduled departure. Attached is the graph from last night including charging. As you can see i tapers down quite fast probably depending on the cold battery. The jagged curve before 2130 is because of current limiting for the main fuse (3x16A). (heat pump, stowe etc). (might be something for the DIY charger? :) ) The total house consumption is times 10 in kW (max 11kW but a bit different phase currents). The Zoe is really responsive on the CP signal and acts within second so this works really good. Fast charging without large main fuses. View attachment 110012 View attachment 110014
Some qs;

Are the vertical axes a unit of something? (The top is kW to the car, the bottom is x10 domestic supply in kW, is that right?)
Is there not some cheaper rate in Sweden for overnight electricity?
Would it be better to time your charge so that it hits 80% by the time you want to leave, rather than 100% some hours earlier?

(y)
 

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Discussion Starter #12
Yes there are a ten fold difference between the vertical axes. (Makes it easier in combined graphs with temperature etc for the total consumption.) In Sweden you can select different types of rate agreements for electrical power. Because I have heating (via an inverter heat pump and 220m hole in the ground), I cannot choose the majority of our consumption during the year. When it is cold we consume the most and it is more expensive. I have an agreement with the same tarif 24/7/365. So it really doesn't matter when we charge. What matters is the size of main fuses. So you can save quite a lot using the fuses as much as permitted. In the summertime when the solar panels produce maximum I can charge at almost 22kW. (10kW from the panels and 11kW from the grid) This goes automatically because of the current sensing transformers on the incoming supply.
 
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