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Smart charging and battery consumption for cooling

m80arm

Member
Jun 1, 2021
15
6
Newcastle
So I picked up my M3 LR on Wednesday evening and I have to admit I'm loving it already. I've just had a rolec charger fitted and switched to Octopus Go. I've set the Tesla delay charge to kick in at 00:00 and then the ev.evergy app overrides this and starts the charging sometime between 00:30 and 04:30 which I understand is the correct procedure and seems to have worked last night.

The question I have is around what happens when the car is plugged in outside of those times? i.e. if I set the climate control will that use the Tesla battery or will it still allow the power to come from the wall charger? Does the charger know the difference between charging the battery and powering the car for normal activity?

Thanks

Michael
 

Durzel

Active Member
Jul 17, 2019
3,468
2,419
Bath, UK
Climate will always use mains power if available.

The charger won't know or care what the power is being used for. The car will dictate the draw depending on its needs. If you are just using climate I would expect usage to be ~4kW, maybe a bit less. If the battery % dips below the desired level I would expect it to use the full 7kW to try and keep it at that level.
 

m80arm

Member
Jun 1, 2021
15
6
Newcastle
OK, so it sounds like the battery will try and use the mains power but chances are the rolec will not allow this outside of the cheaper tarrif that is set via the app. The power consumption is negligible but I'm just curios to understand how it all works
 

MrT3

Member
Jun 26, 2021
170
96
UK
OK, so it sounds like the battery will try and use the mains power but chances are the rolec will not allow this outside of the cheaper tarrif that is set via the app. The power consumption is negligible but I'm just curios to understand how it all works
It will depend if your charger completely disconnects power from the vehicle outside of the schedule. There is also an advanced switch in the app settings to only charge off-peak.

For the cheapest charging you are best to only charge off-peak, then let the vehicle use its battery for pre-heating otherwise you will pay the more expensive electricity rate for the pre-heating if it is coming from the mains.
 
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Soua

Member
Feb 25, 2020
39
25
Lancs
It will depend if your charger completely disconnects power from the vehicle outside of the schedule. There is also an advanced switch in the app settings to only charge off-peak.

For the cheapest charging you are best to only charge off-peak, then let the vehicle use its battery for pre-heating otherwise you will pay the more expensive electricity rate for the pre-heating if it is coming from the mains.
With the difference between peak and off peak at around 9p per kWh on Octopus Go I'm sure if you can afford the Tesla it's not a big issue? I was totally anal about sticking to off peak time, but then realised it's not worth the stress! Relax and enjoy! 😉
 

Adopado

Active Member
Aug 19, 2019
4,175
3,141
Scotland
The question I have is around what happens when the car is plugged in outside of those times? i.e. if I set the climate control will that use the Tesla battery or will it still allow the power to come from the wall charger? Does the charger know the difference between charging the battery and powering the car for normal activity?

Try it and see ... get in your car and bring up the charging screen whilst plugged in at home and make sure the HVAC is running ... you will see if it can draw power from the Rolec. My expectation is that it won't work ... but you never know. This is mainly an issue in the winter when you want to charge at cheap rate but you also want to be able to warm/precondition the car in the morning. You simply set the charger with no timing limits and the Tesla charge start time to 00:30 and limit the charge percentage on the app so that you don't go over your 4 hour limit. Once you have estimated how many percent you can charge in 4 hours you will easily be able to set your limit accordingly. I can add up to about 56% in a 4 hour session on my SR+ so if I'm at 30% I could set the charge limit up to 86% without going over. I think the LR/Performance cars do about 40% of their bigger battery in 4 hours.
 

ACarneiro

Active Member
Jun 20, 2019
1,399
1,123
Shrewsbury, Shropshire, UK
Yes, the LR is about 10% per hour on single phase 32A charging or 15% per hour on 3 phase 16A
Personally I prefer to spend a few kWh in “expensive rates” and have the car warmed and preconditioned on mains power in the winter in order to maximise range and regenerative braking…. Like @Soua said, it only costs a few pennies more :)
 
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Adopado

Active Member
Aug 19, 2019
4,175
3,141
Scotland
Yes, the LR is about 10% per hour on single phase 32A charging or 15% per hour on 3 phase 16A
Personally I prefer to spend a few kWh in “expensive rates” and have the car warmed and preconditioned on mains power in the winter in order to maximise range and regenerative braking…. Like @Soua said, it only costs a few pennies more :)

Definitely. It really is just a few pennies to go out to a warm car and a warm battery so maximising winter range.
 

Mrklaw

Member
Mar 5, 2020
433
228
Berkshire
depends where you’re going. If its just commuting and you’re using nowhere near the range of the car, let the battery warm the car and you’ll top it up later on cheap rate. If you need the range, use the mains.
 
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Adopado

Active Member
Aug 19, 2019
4,175
3,141
Scotland
depends where you’re going. If its just commuting and you’re using nowhere near the range of the car, let the battery warm the car and you’ll top it up later on cheap rate. If you need the range, use the mains.

That's true .. cheaper to use the cheap rate electricity stored in the battery to warm/precondition if you're on the "right" plan, and just suffer the range loss. Much bigger issue in winter when range can be at a premium.
 

SpareHeadOne

Member
Oct 27, 2020
345
222
UK
Yes, the LR is about 10% per hour on single phase 32A charging or 15% per hour on 3 phase 16A
Personally I prefer to spend a few kWh in “expensive rates” and have the car warmed and preconditioned on mains power in the winter in order to maximise range and regenerative braking…. Like @Soua said, it only costs a few pennies more :)

I've found mine slows are the battery gets fuller, so it averages just under 9%/hour - typically it will charge about 70% in 8 hours on single phase 32A.

That said, it's very rare that I need to add that much charge in one night, typically I'm not under 60% SOC for the driving I'm doing at the moment and only very rarely under 40%. I think I've only ever charged to 100% twice - once because I didn't know any better and once for a particularly long day on a "just in case" basis.
 

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