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Discussion Starter · #1 ·
Hi there.
Thanks for the great forum.
I'm busy trying to decide on a home charger to connect to a Polestar 2 and hope someone can help me. My charging will be quite erratic (some days nothing and others a full charge). Which of the chargers out there can connect to the vehicles to read their battery status? I have an economy 7 tariff so would like to use the off-peak time but scheduling won't be easy as I would need to start the charge prior to the off-peak start if I'm doing a full charge, and only later during off-peak if only doing a top up. I would obviously prefer not to do a manual setup every night. Any advise appreciated.
Thanks.
Alan
 

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Hi there.
Thanks for the great forum.
I'm busy trying to decide on a home charger to connect to a Polestar 2 and hope someone can help me. My charging will be quite erratic (some days nothing and others a full charge). Which of the chargers out there can connect to the vehicles to read their battery status? I have an economy 7 tariff so would like to use the off-peak time but scheduling won't be easy as I would need to start the charge prior to the off-peak start if I'm doing a full charge, and only later during off-peak if only doing a top up. I would obviously prefer not to do a manual setup every night. Any advise appreciated.
Thanks.
Alan
I don't think any AC 'charger' can read the car's battery status directly. (Is there even a lead in the standard charging cable that would allow it ?)

What they need to do is to connect to the car's 'app' (where there is one) using your credentials to get that information. That's certainly the way that Ohme do it - albeit with mixed success.
 

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Discussion Starter · #3 ·
I read the Ohme could do it but didn't know how. I thought there was some handshake communications that happen when connecting. The cars are intelligent enough to do it but I suppose no standards as yet.
Thanks for the info.
Alan
 

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The communications channel for AC charging on type 2 connectors is very limited, and amounts to making sure that power isn't connected until a vehicle is present, and that the vehicle doesn't try to draw more current than the maximum rating of the cable or supply.
DC chargers can show the vehicle's state of charge, but they have a much more sophisticated protocol.
 

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Discussion Starter · #5 ·
Thanks.
So, is there any point in going with a more intelligent charger when they all end up just working with schedules or unreliable app connections (which is worse when it doesn't work)?
I was wondering if I should go with something like the Ohme cause of the "intelligence" but now I'm leaning back to the zappi.
Oh well. Time to read more reviews.
 

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Connecting to the vehicle API, via the manufacturers server, is certainly possible with some cars. Doing this for a Tesla is a doddle, as the Tesla API has been reverse engineered and well documented, so it's very straightforward to use something like a Raspberry Pi to log in and do pretty much anything that the Tesla app can do, plus a great deal more. Not sure about other makes, but I'm sure some have been similarly reverse engineered, some may even have made the vehicle API public. This is the technique that some third party apps, like the one from Ohme, use to control some aspects of charging, I believe.

As above, the signalling between the car and AC charge point is very dumb, just an analogue signal to do safety checks, set current and turn the mains on and off to the charger. There's no detailed data exchange over this one wire signalling system.
 

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Before considering some potentially complicated technology, it might be worth thinking about what the next best solution might look like with just the car and a dumb charger.

Like you, I have erratic use and a time of use tariff (in my case Octopus Go Faster). My Leaf has a built in charging timer, which is set for 2030-0030 to match the cheap electricity rate. Most of the time, I wait until the car gets down to around 20% and then plug in and let the car take care of timing. Depending on exactly where the SoC is at the start, I finish with about 90-95%, which is generally fine. There is a view that limiting the number of times you charge to 100% can benefit the battery.

If I know I need to start a day with 100% and I’m already low, I can spread the charge over a couple of evenings.

Coming back from a long journey with low SoC, I just plug in and get what i can from the cheap rate.

So for me, other than deciding whether or not to plug in on a given day, the only time I would need any extra control would be if I returned home with a low SoC and needed more than I could get during the cheap period in time for the next day. To be honest, on those days, I just hit the timer override because there’s not the return on investment to make it worth having more sophisticated control.

There are enough reports on forums about trouble with smart chargers to make me glad I don’t have one. Add to that the number of reports of issues with vehicle apps and the problems that would result if the car didn’t charge at all, my conclusion is that simple is best.
 

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I have the Merc EQA and the Mercedes Me App reads the Battery state of miles and %, but has apparently NO Scheduled Charging feature!!! ... now i have Hypervolt 2.0 Alexa enabled, Plug & Charge immediately, and Scheduled Charging for one session or add multiple session, also the just passed software for Solar Charging, which is great news as I am expecting 5.320 kW PV on 15 September. Just joined Octopus and hopefully be able to change onto Go or Go Faster tariff.

PS Glad I Refused the Mercedes BP Free Charger from Merc Dealer at the time, looking back rotflmao
 

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There are enough reports on forums about trouble with smart chargers to make me glad I don’t have one. Add to that the number of reports of issues with vehicle apps and the problems that would result if the car didn’t charge at all, my conclusion is that simple is best.

I agree wholeheartedly. We have two dumb charge points, one for my car, one for my wife's, and both have time switches fitted so we have the option to charge immediately or only charge during the off-peak time slot. We almost always just leave them set to charge at night, never seems to fail and there are no issues with apps, connectivity, or whatever.
 

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My charging will be quite erratic (some days nothing and others a full charge). Which of the chargers out there can connect to the vehicles to read their battery status? I have an economy 7 tariff so would like to use the off-peak time but scheduling won't be easy as I would need to start the charge prior to the off-peak start if I'm doing a full charge, and only later during off-peak if only doing a top up. I would obviously prefer not to do a manual setup every night.
Maybe you are over complicating it.
I dont have any knowledge of the Polestar but some cars (e.g. Leaf) will make that decision itself. You simply configure the charge end time (leaving start time blank) and the car decides what time to start to ensure you hit that SoC by that end time.

So, if it needs one hour of charging or 10hrs of charging it will dynamically adjust the start time itself each day to ensure you get to 100% by the end time.

Have you checked if the Polestar can do that? Read the manual time!?
 

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End time is a really good point for the OP to look at.

The only issue is that always gives you 100%. Newer Leaf does not have the 80% option that the older ones had but the Polestar may have. For me that would mean 1) charge starts before cheap period and 2) charges higher than I need, with potential reduced life for battery. Although I’m not convinced about the latter, if you don’t need to do it, might be better not to take the risk.
 

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Discussion Starter · #12 ·
The question was purely around cost savings. I know I could schedule a full charge to be by 7 in the morning when I need it. I can also choose in the polestar at what percentage to stop. The problem is that if I only need 3 hours of charge, then it will start at 4 in the morning when the off-peak rate stops and I'm paying full price. And if I schedule all charges to start at 12 when the off-peak rate starts, then I risk not having a full charge when I need it. So, for me to make use of the energy saving I have to manually set it every night. Firstly this will become a big pain to do every night and then I know I will forget some nights resulting in an empty car the next morning. What I basically need is a logic statement built into something that says 'start charge at 12 unless I need more than 7 hours of charge, in which case start 9pm in the evening. But, oh well..... if the technology is not there yet, so be it. If it must be done manually, then it must be done. I'll probably have a schedule that starts every night at 12 and if I know I need more charge, will TRY and remember to manually start it earlier.
 

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If you set the “be ready by” time for the end of the cheap period, wouldn’t that always maximise the cheap charge by starting as late as possible but always finishing within the cheap period?

The only issue you might have is if you arrive home too late to get as much charge as you need for the next day but that hopefully that would be rare and just a case of overriding the timer.
 
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