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Discussion Starter #1
I'd like to reach out to all PS enthousiasts with a background in electrical installations and car charging.

My house has a single phase 230Vx40A connection to the power grid. Here, on older parts of the grid in Belgium, it is not easy to have it upgraded to a three phase connection.
I have a background in industrial power distribution and have installed the electricity of my house myself (yep, you can do that legally in Belgium, as long as it passes certification).

My idea was to evenly distribute current over the three pins of an official Polestar 3x16A three phase charging cable. When running short of time, I could charge the car at for example 3x12A overnight, when not too many home appliances are running, at a rate of 8-9 kW. The big hairy difference from true 3-phase is that the phases are NOT shifted in 0°-120°-240° fashion, but are perfectly in sync.

Benefits of this system would be:
  • no wall-box required
  • no eye-watering bill for power grid connection upgrade to 3x230V
  • DIY installation: extra circuit breaker + CEE 3x32A connector + 5G6 cable < €100 (plus the PS cable of course, which is a bit more expensive. Of course...)

Drawbacks/hazards:
  • 3x12A=36A running over neutral connector pins & wires (yikes)
  • 0° phase shift between 3 "phases"

Questions I have are:
. I can safely compensate for the 36A on neutral in my electrical installation, but how is it handled on the PS side? Is the conversion dealt with in the cable lump, or further on in the car?
. Would not having 0°-120°-240° phase shift somehow destroy components in the cable lump or, far worse, the in-car converters?

I was thinking of dropping Polestar support an e-mail, but I think I better let them focus on real support of actual car owners out there. Better to help existing customers than a DIY-nut killing time while waiting for his delivery somewhere in February (fingers crossed).

Any thoughts?
 

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Well, one immediate issue I can see is that whilst you might be able to beef up the neutral in your supply equipment, you can do nothing about the neutral in the car. There's quite a long cable run from the charge port to the charger.

It really is not worth the hassle or risk. Just go for single phase 32A - 7.2kW. That will still fully charge the car from empty in not much more than ten hours, and how often are you going to need to do that?
 

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Discussion Starter #3
Not going to need it often, if at all, but if you have the choice at installation time, why not?
In the Belgian Polestar web shop there is no 32A-7.2kW cable option, just 1x16A = 3.7kW "blue CEE" or 3x16A = 11kW "red CEE" cables. Maybe the UK webshop offers 1x32A - 7.2 kW

Furthermore, a 6mm² cable is going to waste less power by I²R-losses than a 2.5mm² @16A. Difference may be 0.2%, but it adds up over the years. If you would be able to partition 16A over 3 phases, everything will heat up less because of even lower I²R losses. This adds up even more over the years. I'm aware I'm venturing into deep geek territory now, and I agree it is a risk not worth taking. So I propose to keep it to a "what if"-discussion, out of interest for the technical side of the story.

It's the adventurous era of electrical cars. I remember my dad having discussions with my uncles when I was a kid... "will that carburetor or this supercharger in my Ford Taunus give me 5 hp extra or not" :)
 

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Polestar will just tell you no - which is the only correct answer!

Why not install a tethered 32A charger - that way you won't even need a cable.

If you do need a cable and don't want a tethered solution, the worst possible place to get one from is Polestar anyway - they are three times the price there!

If you want a cable that will plug into a single phase 32A CEE socket, have a look at the Juice Booster range.

They work worldwide and have interchangeable input connectors:-

 

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Discussion Starter #7
"Polestar will just tell you no - which is the only correct answer!"
-> I know, that's why I'm not even considering putting this to practice.
Just checked your suggestions:
  • Tethered 32A charger: €800
  • Juice Booster 2 w/o cable > €1000
  • Polestar 1x16A cable: €350 + €40 for extra circuit breaker + €25 CEE wall socket.

Given the fact that electricity at home is stinking expensive in Belgium (27c/kWh) I think I'll go for the standard cable for keeping the car from vampire drain, and do the serious charging at public chargers (300m on foot from my house). Public charging prices are about 22c-25c/kWh around here, so there you have it.
 

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I'm with @stevelup here ... I would just install one 7kW Tethered Charger, that can monitor your incoming power supply and adjust the Amps to suit. No idea if you can get a Zappi in Belgium, but that's what I would recommend that messing about with everything you are suggesting.
 

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Discussion Starter #9
Thanks for the input!
Apparently the situation varies wildly over different countries. These are my options, I think:
  • public charger, 4 minute walk, 11kW, €1/month subscription, €0.25/kWh and going down every year
  • Wallbox in my garage €850, €0.27/kWh and rising year by year

The €850 of the Wallbox would buy me 15000km of range on public chargers :-/
There is no break-even point with these two options... so how about this:
Get the subscription, public charging and granny socket charging at home using the included cables, see what the situation is in 2 years, then re-evaluate.

Let's enjoy the ride while the Belgian three-layered government figures out a vision on electro-mobility 😉
 

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Public charger seems a winner as long as you aren't caught sort with someone taking the slot when you need it.

I have to say I'm intrigued to know the answer to whether you can split the charging to the 3rd pin. As far as I know it takes a single phase and splits them over 2 of its inboard chargers as each one is only good for 16 amps anyway. So I can't see why doing it on the 3rd charger would matter. Educated guess is that each charger works independently to transform and rectify the incoming charge so it is the same output. My only concern would be introducing a loop somehow. We'll that and ruining your car dicking about with stuff.

If you only do 12 amps each phase you are so close to 1 phase at 32 amps it isn't worth the bother.
 

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I have to say I'm intrigued to know the answer to whether you can split the charging to the 3rd pin. As far as I know it takes a single phase and splits them over 2 of its inboard chargers as each one is only good for 16 amps anyway. So I can't see why doing it on the 3rd charger would matter. Educated guess is that each charger works independently to transform and rectify the incoming charge so it is the same output. My only concern would be introducing a loop somehow. We'll that and ruining your car dicking about with stuff.
Exactly! My hunch tells me it would work, but my brain's left hemisphere is telling me that even a rudimentary risk analysis shows that it's not worth experimenting on your car.
 
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Won’t work three phase means the voltages are out of phase to each other and three phase gives a voltage of 415 v. The charger will sense this and all your likely to do is blow it up.
 

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Discussion Starter #13
Won’t work three phase means the voltages are out of phase to each other and three phase gives a voltage of 415 v. The charger will sense this and all your likely to do is blow it up.
That’s if you assume there is a physical, analog three phase transformer in there. You know, for 11kW that means a monstruously heavy metal box with coils inside. Even diesel-electric trains haven't been using them for the last 30 years. Most likely, it uses three full wave rectifiers (diode bridges).
Anyway, if there is no simple way for a low-cost solution or there is no precedent, it's too risky and I'll drop it
 

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The car definitely doesn't care about whether the supply is single or three phase - like every car except the Zoe it has three single phase chargers on board.

The issue is purely the neutral current, and the car is designed with a maximum of 32A there.

Just buy a second hand 32A EVSE? You should be able to find one for a few hundred euros. Anything else is madness.
 

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Won’t work three phase means the voltages are out of phase to each other and three phase gives a voltage of 415 v. The charger will sense this and all your likely to do is blow it up.
I thought it would take advantage of 3 phase but it appears it uses each single phase @ 16 amp for each inboard charger.

I imagine the advantage is that it is much easier as you don't have to monitor unbalanced voltages and frequencues and all sorts of other issues you get with phase to phase power. That and you can use a single rectifier for single and 3 phases otherwise it would need to switch depending on the incoming supply. (Laziness if you ask me).


Not sure if it holds true about the neutral capped at 32 amps as it would still only be 16 for each charger returning to 0v return. but there is a danger if you get a leak it will affect the neutral line (probably result in a 0v potential difference but your rcd should catch that).

Not even sure it would do physical damage, I'd be more worried about software trips as they could be far more menacing than replacing a fuse.
 

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It's not that easy...

The charger uses 3*[email protected]
Due to the 120° phase shift between the phases, you can not simply connect the phases in parallel. Each phase has to be rectified individually. Only when charging single phase, the rectifiers can be connected on parallel to the power line.

When using 3P in a star configuration, there is actually no* current running over the neutral wire due to the 120/240° phase shift.

The neutral wire is only needed*, when charging single phase.

* simplified
 

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Only when charging single phase, the rectifiers can be connected on parallel to the power line.
This was the original exam question - can you connect a single phase to all 3 chargers in the car.

Sorry my previous post had a couple of errors making it confusing.
 
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