[Mark I]

There is a fairly simple device, in use for about 100 years, to convert 3-phase AC power into 1-phase. It is a suitably rewired 3-phase induction motor, spinning at full speed but not under mechanical load.

To add one of these to a charging cable woud be perfectly feasible, but would have a 4-figure cost and would need to be fitted to a trolley or wheelbarrow. I'd expect it to weigh 50 kg to 100 kg. [That's not a design, nor a detailed estimate... but the 2.2 kW induction motor in my garden shredder weighs about 25 kg, and you'd need something much bigger to handle 11 or 22 kW.]

 

[BurningNaturalGas]

There is a fairly simple device, in use for about 100 years, to convert 3-phase AC power into 1-phase. It is a suitably rewired 3-phase induction motor, spinning at full speed but not under mechanical load.

To add one of these to a charging cable woud be perfectly feasible, but would have a 4-figure cost and would need to be fitted to a trolley or wheelbarrow. I'd expect it to weigh 50 kg to 100 kg. [That's not a design, nor a detailed estimate... but the 2.2 kW induction motor in my garden shredder weighs about 25 kg, and you'd need something much bigger to handle 11 or 22 kW.]

Why does the load across wires need to be balanced; why can't the heat or other side effect not be tolerated? How much inconsistency are we talking about on these unbalanced German wires?

Furthermore, as you have argued convincingly that it is so much simpler to convert 3 phase AC to single phase DC, why did the EU re-engineer EVs to each contain a complex mix of multiple AC chargers instead of simply adopting a pre-existing (and foreign) DC charging standard like CHAdeMO? Does the EU suffer from a "not invented here" mentality?

 

[Mark I]

Why does the load across wires need to be balanced; why can't the heat or other side effect not be tolerated? How much inconsistency are we talking about on these unbalanced German wires?

If a three-phase load is not balanced, so that current flows through the neutral wire, you get less power out of it. To take an extreme example, connect a Type 1 plug between L1 and N, leaving L2 and L3 unconnected... unbalanced, only 1/3 the possible maximum power. The clever thing about 3-phase is that it is a way of getting any combination of loads up to 3 x what you could do with 2 wires, but using only 4 wires of the same thickness carrying the same maximum current. In both cases, plus a protective earth when appropriate.

Furthermore, as you have argued convincingly that it is so much simpler to convert 3 phase AC to single phase DC, why did the EU re-engineer EVs to each contain a complex mix of multiple AC chargers instead of simply adopting a pre-existing (and foreign) DC charging standard like CHAdeMO? Does the EU suffer from a "not invented here" mentality?

This isn't a German plot, and when the EU was agreeing the standard, that negotiation included significant input from the UK (we used to be an important part of the EU, for a brief 40-ish years, until we left that club). Having taken our nice new(ish) EV to France and Ireland last year, I'm very glad the charging connectors are compatible.

And we don't specify just a DC charging standard because it would make home and destination-type fast charging installations prohibitively expensive. The point of providing AC charging is to make charge points feasible anywhere there is mains power: industrial estates or farms with lots of 3-phase, more than half of homes with 1-phase, lots of homes but especially Spain, France and Germany with low-current 3-phase. All can have charge points with the same socket and these then work with practically any plug-in car on the roads. A CHAdeMO home charger would cost a fair bit more than a mere EVSE charge point.

Multiple small chargers is more energy efficient than a single high-power charger. (Each AC-DC converter has a more or less constant rate of power wasted as heat. It runs at its best efficiency when fully loaded. By switching in only as many converters as needed, the wasted power is less than running one high-power converter at a fraction of its maximum.)

It's time I stopped letting other posters here wind me up. I'll try not to take the bait next time.

 

[BurningNaturalGas]

… we don't specify just a DC charging standard because it would make home and destination-type fast charging installations prohibitively expensive.

By that logic prescribing that each car has three AC to DC converters (instead of one) makes the cars prohibitely expensive instead.

Taking the point to its extreme, stripping all the AC gubbins out of the cars would be making EVs cheaper, making them lighter for longer range, and prescribing them faster DC charging everywhere for greater convenience versus your next point:

The point of providing AC charging is to make charge points feasible anywhere there is mains power…

So you agree it is bonkers for a UK local authority to tether a Type 2 plug to an AC charger and prevent about 120,000 UK cars from plugging in?

A CHAdeMO home charger would cost a fair bit more than a mere EVSE…

As above, it’s a shifting the cost from the charge point to the car (an EVSE and 3x AC to DC converters), not saving money.

Multiple small chargers is more energy efficient than a single high-power charger.

Possibly, but I see a few glitches with the philosophy.

As you highlighted, two of the three chargers in Type 2 cars are not activated when those cars are charging in UK, USA or Japan. Is it efficient to manufacture and carry things that are never used? How many millions of units are dead weight are we talking about?

Sharing is more efficient. The collective of AC to DC converters are in other peoples cars so not shared, unlike public DC chargers that are shared.

Your point about overcapacity at home is a moot point because home DC chargers would vary in power and would be matched to the cars in the household, in same way as home AC chargers currently are.

 

[Spiny]

DC Granny charger (26kg) needs a 32A CEEE (commando) socket to plug into.

7KW Portable DC Charger With Ccs Combo 1 Connector | Accraine Ltd

accraine.co.uk

Me I'll carry my emergency granny charger - its a bit lighter and can connect to a standard 3pin UK socket.

 

[Cptn_penguin]

As you highlighted, two of the three chargers in Type 2 cars are not activated when those cars are charging in UK, USA or Japan. Is it efficient to manufacture and carry things that are never used? How many millions of units are dead weight are we talking about?

This, again, is just not true. It seems you're just trolling at this point, but the multiple AC chargers in a Type-2 equipped car are run together when the car is fed a single phase load. If they are all fed L1 they can run together in parallel easily. If they are fed 3ph then they just run the outputs on DC together since the phases are not compatible. Cars that only have single phase sockets wired up just have a pair of these chargers that are always wired together. This lowers costs significantly since you only need one part (repeated) to make a number of different charging combinations. It also means you have more flexibility with the packaging of the electronics since the multiple single phase units can be split up and moved apart. For example, one under each seat, or side by side on top of the motor in the engine bay.

As to why we adopted CCS instead of Chademo? One, the Chademo port is a dead end - it has a maximum current rating that limits charging to 100 kW on DC rapid, which is already and it also means you need a whole separate connector for DC charging instead of a hybrid single connector that can accept an AC-only Type 2 plug or the combo CCS plug.

This lowers costs and parts and the space required to fit the ports.

If we're talking about "carrying things that are never used" I'll take the Chademo port on 95% of Leafs for £200 please Alex.

 

[BurningNaturalGas]

This, again, is just not true. It seems you're just trolling at this point, but the multiple AC chargers in a Type-2 equipped car are run together when the car is fed a single phase load. If they are all fed L1 they can run together in parallel easily. If they are fed 3ph then they just run the outputs on DC together since the phases are not compatible. Cars that only have single phase sockets wired up just have a pair of these chargers that are always wired together. This lowers costs significantly since you only need one part (repeated) to make a number of different charging combinations. It also means you have more flexibility with the packaging of the electronics since the multiple single phase units can be split up and moved apart. For example, one under each seat, or side by side on top of the motor in the engine bay.

As to why we adopted CCS instead of Chademo? One, the Chademo port is a dead end - it has a maximum current rating that limits charging to 100 kW on DC rapid, which is already and it also means you need a whole separate connector for DC charging instead of a hybrid single connector that can accept an AC-only Type 2 plug or the combo CCS plug.

This lowers costs and parts and the space required to fit the ports.

If we're talking about "carrying things that are never used" I'll take the Chademo port on 95% of Leafs for £200 please Alex.

There is no objective reason why the benefits you cite need to be in the car instead of outside the car. All the same volume savings could have been achieved in public chargers, although if the EU had done that then we would have too many public chargers by now..

As a point of interest, can you name any non-EU standard that was adopted by the EU as a standard, for any industry?

 

[BurningNaturalGas]

DC Granny charger (26kg) needs a 32A CEEE (commando) socket to plug into.

7KW Portable DC Charger With Ccs Combo 1 Connector | Accraine Ltd

accraine.co.uk

Me I'll carry my emergency granny charger - its a bit lighter and can connect to a standard 3pin UK socket.

Sure, but with economies of scale, how much would one such granny cost if every car supported only DC charging? Put another way, is there anything in that rare box that does not already exist in the wider technology stacks of cars and chargers?

 

[Spiny]

Its 26kg, I struggle now with a 10 kilo sack of rice... as to the requirement for a 32amp cee socket.
The unit will contain I guess 3 off 3.6kW chargers as its 1 and 3 phase and the 3.6 units are relatively cheap. Then the associated cooling requirements and the communications to allow it to communicate with the car BMS.
A fixed unit will cost more to install than an ac unit as it must cover the current regulations and any requirement needed for hi voltage DC which is nasty stuff imo.

 

[BurningNaturalGas]

Its 26kg, I struggle now with a 10 kilo sack of rice

Ok, I get the feeling I might actually one day lose a debate!

You highlight it is a big lump, but consider the use case: Most people don't physically lift their EVSE and we do not see EVSEs being used in public. My EVSE does not move: It stays plugged in at home all the time. I assume most EVSEs stay in the boot of a car, probably still in their original packaging. My point is that EVSEs are rarely used as intended (as portable things) and in my experience it would not really matter if was 1kg or 10kg or 20kg. I move big bags of rice and sacks of dog food much more often than I move the EVSE, and they are all annoying but equally moving those things is an unavoidable part of life. Besides, all the EVSEs I have seen are 3kWh - how much would a 7kWh AC EVSE weigh?

A fixed unit will cost more to install than an ac unit as it must cover the current regulations and any requirement needed for hi voltage DC which is nasty stuff imo.

The installation in public bays is unavoidable because drivers want DC more than AC. Today most bays have both AC (for compatibility) and DC (for performance).

Today's common home AC installations need to be done by specialists, often meddling with concrete for physical supports and extra earthing, followed by a certificate sign-off that prevents it being a DIY job! Setting aside the cost of the units (as we have other posts focussing on that detail), how much extra effort is needed for a DC installation?

 

[Simon..Hewison]

Today's common home AC installations need to be done by specialists, often meddling with concrete for physical supports and extra earthing, followed by a certificate sign-off that prevents it being a DIY job! Setting aside the cost of the units (as we have other posts focussing on that detail), how much extra effort is needed for a DC installation?

Extra effort? Aside from the fact that DC off-board chargers are an order of magnitude more complicated than AC charge points, and as such are heavier, bulkier and more expensive to purchase, the installation costs are pretty much the same. They still will need to be connected to a suitably earthed, suitably protected, AC power supply, and fastened securely in place.
Because they are bulkier things, especially for higher-power DC charging, the units may need to be free-standing (hence, concrete plinths and ducting etc) rather than wall, or pole-mounting, and if you're going for higher-power, then of course, the supply to the site may need to be reinforced, which makes them a lot more work and expense to install.
For an idea of the complexity of DC charging, compare the Indra Technolgies V2G home charge point with their regular AC charging Smart Pro home charge point. For a start, the V2G unit doen't have a list price on their web site, and secondly, it's a much bigger unit.

 

[BurningNaturalGas]

the installation costs are pretty much the same.

That is what I thought.

... the fact that DC off-board chargers are an order of magnitude more complicated than AC charge points, and as such are heavier, bulkier and more expensive to purchase ...

Surely you purchase all the same gubbins with your EV, so moving them to an external charger would reduce the EV costs and not increase overall costs - it just moves the costs from a car purchase to a charger purchase. Savings include sharing the chargers (in the case of public charging) and not having AC chargers at all.

... compare the Indra Technolgies V2G home charge point with their regular AC charging Smart Pro home charge point. For a start, the V2G unit doen't have a list price on their web site, and secondly, it's a much bigger unit.

You're highlighting the potential of spending extra to extend DC charging to doing things that AC chargers simply cannot; pros without cons.

 

[Rbrian]

Maybe they use the granny cable that came with the car, or perhaps they have a tethered charger at home.
If you have a PHEV and mostly charge at home then paying £100 for occasional use of public chargers doesn't make much sense.


They've also blocked a load of parking spaces from use by the 80%? of Oxfordshire drivers that don't have a plugin car. I don't think there's any intention to benefit everyone.

The tradeoff is that by making it unusable for 6% of plug-in drivers you make it more convenient for everyone else and accessible to people who can't use untethered at all (including those with mobility issues where tethered is significantly easier to use).

That 6% is only going to drop in future, there will be no new plugins that can't use the tethered chargers. The Oxfordshire council chargers are looking to the future: they are intended to make it possible for people to buy an EV when they have no option to charge at home. They're looking to benefit people who currently don't have an EV but could get one in future.

Another good reason to have tethered chargers is that many cars - for example, my new Corsa, and my Vivaro - have no good place to store the cable. It sits on the cab floor in my van, and takes up quite a lot of space in my Corsa's petite boot.

 

[BurningNaturalGas]

Another good reason to have tethered chargers is that many cars - for example, my new Corsa, and my Vivaro - have no good place to store the cable. It sits on the cab floor in my van, and takes up quite a lot of space in my Corsa's petite boot.

Out of curiosity, is there space to mount a coiled cable under the bonnet?

 

[Rbrian]

Out of curiosity, is there space to mount a coiled cable under the bonnet?

I haven't looked under the Corsa bonnet yet, I was working all day and it's dark. I did look under the Vivaro bonnet, and there's loads of room for a froot box. It's a company vehicle though, so I'm not allowed to modify it. I wouldn't want to just put the bag there, in case it fell off, or overheated. I have no idea how hot the electronics get, presumably cooler than a combustion engine which literally has fire inside, but it may still be warm enough to melt nylon.

 

[BurningNaturalGas]

I haven't looked under the Corsa bonnet yet, I was working all day and it's dark. I did look under the Vivaro bonnet, and there's loads of room for a froot box. It's a company vehicle though, so I'm not allowed to modify it. I wouldn't want to just put the bag there, in case it fell off, or overheated. I have no idea how hot the electronics get, presumably cooler than a combustion engine which literally has fire inside, but it may still be warm enough to melt nylon.

It occurred to me there is probably a significant gap between any cars power plant (shaped by utility) and any cars bonnet (shaped by aesthetics). Also, I think NCAP mandates a gap so that the bonnet buckles in the event of a pedestrian's head landing on it.

Might it be sensible for EV car makers to add a pair of clips to fasten EV cable/plug/socket under bonnets?

I did some wibbling with search results suggesting there is no overlap in critical temperatures: Nylon (perhaps used for bags) melts at 268°C. Silicone (perhaps used on the dust caps) melts at 1414°C. In contrast, the electrolyte in EV batteries has a maximum operating temperature below 60°C, and the fan behind the grill of PHEV starts when the coolant reaches about 100°C. (Source: various sites where writers claimed to know technical stuff about cars).

Edit: This might not apply to all cars, but one might need gloves to take out of heated charging cable

 

[Rbrian]

It occurred to me there is probably a significant gap between any cars power plant (shaped by utility) and any cars bonnet (shaped by aesthetics). Also, I think NCAP mandates a gap so that the bonnet buckles in the event of a pedestrian's head landing on it.

Might it be sensible for EV car makers to add a pair of clips to fasten EV cable/plug/socket under bonnets?

I did some wibbling with search results suggesting there is no overlap in critical temperatures: Nylon (perhaps used for bags) melts at 268°C. Silicone (perhaps used on the dust caps) melts at 1414°C. In contrast, the electrolyte in EV batteries has a maximum operating temperature below 60°C, and the fan behind the grill of PHEV starts when the coolant reaches about 100°C. (Source: various sites where writers claimed to know technical stuff about cars).

Thanks, I'll have a look under the Corsa bonnet tomorrow. The cable is surprisingly heavy - I haven't looked at it, just stuffed it in the bag, but it's probably a 32A 3 phase so I can get 7kw on single phase and 11kw on 3 phase. I'm not sure that could be clipped to the bonnet, but perhaps in the van? I'm off work next week, so I could investigate, but instead of resting, I've planned plenty of work - replacing 23x MR16 incandescent spotlights with GU10 LEDs in a friend's flat, which has a fair chance of needing a full rewire, and replacing external lights on another friend's house.

 

[artyman]

Temperature wise you could certainly store a cable in the 'engine' bay, a couple of bungy cords if you don't want to fix a froot box.

 

[Cptn_penguin]

Surely you purchase all the same gubbins with your EV, so moving them to an external charger would reduce the EV costs and not increase overall costs - it just moves the costs from a car purchase to a charger purchase. Savings include sharing the chargers (in the case of public charging) and not having AC chargers at all.

DC charging is not the same as AC charging.

External high power DC chargers are expensive, heavy, large, internally very hazardous even more so than exposed 240 V live terminals, less efficient and loud. Just what you want on the side of your house.

Offloading the AC charger, which is not the same device, from the car into the EVSE would make them more expensive, then you would still need to feed DC to the pack, plus you'd need the AC charger duplicated at every single EVSE. You'd also have to be careful about which cars were allowed to charge on it since the pack might be incompatible with the charger.

AC EVSEs are effectively a monitored and managed connection to an AC supply. They are simple, relatively robust devices which makes them cost effective to build and supply with power.

A DC off board charger is nothing like that.

Still, if you want to make your three phase to single phase adapter by combining L1, L2 and L3 into one wire then don't let me stop you.

 

[Cptn_penguin]

Thanks, I'll have a look under the Corsa bonnet tomorrow. The cable is surprisingly heavy - I haven't looked at it, just stuffed it in the bag, but it's probably a 32A 3 phase so I can get 7kw on single phase and 11kw on 3 phase. I'm not sure that could be clipped to the bonnet, but perhaps in the van? I'm off work next week, so I could investigate, but instead of resting, I've planned plenty of work - replacing 23x MR16 incandescent spotlights with GU10 LEDs in a friend's flat, which has a fair chance of needing a full rewire, and replacing external lights on another friend's house.

If it's the same engine bay layout as the e208, which seems likely, then there will be physical room under there but I wouldn't want to leave the cable there when driving. If you can get 11 kW then you definitely have the 3ph cable. I always thought it was a bit odd that Peugeot made the 3ph on board optional while it was standard on the Corsa. You think they'd have kept those the same.

The inverter and charger assembly is under the plastic cover mounted on top of the motor assembly near the DCC converter.