OT: Electric Car Charger

One thing to think about is your earthing situation. Earthing is a bit complicated:

Also you need an RCD that handles DC (usually Type B, although there are others) - a good charger will have this in, but some of the socket-onna-stick ones need a separate consumer unit with one in. This is why some of the external units are quite large, to contain the PEN fault contactor and the RCD. Buying the RCDs separately can work out more expensive than a fancy smart charger.

Another thing is you may want a current transformer (CT) on your meter tails to dynamically limit your charge current. For example, somebody turns on a

The Zappi seems to be popular, and it was a wireless energy-harvesting CT arrangement that can be handy so you don't have to run a wire to the CT, it's powered directly from the induced current. Alternatively you can run some twisted pair.

Other people like Anderson for the aesthetics (but pricier).

Rolec have a bit of a bad reputation for cooking themselves (they underspecced the RCD for thermals) - not sure if the newer ones are better.

Can't really comment on the controls, but to note many cars already have controls in them so you may not need a separate wifi app/etc for the charger. I tend to be skeptical of anything with apps as they might stop working after a few years.

Theo

I think those features may need you to buy separate Harvi and/or Eddi units to use with a Zappi?

If in Cambridge, flag-down any posh-looking electrician and they'll be sure to give you chapter and verse :-)

Tethered vs untethered is a personal choice. Untethered means that any visitor can charge at your house even if their car uses a different plug. It also means that every fecking time you go to charge, you have to get your cable out of the boot/frunk and plug both ends in.

I opted for tethered and haven?t regretted it. Makes putting your car on charge much quicker and easier.

A third option is to go untethered, but secure your cable to the wall with some sort of lockable hasp and have a ?spare? charging lead in your car.

Tim

Why DC? There?s no DC involved surely?

Tim

In message snipped-for-privacy@4ax.com, Chris J Dixon snipped-for-privacy@cdixon.me.uk> writes

More On Topic than most stuff in here at the moment!

Can't help but I do have a supplementary question. My interest is in recording charge duration and user for billing purposes. Clearly systems already exist for operating commercial charging points but I wondered if this would be affordable for something small scale? My redundant farm buildings are gradually acquiring light industrial/storage tenants. Some of whom will want to charge their parked battery vehicles. As things stand, this is covered by me reading their electricity meters but limits the charge to that from a 13 amp socket.

Stray DC.

On 27/01/2022 09:37, Tim Lamb wrote: <snip>

anywhere near qualifying for the Workplace Charging Scheme?

On the assumption that my wife's future car might have a different connector, I opted for unterthered. It also looks neater. My car came with a bag in which to store the cable. Pity the wall sockets isn't lockable to keep strangers out, but I can always tune it off from inside the house.

Buy your own meter

I do believe there's quite a large DC power supply and high current load in the vicinity of the charger. If any of that were to feed back into the supply, things could be interesting...

Theo

I though the vast majority of UK/EU EVs used "type 2" connectors, with just a handful of early adopters using "type 1"?

Some of the charging point manufacturers have solutions for workplace charging etc, where either they're on a public charger network or have a local user card to activate charging/billing. I can't remember which specific manufacturers at the moment, but in the kind of £1.5k ballpark for the unit (as opposed to a regular charger which might be £700 once PEN protection is included)

Theo

Surely the DC is all after the rectifiers in the car? No DC in the wall ?charger? which really just a glorified switch with some smarts built in and earth leakage protection.

Tim

I believe a lot of the smarter chargers will meter the power delivered and there are several apps that allow charger sharing (and billing). I don?t think you would need another meter.

Tim

Pass! I'll have a look. Prolly only 2 or 3 per day.

So far, I have fitted local single phase meters for billing.

The *work place charging* scheme might work for a central location and be worth lots of brownie points with the planners:-)

Just be prepared for a "type 3".

The smart bit built into mine ia a sensor which checks the load on the 'company' fuse. If it gets near the maximum rating it shuts off the charger. I discovered this when main oven was on when I was trying to charge the car.

There's alos a WiFi connection which tells my phone how things are doing.

You would think that, but an RCD is to protect against fault conditions. You don't want a fault, for example DC leakage or induction from the car into the charger, from jamming the RCD on and preventing it from tripping. For example, suppose one of those rectifiers went leaky in the reverse direction so that DC current would flow - it would feed back into the charger and thus the supply. The RCD would then not be able to detect an imbalance in the supply caused by leakage to earth (eg somebody touching a part that had become live).

It's also why things get tricky when there are two cars parked next to each other, attached to different chargers on different supplies - you need to make sure any earth leakage is going to trip the right RCD to make things safe.

Theo