Dual EV charging

[nothanks]

SWMBO wants to change her ageing car and is thinking of getting an EV (Soul, e-Niro, ZS, etcetera) so I'm wondering what to do about charging. The other car is a PHEV so I installed a Rolec pod to charge that when we moved here. The house is at the end of a pair of overhead wet strings so there's no realistic prospect of 3ph and we're therefore stuck (I believe) with a max of 7kw. If we get an EV I will either need to move cars around to use the pod, get a second pod and a means of switching or load sharing, or fork-out for a dedicated dual EV charger. What have others done, or what do our tame pro-sparks recommend?

[SteveW]

We have an Easee charger (not yet used, as the car won't be delivered until March). According to the blurb, you can simply daisychain a number of these together, designate a preferred charger and they will automatically switch over when the primary vehicle is charged.

[Colin Bignell]

I would get a dedicated diesel generator :-)

[The Natural Philosopher]

I would get a diesel car

[Jeff Gaines]

I think the compromise is to tow a diesel generator behind you so you don't run out of juice :-)

[Theo]

Charging of multiple cars is usually no problem. The chargers can load balance between them, watching the incoming current so the demand never exceeds the supply (including any loads in the house like electric showers). You plug them both in and the chargers sort it out - maybe one has priority, or they both charge more slowly.

How you want to arrange it is up to you, but the actually EVSE itself is fairly simple: you're wiring both cars to the same supply point, and it needs just a little bit of electronics to tell each car how much current to take.

I'm not sure what the best product for this is, but I'd have thought some judicious positioning of the current transformers would enable you to wire a single supply point with two standard chargers, one taking priority over the other. The second one just sees the first as another load in the house and defers to it.

Some of them have open firmware (a Raspberry Pi or similar inside) and it might be easier to add to those than the ones where they decide you are a 'commercial' site and need to pay for that. I think once you have all the circuit protection (type B RCD; PEN fault protection), adding a second EVSE is actually not that much extra.

Theo

[nothanks]

The Rolec Pod that I have now is fairly dumb (an RCBO, a magic box to detect the car and negotiate the charge rate, and a contactor) and I don't want to bu&&er about with current transformers and designing "smarts". If we *do* get the second EV I may just put-together a duplicate "Pod" and switch between the two using a timer to control the contactors.

[Chris J Dixon]

You may find that the rules have moved on, and any new chargepoint installed will have to be smart.

Chris

[Tim+]

Dunno if it’s any use to you, but it’s very easy to add a small Wi-Fi relay to start and stop charging. It only needs to interrupt the pilot wire that lets the charger know that the car is plugged in so it’s handling minimal current.

Tim

[nothanks]

Thanks! I'd completely forgotten about those wi-fi relays, so that's saved me a chunk of research. The only problem now is guiding SWMBO towards making the right choice - TBH, *any* choice would be good at the moment ;-)

[nothanks]

This will be a DIY job so not a problem, and Tim+ has just pointed me towards a very useful YouTube vid.