Home charger cost effective or not?

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Mark55
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Post by Mark55 »

Hi I am looking to get a home charger installed for when our ID.3 Max Pro arrives next year sometime.

I do around 8,000 miles a year, if the ID.3 returns 3 miles per KWh on average then the car will need about 2,666 KWh of electric going in to its battery per year.

Which is about 51 KWh a week or 7KWh a night. A 3 pin plug lead will charge at around 2KWh so 7 hours (economy 7) will give me more than sufficient electricity in to the cars battery.

If I also have to pay, say £500 for the charger and install, that £500 would buy £500 / .08p = 6,250 KWh that's around 18,000 miles.

Am I missing something or is my maths that bad?
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nkajkmuk
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Post by nkajkmuk »

If only everyone had such a structured lifestyle. Yes if charging on a 13 amp socket every night fits the lifestyle requirements then a wall charger is redundant.

But many will find not having a wall charger very limiting and almost a chore everyday and would like to have a more convenient alternative and your math is just missing that ‘cost of convenience’ 😃
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Utumno
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Post by Utumno »

Look at it the other way - You can put 14kW each Economy 7 overnight cycle into the battery (2kW/h for 7 hours = 14kW). At 3m/kWh efficiency that's 42 miles a day. The slightest "longer" journey will then dent that, and you can't put energy back into the car any faster than you can with the granny without dipping into much more expensive kW at non E7 times, or on public chargers. In effect if you do a long-ish round trip, you'll need to not use the EV for several nights to allow the E7 to catch up.

Conversely a wall charger can put ~51kW into the battery in a single E7 charge. This means you can probably completely forget about any kind of range anxiety, because your vehicle will always be capable of what is basically a full charge each and every night at 8p/kWh. So you're paying for convenience at 8k/year approx...and don't forget you'll have to spend £200 on buying the Granny charger in the first place which you almost certainly won't need with a home wall charger.

Of course only you can decide, but I opted for the wall charger because life's too damn short to worry about charge in the car and stringing a granny cable to and from the car each night for me :-)
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Post by Deleted User 192 »

If you fancy the equivalent of running a kettle through your regular house wiring for an average of 3.5 hours every night, go ahead.

I was always going to get a proper charger installed, even though I already had a regular 13-amp socket within range to use a granny lead, and my house is less than 4 years old.

The charger has it’s own RCD in the consumer unit.
Smitten
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Post by Smitten »

There will also be times when you want to do a quick top up at home without paying for a public fast charge somewhere. This has happened to me a few times. Battery at 30% but I suddenly need to do a 100 mile unplanned trip that day. Couple of hours on a 7kWh charger at home can give you a very useful range boost and much cheaper than public charger. Its convenience for me but nothing wrong with your maths.

I also prefer the electrical load to be on a dedicated circuit with its own RCD protection/earthing. Charging a car on a granny cable 7 hours a night every night for months is a bit like leaving a kettle boiling or a toaster going overnight, every night. Its a lot of load going through a 3 pin socket. I think a granny cable is really intended for temporary charging rather than permanent.
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G43FAN

Post by G43FAN »

Utumno wrote: Fri Oct 15, 2021 4:32 pm Look at it the other way - You can put 14kW each Economy 7 overnight cycle into the battery (2kW/h for 7 hours = 14kW). At 3m/kWh efficiency that's 42 miles a day. The slightest "longer" journey will then dent that, and you can't put energy back into the car any faster than you can with the granny without dipping into much more expensive kW at non E7 times, or on public chargers. In effect if you do a long-ish round trip, you'll need to not use the EV for several nights to allow the E7 to catch up.

Conversely a wall charger can put ~51kW into the battery in a single E7 charge. This means you can probably completely forget about any kind of range anxiety, because your vehicle will always be capable of what is basically a full charge each and every night at 8p/kWh. So you're paying for convenience at 8k/year approx...and don't forget you'll have to spend £200 on buying the Granny charger in the first place which you almost certainly won't need with a home wall charger.

Of course only you can decide, but I opted for the wall charger because life's too damn short to worry about charge in the car and stringing a granny cable to and from the car each night for me :-)
This and future proofing (maybe there will never be a need but who can say) and you do need to consider that charging isn't lossless. so you'll consume more than 2666kW recharging.
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Mark55
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Post by Mark55 »

If I need to top up quickly I have a Tesco store less than a mile away, they have 7 and 11 KW (22KW) chargers, free at the present time. Plus a 50KWh at 28p a KWh. Plus a Lidl store with 43KW at 26p per KWh.
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Cherry
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Post by Cherry »

Calculate your payback time and then the cost of maintenance or repairs to the charger.

It may not be cost effective compared to using free and paid for chargers.

It is about convenience.
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G43FAN

Post by G43FAN »

How is driving to a supermarket car park or similar sitting around waiting for the car to charge, more 'convenient' than plugging it in at home and sitting in your favourite armchair?
Cherry
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Post by Cherry »

G43FAN wrote: Fri Oct 15, 2021 6:16 pm How is driving to a supermarket car park or similar sitting around waiting for the car to charge, more 'convenient' than plugging it in at home and sitting in your favourite armchair?
It is not. This is why a home charger is about convenience and not is always cost effective.

Freeloader friends will want to charge too!
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Utumno
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Post by Utumno »

Mark55 wrote: Fri Oct 15, 2021 5:49 pm If I need to top up quickly I have a Tesco store less than a mile away, they have 7 and 11 KW (22KW) chargers, free at the present time. Plus a 50KWh at 28p a KWh. Plus a Lidl store with 43KW at 26p per KWh.

Whatever works for you 😀
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monkeyhanger
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Post by monkeyhanger »

Maintenance costs? It's not a condensing boiler - it doesn't need maintaining. It needs fixing if it breaks and most come with a 3 year warranty.

I'd rather do 4 hours on my 7.4kWh charger twice a week at 5p per kWh than mess on charging at Tesco for an hour a night, every night, if the chargers are free/unoccupied. Or charging every night on a granny cable - slowly burning out my plug socket.

Convenient and cost effective.

As for freeloading friends...grow a pair and tell them its not on to be sapping your peak rate electricity for hours at a time.
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sidehaas
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Post by sidehaas »

A slightly different perspective - rather than calculating a rate of return for the charger over the next year or two, I saw it as an investment for the future. I expect to be in my house for 20 years and I don't expect to buy another ICE, so I sure will want a charger at some point. It just made sense to get it now, even if I don't earn the cost back in the time I own the ID.3 (although I'm hoping that'll be a long time.) I expect that in ten years time, anyone buying a house with a driveway will want a charge point; it'll just be the norm.
Of course the charger could fail but it's not that complex and seems well made, so it could equally last many years.
I don't know if this applies to you, but it's worth thinking about.
A secondary consideration was that I didn't really want to be plugging it in to a standard socket the whole time for safety reasons.
And also the convenience factor that others have mentioned - why spend £30k on a car and then be inconvenienced for the sake of £600.
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Post by Deleted User 192 »

Mark55 wrote: Fri Oct 15, 2021 5:49 pm If I need to top up quickly I have a Tesco store less than a mile away, they have 7 and 11 KW (22KW) chargers, free at the present time. Plus a 50KWh at 28p a KWh. Plus a Lidl store with 43KW at 26p per KWh.
The free Tesco chargers are for customers while they’re doing their shopping, not for those without proper home chargers to get a free boost.
MotMot
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Post by MotMot »

It’s an interesting argument whether a home charger is worth it. Much depends how much the electricity costs you at home.

With octopus go it’s probably a no brainier cost wise after a year or two. But if that tarrif disappears then it’s a very different proposition.

Let’s say your elect costs 17p kWh at home vs 27p at Lidl. 10 p difference. £600 for a home install (could be a wee bit less but may be more). 600 / 0.1 = 6000kwh. Assume generously you get 4 miles/kWh then that’s 24000 miles of motoring… before the charger has paid for itself.

I doubt many smart chargers will last more than five years (companies will fold, old versions will not be supported) though may well work as a dumb charger for longer.

If you can get a good chunk of your chargers for free (Tesco / or at work) then the equation skews away from the home charger more… if you do 10k miles per year and can get half of your juice for free then it’ll take 5 years ish to recoup your chargers price.

Changes in electricity price at home or for public charging of course change all this again.

Of course having a home charger gives you the flexibility to do either… I have one - but if I had an EV on say a 2-3 year lease and did 10k a year I might not bother.
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Post by BeesKnees »

Home charger is a winner on convenience and safety alone.

Plus it's an investment in your home for the future.
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Cherry
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Post by Cherry »

Has anyone got any advice (pros and cons) of Ohme Home Pro EV?

2G/3G/4G multinet sim card – cost covered by Ohme for the first 3 years.
What happens after 3 years.

Any recommendations for a smart tethered home charger (no solar panels) which does not require a sim card?
Last edited by Cherry on Fri Oct 15, 2021 9:46 pm, edited 1 time in total.
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Utumno
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Post by Utumno »

I also looked at it as savings in the first year coming from ICE.

My ICE Focus cost about £2000 a year in fuel. For the equivalent BEV mileage at 3m/kW delivered at 5p/kWh, that’s about £200. The charger then “breaks even” in the first few months of use in fuel savings alone versus the ongoing cost of an ICE, paid for mostly by Octopus Go 😂 After that, it’s convenience and gravy all the way.

I do appreciate not everyone will see it this way, it makes less and less sense the fewer miles you do, and you may already have factored your fuel savings into higher finance costs for a BEV as well.
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Post by Warminster id »

I must be the only one on this forum that doesn’t have a home charger and have no possibility of installing one. I live in a small flat.
So public chargers all the time for me, you soon get used to the inconvenience of parking at the chargers and walking home for a cuppa or dinner, for my usual commute I only pay £7.85 pm and charge 6 times a month at around 30-35 kw per charge.
I will leave the math to you
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monkeyhanger
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Post by monkeyhanger »

BeesKnees wrote: Fri Oct 15, 2021 9:03 pm Home charger is a winner on convenience and safety alone.

Plus it's an investment in your home for the future.
Exactly this. People with an EV, but without a charger when they have the facilities to install one at home must be serious tight-arses. Even at standard electricity rates and mileages, they'll pay for themselves within 3 years vs 30p per kWh charging publicly. Get on Octopus GO ir similar and it's paid for itself in a year.

If you choose to charge your car on a daily basis at Tescos or wherever rather than install a charger (if you can), you'd make Ebeneezer Scrooge look like an amateur money saver.

It's a pretty sad state of affairs when people put no value on their time and would inconvenience themselves by an hour daily for a £2 saving.

I'd expect a smart charger to last at least 10 years on average - there's not a lot to them, no moving parts, and they're weatherproof.

The Ohme charger only commits to giving you 3 years SIM access for smart tariffs, but it would be commercial suicide for them to stop it after 3 or charge more than a token £10 or £20 per year continued subscription.

I'm very happy with my Ohme right now.
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