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Question of the Day: What is your preferred luxury car brand?
Sign up with Google13 exciting electric cars coming to SA next year — and what they will cost
- Thread starter Bradley Prior
- Start date
Yes. It would be nice to have future technology. You stop. Fill up and go. And this future technology will make cars much cheaper.
Oh wait. We have it now. It is called petrol.
Yes. It would be nice to have a future technology that doesn’t go up in price every other month. Charge up and go. And this technology will make running costs of cars much cheaper.
Oh wait. We have it now. It is called electricity.
itareanlnotani
Executive Member
Reposting this again to stop all those dumb ****ing - but... Eskom, loadshedding, can't charge an electric car bla bla posts.
Was a forum post, but I have added a few things
Was a forum post, but I have added a few things
Why would the government do that? They get tax money from fossil fuels. They have no reason to want to encourage the use of electric cars.
Good post. But please fix the kW/h stuff. It makes no sense.
kW is a rate like km/h or like l/h…electricity is special and you don’t have the ‘/something’ you have for everything else. ..you can’t say km/h/h because it makes no sense….that’s what you would be saying with kW/h.
What you mean is kWh/h…or better yet just use kW. From fractions we know that you can cancel out the hours.
A kWh is a unit of energy like liters. Think of kW of the flow of water and kWh a filled swimming pool.
Using your example with the 20A plug.
230 V * 20A * 1h = 4600 VAh = 4600 Wh = 4.6kWh
But you probably should not be running that plug at 20A continuous rather 16A
230V * 16A * 1h = 3680 VAh = 3680Wh = 3.68kWh.
The duck curve is also mainly due to people cooking food and/or heating/cooling their home and not due to solar or load shedding. Once they leave home or go to bed the demand drops.
Thanks again for posting - it goes a long way to simplify and to clarify things for skeptics.
Ϲhristopher
Senior Member
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Already pointed out above, but statements like the following make no sense: 20KWhr / 100KM
I'm probably being a douche, but 20kWh / 100km would be correct.
Electrical units
I'm probably being a douche, but 20kWh / 100km would be correct.
Electrical units
itareanlnotani
Executive Member
The 20A I have as down as a 3kw draw specifically due to that, so thats already taken into account. I'll update to mention that explicitly though.
@christopher
kw is an instantaneous power level.
A car engine might draw 10kw from start then go to use 5kw when moving.
KW/hr or KWh (both are valid use) is a rating of energy used over (for an assumed time span). KW/hr's are a common measure of energy.
eg 1KW/hr would be equivalent to the same energy as running a 1KW item for an hour, or a 2KW item for 30minutes, or a 4KW item for 15 minutes.
Battery capacity is commonly measured in KW/hrs.
I get complaints from the peanut gallery when I don't use it to simplify, I get complaints when I do use it, shrug <grin>.
20KWhr / 100KM is correct, as is 20KW/hr, 20KWh, 20KW-Hr, 20kw-hr as the car will use 20kw hours worth of electricity for every 100km travelled.
If you want it in other measurements, that's equivalent to:
- 68,242,849BTU / 100km (British Thermal Units)
- 17,196.9 kcal/h/100km (Kilocalories)
- 72000KJ / 100km (Kilojoules)
I'll change to SI unit notation though to appease you ****ers.
Moving those all to kW.h in a few min.
Lower end EV's in SA like the gimped BMW branded ones have low capacity - eg the i3 or the Mini Cooper SE have in current models 30kw/hr batteries, although older models of the i3 were far worse with 18kw/hr batteries.
What we should be focusing on for Electric cars is efficiency, and storage capacity.
You'll note that BMW for example doesn't publish these numbers in a clear way, and instead prefer to publish Ah (Amp hour) ratings. eg the current models are 120Ah, which is confusing to consumers. They really should standardize on things.
I linked to a site that lists efficiency ratings (kW.h/100km), some EV's are great - 11kW.h seems to be the best, others are atrocious (and on sale in SA) eg the Jaguar Pace.
That problem is easily solved by regularly increasing the price of electricity by large amounts.
Looks like it completely misses the point.
But also if there is plenty of capacity at night why is there ever load shedding after 6pm?
RedViking
Nord of the South
So much excitement......
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When you live in a flat do you just run a long extension cord out a window? Actually I’d even have to do that.
Just buy two. That way you have one to use while the other is charging.
itareanlnotani
Executive Member
How have I missed the point? - would be interested to know so I can amend to fill any missing bits.
As for the 2nd question - that's a rather long answer to a deceivingly simple question.
I'll attempt to make a brief answer but that really needs to be whole separate writeup.
If we look at a statement from Eskom where they have load shed at night:
In order to replenish emergency generation reserves, Stage 2 loadshedding will be implemented starting tonight from 21:00 to 05:00 in the morning, and will again resume on Friday night at 21:00 to 05:00 on Saturday morning - Eskom
Thursday, 07 October 2021: In order to replenish emergency generation reserves, Eskom regrets to inform the public that Stage 2 loadshedding will be
www.eskom.co.za
You'll see that they load shed at night mainly to replenish emergency reserves.
Let's break that down.
Firstly what does that mean, and what are emergency reserves?
Eskom keeps some storage as a backup in case they need to call on it.
This could be things like Diesel or Gas, or it could be water (i.e. in pumped hydro).
They could be waiting on deliveries for the former, or have used up all the latter.
If they need to replenish emergency reserves, it usually means that they've been running the system far in excess of where its supposed to be run. This is usually done at election time for example, where the ANC government explicitly tells Eskom no load shedding.
This costs the country a huge amount, as Eskom then needs to use diesel or gas to power things.
The short version is - we don't have enough capacity to run daytime in some cases.
Our alleged total capacity is 45GW, however with ANC misappropriating maintenance funds for decades, this is down to 25-30GW, sometimes even less.
We can compensate for around 2GW.h or so using pumped storage or diesel/gas generation, but this means we have no margin for the next day.
Assuming we have a serious outage and generation sits at 20GW, but we really need 25GW for the day, Eskom will both load shed, and use backup generation. This leads to having no margin for the next days issues, so while overnight load is lower (typically 10GW.h lower), they may need to use all that excess just to refill pumped storage so it can be used again.
In reality its more involved and complicated, but thats the gist of things.
Using another analogy -
We're borrowing from our next days emergency funds to pay for todays.
Luckily overnight we can still save some cash to pay for tomorrows emergency.
If they didn't load shed at night in those situations, the next day's emergency would basically shut down the grid, or force them to load shed even more.
It's unusual for that to happen, although this coming year I expect it to become a lot more common as our Nuclear generation at Koeberg will be mostly offline for maintenance, which will leave a huge hole in our generation capacity.
Addendum - have found a thesis which explains emergency reserves in an Eskom context in more detail - https://open.uct.ac.za/bitstream/handle/11427/13727/thesis_ebe_2015_van_deventer_a.pdf
Have a read.
I've also written this up as a followup to my last post - https://goingsolar.co.za/2021/12/24...at-night-if-we-have-plenty-of-extra-capacity/
Thanks for the question @noxibox
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So what? It’s still cheaper to run an electric car.
Normal car (average consumption):
8l/100km * R20/l = R160/100km
Electric car (average consumption):
20kWh/100km * R2.50/kWh from Eskom = R50/100km.
So R160 vs. R50
Even if the price of electricity would double or triple it would still be cheaper to run an electric car.
itareanlnotani
Executive Member
To add to this -
1L petrol is roughly equivalent to 9.8kW.h of energy.
Electric cars are far more efficient, your average Electric car "uses" the equivalent of 2L of petrol for 100km.
Electric cars will always be cheaper to run than gas cars.
The other bonus is that it's easy and cheap to add an electric generation plant at home.
Less so for gas
You are the one trying to educate people on your blog. At least get your facts right.
The only valid unit for electrical energy is kWh. Electrical engineering and physics is all about the correct use of units. It all has a meaning. The W is always capitalised. The k is always lowercase as in kilogram. The h is added to the end of kW if this instantaneous rate is needed for a duration of time…hence energy. Instantaneous power multiplied with duration = energy.
There is no kw/h or KW/h only kWh for energy.
Again no. The only valid one is 20kWh/100km for the car when driving or the 20kW charge rate when it is plugged is. Yes it is true that the car charging with a rate of 20kW will charge 20kWh worth of energy in an hour but that’s because of 20kW * 1h = 20 kWh.
And there is no need for name calling and insults. You’re the one with the blog. Not us.
itareanlnotani
Executive Member
There was a
after that appease you ****ers , seems to have a vanished on posting.Was made in jest, not in anger.
As I noted, I have changed to SI units, which are kW.h or kW h (not kWh).
I agreed it could be confusing, and moved it to use SI units.
From now on I solemnly swear to use kW, kW.h, GW, GW.h as appropriate
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WollieVerstege
Expert Member
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Actually ran the numbers for one of my employees.
He just bought a new entry level 3 series, when I told him an entry level i3 would have been cheaper to run day to day, he didn't believe me. So I showed him the calcs.
Monthly payment plus fuel plus insurance on the i3 ended up about R300 a month cheaper than the 318i. This is even if I scew the calculations in favor of the 318i.
*This is of course for his use case, but I think people really need to run the full cost of ownership calcs.
porchrat
Honorary Master
Gwede will give import duty reduction to cars that run on clean coal.
porchrat
Honorary Master
The range is terrible and they cost more than houses.
Yay... I suppose?
Yay... I suppose?