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Regen only recovers about 25% of the kinetic energy that you put in as electrical energy
Much higher than that Molgrips, I've saw some stuff on the orignal Zoé that said that recovery went from 0% below about 10kmh (because it desn't work at all at very low speed) to 70% at higher speeds.
I was just about to say that this 25% doesn't seem to make sense. Slowing 2 tones of machine from 60mph to a standstill using nothing but electromagnetic force dragged from the rear axle. that energy must go somewhere. some will be lost to head, some to friction, some to the efficiency of the process, but it can't be that much loss or it simply wouldn't work.
I think you're confusing energy recover vs energy used as a mark of efficiency. We're only talking about how much kinetic energy is in the vehicle at the point the regen cycle beings to decelerate and what percentage of that energy can be recovered.
Kinetic energy lost to braking is only around 8-10% of the energy used by the vehicle. So if 10% of your 200 mile range would normally be lost to braking, you can expect to recover 12-15 miles of range using regen.
Slowing 2 tones of machine from 60mph to a standstill using nothing but electromagnetic force dragged from the rear axle. that energy must go somewhere. some will be lost to head, some to friction, some to the efficiency of the process, but it can’t be that much loss or it simply wouldn’t work.
The retarding force comes from the current flowing in the motor. The generator isn't 100% efficient, the cabling isn't, and battery charging also isn't 100% efficient. The estimate I'd read for the Prius many years ago was for the full battery-to-battery journey for the power - meaning that if you were to use 100% of the battery going up a hill and then you braked back down your SoC would only go up to 25%.
I admit that my figures might be wrong as times have changed, but as said I don't see large amounts of range going into the battery when braking. Most of the time when driving normally the little regen meter shows maybe 1/8 of a mile of recovered range if I'm driving down a hill and stopping.
Kinetic energy lost to braking is only around 8-10% of the energy used by the vehicle. So if 10% of your 200 mile range would normally be lost to braking, you can expect to recover 12-15 miles of range using regen.
That's not far off my estimate, is it? Those numbers would be 6-7%. Like I said it's there, but it's not massive.
I'm sure Edukator could do an experiment. Drive up a big steady hill, enough to use a significant charge percentage, then drive back down at the same speed. Then drive the same distance as the uphill but on the flat, and measure the energy loss. We should then be able to work out how much is lost in the conversion from kWh to gravitational potential energy then back again.
I have played with the Zoé up and down various big hills of around 1000m +/-. But the battery capacity display isn't accurate enough to do reliable calculations and it's very hard to drive up and down in exactly the same style.
The instant power display can be used. It shows 6-7kW at 70kmh on the flat so that gives you a base for wind and rolling resistance which you deduct from the instant power to get the energy going to potential energy on the way up. On the way down you add 6-7kW to the energy recovery displayed to get total energy recovery. the difference between the potential energy being stored on the way up and the total energy recovered on the way down is what you've lost in generator inefficiency.
I did work it out but I can't remember the numbers well enough to publish them here. They were good. Most of the energy was being recovered and most of it was going into the battery, and hopefully most of that ended up as charge. I'll have another go on the straight section of the Aubisque when I go up next.
You come to Norway and I'll show you some regen 😉 Case example, skiing in the winter. Charge at bottom of BIG hill, battery drop 80-35% in 30kmish. On the way back, and now the battery has dropped to -10,-15, battery drops 35-25% at most. On the way down it's regen all the way
Bjorn Nyland has made the observation that he thinks he gets better efficiency on a slightly rolling road compared to dead flat, but that doesn't really make sense to me
The regenerative breaking can be very effective. I've posted this video before, the first 2 minutes gives you can idea. It's on a mountain but gives an idea.
Case example, skiing in the winter. Charge at bottom of BIG hill, battery drop 80-35% in 30kmish. On the way back, and now the battery has dropped to -10,-15, battery drops 35-25% at most. On the way down it’s regen all the way
Not sure I follow. You go from 80 to 35 on the way up, and 35 to 25 on the way down? Surely it should be going UP on the way down a big hill?
Ok so that Audi is better than I'd expected, if they descended 2500m in a car with 2740kg ish assuming two 70kg people that's about 67MJ of potential energy or about 18kWh. They regained 10kWh so it's about 55% efficient in terms of converting gravitational potential energy into battery charge.
But of course, there are also inefficiencies on the way up too. They will have used more than 18kWh of energy getting up the hill in the first place - but the question is - how much? If it's approaching 50% then my figures would still be ball-park.
Remember, I'm talking about taking energy out of the battery, converting it into kinetic or potential energy, then using regen to convert it back. The whole round trip was calculated to be about 25% efficient all those years ago. Not just the regen part.
You're forgetting that even downhill there is wind resistance and rolling resistance, Molgrips. So a part of those 18KWh will be used overcoming those, the regen braking can only recover what's left over.
My calculation took that into account based on the energy needed to overcome wind resistance and rolling resistance on the flat. Much more than 55% but I don't want to post half remembered numbers.
In Summer it doesn't matter what the battery level is when I get to the ski resort 55km away and 1200m higher because the regen will get me home. In Winter with a freezing battery regen isn't as good and I fall about 10-15km short, the heater doesn't help either.
You’re forgetting that even downhill there is wind resistance and rolling resistance, Molgrips.
No not really, it's factored in. That's why the experiment I suggested also included a flat journey at the same speed.
Looking at getting a 2nd hand Zoe, does anyone know real life range for both the 22kwh and 41kwh versions? Anything to look for or look out for when looking at them, and roughly how much to buy out the battery lease?
Many thanks
Not sure whether this has been done but I found this video interesting. It sounds like there might be a substantial and pretty low environmental impact source of lithium in Cornwall.
Also Fully Charged generally - I find it very watchable. Made like proper telly and I think the presenters are very good, especially Helen.
Disclaimer - there's little in here about either the quantity available or the commercial viability of the whole process to making batteries with it. I guess it's too early to say/commercially sensitive/whatever.
Regarding REGEN:
Most of the passcar BEVs ive tested sit at between 68 and 74% efficiency of the regen, when considering just the energy flowing into and out of the vehicles mass at speed (ie the Kinetic Energy).
This does not include the energy flow into, and being irrecoverably lost too, drag at the same time.
Therefor the percentage you can recapture is entire due to how dynamic your journey is.
Take an immaginary constant speed motorway journey, where we accelerate from rest straight down the slip road to 70mph, drive 70 miles at that fixed speed (ie for 1 hour), then leave the motorway, using regen to come to a stop at the end of the exit slip road.
The regen will have recaptured lets say 70% of the energy "loaded into" and "stored by" the vehicles mass at speed over that journey, but because we only accelerated and deccelerated once, the total KE exchange will be almost totally lost in the huge amount of energy we have continously expended against the drag of doing 70 mph for an hour.
For a typical EV, weighing say 1,800 kg and returning say 3.3 ml/kWh at 70 mph, that means:
KE at 70 mph (31m/s for 1.8 tonnes) = 0.86 MJ = 0.24 kWh
total drag energy (3.3 ml/kWh over 70 miles) = 21 kWh
At 70% regen recovery, we'd get back 0.17 kWh as we regen up the off ramp.
So our ratio of recovered energy to drag is tiny, 0.17 kWh / 21 kWh = 0.8%
The opposite case is in town. Low average speed means low average drag and plenty of stop/starting due to traffic features and high traffic density means lots of speed change dynamics. Here, the recovered energy could, ime, get as high as 25 to 30 % of the consumed total energy.
So in summary, any energy balance numbers you see on the display are simply an indicator of the sort of driving conditions at which you are operating your car, and nothing really much to do with the efficiency of the system to recover KE.
(BTW to get these figures we run extremely controlled tests of either cars on chassis rolls (which obvuously includes tyre losses) or of the bare powertrain attached to dyno motors that simulate the roadload, and measure everything! Typically we spend up to 3 months simply instrumenting a test vehicle or powertrain and setting up the test facility, and tests will be repeated over and over until we get a statistically valid result.)
apropos of nothing, but Helen Czer has possibly one of the nicest pair of legs on the telly!
I've been lucky enough to meet and talk/discuss with her at length on a couple of occasions now for various ends and she is, frankly, wonderful! 🙂
Helen Czer has possibly one of the nicest pair of legs on the telly!
Careful, that may not go down well here given recent bans handed out on certain other threads...
Karnali: we had a Zoe 2015 reg (21kwh). Summer distance when new was 90 odd? Mixed driving. Winter range dropped to 57 in year two.
Sorry to hijack this thread - I have an Etron, I've just moved onto a tariff with EDF that gives cheap charging Midnight-0500hrs. I've tried setting the charge timer in the car but it seems to make no difference, I've plugged it in anticipating no charge until MN but its started straight away...any ideas what I'm doing wrong?
A Guess: Is there enough time within your tarrif window to charge the battery with the charger power you have connected.
If you have a 7kW charger, and need say 63 kWh, this clearly will take at least 9 hours. If your tarrif window is say just 8 hours, the car will probably start charging immediately to ensure the battery is fully charged
Well to avoid calls of sexism against my behalf, i will also say that Robert ( llewellyn) from Fully charge also has a lovely pair of legs too..........
(and he is also a lovely chap to converse with 🙂
Here, the recovered energy could, ime, get as high as 25 to 30 % of the consumed total energy.
Hmm, when you drive around in town you are going much slower and recovering more energy, the consumption only goes up about 20% at most.
Also Fully Charged generally – I find it very watchable.
Generally I'd agree with you but lately it seems to consist mainly of infomercials for dodgy renewable startups.
Also Robert Llewellyn's ranting about SUVs are getting tiresome. He recently went off on one about the Volvo XC40 recharge so I looked up the dimensions of his Tesla Model 3 and guess what, it has a larger footprint on the road than the Volvo!
I looked up the dimensions of his Tesla Model 3 and guess what, it has a larger footprint on the road than the Volvo!
Now look at efficiency, aerodynamics and pedestrian collision.
Hopefully agreeing on a 2017 signature 41kwh Q 90 tomorrow. Anything I really need to know or ask. If all goes ahead I'll need to drive it back and charge on route, this is all a learning curve, us there any chargers I can't use with a Zoe, or any places that people can recommend to stop and charge between Lincolnshire and Cumbria, journey is 230 miles
Zap Map.
Nissan Chademo won't work on the Zoé, nor will the Euro Combo, you need a type 2 which happily are the most common.
Now look at efficiency, aerodynamics and pedestrian collision.
Why should I they are both zero emissions and Euro NCAP 5 star
Also Robert Llewellyn’s ranting about SUVs are getting tiresome. He recently went off on one about the Volvo XC40 recharge so I looked up the dimensions of his Tesla Model 3 and guess what, it has a larger footprint on the road than the Volvo!
Increase in footprint isn't a particularly important variable with regards power consumption. Aerodynamic drag of a XC40 is likely to be a chunk more than a Model 3. His ranting about it might be tiresome but I'd say the impact on our emissions of our collective SUV habit is more so.
I assume (certainly hope) it's not still be the case but about a year ago all our improvements from moving to smaller petrol engines, hybrids and EVs were collectively not enough to counteract the increase associated with our shift from normal format cars to SUV type vehicles.
Worth knowing (particularly with Zoe) that Gridserve are cracking on with motorway services rapid charger replacements. Worth checking zapmap and http://evmap.mazshar.com for current status. Mostly AC that older Zoes need is coming via separate units after so aim for services not done yet or BP Pulse (Polar), Shell, Osprey or similar just off the motorway.
His ranting about it might be tiresome but I’d say the impact on our emissions of our collective SUV habit is more so.
Like I said both are zero emissions vehicles and petrol equivalents will not be on sale after 2030 so is a difference in efficiency of something like 1 or 1.5kWh really a problem in a world where the power grid is decarbonising and the ICE is being legislated out of existence.
Personally I think RL's time would be more constructively spent ranting about the lack of charging infrastructure in a country where we expect EV use to grow exponentially in a couple of years.
So...posting on a thread with electric car users to garner opinion rather than start a new thread.
We have a holiday cottage we run next door. Current punters have an electric car. An MG ZS EV. Looks ok. This is the Highlands and they've had a very active holiday travelling (relatively) far and wide. I'd say they've covered 500 miles and will be driving home 200 tomorrow. Good to see you can have that sort holiday seemingly unperturbed by being in an electric car.
But this is the thing....I paid for it!
Car plugged in to a 13 amp plug through the window whenever they are in. A quick bit of (very rough and probably inaccurate maths) that'll be £30-40 of leccy.
As electric car users would you say plugging your car in to a holiday cottage without asking is just the expected thing you can do if you own an electric car? I'm thinking probably yes. But it still feels a bit cheeky. I don't pay for the fuel for petrol car owners. At the same time I'm all for electric cars becoming a thing so kind of support it...
Long term it looks like it's something I'll have to account for. Maybe put a charging point on the cottage and make it a selling point. But I'll maybe have to put the prices up too if I'm going to be pay for their travel whilst they are with us.
I've always asked and offered to pay giving them an idea of what it'll take in electricity, usually about 5e worth, they've always said help yourselves, it's free, and found us a suitable socket. Except once where they point blank refused, so we cancelled and moved on.
We rented out a ski flat a few times, the people who turned on all the heaters flat out cost us a lot more than an electric car can draw without a special socket - do you charge extra for people who turn the place into a sauna?
The most a car car draw from a standard domestic plug is 10A so 2.2kW.
We rented out a ski flat a few times, the people who turned on all the heaters flat out cost us a lot more than an electric car can draw without a special socket – do you charge extra for people who turn the place into a sauna?
This is true - though the heating controls are beyond reach. They could stay in 24/7 and have 3 baths a day. Or just scratch/damage stuff through carelessness. So in comparison it's not a biggie.
But you are still saying you'd ask?
Interesting question. I would ask before just running a cable. I don’t think it’ll be quite as much as £30-40 but I think common courtesy would be to talk to you about it.
I’ve wondered about this at campsites.. heading to Goodwood (hopefully!) in a couple weeks but the extra for an electric hookup pitch is waaaay more than just hitting a rapid charger for 20 minutes.
Can I ask how long anyone might have waited for UK Power Networks to get in contact and then install a 100amp fuse?
Submitted request over a week ago and waiting for call now, not 100% sure as and when they come out that my electric kit meets their standards to fit a 100a, but wondering how long that might take.
Ready to order an EV but not doing that till know we are on for a charger at home.
@boombang What is your current main cutout rated at? I had my 32amp podpoint on our 63amp main cutout for a year with no issues whatsoever.
Our DNO is Northern Powergrid and we eventually got it upgraded it to 80amp. 100amp wouldn’t be done unless there was an exceptional reason. I think from logging the call with the DNO to getting the works done it was maybe 2 months and involved digging up a bit of the driveway.
A quick bit of (very rough and probably inaccurate maths) that’ll be £30-40 of leccy.
About £6 if completely empty. Bit cheeky of them to do it without asking, IMHO.
You could ask them not to do it on safety grounds, I suppose.
Aye, think I’d be more worried about the safety element of it more than the cost.
Yes, I ask and offer to pay, seems fair and polite. If I charge for 12 hrs that's half the battery, 25kWh which is 4 euros here. I couldn't use £30-£40 in a week. It takes over 6 hours to empty the battery on main roads which leaves 18 hrs to charge so even doing that every day for a week wouldn't get to £30. It depends on what you pay for leccy, I did feel a little guilty in Germany where it's three times the price and they simply said plug in, it's free.
You could ask them not to do it on safety grounds, I suppose
In which case they might report you for having a dangerous electricity supply, it's 10A, that's an electric kettle.
I wouldn't ask to plug my car in but I would give the owners an extra £20 or whatever it was.
Why are you lot having your supply upgraded? 7kW charger not enough? Or is it everything else as well?
Is my house going to trip out when the car starts charging tonight? Our boiler's on the blink so I've got the immersion heater on.
@nickewen not sure, not opened it to see but according to the guy lined up to install based on photos:
'You haven't got a big enough head fuse to have a car charger. Yours is only a 60/80. You'd need to have it uprated to a 100 amp. You would need to contact UK Power networks and request for a new cutout fuse.'
When I asked about adaptive fuses he said 'most manufacturers don't do adaptive fuses they just have a CT clamp. You can't get the grant without the 100 amp cut out fuse though as UKPN need to be notified its been done. They won't accept anything less than a 100amp on the paperwork as a formality.'
I have taken that at face value then everyone I spoke to since with a charger says they on smaller fuses and had no issues.
Maybe put a charging point on the cottage and make it a selling point.
EVs make up less than 1% of the vehicles on the road so you might never have another customer driving an EV for the next couple of years. Plus if they really have driven 500 miles in the week plus another full charge to get home then they've used about £28 of leccy. I suspect given what you are probably charging them in rental that's peanuts.
I know UK holiday accommodation just now is a sellers market but in a years time it won't be and for an EV driver like me having access to a fast charger would be a great selling point. At £0.16 per kWh the most anyone is going to take in a 10 hour period is £3.84 so either suck it up, add it to the rental or install a fast charger and enroll in Co Charger.
Charging a car with, say, a 100kW battery from 10% full is probably only about £0.15 x 80 = £12 maybe bump it up to £15 if you’re allowing for losses or the air conditioning is left on.
edit and that assumes there’s enough current. As quicker folks than me point out, charging at 3kW/hour is even less: 3kW x £0.15/ kWh x 10 hours =£4.50
It is not different from having a 3kW fan heater on. I was almost embarrassed when a nice chap offered me £20 after using my charge point to charge his EQC overnight.
Still, it’d be polite to ask if it’s OK. I would have and I’d have offered £10. With EVs still rare an extra £10 of electricity disappearing could be an unwelcome surprise to a host.
On 100A supply fuses. Interesting. I’ve told my supply fuse tale before. 7kW charger was installed on our second consumer unit. We had a 60A fuse to supply both units. OK most of the time. But one night: bang! Seems all the regular things + car (32A) + washer + drier was a bit much. North west power were with us a couple of hours later and installed a 100A fuse very quickly. Any supply fuse 60A+ should be fine. But 7kW charging will suck up over half the possible current.
In which case they might report you for having a dangerous electricity supply, it’s 10A, that’s an electric kettle.
Yeah, but most people don't run an electric kettle for ten hours straight on an extension lead through the window. They're also double-insulated so safe in the event of a PEN fault.
BTW, 80A fuse in a 100A cutout here, no issues with a 7kW charger install. DNO not the slightest bit bothered about me having a car charger on a looped supply, though may cause a headache for the neighbour if they want one too.
A quick bit of (very rough and probably inaccurate maths) that’ll be £30-40 of leccy.
The MG ZS has a 43Kwh battery a socket will provide 3Kw. 43/3 is a little more over 14 hours. Let’s say you pay 15p an hour for easy maths.
3x15x14 = £6.30
They have around 140 mile range so let’s say 4 full recharges, if they only recharged at the cottage. That’s just over £25
It would be polite to ask but I bet that doesn’t eat into your profit margin much. We’re off to the West Coast this year to a cottage we visit every couple of years. It’s a fraction of what they charge off peak never mind post peak.
I agree install a charger make it attractive for EV uses it’s a nice selling point if you’re in a remote area.