BMW UK i3 REx without plugging in?

[Kundalini]

BMW i3 question

Hi all, new UK member here but have perused the site often as a guest.
My daily travel (5 days) consists of a relatively flat 5 miles averaging about 40mph* then a steep climb up over the Campsie fells which is a rise of approx 500m in 2.5 miles to the top and the same down the twisty other side with a further 5 miles of flat terrain to destination. My return journey is the same in reverse (not gear for the jokers).
Having gone through many sets of brake pads over the years, i acknowledge and bemoan the wasted energy going downhill whilst braking.
I've been weighing up the merits of the electric BMW i3 with range extender (plugging in the pure electric version every other night may become irksome when the novelty wears off, not to mention the prospect of getting stuck on top of a snowy mountain road in winter with a low battery level and no phone signal)
Theory is If i started the REx at say 75% battery level all the way up to the top of the fells then switch off and top-up the battery with regenerative energy from the steep descent.
My question is this:
Would it be possible to reach anywhere near 100% state of battery charge with regenerated electricity during descent, meaning no plug-in required "EVER"?
I suspect it's a lot more complicated than described but it would be my ideal situation.
Any comments or views from you knowledgable guys might sway me towards an i3 REx.


Thank you,
Peter

Edit: * Just noticed Where i said i averaged 40mph i meant a maximum of about 40mph, the average being closer to 15mph.

 

[Jeffj]

You can certainly increase the charge level of the i3 by descending and engaging the regenerative brake to capture the energy. However, nothing is 100% efficient, so you will use more energy to climb the hill that you will re-capture descending. I've descended 6,000+ ft. across ~20 miles with my i3 and (coupled with running the REx) have been able to go from ~30% SOC to 75% SOC.

I'd guess, however, from your description, that you wouldn't really gain more than a couple of percentage points on your SOC with the descent.

Why do you think plugging it in "every 2 days or so" would be a problem? It takes maybe 5 seconds to plug in the car, and about the same to unplug it, unless you have a really tortuous process for getting power out to your car.

 

[jadnashuanh]

You certainly would minimize your brake pad wear with any EV, especially with the i3 if driven properly. Plugging in is not a big deal, but maybe bigger in the UK where you'd have to coil and uncoil the cord each time. The EVSE's in the USA have a cable tethered to the EVSE, but that is not the case in Europe. Still, it should not take much more than a minute. Not knowing the total distance of your typical trip, you might find that the BEV would work for you as well. The car does not use much power when it is not moving, and the REx is less efficient, especially at heating than the BEV (the BEV has a heat pump (standard in the USA, not sure about Europe) while the REx must rely on electrical resistance heating, which is much less efficient). Plus, the REx, being heavier, creates a hit on efficiency. Now, having the REx may mean you might get by with it as your only vehicle, and you have to consider that as well. It wouldn't suffice for my driving needs, but might for yours, which is why I bought the BEV verses the REx...we have few CCS charging units where I live, and my typical trip would be an annoyance trying to use the REx on petrol most of the way.

 

[MikeS]

“Plugging in is not a big deal, but maybe bigger in the UK where you'd have to coil and uncoil the cord each time. The EVSE’s in the USA have a cable tethered to the EVSE, but that is not the case in Europe.” This is true for public EVSEs where in UK we use our own cable. However, on my EVSE at home the cable is part of the EVSE so all I do when I charge is pick up the plug, remove the cap on the car and plug in. In reality, no more time consuming than plugging in my phone!

 

[janner]

You should think of the ReX as a BeV with 40kWhrs of energy storage and not as a car with a small engine. If you want to use the car for journeys other than your commute then get a ReX otherwise BEV and a home charger.

In the UK lots of home EV Chargers have tethered cables. It's only at public level 2 charging points that we need our own cable. Plugging in is not a problem if you do it at home. Don't think about an electric car if you can't charge at home.

Under most conditions 75% charge will be reached after 15 - 20 miles so you probably won't have reached this until you get to work. On the way back you might gain from being able to turn on the ReX but you shouldn't need to. If you count your 2.5 miles up and 2.5 miles down as say 10 miles flat then you one-way journey is 20 miles equivalent. You should be able to get there and back with lots to spare.

 

[Kundalini]

Oh dear........ Thanks for the replies guys.

Currently, plugging in at home would require the cable to cross a public pavement which wouldn't be allowed.
The nearest "fast" charge station would be the BMW dealership (9 very slow/ heavily congested miles away).
I do live opposite a petrol station though (typical).

I had originally thought the small 2 cylinder petrol engine in the UK spec i3 REx could only be used to maintain battery charge state, not increase it (although how they worked that one out whilst combining it with battery charge increasing regenerative power I'll never know).
If I was wrong then, problem solved.
Charge the battery pack to max with the engine then drive on near silent electron power till i next need to use my onboard generator to charge up.

RESULT !!!

Thanks again guys,
Peter

 

[jadnashuanh]

There are limits on how much the REx can increase the charge state of the batteries and WILL NOT recharge it to full capacity...it will shut off way before that happens, either from running out of fuel or from the computer. In normal practice, you can't turn the REx on manually until the SOC has dropped below 75%, and whatever level you engage it, that is the maximum it will try to maintain.

 

[psquare]

Currently, plugging in at home would require the cable to cross a public pavement which wouldn't be allowed.

What about renting a garage or place to park nearby, which might come with a power socket? Not being able to charge at home and using hills/REx to keep SOC sounds like a pain to me. They say 85% of all charging is done at home...

 

[Kundalini]

The home charging problem COULD be circumvented in the future.
In the meantime there must be, or soon will be, a software tweak available to allow the battery pack to be fully charged using the petrol engine alone while stationary (don't mind keep topping it up with petrol or storing a spare can in the boot).
I realise this might sound like it defeats the purpose of using an electric car but
the unique driving experience and the futuristic design appeal more to me than charging with plug-in electricity (of which up to 70% is derived from burning huge amounts of fossil fuels here in the UK).
Any significant rise in demand on the National Grid due to the rapidly increasing number of electric plug-ins, only increases the use of "dirty" fossil fuels to balance supply.

Thanks,
Peter

 

[psquare]

I realise this might sound like it defeats the purpose of using an electric car but the unique driving experience and the futuristic design appeal more to me than charging with plug-in electricity

Glad you've pointed this one out yourself.

(of which up to 70% is derived from burning huge amounts of fossil fuels here in the UK).

Ok, three things:

You could of course switch to a renewable energy supplier, thereby personally supporting the increase of renewables in the UK mix. And 70% fossil a tad high, by the way. We're talking 45-55%, depending on demand, time of day and weather. Renewables are almost 20% at the moment, not even including PV. Gridwatch is good for relatively up-to-date figures.
http://gridwatch.templar.co.uk

You're also forgetting about effects on air pollution by having an emission-free car (when driven as a pure EV).

Anyway, enjoy your REx.

 

[Kundalini]

psquare , my figure of up to 70% cheekily guesstimated an additional amount to take into account the horrific electrical losses incurred in its distribution.
If you check the site you mentioned around 6pm on a cold calm day, you may be surprised.
Most renewables cannot be relied upon regardless of the scale of operation.
I totally agree with the benefits to town and city air pollution levels if we were all to drive electric vehicles, i just wonder where the HUGE supply of electricity to keep us all charged up is going to come from.
We could always turn off all the lights and go back to the dark ages

 

[psquare]

psquare , my figure of up to 70% cheekily guesstimated an additional amount to take into account the horrific electrical losses incurred in its distribution.

You're right there, but all forms of energy generation have losses.

If you check the site you mentioned around 6pm on a cold calm day, you may be surprised.

As long as YOU check on a windy, sunny day - who knows, maybe you will be surprised too?

Most renewables cannot be relied upon regardless of the scale of operation.

Yes, we keep on hearing that, but the progress in wind, hydro, solar and storage will soon eat into these arguments.

I totally agree with the benefits to town and city air pollution levels if we were all to drive electric vehicles, i just wonder where the HUGE supply of electricity to keep us all charged up is going to come from.
We could always turn off all the lights and go back to the dark ages

Hey, don't put the head in the sand just yet. Saving energy is more important than generating it. That's where the focus needs to be. Hence the development of the i3, which is the most energy efficient EV to date (well, unless you use the REx a lot).

Will EVs save the world? Of course not. Are they better than ICEs? Most definitely.

 

[Kundalini]

Anyway, now my head is back out the sand, to return to the original question which remains unanswered.
Until science achieves what now seems impossible, my best bet and the most ecologically friendly, is to collect water in many large bags from the stream passing under the road near the hilltop and use the extra momentum on the way down to super-regenerate my batteries, negating any losses.
I must remember to dump the water at the foot of the hill though.

EUREKA !!!

The first Hydro-electric-range-extending-never needs plugging in (cos boy am i sick to death of charging the plethora of devices i now need to remember) funky i3.


On second thoughts, i might just hang on to my super efficient 15 year-old petrol driven 3 series (Still has original battery).
What with fuel prices as low as £1.17 per litre of super-unleaded while retaining the ability to drive up a mountain much faster than i would ever dare descend, it would be foolhardy of me to make the switch at this time.

Tongue firmly in cheek,

Peter.

 

[jadnashuanh]

The REx as a generator will likely never reach the efficiency of a utility fossil-fueled power plant. Throw in that some of that grid power is from clean sources, and thinking that generating it yourself on-site from the REx is more efficient, just doesn't add up to me. Now, should you install some solar panels, you could charge the thing at no cost, other than the cost of the equipment (not insubstantial!). Plus, consider that the REx is a moped motor...it works, but isn't really designed for constant use like an engine in an ICE. Sitting stationary, the heat will likely cause issues if left to burn through an entire tank. Momentarily, as allowed by the current software, not an issue.

 

[Kundalini]

jadnashuan, i really only wondered if using the REx as a generator (software permitting) would be more "efficient" than charging using electricity from our National Grid. Who can say for certain? I suppose the answer would depend on which way can be made most profitable.

As an alternative to psquare's earlier link, this site seems to put a different spin on what our green/clean generating capacity actually is here.

http://nationalgrid.stephenmorley.org

There's little doubt any increased "green" demand would be met by "brown" supply.

As for solar panels, they're fabulous if you're in the business of making them or are lucky enough to live in a sunny Country.
I'm afraid to say that the sun don't shine much in this part of the world so they are of little practical use here (unless your in it for the subsidies).

Ta guys
Peter

 

[jadnashuanh]

A US gallon of gasoline can produce the equivalent of 114,100 BTU, converted to watts, that's 33, 439W. Considering that the usable capacity of the battery pack is around 18-19Kw, and the REx on it's full tank is stated to get you a range increase of maybe 70-miles using 2.4gUS or almost 274Kw , the efficiency is lousy in conversion. You can do the rest of the math. Large utilities are LOTS more efficient, even when you take into account distribution losses. So, Kw/fossil fuel used, the utility will win hands down. Maybe I'm missing something. Throw in any green suppliers, and that tips the scales even further.

 

[Kundalini]

I think you may be missing something quite unique to the UK and your figures confuse me (not difficult).
I'm led to believe the UK’s existing nuclear power stations will close over the next decade "all but one expected to stop operating by 2025" and the first new plant not expected to come online till after 2024 (originally planned for 2017).
The UK also aims to close all of it's coal-fired power plants by 2025.
Building more gas fired plants to ensure continued supply seems to be the preferred solution (claimed to produce 1/2 the CO2 of coal fired stations) but with gas supplies increasingly coming from inefficiently extracted, unconventional fossil gasses (Shale Gas, Coal Bed Methane and even Underground Coal Gasification), they bring with them their own environmental HORRORS.
The simplest solution here would be to reduce as much as possible the demand for electricity and in my mind, the rapidly rising use of plug-in electric vehicles can only hinder that.
The i3 REx is almost there, if only it didn't need plugging in.

 

[jadnashuanh]

FWIW, the bane of the electrical power grid is peak loads. There is often an oversupply overnight when most people recharge their EV's. Power plants that must come on during peaks tend to cost money warming up, or cost money kept in standby mode so that they can come up on grid fast. Much of the problem is that the wind blows more during the day and slows overnight, and solar only works when the sun is out. Over the years, there hasn't been much research into how to store excess production capacity so it can be released economically during peak loads to help keep the production level steady. Anything you can do to shift the load and make it more even means higher efficiency. An EV can help. Making power with current small production sources is not as efficient. You can be fairly efficient on smaller units, but the REx is not in the same league as a utility company's production of electricity except in maybe convenience. There are a few places where electricity ends up essentially free during some hours of the night.

Hydro is good, but not everywhere has enough flow to make things useful. AN interesting technique that has been in use for decades is at Niagara Fall, NY in the USA and Canada. At night, they essentially almost shut down the falls (not readily apparent to the casual eye), redirect the water into storage areas, and then can release it during the day to help if they need a bit more power to be produced while keeping the falls running for tourists!

 

[Kundalini]

I've learned a lot lately, so
hear this anyone who's interested.

If the predictions of future power (electricity) cuts here come true,
according to whats shown below, it is technically possible to stay mobile using petrol alone in the REx.
i.e. No additional electricity, so no plug-in necessary "EVER".



------There should be an image explaining everything here but i don't know how to add it ------



Now, when you consider the REx petrol engine is capable of producing 25 Kw then, without restrictions, it could charge the battery pack from 1/2 empty to full in just 23 minutes (disregarding losses and warm up time).
Thats a Rapid Charging station in the boot.

Oil is how much a barrel ? $30/£21/€27.5 and falling ??
That's multiple times cheaper than bottled water

 

[psquare]

I love it how Llewellyn compared petrol and electric using lawn mowers.

Battery V Petrol. The Lawnmower Test