Why Matching Battery Size To Vehicle Use Matters

SEP 19 2018 BY MARK KANE 63

Right battery size for the purpose is an important choice

Ricardo released a new Life Cycle Assessment (LCA) study for the Low Carbon Vehicle Partnership (LowCVP), concerning various types of vehicles and noticed big differences in environmental impacts depending on powertrain type over the entire life of the vehicles (manufacturing and driving).

One of the important things is that battery-electric vehicles affect the environment mostly during the production process (20-95% of the total over entire life), as they don’t emit any CO2 or GHG while driving (even emissions from power plants are relatively low). Battery production will be the single-biggest factor we believe (because it’s the heaviest and biggest part).

Typically, BEVs notes 40-60% lower CO2 emissions than internal combustion engine cars, but benefits could be decreased/lost if vehicles are equipped with two or three times bigger batteries (at least until higher capacity is not the result of a technological progress, but increase of the size of the battery).

“For electric and plug-in hybrid vehicles the carbon intensity of the power grid is, of course, also a key factor in terms of the vehicle’s full life cycle emissions. Well-to-wheel CO2e emissions of current electric vehicles are already significantly lower (40-60%) as a proportion of full lifetime emissions than those of typical current passenger cars (70-85%) and this difference can increase as the electricity grid becomes increasingly decarbonised. However, if a race for bigger and bigger batteries is left unchecked, EVs doing low mileages could undermine some of the potential benefits.”

The problem is especially big if mileages remain low and people start to carry unnecessary batteries in their long-range BEVs. Moreover, weight will affect other parts of the vehicles like tires.

That leads us to the conclusion that battery capacity should increase within the size and weight of the current or even previous generation of electric cars instead of turning cars into battery-haulers. The other conclusion is that customers should have choice to purchase particular cars with smaller or bigger batteries, depending on rational needs.

Source: Low Carbon Vehicle Partnership (LowCVP) via Green Car Congress

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63 Comments on "Why Matching Battery Size To Vehicle Use Matters"

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Nice article. Finally someone who makes sense in the endless bigger battery debate.

So just some rudimentary searching shows that this LowCVP group is based in England and has more then a few people from the fool cell side of electrification.

I’m not going to argue their premise that having just enough battery is ideal but the reality is that unless the public sees EVs as compelling then the necessary transition will not happen quickly enough.

Basically, Tesla’s approach to making very desirable, compelling EVs is working to get the laggard, legacy LICE industry moving so reality as usual trumps theory here.

Agree, too small of a battery isn’t useful and people won’t buy at all. I think somewhere between 150 and 400 mile range is ideal. Like an urban car might be fine with 150.

A point to make is Li-ion life span is tied to cycles, so a large battery has a much higher mileage life than a small battery. Given identical battery tech, a 75 mile range car will only go 1/4 the miles as a 300 mile range car before the battery needs replacing. Sometimes they use different tech for the low range battery to increase life, but this often makes the battery heavier.

Well, everything else being equal, a car with a larger battery is slightly less efficient… Though the effect on lifetime emissions shouldn’t be too terrible. Buying too big or inefficiently shaped cars is much more of a problem.

Fair enough, so 4x the capacity won’t be 4x the range. However, cars like Gen 1 Leaf and early i3 BEV are arguably not smart ranges, especially as they age. I didn’t read the report, but I wouldn’t be surprised if they ignored this important bit of information. It makes a big difference in the cars overall life and CO2 emissions.

Edit: I stand corrected, they did account for larger battery vehicles lasting longer.

I think this discussion about ideal battery size is may be more useful in 2025 when there are fast charging possibilites in all road distances, and cheap slow charging available on most parking spaces. I drive my Gen 1 Leaf here in Norway without big problems, but that is because there are noe fast chargers about every 20 km on the roads i usually drive. And I can charge at home, at work and at most places i usually go. But even here there are roads where i will not drive my 24kWh Leaf because there are no charging infrastructure. And I won’t use it to drive into the mountain ski-resorts because short range and fast charging in -20 degrees Celsius won’t make that a nice experience. If the car was bigger and had bigger battery (and temp managed battery) I would be able to use it for “everything”. Another thing: bigger batteries put less strain on the grid as they can be charged when the grid prefers it, smaller batteries must be charged when the car requires it. Bottom line: today we need more cars with bigger batteries to deal with poorly infrastructure, but in future we may very… Read more »

So people should believe you instead of a report commissioned by a globally-recognized NGO and conducted by a globally recognized engineering and consulting firm?

Try going beyond “rudimentary searching” – you might learn something.

Rational, logical arguments based on established facts should be judged on their own merits — not on the source of the argument. If you’re judging an argument solely on the reputation or popularity of the source, then you’re falling into the fallacy of the “appeal to authority”.

But that fallacy is a common human failing. It’s why advertisers use celebrity endorsements.

I’m not judging the argument at all – it doesn’t need my help. Just pointing out the imbecility of casting completely uninformed aspersions on two reputable organizations.

I am happy, however, to get a lesson in logical fallacy from someone whose goto argument is “You’re a Tesla shorter”.

I have no problem with this or other NGOs.
I’m simply pointing out that perception is reality and this will always trump an idealized theory.

I didn’t even mention all the other compelling reasons that the other posters brought up such as battery life.

Curious as to why, if you have no problem with LowCVP, your first
move was to attack them.

You are over sensitive RussB. I did not attack them.
I simply wrote that my 5 minute scroll through their website found several of their staff had H2/fool cell experience.

I and most other informed advocates for clean transportation see H2 for at least light-duty transportation as an evolutionary dead-end that cannot compete with rapidly improving battery performance and cost. Also, we get people who come onto InsideEvs and shill for fool cells/H2 rather frequently, https://insideevs.com/hyundai-launch-1000-hydrogen-trucks/

So I have to ask the question, are you associated with H2 or LowCVP?

Exactly. A “right-sized battery” may mean, according to some, one that’s barely big enough for daily use. But EVs are never going to go mainstream if they are limited to a range that’s barely large enough for daily driving. Auto buyers prefer cars which fit 98-99% of their yearly driving and hauling needs, not merely 51% or even 95%.

Let me just remind everyone that repeating endlessly the expression “fool cell” is neither original, nor too funny, nor appropriate for a technical discussion. Mr. Musk is an eccentric genius and a flamboyant salesman of new ideas; in accordance with the old wisdom “Quod licet Iovi, non licet bovi”, he gets to crack some risky jokes (like “fool cells” or “funding secured”), and gets away with it … most of the time.

Back to the subject of the article: I found the analyses not biased towards FC or otherwise. By the way, it’s worth knowing that FCEV’s are hybrid-style EV’s, therefore the fuel cell replaces not the high voltage battery, but the ICE. I have no problem with it, because FC can be made much more efficient than the ICE. I am not convinced, though, that H2 is the best solution for FC.

That is my point.
Because of the unchangeable physics–H2 for at least light vehicles is an evolutionary dead-end.

I stand by my main point that unless most EVs be perceived as compelling vehicles that can replace LICE vehicles, the necessary transition will not happen very quickly.

Tesla’s success is an excellent example of this phenomena in action.

For some people It would make a lot of sense to have a small built-in battery for everyday use and a rental additional battery for occasional trips.
Just use battery swap tech/process for the extra battery.

It is already much cheaper to make a big bespoke battery than create new standard battery and related swap-stations – Remember these things are not exactly handheld. (Pst… Better Place)

Modular makes sense, but car makers don’t want to sell the base model to everyone.

Yeah….I can see a base 150 mile range and then a trailer that gives you another 200 miles range for long trips. But a lot of people of driving with a trailer.

They could start with 40 kWh, then 60 or 80 plugged into the car. Most would buy the 40 because they can upgrade, not good for initial revenue.

Marketing says you find out what people want/need then design.
EVs like the Leaf just built it then they came.

The problem is in the discrepancy between “want” and “need”. Nissan tried to build a car that should be sufficient to easily cover most people’s daily needs — but it turned out most people wanted more…

They wanted a battery pack that did not lose capacity.

There are “daily” needs and long term needs.
Rationally – we would have daily haulers and rent road travelers – but no one wants that.
But the fact is a Leaf works great as the second car in the household. And that could be 20% of all cars sold very easily. Gas at $6 a gallon would go a long way to making that happen.

Leaf for 5.5 years; S for 3.5 years here. 2 car household. We would have issues with 2 Leaves. Partly because I have a long commute once a week.

Agree. Our little, short range iMiEV ( what a stupid name!) works fine for us as second car for daily chores. Use the Prius for long trips. Good combo. Then consider, that the Prius is not driven sometimes for days! How efficient is that?

Battery size might matter with regards to CO2 emissions but for resale purposes a smaller battery could reduce your buyer market pool.

NPNS! SBF!
Volt#671 + BoltEV + Model 3

Now let’s talk about onboard charger size. 20 kW or bust!

Except there are incredibly few public 20kW chargers. And then many houses would have issues installing that.

There are also very few occasions when you need a big battery, but you want one anyway. You may be surprised, 40 and 80 amp stations are around, and I am not even talking about Tesla wall-connectors. The Clipper Creeks installed as part of the Tesla destination charging are often 48 amps, the Volta stations are 40 amps, stations throughout Europe are 22 kW 3 phase, Canada’s Sun Country uses high-amp Clipper Creeks.

I haven’t looked specifically; but all the public stations I happened upon so far here in Berlin seem to be 11 kW, not 22.

Yeah – this slant that the article makes – is totally wrong headed. Large batteries decrease the need for continually fast charging the vehicle on a trip. Last weekend’s ERIE, PA drive electric event is a perfect case-in-point. In my BOLT ev I was the only Bolt there since I was the only non-Tesla car that didn’t need to charge up – since the event was staged at the ERIE, PA Supercharger which had no other charging facilities for non-supercharger-compatible cars. Didn’t matter – the 220 miles of the trip was easily accomplished without any kind of public charging. Good thing as the only docking station along the route in Dunkirk, NY has been permanently shut for outsiders and is for future marina ev boats only. Small batteried BEV’s usually Fast charge during very ungridfriendly times. My Bolt ev in this case needed no charging during difficult times. Now if the author wants to make the case that PHEV’s with smallish batteries (50 mile AER, etc) make much more sense during long trips and over the life of the car – that would be another thing I’d agree with since it avoids the need for any electric infrastructure as most… Read more »

Gasoline drive train less weight than equivalent battery…..
Just for discussion – what exactly does the gasoline drive train weigh? Should include gas weight of full tank. I am guessing 600 pounds. Make sure to include exhaust and all parts.
Then look at the weight between the Volt battery and the 3 battery. I am guessing they are pretty close all added up.

Now – lets talk the percentage of miles driven in the US on trips that are above 300 miles. I am guessing 5%. So the grid unfriendly charging would be on 5% of miles. Oh wait – some of those are on weekends or nights – probably 50%. So now you are worrying about 2.5% of miles?

Weekends are low use around me – and completely off peak. Regions may differ for sure.

I have a 70D with 60k miles. I have supercharged 15 times perhaps (average 80 miles). More than 50% were weekends. More than 80% would have been avoided with a 3LR. So in my use case, I am thinking .5% of miles would be peak charging with a 3LR.

FWIW, the Model 3 seems to be a tick heavier than comparable combustion cars; though not much. Future battery technology should make up for that. (Unless it goes into larger batteries instead…)

Haha! The Gasoline in a full tank in the volt weighs under 53 1/2 pounds.

Yeah I’m worried about the ‘ 2 1/2 %’ as you call it (although around here at least its MUCH MUCH more than that since free supercharging is utilitzed by the locals to make sure they get their ‘moneys worth’). Actually I’m not worried about it at all since SOMEONE somewhere is paying for it.

What bothers me is when SOME ev car owners clamor for STATE PROVIDED FREE charging, or State Provided Free Infrastructure. This occurs in my State to a trivial extent so here currently I’m not worried about it. Then other taxpayers are paying for basically a rich person’s fancy. Ask ev drivers in Ontario, Canada how that ultimately ended up for them.

But its rather a silly question to bring up – I know my Bolt EV is heavier than a Sonic which can go further.

Why bring up a silly indefensible point? I just mentioned it for what it was – a stated unarguable fact.

This doesn’t make a lot of sense. Smaller batteries have to be pushed harder to charge at the same rate. They have to be pushed harder to accelerate at the same rate. They get cycled more often. This means they don’t last anywhere near as long. More battery replacements mean more resources used, so worse for the environment.

It has to do with all the pollution a battery creates by being buildt (getting raw materials and all that).
The point is, if you have a small transportation need, don’t buy a car with the largest battery.
If you drive a lot, buy a car with a larger battery. If the battery match your driving range, it should last the lifetime of the vehicle.

Not a cut and dry conclusion. Batteries degrade over time considerably. The Model S battery will get hit really hard by this if not driven a lot.

I have a 1997 dell laptop with lithium batteries that have only been moderately cared for. It still runs for hours on that 21 year old battery. with the improvements in chemistry and how much better car batteries are cared for, they’ll last an incredibly long time.

That was a NiMH battery though I suspect, not Li-Ion? NiMH batteries don’t have issues with shelf life; while Li-Ion — especially the early ones — were pretty bad.

Why not a medium sized battery instead of small vs. huge?

Yes, an i3 with a 22kWh battery is going to get cycled a lot and pushed hard to charge fast, but that i3 with 100 kWh battery recently? Exorbitantly large.

Who is going to use the last 40 kWh of that 100 kWh battery frequently in an i3? Very, very few people.

Give it a 50-60 kWh battery and let it charge at 100 kW+ and have 200+ miles of range. That’s going to result in low cycling for commuting and decent trip performance. Going to 100 kWh is going to add cost, weight, pollution, etc. for very little relative benefit compared to 60 kWh in an i3.

I don’t think everyone should try to get by on 22 kWh like the original i3, but we can find a very useful middle ground like 40-60 kWh for a car like the i3 rather than going to a ridiculous number like 100 kWh that will almost never be used or benefited from.

I’d have no problem with a 100 kwh battery. I find it not ridiculous at all on a large vehicle which could only go 200-250 miles. Unless you want to ban all medium and larger vehicles. Do that and try to get a refrigerator delivered.

All the mainstream BEV compact SUVs are nearing 100 kwh. When larger BEV SUVs are sold, they will obviously need 150-200 kwh batteries.

Unless you crusaders say that such batteries are ‘ridiculous’ and therefore should be positively banned, so say you.

Now if THAT comes to pass, I guess there will only be 60 kwh PHEV large vehicles… Oh well, that’s a better situation than we have now. That way, at least 90% of my driving could be electrified. Whereas right now the only choice for said vehicles is 100% ICE so that eventuality is much better than nothing.

I fully agree with these fool cells logic. They also claim , This will also reduce pollution.
1 small rage car for that day
1 long range car for that day
1 fast perforce car for that day
1 safe heavy car, for that day
They claim, this will certain reduce pollution and I think bankruptcy will not be too far away
Why not just buy the M3 ????

Why not simply leave space to install extra batteries in longer trips that could be removed during short trips? Given that such battery would be used sporadically, it could be built simpler, like without liquid cooling.
Another way to see this is that most people in the US drive around in cars that are much bigger and loaded than they need for their daily drives just because of a ski trip once a year, so hauling the marginal extra weight of bigger batteries is just a little compared to other carry-around-extra-just-in-case-I-need stuff. Even if you could remove half of the batteries for the daily trips, most people would just leave then there.

I’d be willing to have a system like that, but with most people unaware as to how to change their oil or do anything mechanical, the idea of “swapping” high-voltage, heavy batteries opens up a whole list of issues for those without any mechanical or electrical know-how.

Realistically the only way you could do it would be to go to a shop/garage. Each additional battery pack will weigh far more than most people could manhandle themselves, and cost thousands (more than an internal battery because of the connections and casing). That pretty much puts paid to the idea as people will have to go out of their way to rent one, pick it up and pay a charge to get it installed.

The weight should be manageable, if it’s divided into several smaller modules, with wheels and handles… But yeah, that’s way too complex and expensive to be practical.

I think the best solution might be an optional range extender (using either batteries or a generator) that can be attached as a trailer when needed…

Extra big batteries defeat most environmental benefits that were promoted when having small battery EVs in mind. Fanboys will hate it, but it should be obvious that batteries take resources to produce and create emissions before a car is even made.

As low range battery only EVs didn’t get very popular as well, it is hard to find middle ground where it would make sense.

A serial EV-basher is agreeing with an argument that EVs should have smaller battery packs.

That by itself is a pretty good sign that the argument is wrong.

“Rational, logical arguments based on established facts should be judged on their own merits — not on the source of the argument. If you’re judging an argument solely on the reputation or popularity of the source, then you’re falling into the fallacy of the “appeal to authority”.

But that fallacy is a common human failing…”

Who said that? Oh wait….

Except that big batteries last longer, and thus don’t change the environmental impact all that much.

The right size battery is the most efficient. But so are these 5 other FACTS.

All battery packs should be liquid cooled like Tesla for long life. Not like the wilted LEAF with no Thermal Management!! TESLA wins.

Cars should be very aero dynamic. TESLA LEADS and WINS again.

Cars should have at least 2 battery size options. The TESLA model 3 wins again.

Cars should have light weight materials. BMW and TESLA win with carbon fiber, aluminum and steel.

Very Fast Charging should be on all Highways for recharging. TESLA is the only one with this so far.

I do not usually upvote fanboyish “Tesla is best” posts… But this is actually both true and relevant on all points 🙂

“However, if a race for bigger and bigger batteries is left unchecked, EVs doing low mileages could undermine some of the potential benefits.”

Honestly, I don’t even understand why this should be worthy of discussion. Yeah, if you only need an EV that does a few miles a day, then you don’t need one with a big battery pack, In fact, if you use a car only for local, short trips, so you don’t need a highway-capable car, then get yourself a low-speed NEV.

But most people need more flexibility in their cars. People in general don’t buy cars which barely meet their everyday needs. If they did, then they would buy 3-wheel microcars with seating for just one and almost no cargo space. No, people buy cars which will meet something like 98-99% of their perceived transport/ hauling needs for the entire year. They’ll rent a larger truck or a trailer only for rare events such as moving; otherwise they expect their one car to do it all.

So let’s count the ways in which it’s wrong to suggest everyone should buy an EV with a “right-sized” battery pack:

1. A range barely big enough for daily needs means having to stop to recharge on any day when you need more range than your battery pack will allow with a single charge. Not exactly convenient, and how many people would buy an EV if they had to do that?

2. A battery pack barely large enough for daily needs means no “safety margin” for days on which it’s bitterly cold, or for decreased capacity as the battery pack ages.

3. A smaller battery pack loses capacity faster over time… see #2.

4. A smaller battery pack means used EVs will have less range, and therefore less appeal in the second-hand market. This article completely ignores the very large used car market.

5. A smaller battery pack may have to be replaced before the car wears out. A larger battery pack should last the lifetime of the car. A smaller battery pack is false economy.

6. A BEV with a larger battery pack may give the owner the confidence to get rid of his other (gasmobile) car.

Depends where you are living …. in central Europe 90% of daily trips are commuting for 20km and less (distance, so total return 40km) with 1.2 passenger as average. This would require just a small car with 80 km/h (50 mph) top speed and 100 km range.
The rest especially 1000 km holiday trips (one way km) then get a rental family van with lots of baggage space. The German EV producers MB, VW and BMW are offering a few weeks of rental or Big Auto company owned cars included for free in the purchase of the EV.
This would require a paradigm shift thou, away from big “fit all purpose” owned cars to small cars owned for daily use and rent sporadic specialty cars when needed.

Herein lies the problem with averages in this discussion. The “average” distance travelled each day may be 20km, but that doesn’t mean a vehicle with 20km of range would be acceptable. A lot of people may do daily trips of 10km and one weekend trip of 60km, so they’ll realistically need a vehicle with 60km of range, yet their average is 20km… Someone else may not commute by car at all and only do 200+km trips at the weekends, which means their average is also 20km… Most people do more than one longer trip a year, even if they commute, which is where the one large and one small vehicle from each family standard came from. Having to rent out a vehicle 10-20+ times a year would be cost ineffective and waste a lot of time. I’ll use myself as an example. I do around 10,000-15,000km a year, so on average around 20-30km a day. Yet I actually only use my car about twice a week and my average trip length is around 300-400km… Those are two extremes, but most people are in the middle – they commute, but regularly drive a lot further than their commutes as well, so… Read more »

The first three points at least are invalid, since nobody suggested that a “right-sized battery” is one that barely makes the daily commute.

The pollution aspect has been featured in highly regarded scientific journals.
If I was owning a sweet Tesla Model S with a huge battery, I would be polluting more – then if I drove a small ICE vehicle with a small diesel engine. By polluting, I mean there would be more CO2 emitted to the air.

At the moment I drive (privately) very little. About 4500km a year.. and to compare, I use my e-bike about 3500km this year..

At work I drive longer, and there are only benefits by driving the i3.

For people who drive a lot, the benefits of an EV with a huge battery is massive.
It is of course based on global emissions. Locally an EV is always a plus, no matter what.

For a Tesla Model S (can not remember battery size), the distance where it was better then a small diesel car was at least over 15 000km a year.
All taxies for example should be EVs. Everybody that commute a fair distance to and from work should also drive an EV.

For people who drive short distances, it is better they buy an EV that has a small battery.
Even a PHEV could do the trick.

Estimations that take battery production into account, are always very fragile, since there is actually no good data about energy use in battery production. Existing estimates have a spread of a factor of 10 or so…

Looking only at usage, an efficient combustion car will generate less GHG emissions compared to a large EV only in regions with a very polluting grid. In most parts of the USA, even a Prius can’t match a Model S.

This is why we need fully self-driving cars ASAP. You always get the BEV with the spec needed to complete your trip. That means most self driving taxi BEVs will have small fast charging batteries. Highly efficient and low cost.

People are not rational. Having a 100 miles (160km) range could be enough for most usage in town. Psychologically it’s just not enough. You could need to do a longer trip occasionally or you don’t have a private parking with charging facility, so bigger batteries just make sense for these customers (majority of people living in towns in Europe for example.)

When I considered buying an electric vehicle I did a rough estimation of my travelling pattern. By my estimate an 100 km range was enough for 80% of my travels, a 300 km range would cover 99%. Now I am on a limited budget, so in the end I bought a second hand, first generation Opel Ampera. On a single charge I get a range of 60 to 70 km. I own this car since January and I’ve travelled over 16.000 km since. The onboard computer says I used almost 50 ltr of petrol and my estimate is that when the range-extender is working, the economy is about 1:16 (6.2 ltr/100km). Now we can compare my estimates with the real world figures: I’ve travelled over 15.000 km on electricity and about 800 km on petrol. So a range of 70 km is actually enough for 95% of my travels. I do realise that my circumstances may be favourable (daily commute within electrical range, charger available at home and work, no frequent long-distance travel) and not repeatable for everyone. However I think people tend to over-estimate the range they really need. So I tend to agree somewhat with the article. That… Read more »

Crossing the motorcycle with the car is the answer. Such slim vehicles will weight 1/3 that of a standard car. Given high-tech roll cage, crumple zones, and crash avoidance IA makes the vehicle far safer than a motor, approaching that of a small car.

Bottom line, even if EVs fully replace current cars, the environmental improvement will be marginal. We must stop hauling around 4-8 thousand pounds for every 200 pound human.