Hacker News new | past | comments | ask | show | jobs | submit login

Why don't electric cars use replaceable battery modules with a standard form factor? Advantages would include:

1) It allows the battery to be easily replaced as the car gets older.

2) With a suitable generic form factor, it would allow batteries to be upgraded as technology changes.

3) It would allow people to only populate enough battery slots for their daily needs. Communing to work: you only need to insert a few battery modules. Going on a road trip: you can buy/rent extra battery modules and populate every battery slot.

4) Matching battery capacity to the task at hand is also safer, as there is less energy in the system in case of an accident.

The manufacturers may be using batteries as built in obsolescence or differentiation, but surely there is enough competition for someone to break ranks and build a car with some modularity. It could stimulate sales by giving people confidence in the battery, the weakest part of an electric car. Maybe Framework should start building cars as well as laptops?




Some manufacturers actually do this. NIO particularly does this at scale in China and I believe they are starting to expand to the US and the EU now as well.

But the reason that this is not a thing are that most of your assumptions as to why that would be a good idea are probably wrong.

1) Batteries outlive the vehicle. Not always but on average they do. There are plenty of first generation EVs that are more than ten years old now that still work fine with their original battery. And the batteries in the newer ones are far better than those first generation ones.

2) Replacing the battery is actually not that big of a deal technically if it needs to be done. It's a bit costly but otherwise just a routine maintenance operation that can be done in a day or so. There are of course lots of older EVs with lots of miles that have had a battery replacement at some point to get a second life.

3) most people are a bit irrational about how much battery they want vs. what they actually need. The reality is that most people end up being perfectly happy with a modestly sized battery. Charging infrastructure is rapidly improving and mostly you only need it when you go on longer journeys. My father has had an EV for one and a half year. With the exception of their summer vacation a few months ago, they never use any chargers other than the one at home.

4) Battery safety is just fine. Yes there is the occasional battery fire. But it's far less common that ICE vehicle fires. There are a few hundred thousand ICE vehicle fires in the US every year. And unlike with battery fires, fatalities are very common. Hundreds per year. Unlike batteries, petrol burns fast, hot, and explosively when it burns. Modern batteries are a lot safer than the first generation ones. Manufactures test that by crashing vehicles, shooting at the battery, puncturing them with nails, etc.


Isn't there something wrong to you if a "routine maintenance" takes a day?

The whole thing makes me think of home renovation, apparently the majority of landfill is cast-off material because re-use isn't a consideration.

I don't think "most people" arguments are great. People want freedom and flexibility, they don't want to have to sell their car and buy a new one if their conditions change.

I hope the first mainstream car in my market that takes a very modular approach wins out. In fact imo there should be regulated form factors, since the impact of these things at scale is huge, and I doubt battery recycling is that efficient.


Something that happens zero or 1 time in the lifetime of the vehicle is not "routine maintenance".

And if you haven't had maintenance on a gasoline powered car that lasted more than a day I would wonder if you've ever owned a car?

Every gas car I have had has had several maintenance issues that took a day or two and the dealer had to give me a loaner car.


The comment I am replying to called it "routine maintenance."

With this attitude (it can always be as bad as it is now), when will the change be? Never.


> I doubt battery recycling is that efficient.

Lithium recovery from battery recycling is in the 80-90% range. Sounds pretty good to me, but draw your own conclusions.

* https://www.kedglobal.com/batteries/newsView/ked202307310010...


Recovery is just one factor, there is often a lot of overhead in use of chemicals, labour, etc. The more they are designed for this process, the more sense it makes, that goes along with modularity.


Because batteries last hella long and it's not a particular concern. Nobody's going to be ad-hoc adding or removing batteries in the floor of the vehicle when a longer trip comes up.

Besides, the technology is seeing rapid iteration of cooling systems and integration with the rest of the vehicle (like structural battery packs). This is not the time for such standards.


>Nobody's going to be ad-hoc adding or removing batteries in the floor

But, some do swap batteries?


I am not sure there are many people who want to swap out batteries when they weigh over 1000 pounds. Inserting a battery would require something to help carry and insert it which makes it have enormous user friction which makes it a non starter for most people. Not many people even want to swap out phone batteries despite those batteries being easy to carry.


Not the entire battery. Something in between an individual cell and an entire battery. Small enough to provide practical manual handling and some granularity in total capacity. Big enough that a reasonable number of them add up to a full battery.

Maintenance would be similar to cars today, in that those who change their own oil might be inclined handle their own batteries, whilst those who get a mechanic to change oil might get a mechanic to manage their batteries.

If batteries are cheap enough and long lived enough it's not an issue, but right now battery cost and longevity is a limiting factor. Not everybody replaces their car after a few years. The average car age is over 10 years [1], so there are plenty of cars out there much older than 10 years.

Maybe that's what is behind the sales growth slowdown? Those who replace their cars regularly (fleets) and don't care about battery longevity, are buying. Those who keep their cars for longer are hesitating, limiting the market.

Edit:

It seems like EVs already use a cell/module/pack hierarchy [2]. There's hope yet, if a particular module type emerges as a defacto standard.

[1] https://www.abs.gov.au/statistics/industry/tourism-and-trans...

[2] https://www.secondlife-evbatteries.com/collections/ev-batter...


You are probably thinking about the whole battery. But if you consider that it can be split into multiple modules, the weight of a module will not be that big.

Benefits of such design will be: * lower operating weight since you wont need many modules for short trips * lower registration weight of a vehicle * the tires and road won't be damaged as much * one can swap modules at gas stations instead of charging and waiting * and the modules can be used as part of a house battery

In fact there is an european startup for microcars https://www.helixx.tech/ where they explore similar idea.


People also don't want to swap their own engines or transmissions, but shops will gladly do it for you. I don't think that the need for specialized equipment is a good counter-argument - plenty of car repair tasks require specialized tools.


10 years ago: "Better Place" burned through about $1B trying exactly that.

Today: "Nio Power" has gotten a lot further, with more cars and a chain of robo-garages to do the swap in a couple of minutes.

(Still a single unified module, but it's not clear anyone needs to manage several-hundred-pound modules just yet, maybe when it scales a bit more...)


I'm not thinking that battery replacement would be seen as a way of recharging or be done on the road. It would be infrequently done, when a change in capacity/technology is required or the module is worn out.

The interface specification could go beyond the electrical, including things such as heat removal.


Related Tom Scott video:

"A robot just swapped my electric car's battery" - https://youtu.be/hNZy603as5w


As mentioned in the video, building these stations is expensive and the company building them (Nio) is losing massive amounts of money.


Then again, Tesla was also losing massive amounts of money while it scaled up its infrastructure initially.


They probably use stanard cells. However modules don't make sense as they need to pack cells where they fit and that goal sit in conflict with a standard module.


Because it wouldn't save a meaningful amount of money over the life of the car, but it would make developing and manufacturing them significantly more expensive.


Last time I tried to do the math, the heaviest battery a normal person could hoist into place would only give you about 15 miles of distance.

And that was up from the previous time I did the same. We need about double the power density before this becomes interesting.




Join us for AI Startup School this June 16-17 in San Francisco!

Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact

Search: