[user_7832]

+1 for battery university, they're an excellent source. Does anyone have any other suggestions for similarly technically deep (while approachable) articles on any other facet consumer electronics?

My understanding from this article is that:

1. Charge the battery to as low a max percentage as possible (till about 65%) 2. Keep it as cool as possible (up to zero degrees C at least) 3. Use it as little as possible before recharging it (minimize charge-discharge bandwidth)

Aka, over-rate and over size the battery if you're building the device, and minimize extremes on any side of soc (state of charge).

Do EV manufacturers use any other tricks not covered by this?

(Of course, use the device as needed, these are just guidelines for the best perfomance.)

[stavros]

I don't think this advice is useful. You're going to use your devices, so you won't control the temperature or, largely, the charge percentage.

I think good advice is to keep your devices as cool as you can (ie don't leave your cars in sunlight when there's shade), which you probably did anyway, and keep the battery between 20% and 80% as much as possible. If the battery is going to stay unused for a while, leave it at 3.8V (or close to it), or at 50%.

Batteries are ultimately consumables, so don't stress too much. Just care for them as much as convenient, and that's it.

[VorpalWay]

> I think good advice is to keep your devices as cool as you can (ie don't leave your cars in sunlight when there's shade),

In some climates, such as where I live, the larger issue is the cold in the winter. From what I understand, Li-ion batteries don't like being charged below 0 C. And it is not uncommon for it to dip to -15 C or even -20 C here.

Really, from what I understand, batteries want to be kept above freezing but cool. So yeah, don't leave it in direct sunlight in the middle of summer. The more difficult problem is the winter (unless you happen to have a heated garage).

[stavros]

Yeah, they lose capacity temporarily when it's very cold. Most EVs now precondition the battery before charging by heating it up.

[user_7832]

> You're going to use your devices, so you won't control the temperature or, largely, the charge percentage.

> I think good advice is to keep your devices as cool as you can (...), and keep the battery between 20% and 80% as much as possible.

Yeah that's kinda what I meant. Where it's easy or possible to do so (for eg lots of modern laptops & phones allow charge limits), it's better to follow these guidelines.

> Batteries are ultimately consumables, so don't stress too much. Just care for them as much as convenient, and that's it.

Yeah I agree (and that's what I meant by my last sentence), however, a lot of people (including eg my dad!) end up having battery issues while being unaware that they can do things to protect their hardware.

For example, my phone has enough capacity to last the whole day even at 60% of it's capacity. I've set it to stop charging at 80% (the lowest possible SOC) for this reason. On my laptop, I frequently reduce it to 60% as I use it plugged in.

> I don't think this advice is useful.

I'm afraid I don't get what's not helpful? We're probably talking across each other.

[stavros]

It came across to me as "keep your batteries always under 0 C", which obviously almost nobody can do, and it leads to a sense of "eh, I won't go to these lengths, might as well do nothing", which is counterproductive.

I see the same reaction with healthy eating, where people are so put off by extremely militant advice that they think "I can't eat only vegetables all day, fuck it, I'll eat these three cheeseburgers".

I agree with your second comment, the first one just could be misconstrued as very hard-to-follow advice.

[Filligree]

That's backwards. At too low temperatures batteries start to take damage during discharge or (especially) charge, so 0C is the lowest temperature at which you should charge it. 5C would be better.

It's a concern mainly for e.g. offgrid batteries being used in the winter.

[stavros]

I know, but "as cool as possible (up to zero degrees C at least)" is conflicting, and kind of means "below zero degrees".

[averynicepen]

Degradation is driven by many things, but a big one is heat. Elevated temperatures during both charge and discharge is very bad for battery longevity. To manage this, almost all EVs use liquid cooling, with a cold plate directly contacting as many battery cells as they can to move heat out of the battery. This coolant is then cooled by a radiator, an AC chiller, or both.

The worst temperature abuse case is DC fast charging, aka Supercharging, where high current charging creates tons of heat due to resistive losses. This is why frequent fast charging causes faster battery degradation, but ordinary charging and driving does not, because the coolant loop is sized for the DC fast charge heat transfer requirements.

Besides removing heat, adding heat into the system is also desirable. Cold weather environments approaching freezing or below is also bad for battery longevity, and more importantly, terrible for range. Resistive heaters are super power hungry, and to heat the battery coolant loop requires power from the battery. This is why, conventionally, EVs are terrible in cold weather.

> Do EV manufacturers use any other tricks not covered by this?

And now, onto the magic trick.

Heat management is so important to both the driving range and the longevity of a vehicle that EVs have moved from traditional resistive heaters to heat pumps. These magical thermodynamic devices can move heat from anywhere, including drawing heat out of cold ambient air.

When you combine that with a valve design that allows the heat pump to access the battery coolant loop, the motor drivetrain coolant loop, the cabin coolant loop, the vehicle computer(s) coolant loops, and external ambient temperature, you can have a super efficient system that shuffles heat where it's "wasted" to where it's "needed".

Tesla has an excellent video briefly covering their heat pump and their very clever Octovalve design: https://www.youtube.com/watch?v=DyGgrkeds5U

For more depth, this video covers the heat pump and the ~22 different sources of heat it can draw heat from: https://www.youtube.com/watch?v=Dujr3DRkpDU

[HPsquared]

Light bulbs (including LEDs) are similar. If you use them at slightly lower then their maximum rating, things tend to last a LOT longer. The "Dubai lamp" uses this concept - oversized LEDs that are derated, and last a very long time (100k hours). You can do the same by buying oversized dimmable LEDs and simply turning down the brightness.

[butvacuum]

That doesn't help nearly as much as reducing the current through them. And, PWM doesn't change the lumens per watt at all.

[SV_BubbleTime]

> Do EV manufacturers use any other tricks not covered by this?

Automotive EE here. EV aren’t ready for world wide use. That statement is constantly ignored by people in California who see zero issues with their new expensive fancy cars.

Shortest version… The heating and cooling systems of the battery are there to prevent damage. BUT… who powers the heating and cooling systems? The battery of course.

In a traditional or better yet a plugin hybrid, you can use the gas engine to control how much electric you are using in conditions that would be harmful to the battery. In EV vehicles you have no choice. The car won’t tell you “you can’t drive right now”.

The marketing of EVs was a mistake, and every mfg is paying for it. Ford taking a 2 billion write off this year on their EV line and canceling a lot of their vehicles.

They will be cool, but this generation makes a great second vehicle or town vehicle. Absolutely not an extreme weather highway vehicle.

[s-y]

Are you a technician or an engineer? And as a follow up, what part of the vehicle do you engineer?

Because this sounds a lot like a case of a dentist seeing a lot of cavities and making conclusions that teeth are "bad tech".

I live in a climate that's in yearly flux from -20 to +35 C and EVs have been normal here for a long time(7+ years) with no major issues. What parameters and therefore regions does your statement cover? I'm sure you can't run an EV in Syberia(RU), but people with petrol cars there have to run them even parked to avoid freezing during the winter so there will always be extremes.

As for the commercial equation: BYD and Tesla don't seem to be fitting that narrative. So this is not a matter of a marketing mistake - but an overall execution on the failed manufacturers.

[SV_BubbleTime]

Engineer. I started in core competency groups, worked on powertrain integration, and now, I’m a specialist. I roam around and put myself to use wherever needed. I’m now a consultant but I have badges for idk, maybe 20 facilities.

[knowitnone3]

Sure. You're a "specialist" but roam about doing anything and everything? That's the complete opposite of a specialist. I'm a networking expert but I just roam around fixing computer issues just like a basic tech.

[bahmboo]

I don't see anything in your comment history that would indicate a strong engineering role. Mostly political engagements really. You haven't said anything useful on this thread regarding TFA and it's content. Listing your credentials while making obviously false and dismissive statements is not good faith discussion.

[SV_BubbleTime]

lol… “I checked your post history and made bad assumptions” is the most Reddit Detective vibe I’ve ever seen outside of Reddit :D

You own an EV right?

[s-y]

I'd have to agree with the "Redditor Detective" here. I've asked you a lot about your statements and all you basically said is "i know shit".

The redditor comment here is sort of a projection. Kind of like ..a redditor mod.

[ninalanyon]

They seem to be working just fine here in snowy Norway.

[kuerbel]

...what? You leave your car plugged in, and that's it. Then the BMS will take care of the battery without having to use it's energy.

If I preheat the car it also preheats the battery. If it's not warm enough it won't allow full recuperation. Oh my god, I have to use THE BRAKES for a few minutes, literal trash car.

And all those people in Norway, you know, with their heat pumps and EVs. Obviously life just grinds to a halt there every winter. *dramatic eye roll

[SV_BubbleTime]

Cool. And when you need to drive it? Most systems do not keep the battery heater running indefinitely.

No one is talking about the brakes.

I’m an automotive engineer that has worked for two of the big4. What is your experience?

[ninalanyon]

> And when you need to drive it?

When I need to drive me EV I open the door, get in, close the door, put it in drive and drive off.

Were you expecting something different? I'm in Norway by the way where it is expected to be -15 C in a few days; after eight years of EV driving (2015 Tesla S 70D) I am not anticipating any problems.

> What is your experience?

I've told you mine, what's yours? Or will you argue from authority again?

[kuerbel]

driving an ev for the past 2.5 years with 97% SOH remaining. So I must be doing something right wrt treating the battery nicely. And I don't have a garage, it's outside most of the time. I drove thousands of km in subzero C temperature.

>Cool. And when you need to drive it? Most systems do not keep the battery heater running indefinitely.

I get in and put it into drive. When it's cold, I preheat it, I can program departure times, so the battery is conditioned and the cabin warmed in advance. Even at sub-zero temperatures, it always starts reliably, unlike a diesel engine, which, as you know, requires preheating and can struggle with extreme cold starts. Also requires winter diesel.

[pengaru]

How is this not an instance of "perfect is the enemy of good enough?"?

[user_7832]

Honestly in this situation, hybrids (ideally of the plug in variant) are the "good enough" thing when you're shifting from ICE.

Shifting the easy 70% first gives a very nice boost, and the rest can be cajoled/fed hydrogen (if it matures by then) etc over time.

[SV_BubbleTime]

Depends.

I have a vehicle in my personal shop right now. It needs a new battery, it is effectively totaled.

The battery costs more than the vehicle.

The effort for me to replace the battery modules (not even the cells inside of them) involves taking the entire suspension out, and then, you have the ACTUALLY FATAL issue of working on the battery pack. You need 1000V+ gloves that expire every six months, composite ratchets and sockets, and for me high voltage certification.

There is nothing on an ICE vehicle that can kill you while working on its parts.

I will be downvoted by people who need (literally) to defend their purchase. Always am on this topic.

[user_7832]

> EV aren’t ready for world wide use.

Fully agree (I'm 100% team PHEV or EREV/REEV) as a mechanical engineer. IMO BEVs and PHEVs/REEVs should be on parity in terms of tax/govt incentives, while encouraging electric use - for eg, subsidized (PH)EV charging, high(er) costs in city centres if running in ICE mode, etc.

I was just curious if EV manufacturers use any other tricks that're "well known" in EV-land but not for the average consumer.

[simulator5g]

These acronyms are a nightmare, what the hell is a PHEV? EREV? PZEV? Consumers are just expected to know this stuff somehow, it’s nuts. Sometimes I buy parts for my car and just hope I selected the right one, because some models are PZEV/not PZEV but the sticker that would tell me has turned completely white & can’t be read.

[user_7832]

> These acronyms are a nightmare, what the hell is a PHEV? EREV? PZEV?

PHEV is the old term, it's a plug in hybrid EV. I.e., you can plug it in and use the battery, or use the ICE engine via petrol (gasoline).

(B)EVs are pure battery EVs. Think Tesla.

REEV/EREV is range extender EV. Essentially an EV that has a small ICE engine that's very handy for making the 50 or 100km battery "run" for 500km if the need arises, by using the ICE as a generator.

In some countries, you also have "strong" and "weak" hybrids - these are not cars you can plug in (they only take petrol), but they use some motors and battery to vastly improve the efficiency of the engine. Think doubling your mileage levels of good.

> Consumers are just expected to know this stuff somehow, it’s nuts.

Yeah no I don't think that's good design either. May I ask what kind of parts do you buy that makes it so confusing? Our car (Honda) has a very simple model name, there's not a lot of variations or options to confuse to begin with.

Btw, if you want a real fun doozy, look up the parallel series hybrid system that iirc GM had. It was a beautiful beast - it could basically take any power source, and do anything with it (charge battery, run wheels etc). There's a good YouTube video on it if you search for it.

[simulator5g]

Whenever I buy parts for my regular gas car the parts site asks if it’s PZEV or DOHC. To make matters worse the PZEV version is also DOHC (dual over head cams) as far as I can tell. And the VIN number doesn’t say if it’s PZEV or not. It’s not on any of the paperwork I got with the car either.

[user_7832]

Ah, I see.

I googled PZEV, and apparently all it means is that it isn't releasing gasoline vapours - other emissions don't matter.

So it's essentially just an ICE engine car that's not super polluting. It has nothing to do with EVs apart from being misleading in its name (perhaps on purpose?).

[fragmede]

Consumers just take their shit to the dealer which hires technicians who job it is, literally, to know "what the hell". If that is too complicated for you to figure out, I can't recommend you do your own work on your car.

[kanbankaren]

AFAIK, they charge only to 4.0 V. I think the batteries on satellites are also charged only to 4.0 V

[user_7832]

Thanks! That's very helpful (and unsurprising) to know. Any idea if satellites use LTO batteries btw? They have much longer lives and apparently can tolerate much more abuse.

[user_7832]

I don't know why I'm being downvoted, but I live in a developing country where the tailpipe emissions from a modern well maintained car are literally cleaner than that of commercial (power) plants - potentially making EVs worse. Ofc I'm sure it's much nicer if you're in a 1st world country, but unfortunately that's not where I am.