Think outside the bubble.

I have always known that the SF Bay Area was a bubble, but since moving to Chicagoland, and going about the mundane things in life, this has become very clear. I’m not talking about the perfect-temperature-summer-or-winter and always-sunny weather bubble.   When Mark Twain apparently said that the coldest winter he ever spent was a summer in San Francisco,* I can only assume that he was never in Chicago anytime between November and April.   

No. I’m talking about the show-me-the-next-big-technology bubble in the Nor. Cal. area.   Where every fifth car is a Tesla, every third is a Leaf, and a roof without a solar panel means it has the latest in architectural solar shingles.

I have seen a total of ten Tesla’s in the last 3-4 months in the burbs of Chicago.  Five of them are the same color, so highly possible I keep seeing the same ones again and again.  I have seen a handful of Leaf’s.  I got all excited when I saw my first BMW i3 the past weekend; I now know what a Big Foot sighting feels like. 

The grocery store we shop in has a few slots allocated for clean vehicles.  The first time we drove up there in our Prius, I parked next to these spots, because, in the Bay Area, a Prius is not really a clean vehicle.  I had assumed that these are for the oh-so-many-EVs we have in the road.  Well well well… what do you know?  I see everything except clean vehicles take up those spaces.  I once saw a F150 parked in the slot.  And No. It was not an indie-convert F150 with a 150 kWh battery pack in the flat bed.    I suppose the driver interpreted the sign as being referenced to a big rig. 

We have been house hunting for the last month and as with all home buyers we don’t look at the road when driving, but the roofs of the homes on the side of the road (one reason why we desperately need to move to automated cars).  We have yet to see a roof line that has a solar panel, unless it is hiding somewhere within the folds of the enormous structures that people here call homes.  When we bought our home in CA in 2011, rooftop solar was still a novelty.  But by the time we moved, ~30% of my neighborhood had solar and the number was increasing. 

The difference in solar penetration is easier to understand; with electricity at 9c/kWh in IL compared to 15c/kWh in CA and less sunny days, the economics are harder to justify.  And there is the well-known effect that if your neighbor has solar, you get to understand the technology, get recommendation on installers, tips on using it etc.  Adoption becomes easier with knowledge. The bubble in the Bay Area has certainly helped solar PV.  Imagine the ego boost when you can proclaim that you have more MWh generated than anyone else on the block.  Never underestimate the power of peer pressure. 

CA jumpstarted its solar push using state incentives.  A bill that was recently passed in IL will, hopefully, help in this regard.  And the steady dropping costs of solar will also help.  Solar module prices are dropping like a brick; the latest word appears to be close to 3c/kWh.  Maybe the next 6 years in IL are going to be the same as what I saw in CA when I bought a house 6 years ago; a steady rise in rooftop solar.  Maybe... 

The EV penetration differences are going to be harder to bridge.  So, gas is a bit cheaper in IL, but not by much. The lower electricity cost will certain help EVs.  Driving distances are not that dramatically different.  Yes, the cold weather will kill the range (and damn, is it cold here!) with all the heating needs, but these are trivial differences.  There has to be a deeper reason. 

We all like to think car buying is a rational process involves some sort of financial calculation.  Reality is that once we sit in the car, rationality goes out the window.  The car we drive is a statement about who we are.  I remember years ago, when we had just about gotten a job, me driving thru a fancy neighborhood in a Subaru and commenting to my wife that we don’t belong there.  A few years later, my wife bought a Prius, and we drove thru the same neighborhood and I commented that we still don’t belong there, but no-one there knows it.  This was the mid 2000’s when the Prius was the ultimate leveler:  If you were green you had a Prius, irrespective of your economic standing.  Larry David had one, and so did I. 

A decade later, we have bifurcation in the EV/plug-in market.  There is the “value for money” car (Leaf), the “reliability is key” car (plug in Prius), the “German handling” car (i3), the “driving-range flexibility” car (Volt), and the “I have the green to make a statement” car (Model S).   

These work very well inside the bubble.  But outside? 

I wonder if the bifurcation we need is not the above, but the “this is the next cool thing that happened to mankind” one.  The Model 3 preorders seems to have tapped into this part of our brain (the Model S has this angle, except at a price tag to ensure exclusivity).  A purely economic argument may not be enough.  Rather, we need EV’s to provide the buyer with a lifestyle they want to see themselves in.

In a post last year, I was examining the rise of the 200 mile EV segment and wondering if this will change the pace of adoption.  It certainly will in the Bay Area. But now I wonder if we need more than just the driving range at the price we can afford for adoption in places like my new home.

Not sure the same “imagine yourself sitting here” argument works for home solar (same for solar+storage) in my new neighborhood.  When one turns on the light switch, it works exactly the same whether the electrons came from coal or from solar.  The economics need to make sense.

But I also do think it would help to create a bubble; one that helps breakdown some of the myths around new technologies and allows familiarity.  Worked for the Bay Area. May work in the burbs of Chicago.

If only we had a nucleation point for this bubble (pun intended).  Maybe someone who thinks about energy, thinks about adoption of new technology, thinks of themselves as a first adopter, and is looking for a new home wherein solar can become part of the solution?  

Did I mentioned that I was in the market for a new home?  And that Prius does look a bit beaten up.    

 

Venkat

* Snopes tells me that Mark Twain probably did not say anything like that.  But as I have pointed out before, I feel that facts just get in the way.    

Batteries: a technology that never gets old.

The New York Times rarely talks about my favorite subject, but when they do, I feel the need to spread the word (I hope their servers can handle the traffic this plug is going to generate). 

This article is about John Goodenough, who invented a key material in the battery that powers pretty much every device we own.  He then went on to invent a few more of these materials. 

I have been known to be rather distressed by the fact that he has not gotten the prize yet.  I suppose discoveries that have changed the way we interact with the world don’t typically qualify.  Rather, the prize is reserved for ones that appear to show enormous promise to change something sometime in the distant future, continue to show said promise for three decades and will continue to show that promise for three more.  Buckeyballs anyone? 

Prof. Goodneough is now in the middle of a controversy with his recent paper where he claims a new way to think of how energy is stored in a battery.  I’m ambivalent about blogs and news reports suddenly trying to be scientific journals.  I think the scientific method of reproduction, verification, peer review etc. should be followed.

Irrespective of the controversy, Prof. Goodenough is a legend.  You can read more about his deep intellect here. 

Also, if you are feeling old, the Times article is a real picker-upper.   Maybe I do have hope and will find the next breakthrough.  I do have the formula dialed in!

Venkat

p.s. For all seven regular readers, I do know that I have been AWOL from blogging.  Hoping to change that.   

Tips on extending battery life; from a battery guru.

Probably best to get this out of the way right upfront: The battery guru referred to is yours faithfully.  Sorry to disappoint.  

Regular readers of this blog (all seven of you) know my rather famous (!) blog post titled “Battery rules”, where, inspired by Michael Pollan, I penned a poem that went,

Don’t charge them too high

Don’t swing them too wide

Keep the temperature low to extend their life.

This post was a follow on to my other tremendously popular (read:  eight total views) post titled “Pull the plug.  Your battery will thank you.”  The posts were meant to provide an understanding on why Li-ion batteries fail and how one can use this understanding to extend the life of batteries.  

Just to be clear: These rules are for Li-ion batteries; for phones, laptops, cars etc.  Not for other kinds of batteries.  And not for every Li-ion battery known either; but the most popular ones.  

The reason’s for these rules are simple.  Li-ion batteries don’t like to be at the top of charge (because of side reactions that consume lithium).  They don’t like being charged and discharged completely (because of the volume change associated with moving a lot of lithium back and forth and the associated stresses).  And higher the temperature, more the side reactions that impact battery life. 

When the blog post was written, the whole fast charging of batteries was not a big deal.  But now, we are seeing more and more emphasis on this.  Fast charging can also be bad.  More on this at the end of the post. 

The simple statement “Pull the plug” was really a way to implement the 1^st rule “Don’t charge them too high” without much thought.  In other words, don’t use your laptop like a desktop and keep it plugged in.  All. The. Time.  This only makes the side reactions worse.  Stop charging.  Let the battery discharge a bit. 

Every time I walk into a meeting and see the inevitable dive under the table to find the charging plug, followed by attaching the charging cable to the Mac laptop, only to see that the charging light is green, my blood pressure increases.  I then go thru the sermon explaining why they need to pull the plug. 

They comply.  For 15 mins. After which they are back to plugging it in.  Blood pressure increases.  Cycle repeats.

And No.  No real breakthroughs have occurred since the post that makes the rules obsolete. 

Clearly, the rules are not working.  I’m sure it is not the messenger (?).  I’m sure it is not the message.  So it must be the way the message is delivered. 

So this post is battery rules redux.  I will explain how I charge and use my battery.  Hopefully, this gives folks a sense for how they can maximize their battery. 

My track record:  I have a computer that lost 4% capacity in 2 years.  I have a phone that lost 5% capacity in 2 years.

In this post, I will focus on the phone and how I baby the battery.

First some basics:  On any typical day I only discharge my battery around 30-40%. There may be an occasional day when I will discharge the battery by 70%, but those are rare.  In other words, I could use my battery for two days without needing to recharge it. 

If my usage seems rather minimal, it is not (although I never got into the pokemon revolution).  Rather it is because of two attributes that many of you probably share. 

First, I have an iPhone 6 plus (the YUGE one that does not fit in any normal size pocket).  This means that the phone has a pretty large battery.  And although the screen size is larger, the bigger battery more than compensates for the power draw of the screen.

Second, the operating system on the phone, iOS, is very battery friendly.  I moved to the 6 plus from an Android phone (with, I believe, the KitKat version).  That phone had to be charged after an eleven hour day, despite having a reasonably large battery.  It would drain 5% of the battery capacity every hour, even when the phone was, supposedly, idle.  iOS appears to lead to less battery drain, especially during rest.

Based on my usage profile and the attributes of my phone, here is what I do:

- I charge my phone in the evening close to when I’m about to go to bed.  My battery is around 40% state of charge (SOC).  I charge it to around 80-85% SOC.  Takes me ½ hour or so.  I don’t agonize over the exact SOC, I pull the plug when I remember to. 

- I sleep and when I wake, the battery has lost maybe 3% of so of its capacity (No. I don’t sleep for 1 h.  I sleep the normal 7 h).  I don’t plug it in. Rather, I go about my day, make calls, check email, listen to podcasts, etc.   I use the phone as much as the next person.  When I get back home I’m at approximately 50% SOC and a couple of hours later, when I’m ready for bed, at 40%.  I repeat the charging cycle.

In effect, I don’t let the battery charge too high.  I don’t let it swing too wide.  In other words, I follow my rules.  I don’t leave it charging all night (i.e., where the battery is fully charged a couple of hours after we hit the bed and is sitting at the top of charge for the next 5-6 hours).  I don’t discharge it all the way down each time before charging it.

- When I feel like my day may be particular long with a lot of phone use, which for me typically means I’m on travel, I charge the phone upto 100% SOC, typically in the morning before the day starts.  Meaning, it is fully charged, but is not sitting at the top of charge for hours on end. 

- Every few months, when I’m not on travel and have a predictable week, I fully charge the battery and drain it down all the way before recharging it.  This should allow the phone to calibrate the SOC by performing a discharge capacity check. 

This may sound counter intuitive:  I have a battery that should last 2 days.  But, I choose to charge it every day.  In effect I’m racking in cycles, twice as fast as I need to.  Is that not bad? 

I would posit that it is not.  The number of times the battery is cycled has to be put in context of the SOC that the battery swings, and how much time it spends at places where side reactions can dominate.  We know that batteries can cycle 300,000 times (yes.  Three hundred thousand!) when the SOC swing is kept rather small (say 3%, like what occurs in a hybrid electric vehicle).  In these situations, the calendar life of the battery (i.e., how many years it lasts) is more critical than the number of cycles.

As we widen the SOC swing, the battery life decreases.  The worst is fully charging and discharging the battery.  Even worse is going to the top of charge where we have side reactions.  My scheme minimizes the time spent at the top of charge, without overly swinging the battery. 

And it keeps me on a reasonably manageable daily schedule for charging without having to think too deeply about it.

Frankly, it would be better for me to charge the battery upto say 50-60% SOC and let us drain down to 10-20% each day.  But, that, to me, is living dangerously.  Having that extra 20%-30%  of buffer capacity gives me peace of mind (What if I get lured into Pokemon Go on my way home?).

Irrespective of what phone you have, and how you use it, the two rules (don’t charge them too high and don’t swing the too wide) will help you.

As far as the rule to keep the temperature low, I don’t keep my phone on my car dash where it is hot. My phone happens to be sitting somewhere in front of the air vents, which helps during summer.  I don’t keep my phone on hot metal tables in summer. 

I have been known to go so far as to contemplate living in frigid conditions just to avoid the high temperatures in some parts of the world.  Talk about taking ones job seriously… 

Now for the whole fast charge issue. 

In my blog post titled “The Hero with four faces: Part 1” I explored the question of fast charge and the issues surrounding it.

Short summary:  Lithium can plate (which makes the battery go boom).   If you swing the SOC too much and too fast, you can break the particles (although this may not be as big a deal as folks think it is).  And the battery tends to get hot when charged fast , violating the rule to keep temperatures low. 

Turns out that one does not want to go too low in temperature either.  We know that lithium plating is much more of a problem at low temperatures; i.e., Golidlocks effect. 

Of these, lithium plating is the one to avoid at all cost; the rest only degrade the battery and are not dangerous (unless the battery really starts to cook).  All it does it kill the battery capacity rapidly, which, for a device that one changes every 2 years, is not really a big consideration.

Having said all this, the phone maker meters in the charge from the charger.  Meaning, just because you get yourself a beefier charger does not mean that your phone is going to accept the charge.  The phone maker is supposed to watch out for the battery. 

But there is a push to use fast charge as a differentiator in consumer electronic devices.  This means is that unless the company is performing some sort of smart charging to avoid the problems above, the battery is probably not going to do well. 

So, unless you hear it from this blog, best to avoid fast charging your phone. Assuming your phone maker gives you such an option. 

In the meantime, assuming poems are not your thing, can I remind you all that that friends don’t let friends keep their batteries plugged in.  So, be a nice buddy, and ask your neighbor to pull the plug. 

Venkat