How to charge your cell phone in seconds instead of minutes

From phone on plane...
Brainstorm only no links.

I came back around to this why studying for interviews. I was reviewing the difference between Watts and Volt Amps (same thing really... Just one emphasizes the factors to respect individual current and voltage limits) - anyhow...

Long ago a non-paying customer requested a "quick charge box" that he could plug into a standard NEMA 5-15 to charge a cell phone auxiliary pack as fast as possible.

You may be wondering why this does not exist.
It is possible, easy really, but it requires some understanding.

We will use round numbers for this and assume the following:

* Wall can provide 1kw continuous, About 100V and 10A
* Cell phone battery is about 10wh
* Some modern lithium can charge at 10C
* 1Ah is about the smallest high C charge rate we can easily obtain.

The reason we need to respect VA is due to voltage charge limits and current charge C-Rate Limts. A cell phone is say... 4V @ 2.5Ah, 1C or maybe 2C... Possibility 3C. At best that is a full charge in 20 minutes. I wish to lower that by an order of magnitude.

10wh...

To collect that much in 6 seconds with a 1S battery would require 250A charging
(2.5A for an hour @ 4V... So... 25A for 6 minutes)
(That's 250A for about half a minute)
That equates to a 100C charge rate btw... Which is not yet currently possible.

We can draw the 1kw off of a plug.... But extreme buck would be required to turn the 100V 10A into 4V 250A... not reasonable at all.

So... Since we are keeping the mind busy and productive... Let's work orders of magnitude for the trivial solution.

If we increase our battery voltage to 40V we would need only 25A
If we run a 100V battery we would need only 10A for less than a minute.

Proof:

We need to transfer 10Wh
100V @ 10A transfers a kw in an hour, 100wh in 6min, and about 10wh in under a minute.
There is no shift required in voltage... A simple full bridge rectifier would do it.
One would need to rail current to 10A, peak and average

By using a very high voltage battery you can overcome C-rate limitations.
By matching battery voltage to Maine power you can significantly simplify and lower charger cost.

You would need a BMS on this 24S 1Ah brick... But it would be very compact overall... About 1/8th the size of a standard 24S 10Ah ebike pack.

Charger would be fanless solid state meant to run only 30 seconds and get hotter than hell.
Charger would be the ugliest form of feedback CC with huge ripple

We would incorporate a 5V USB adapter... To slowly transfer energy to the phone.

30 second full charge for a smart phone.

To make it worth the investment... User has 100X capacity margin for those times when more than 30 seconds are available... Meaning ... You could easily store 100 cell phone charges in the pack... So 100 days inn the road without a charge.

Ok - so we only accepted 1Ah due to C rate limitations, wall standards, and availability.

What if we did it with ultra low ESR caps... And only 10wh worth?

100V * C/3600 = 10wh
360F of 100V low ESR?
Meh... can't be right.

Ok, nap time.
All I smell is half chewed peanuts and stale farts.
Even SJO main lobby smelled like hot farts are 5AM this morning...

Final Answer?
In the not so distant future we will all be carrying at least 100Wh on us at all times so don't worry about it. Capacity will just be required to maintain our trajectory (picture goggles... And people zoned out everywhere... Or at least augmented glasses... It's coming FAST, it will be).

And who does not want a 70,000 lumen LED flashlight to blind bad guys???
(Make a good directional stun weapon)

-methods

I can see this working with ebikes etc but a mobile phone at 100vdc would be deadly if operator error occurred the potential electric shock death risk is much greater than a lithuim burn or explosion.
And one mofe point, As we charge the cap the potential difference in voltage decreases so the charge time increase so the one minute math wont work with general practice when we take into account how they behave when charged.
I know this is for 16 years old but I'm not taking the piss it is fairly advanced for basics to give you an idea of the math you had a good stab at it mind.
http://www.schoolphysics.co.uk/age16-19/Electricity%20and%20magnetism/Electrostatics/text/Capacitor_charge_and_discharge_mathematics/index.html

But the whole reason we use lithuim today rather than caps is the area under the graph is weak towards the end of discharge caps give great instant bursts while lithuim batts give good discharge throughout the cycle.

We did a demo a while back to show that we could charge a cellphone battery in 90 seconds. Worked fine, although it was a very specific battery (A123 cells that could handle 50C.)

You can buck down approximately any ratios for no added losses. Including bucking from 110vac to 0.5v or 4v or whatever. If the bucking inductor magnetics have approximately the same copper fill it will buck at approximately the same efficiency (really high efficiency either way).

If you have a string of cells in series, or a string of cells in parallel, you have no difference in the rate the cells can be charged. It would just add losses and bulk to the phone side of needing to buck down from above 4.2v to the <0.7vdc modern phone processors use.

My Sony XZS uses USB C (aka, USB 3.1) to request 1.7A at 12vdc, which it then bucks down inside the phone to charge its 4Ah cell at ~2-3C when it's SOC is very low and the cell has plenty of anode space to support the diffusion rate needed for fast charging, then as it goes to a higher SOC it ends up dropping below 1C to preserve the cells.

Existing USB C charge protocol goes to 20v at 3A for 60W of charge power delivery available today to phones, but it's the battery power charge limit not the chargers or infrastructure holding them back on charging harder.

Before my current phone, I had an LG g5 with fast swappable batteries. That felt like a real solution, and I would rarely even bring a charger for weekend trips and business trips, because carry a few extra charged batts in your pocket takes up less space than a charger and let's you swap to 100% full in about 20sec.

Ianhill said:

I can see this working with ebikes etc but a mobile phone at 100vdc would be deadly if operator error occurred the potential electric shock death risk is much greater than a lithuim burn or explosion.

The point is to make a black box that will charge at 1KW with minimal components for use to *charge* a cell phone.

And one mofe point, As we charge the cap the potential difference in voltage decreases so the charge time increase so the one minute math wont work with general practice when we take into account how they behave when charged.

Hook up a power supply with a 100A limit and see that in practical application it will charge at over 10A even when the voltage is near equal hence the need for a Constant Current feedback limit. Your talking about how a capacitor behaves in the time domain. In my example you could parallel many high impedance Super Capacitors and achieve the same 10KW fast charge in a much smaller and lighter package than Lithium. We only need to store 10WH.


I know this is for 16 years old but I'm not taking the piss it is fairly advanced for basics to give you an idea of the math you had a good stab at it mind.
http://www.schoolphysics.co.uk/age16-19/Electricity%20and%20magnetism/Electrostatics/text/Capacitor_charge_and_discharge_mathematics/index.html

But the whole reason we use lithuim today rather than caps is the area under the graph is weak towards the end of discharge caps give great instant bursts while lithuim batts give good discharge throughout the cycle.

Click to expand...

Yea sorta... charge is charge and if I discharge it at a constant current or constant power then I am going to extract the WH from the carrier. The step down from 100V to 5V will negate any decay issues. -methods

billvon said:

We did a demo a while back to show that we could charge a cellphone battery in 90 seconds. Worked fine, although it was a very specific battery (A123 cells that could handle 50C.)

Click to expand...

Nice

Love to hear how many times you could do that and what the effects on the battery would be.

-methods

methods said:

Love to hear how many times you could do that and what the effects on the battery would be.

Click to expand...

These were LiFePO4 batteries optimized for a pretty punishing EV application (Formula 1 vehicle regen braking/acceleration assist.) We were operating them at much lower discharge rates and temperatures that they were designed for, so I have a feeling they will last a very long time.

liveforphysics said:

You can buck down approximately any ratios for no added losses. Including bucking from 110vac to 0.5v or 4v or whatever. If the bucking inductor magnetics have approximately the same copper fill it will buck at approximately the same efficiency (really high efficiency either way).

On paper... except I was talking about bucking 100V AC down to 1KW @ 4V... so good luck building that 100V 250A Buck for the same price as I can build a full bridge rectifier with a PWM feedback off of a shunt made of toaster wire. I would guess. 3 orders magnitude difference in price and size.

Agreed that the buck from 100V down to 5V for the 10W cell phone charging will be negligible loss.



If you have a string of cells in series, or a string of cells in parallel, you have no difference in the rate the cells can be charged. It would just add losses and bulk to the phone side of needing to buck down from above 4.2v to the <0.7vdc modern phone processors use.

Not sure what you are talking about. If I have 10 cells in series I am limited by Charge C and 40V. If I put the same 10 cells in parallel I am limited by 10 x Charge C and 4V. That was my point regarding VA vs W which call out the practical limits of making power with either Voltage or Current and the 2nd order effects of the choice in application. Making a KW into 40V is VERY different than making a KW into 4V. Its the difference between practical and what you can conger up on the back porch.... which will just result in $80 lost, 15 hrs work, and a bunch of smoke.

My Sony XZS uses USB C (aka, USB 3.1) to request 1.7A at 12vdc, which it then bucks down inside the phone to charge its 4Ah cell at ~2-3C when it's SOC is very low and the cell has plenty of anode space to support the diffusion rate needed for fast charging, then as it goes to a higher SOC it ends up dropping below 1C to preserve the cells.

Existing USB C charge protocol goes to 20v at 3A for 60W of charge power delivery available today to phones, but it's the battery power charge limit not the chargers or infrastructure holding them back on charging harder.

Before my current phone, I had an LG g5 with fast swappable batteries. That felt like a real solution, and I would rarely even bring a charger for weekend trips and business trips, because carry a few extra charged batts in your pocket takes up less space than a charger and let's you swap to 100% full in about 20sec.

Click to expand...

That bit is interesting. I remember that phone you had.

What I am steering toward here is a general power solution instead of trying to build it into everything.

-methods

billvon said:

methods said:

Love to hear how many times you could do that and what the effects on the battery would be.

Click to expand...

These were LiFePO4 batteries optimized for a pretty punishing EV application (Formula 1 vehicle regen braking/acceleration assist.) We were operating them at much lower discharge rates and temperatures that they were designed for, so I have a feeling they will last a very long time.

Click to expand...

At 50C charge
Eh....

Maybe I misread your post.

-methods

As always... the lesson for me and others it to keep the post short or break it up with pictures.
If we dont... people skim... high level ideas get miss-communicated... topics derail... misunderstandings occur... personalities come in to play.

Big picture:

ME WANT DRAW 10Wh @ 1KW OUT OF WALL SUPER FAST FOR 30 SECONDS FOR SUPER CHEAP
ME WANT SLOWLY TRICKLE THAT DRAW BACK INTO CELL PHONE
ME GO EAT DINNER NOW

-methods

I had thought of doing this with a the Toshiba energy dense LTO cells. At 280C charge rate, they could in theory be charged in 13 seconds.

Two in series would have a nominal voltage of 4.8v and roughly 14.4wh - maybe about 10wh useable.

The problem I came across though, was how do you get 5.4v @ >800A to do the instant charging?

Lukeman will build you a AC-DC converter that will take standard 120V AC and pump out 5.4V @ 850A.
It will be efficient.

You will have to take apart 10pcs of 12" subwoofer to make the coil...
You will need a $400 IGBT
Eh... Yea...

I just want to see you charge those batteries at 280C on video.

-methods

and for a non-fail:

Naeem rocks
https://www.electricbike.com/pakistan-ebike/

-methods

Haha. Maybe I could settle for a 10C charge instead (which is their recommended charge rate).

I think a 5v charger @ 30A would be achievable commercially.

And awesome signature you have.

I can not agree more that the experience of buying a Justin controller... vs buying an Ebay controller... is night and day.

If someone is reading this (first, stop - dont) and if you still are... budget more and buy the right gear up front.
Justin's controllers have margin built in... and unless you are into swapping out all sorts of TO220 mosfets and learning out to surface mount solder... eh... just go the easy route.

(Tho I imagine many now offer higher end controllers on the cheap)

-methods

[youtube]UCHsu4AaCIs[/youtube]

methods said:

And awesome signature you have.

I can not agree more that the experience of buying a Justin controller... vs buying an Ebay controller... is night and day.

Click to expand...

Thanks. I used to be really tight with money, even though I was never all that poor, but I learned after a while that it's true that "The poor pay twice". I'm still learning, but I'm getting better at distinguishing paying for quality (which I am totally happy to do now), and paying for brand name/prestige/excess profit margin, which I'm not happy to do.

No doubt.

I am willing to pay for Justin's gear because I watched him listen to the market over the years.
The mosfets
The current ratings
The voltage ratings and range
The IP ratings
The connectors
...

Even when he wanted to roll 36V 20A stuff... he still made a line of high power stuff... and in the end - it paid off, in the form of huge margin and reliability.

-methods

methods said:

As always... the lesson for me and others it to keep the post short or break it up with pictures.
If we dont... people skim... high level ideas get miss-communicated... topics derail... misunderstandings occur... personalities come in to play.

Big picture:

ME WANT DRAW 10Wh @ 1KW OUT OF WALL SUPER FAST FOR 30 SECONDS FOR SUPER CHEAP
ME WANT SLOWLY TRICKLE THAT DRAW BACK INTO CELL PHONE
ME GO EAT DINNER NOW

-methods

Click to expand...

The output voltage and current is effectively unrelated to charger size, and entirely related to power. The Vicor modules for 5v 125A output are the same size and efficiency as the 24v and 48v supplies of the same power levels. Ganging the cells in series or charging them all in parallel changes nothing from the cells perspective which only feels the C rate (as I'm sure you know). USB C power levels today already exceed the charge acceptance rates of any phone cells, so chargers aren't actually today's bottleneck on modern phones anyway.

Where the project to take on 10Wh in a few seconds starts is in the battery lab making cells that are 95% anode by mass and volume and 5% cathode. You can make about any type of cell capable of charging at about rate if you engineer the cell specifically for absorbing charge into the anode. This comes at a very meaningful disadvantage to energy density though, and at some point only getting say 20% charged with a 5x larger capacity pack let's you take on more net energy faster in the same 30sec window, and gives you the option to store more if you choose to leave it charging longer.

The part that seems silly though, is for the weight of a 1kW for 30sec power supply, you can carry enough spare batteries for weeks or months of use, or carry a 1lbs power bank that can give you a week of use, and since it can fit in your pocket with your phone it's even more handy than needing to find an outlet. Just leave power bank plugged in while working or sleeping or whatever once in a while seems like a better user experience and lower cost and drama to end up with the same end result of the phone being charged.

liveforphysics said:

Just leave power bank plugged in while working or sleeping or whatever once in a while seems like a better user experience and lower cost and drama to end up with the same end result of the phone being charged.

Click to expand...

That suits some people. When I do day travel for business, I often leave the house at 5am, am on my phone/tablet all day, and home by 11pm. On those days, I try to not carry a bag with me. I usually carry a single 18650 based phone charger, which leaves me just short of a full day, and does nothing for my Surface tablet. (Short battery life because the Surface has no 4G card, and making the Samsung a Mobile WiFi point uses a LOT of power).

I had at one point thought of doing a 4S2P 18650 custom charger that would give me plenty of power for the full day for both devices, and be *just* small enough to fit in my pocket, but by the time I added all the voltage regulators and BMSes, it was too big.

I then thought of using smaller prismatic cells, and getting about the same amount of power in a smaller package. That's still one option.

Or a very fast in-built charging smaller pack - I meet with a client for 30-40 minutes at a time, I ask to charge the battery pack while in the meeting, then charge my devices between meetings. This is where I was last at when I saw this thread.

It's one of those little annoying things I probably will never fix, but it gets a lot of thought when I run out of power, am stuck in an airport lounge with nothing to entertain me but my thoughts. (And the annoyance that I can't google parts and ideas on how to solve this).

[youtube]A8dqzVlhFkA[/youtube]

Check this out for shits and giggles.

I love the way that the woman behind the product has her silly speech to try make engineers look stupid as if we don't think out of the box when she's has no business throwin insults when she has not done her homework on a technology that is so stupid an inefficent it's unbelievable someone could back it, same with solar roadways and a self filling water bottle all these silly inventions have tricked the investors they all need a good face palming, please take a look and try not to let wee out.

Lol... hammer time!
I love that guy. He pulls no punches and provides a great balance of entertainment and education.

I have to admit.. since being out in the startup world... I am guilty of on-boarding with a few ideas almost that wild. When you are a contractor and someone offers pay and says "shut up and try to make it work"... eh... if you are in a tight spot you do it.

I am always sorry afterward - as once you reach a proof (after an hour or a week or a few months)... its kind of like this:

ME
THEM

"Hey - this aint going to scale"
"yes it will - do this and that better"

"Uh... no man... that is polishing a turd. This aint going to fly"
"yes it will - I am the business man. Shut up engineer."

"Um... ok... I need to pay my lawyers and bills... uh... I am putting my concerns in email"
"NO - STOP WRITING EMAILS. JUST DO IT OK? STOP TALKING SO MUCH"

"eh... then... when it does not work out in 6mo and all the money is spent... folks will look at me like I am the dumbass"
"Just go build it ok?"

Sigh....

Tech Boom

-methods

Perhaps don't be so hard on an employer that pays you to try to accomplish anything good idea or not. I remember when you were your own employer for years and I kept excitedly waiting for a project to be finished or something to end up working well as an outcome.

Perhaps Luke.

My books show that you have no experience running your own business funded or otherwise.
My books show that while I ran my own business it was completely unfunded, off my own credit cards, and what I was actually doing was collecting the experience and discipline you sorely need right now.

I have worked for 8 different entities over 17 years in the field post Bachelor. (not including my hobby and apprentice experience before Bachelor)

Sandia National Labs
Methods Technology
Zero Motorcycles
Tesla Motors
Electric Movement
Off the Grid
Schindler Engineering
Calfee Design

I have watched startups FAIL EPIC in first person and once removed.
I have watched some maintain funding and the compromises they had to make to achieve that.
I have studied Entrepreneurial Engineering at the best institution.

My opinions and motivations are based on personal experience.
Once you have a bit more you can come and school me.

You are a Blow Hard Luke
I am and have been done dealing with you for years.

Your savage competitiveness makes you impossible to work beside. You are a master of manipulation... and it irritates me.

Live long and prosper buddy.
Thanks for sharing all of your knowledge and ways. It put me ahead more than it set me back... and for that... when and if the world ever goes to shit... you will be welcome in my village.

-methods