# usb phone charging question, intelligent chip?



## Nazar (Nov 20, 2017)

ok, tesla cars are tech cars - so hopefully the phone chargers have an intelligent chip for charging - does anyone know?

with my car (ICE car, hanging out for a Tesla) the USB charging ports for the phone give something like 4.8 amps, this is not a problem when charging but when my android got fully charged and stayed plugged in - it killed the battery, so i got a tester and found that even when the phone was fully charged it was still pushing full amps into the phone.
with my intelligent chip chargers (or any chargers from apple) as it gets close to being full charged it starts to slow down the amount of amps it pushes to the phone, until at 100% it stops charging automatically..

so my question again is - do Tesla's have an intelligent chip for charging phone? anyone have a tester and can check on the S or X?


----------



## MelindaV (Apr 2, 2016)

i could be wrong, but believe on apple, this happens on the phone side, not the cord/charger brick side. so no matter the cord or what it is plugged into, the phone's charger port manages the power being pulled from the cord.


----------



## JWardell (May 9, 2016)

All phones and any other USB-powered device have charge controller chips built-in. The car or USB supply does not control the amount of power consumed or "pushed." They simply have an upper limit that they are capable of. It's up to the phone to use the power properly.

I'm not sure which android phone you had, but I highly doubt it's the car's fault for killing it, with the only exception being that the voltage was not 5V as it must be. The only other thing I could think of is a loose, dirty, or damaged USB cable that was constantly interrupting the power feed. A phone should be able to handle that safely but I have seen instances where some can't.


----------



## mishakim (Sep 13, 2017)

The above answers are correct. There is a question to be asked, though: how may Amps do the USB ports allow a phone to draw, and what USB version are they? Standard USB 2.0 ports only allow 0.5 A, and only after the phone has asked (so it has to have some charge already to be powered up). More likely they're using the Battery Charging 1.2 standard, which provides up to 1.5A (many wall-wart chargers provide more, but not in compliance with spec). The best answer would be that they are USB 3.1, and configured to allow that version's higher-power charging, but I think that would require a type C port on the car side (not just on the phone side)


----------



## Nazar (Nov 20, 2017)

sorry about the amps, i got that wrong (it was a long time ago, maybe 0.42 or something)....i will test it again, most modern chargers now days have an intelligent chip... at the time i tested the iphone/ipad (at 100%) and it was still pushing the amps to it..... the way the android tried to handle it (because there is no way of dumping excess energy) was to turn the screen on super bright,,

think about it for a minute (the only way i know this is because i have seen it) the phone or tesla car (same principle applies) the charger talks to the phone (or the supercharger talks to the car), but if there is no way for the supercharger or phone charger to very the output, there is nothing the phone or car can do unless the phone or car can break the connection (switch)..

just to confuse matters, we have all bought devices that specify "do not charge for longer than ??? hours" with the charger they supply (thinking remote control car batteries ect), and yet if we use the computer or an intelligent charging usb charger - they very the charge with no input from the device.... the only way i can figure it is the intelligent chip recognises resistance to charging (eg 80% to 100%.) and adjusts the amount of power according to the amount of resistance (this is just an assumption).

you guys/gals  are keen on amazon over there, i use a device similar to this hmmmm, link isnt working, says media instead of url - google "amazon usb tester", will try my own link just below

but as i said i will check it again and get back to you..


----------



## Nazar (Nov 20, 2017)

ok, have seen people do links, is there a restriction on my account? (makes sense for noobs)


----------



## taylortbb (Sep 1, 2017)

There's no such thing as pushing amps, it's simply not how electricity works. The tester can measure how many amps are *available*, but it's always up to the phone how many are actually used. Absolutely no way to push an amp, and no amount of fancy circuitry can change that.

Most chargers actually don't have an intelligent chip. They just use resistors connected between the data lines to tell the phone how many amps are available, and then the phone chooses how many to draw.

An EV charger simply signals to the car how many amps are available, just like the phone it's the cars choice how many to actually draw. The only thing the car can't change is voltage, but USB is required to always be 5V. If your USB wasn't 5V the phone would either blow a safety fuse, or be fried as soon as it was connected.

A phone won't continue drawing amps after it is fully charged, which means it will stop drawing power (power is amps * volts). RC car batteries work totally different from a phone and really aren't comparable.


----------



## garsh (Apr 4, 2016)

taylortbb said:


> There's no such thing as pushing amps, it's simply not how electricity works. The tester can measure how many amps are *available*


It doesn't really make sense to talk about available amps either. Current is a byproduct of the potential available and the resistance of the thing to which a potential is applied.


> ...but USB is required to always be 5V


Only true for older versions of the standard. USB Power Delivery now permits up to 20V.
https://en.wikipedia.org/wiki/USB#Power_Delivery_.28PD.29


----------



## taylortbb (Sep 1, 2017)

garsh said:


> It doesn't really make sense to talk about available amps either. Current is a byproduct of the potential available and the resistance of the thing to which a potential is applied.


Definitely technically accurate, but I'd consider "available amps" a good simplification of USB charging where safe amp limits are communicated to the device (which is probably what the USB tester is measuring). When the conversation started at "pushing amps" simplification is good, and I thought talking about how current is determined would end with trying to explain charging controllers.



garsh said:


> Only true for older versions of the standard. USB Power Delivery now permits up to 20V.
> https://en.wikipedia.org/wiki/USB#Power_Delivery_.28PD.29


Good point, I forgot about PD in my previous reply. PD only supplies additional voltage after proper negotiation though, so it would never be supplied a phone that doesn't support it.


----------



## Frank99 (Aug 3, 2017)

garsh said:


> It doesn't really make sense to talk about available amps either. Current is a byproduct of the potential available and the resistance of the thing to which a potential is applied.


Well, to be excruciatingly pedantic, it doesn't really make sense to talk about "resistance" when the 5V is being applied to a switching power supply now does it?

Nazar -
I don't wish to dispute the experience you had, but the interpretation is simply incorrect. As taylortbb noted, all the charger does is supply a voltage to the phone/tablet. The charging circuitry on the phone controls the amount of current drawn from the charger, and should stop the current flow when the battery is full. If it doesn't, it's a REALLY BAD THING because LiIon cells do not like to be overcharged.

Devices that tell you "Don't charge for more than 8 hours" or "24 hours" are doing so because they saved $0.25 when building the device and didn't put in a smart charging circuit - oftentimes they simply put in a resistor to limit the maximum current into the battery. When the battery is fully charged, an unhealthy amount of current is still flowing into the battery. You can get away with this with Lead-Acid and NiCd batteries for short lengths of time - hence the warning to disconnect them. Doing this with a LiIon cell would be criminally negligent and would cause fires.


----------



## JWardell (May 9, 2016)

Original USB standards only allowed up to 100mA (1/10 Amp) before the port got shut down by the computer or hub. They added the ability to negotiate through software to allow up to 500mA (Half an Amp. That's still just 2.5 Watts)
That's back when most USB devices were mice and keyboards, and the higher current allowed some hard drives to be bus powered.

The concept of USB as a power source (only) came a bit later, and is somewhat of a hack. Instead of sending data over the wires, the device and/or the charger brick placed a special resistance across the data wires. This was not standard. Apple had a certain resistance, other companies had a different one. If both devices saw no data and the right resistance, they would then allow up to 1 Amp (5W) draw. But, you couldn't use chargers from different devices, because they picked different resistance values. If you did, they would only allow up to 500mA to be safe.

THEN Apple came out with the iPad, with a giant battery that would take all day to charge at 5W. They created another resistance value and shipped a USB charger almost as big as their laptops that with an iPad, would allow 2.1A--10Watts. Every other charger still worked with the ipad, just at the slower 5W. 

Third parties started to get smart and began making "smart" USB chargers that could change their resistance and figure out which device they were attached to and work with many brands, and even push the 2 amps to an ipad.

This was a limit where we stayed at for a while. USB cables only require a specific wire size, and pushing more than 2 amps through the wires could cause them to fail (or worse). 

USB had always been based around 5V. No matter what current was supported at either end, at least everything worked at 5V. A different voltage is what could cause expensive damage to a device.

But innovation kept happening, and (I want to credit Samsung or Qualcomm here, not sure) Quick Charge came out. It used data negotiation to be VERY sure that both devices were compatible, and if so, it changed the voltage up to 9V. Now at 9V, the same 2.1A limit allows the wattage to climb to 19Watts. Much faster charging, yay! But very proprietary. Your phone could charge really fast, but only if you lugged around the giant quick charge charger that came with it. Apple never supported this proprietary sorta-standard.

(And now to make your head explode)
With the real USB standard still stuck down at 500mA and plenty of great proprietary innovation out there, they finally came out with the USB-PD (Power Delivery) standard, which is just starting to become adopted. This requires a USB-C port so it doesn't even apply to cars with standard USB-A ports. But thanks to allowing multiple voltage levels (5, 9, 15, and 20V) and even higher currents (up to 5A because USB-C cables can have multiple power wires), devices can now negotiate the best charge level and achieve charging rates up to 100 Watts (20v @ 5A). It's very impressive to see my MacBook Pro running full tilt, while also charging an iPad, powered by just a tiny USB-C cable! Even more impressive is it's all backwards compatible--my macbook can also charge (very, very slowly) off a pocket USB battery.

But the bottom line is that the device and charger need to both be very smart to achieve anything higher than the original 5V at 5 or 10 watts. In fact, I have yet to drive a car that supports that, most seem to only allow up to 1 Amp, and with my phone running Waze and music in bright sunlight, it still loses charge slowly. I'm pretty sure Tesla's ports do push 2A.


----------



## Nazar (Nov 20, 2017)

garsh said:


> Only true for older versions of the standard. USB Power Delivery now permits up to 20V.
> https://en.wikipedia.org/wiki/USB#Power_Delivery_.28PD.29


did't know that!!!! thankyou


Frank99 said:


> Nazar -
> I don't wish to dispute the experience you had, but the interpretation is simply incorrect.


thankyou guys for your patience, obviously i am wrong but it still leaves the question why it happened?
if it was just the nexus (android) i would say it was the phone.
except that the tester said it was still giving the same amps when the iphone or ipad was flat or fully charged?

anyway, it is something i will be cautious off in the future... regrettably i can't take a video of it (i just tested it and it has stopped working)....... obviously was a fault with the xtrail usb outlet - but i would be keen to hear any ideas what could have been wrong.

Thanks for the info and setting me straight, a lot of talented people here


----------



## nupe1980 (Apr 8, 2018)

Thanks for the detailed explanation.

So I have learned driving the Model 3 for 3 hours, my iPhone X plugged into one of the front ports, and running Waze, that the phone lost 1/2 the battery level. Clearly the ports can't keep up with the power need to charge and still run Waze. What is your recommendation to do both at the same time?



JWardell said:


> Original USB standards only allowed up to 100mA (1/10 Amp) before the port got shut down by the computer or hub. They added the ability to negotiate through software to allow up to 500mA (Half an Amp. That's still just 2.5 Watts)
> That's back when most USB devices were mice and keyboards, and the higher current allowed some hard drives to be bus powered.
> 
> The concept of USB as a power source (only) came a bit later, and is somewhat of a hack. Instead of sending data over the wires, the device and/or the charger brick placed a special resistance across the data wires. This was not standard. Apple had a certain resistance, other companies had a different one. If both devices saw no data and the right resistance, they would then allow up to 1 Amp (5W) draw. But, you couldn't use chargers from different devices, because they picked different resistance values. If you did, they would only allow up to 500mA to be safe.
> ...


----------



## JWardell (May 9, 2016)

nupe1980 said:


> Thanks for the detailed explanation.
> 
> So I have learned driving the Model 3 for 3 hours, my iPhone X plugged into one of the front ports, and running Waze, that the phone lost 1/2 the battery level. Clearly the ports can't keep up with the power need to charge and still run Waze. What is your recommendation to do both at the same time?


This is unfortunately all too common in with many cars' USB ports. I usually get a 2.4A dual USB lighter charger and hide wires going to that so the phone can get full power. I think I read the rear USB ports also have more power than the front.


----------

